Maritime Glossary

Maritime Glossary: A

 

Administration Maritime administrations, also known as flag state administrations, are the executive arms of each government responsible for carrying out shipping responsibilities within their territorial waters and for vessels flagged in their country. These administrations administer national shipping and boating laws, ensuring safety, compliance, and efficient maritime operations

ACV Air-cushion vehicle (ACV), also known as a hovercraft, is an amphibious craft capable of traveling over land, water, mud, ice, and various other surfaces. Hovercraft use blowers to produce a large volume of air below the hull, creating an air cushion that is slightly above atmospheric pressure. The pressure difference between the higher-pressure air below the hull and the lower-pressure ambient air above it produces lift, causing the hull to float above the running surface.

100 A1 Marine classification societies issue the category symbol 100 A1, which indicates that a vessel was built under their survey and satisfies strict requirements for structural integrity and maritime safety. This designation certifies that the ship’s hull was constructed in compliance with the strict requirements of the society and is in excellent shape. For a variety of marine operations, vessels classified as 100 A1 are regarded as dependable and secure, guaranteeing adherence to global safety standards. This certification is indicative of a dedication to upholding the highest standards of quality and safety in maritime engineering.

ABS The American Bureau of Shipping (ABS) is a leading international classification organization, specializing in maritime safety and regulatory compliance. Founded in 1862, ABS ensures the structural integrity and operational safety of ships and offshore structures. It provides services including certification, engineering, and risk assessment to the global marine and offshore industries. ABS is recognized for its commitment to innovation and sustainability in advancing the marine sector.

Aft In maritime terminology, “aft” refers to the rear section of a ship or vessel. It is the area located towards the stern, opposite the bow. The aft section typically houses essential components like the engine room, steering gear, and accommodations. Navigating and managing the aft section is crucial for maintaining the ship’s balance and propulsion.

Aft peak tank The aft peak tank is a compartment located at the rear (aft) end of a ship, below the waterline. It is primarily used for storing ballast water to maintain the vessel’s stability and trim. This tank helps in balancing the ship during loading and unloading operations. Additionally, it can provide some level of protection to the rudder and propeller shafts from damage due to impacts.

Alleyway An alleyway on a ship is a narrow passageway that runs along the length of the vessel, typically connecting various compartments and cabins. It provides a route for crew members to move between different areas of the ship safely and efficiently. Alleyways are essential for ensuring quick access during emergencies. They are designed to optimize space and often contain safety features like handrails and emergency lighting.

Alongside Amidships”Alongside amidships” refers to the area adjacent to the central section of a ship’s hull, extending along its length from the port or starboard side. This location is crucial for docking and mooring operations, allowing for the transfer of cargo, passengers, or provisions. Being amidships, this area experiences minimal motion, making it ideal for safe and stable operations. It is also a key point for boarding and disembarking during port calls.

AMSA The Australian Maritime Safety Authority (AMSA) is a government agency responsible for ensuring the safety and environmental protection of Australia’s maritime activities. AMSA oversees maritime safety regulations, conducts inspections, and responds to marine emergencies, including search and rescue operations. It also manages marine pollution prevention and response initiatives. Through its comprehensive oversight, AMSA plays a crucial role in maintaining safe and sustainable maritime operations in Australian waters.

Anchor An anchor is a vital piece of maritime equipment used to secure a vessel to the seabed. Typically made of heavy metal and featuring flukes or arms that grip the seabed, anchors provide stability and prevent drifting while ships are stationary. Anchors are deployed using chains or ropes called anchor cables, which connect them to the ship’s hull.

Anchor cable Anchor cable, also known as anchor chain, is a heavy-duty chain specifically designed to connect the ship’s anchor to the vessel itself. It plays a crucial role in anchoring operations by providing a secure link between the anchor and the ship’s hull. Anchor cables are constructed from high-strength steel to withstand the stresses and forces encountered during anchoring and mooring. They are typically marked with intervals to measure the amount of chain deployed, aiding in determining the depth at which the anchor lies.

Anode An anode in marine contexts is a sacrificial metal component attached to a ship’s hull or submerged structures. Its purpose is to protect the hull from corrosion by attracting corrosive elements away from the main structure. Made typically of zinc or aluminum alloys, anodes gradually corrode over time, requiring periodic replacement to maintain effective protection. Anodes are crucial in ensuring the longevity and structural integrity of marine vessels and equipment.

Antifouling (paint) Antifouling paint is specially formulated marine paint applied to the hulls of ships and boats to prevent the accumulation of marine organisms such as barnacles, algae, and mollusks. It contains biocides that deter marine growth and help maintain vessel performance and fuel efficiency by reducing drag. Regular application and maintenance of antifouling paint are essential for preserving the hull’s smoothness and integrity, thereby optimizing the vessel’s speed and maneuverability.

Appendage(s) Appendages in marine terminology refer to additional structures attached to a ship’s hull, such as rudders, propellers, stabilizers, and thrusters. These components play crucial roles in maneuverability, propulsion efficiency, and stability of the vessel. Appendages are designed and positioned strategically to optimize performance and minimize drag, ensuring safe and efficient navigation at sea.

Astern Astern refers to the direction opposite to the vessel’s forward motion, where the ship moves backward or in reverse. This maneuver is typically controlled by reversing the thrust of the propulsion system, such as engines or propellers. Going astern is essential for docking, maneuvering in tight spaces, or reversing course safely in maritime operations.

Auxiliary (machinery) Auxiliary machinery in marine contexts refers to additional mechanical equipment aboard a vessel that supports its primary operations. This includes generators, pumps, compressors, and refrigeration units, among others, essential for power generation, fluid transfer, and climate control. Auxiliary machinery ensures the functionality and comfort of crew and passengers while complementing the main propulsion systems of the ship.

Azimuth thruster An azimuth thruster is a versatile propulsion system used in marine vessels, capable of rotating 360 degrees around a vertical axis to provide thrust in any direction. It enhances maneuverability and precision during docking, dynamic positioning, and tight navigation in confined waters. Azimuth thrusters are commonly mounted on the ship’s hull, often retractable, and used in combination with traditional propulsion systems for efficient control and enhanced operational flexibility at sea.

Maritime Glossary: B

Ballast Ballast in marine contexts refers to heavy material, such as water, sand, or gravel, loaded into a vessel’s ballast tanks to ensure stability and proper trim. It helps maintain the ship’s balance, prevents excessive rolling, and improves handling, especially in rough seas or when the ship is not carrying cargo. Proper ballast management is crucial for the vessel’s safety, operational efficiency, and compliance with environmental regulations.

Barge A barge is a flat-bottomed, non-self-propelled vessel primarily used for transporting cargo, often on inland waterways or sheltered coastal areas. It relies on tugboats or towboats for movement and is ideal for carrying heavy or bulk goods such as coal, grain, and construction materials. Barges play a crucial role in efficient and cost-effective transportation within the shipping and logistics industry.

Baseline In marine terminology, the baseline refers to an imaginary horizontal line drawn at the lowest point of a ship’s hull, typically at the keel. It serves as a reference point for measuring vertical distances, such as draft and freeboard, ensuring accurate and consistent ship design and construction. The baseline is essential for naval architects and marine engineers when calculating stability, buoyancy, and overall vessel performance.

Beam The beam of a ship refers to its widest point, measured horizontally across the vessel’s hull from side to side. It is a critical dimension that influences the ship’s stability, cargo capacity, and handling characteristics. A wider beam generally provides greater stability and deck space, enhancing the vessel’s overall performance and safety at sea.

Bed plate A bed plate in marine engineering is a robust, machined surface foundation to which a ship’s engine and other major machinery are securely mounted. It ensures precise alignment, stability, and vibration dampening, critical for the reliable operation of the engine and mechanical systems. The bed plate is typically made of cast iron or steel and is bolted to the ship’s hull, forming the structural backbone for the machinery installation.

Berth A berth in maritime contexts refers to a designated location where a ship is moored or anchored in a port or harbor. It provides a safe and secure spot for loading and unloading cargo or passengers and performing maintenance or repairs. Berths are equipped with necessary facilities, such as mooring lines and fenders, to accommodate vessels of various sizes and types.

Bilge The bilge is the lowest part of a ship’s hull, where water and other liquids collect. It serves as a drainage area, and bilge pumps are used to remove this accumulated water to prevent flooding and maintain the vessel’s stability. Proper bilge maintenance is essential for the ship’s safety and operational efficiency.

Bilge bracket A bilge bracket is a structural component in a ship’s hull, providing reinforcement where the bottom shell plating meets the transverse frames. It enhances the vessel’s structural integrity, distributing stresses and preventing deformation in the bilge area. Bilge brackets are crucial for maintaining the strength and durability of the ship’s hull, especially in rough sea conditions.

Bilge keel A bilge keel is a longitudinal fin-like structure attached to the bottom sides of a ship’s hull to reduce rolling motion. It enhances stability by increasing hydrodynamic resistance when the vessel rolls, thereby improving passenger comfort and operational safety. Bilge keels are particularly effective in minimizing the side-to-side motion in rough seas.

Bilge strake A bilge strake is a specific row of hull plating located along the bilge area of a ship, where the bottom and sides of the hull meet. It is crucial for the vessel’s structural integrity, providing additional strength and durability to withstand stresses and impacts. The bilge strake plays a key role in ensuring the overall stability and seaworthiness of the ship.

Bitts Bitts are sturdy posts or fixtures on a ship’s deck used for securing mooring lines or cables. They provide a strong point of attachment for ropes, preventing the vessel from drifting when docked or anchored. Bitts are strategically placed around the ship to accommodate various mooring configurations and ensure safe and efficient berthing operations.

Body plan A body plan in marine architecture is a graphical representation showing the cross-sectional shapes of a ship at various points along its length. It provides detailed profiles of the vessel’s hull design, including contours, curves, and dimensions. Naval architects use body plans to visualize and refine the ship’s hydrodynamic characteristics, stability, and performance in different sea conditions.

Bollard A bollard is a sturdy, vertical post on a dock or quay used for securing mooring lines of ships. It provides a fixed point of attachment to prevent vessels from drifting away while loading, unloading, or during docking maneuvers. Bollards are typically made of metal or concrete and are strategically placed along the waterfront to accommodate various sizes and types of vessels.

Boot-topping Boot-topping refers to a distinct painted stripe or band along the waterline of a ship’s hull, typically applied just above the anti-fouling paint. It serves both functional and aesthetic purposes, such as providing a visual indication of the ship’s load line or draft when fully loaded. Boot-topping also helps in keeping the hull clean and free from marine growth near the waterline, enhancing the vessel’s overall efficiency and appearance.

Bossing Bossing in marine engineering refers to the process of shaping or reinforcing metal plates, typically in the construction of ship hulls. This technique involves forming raised or recessed areas on the plate surface to enhance structural integrity and accommodate fittings or connections. Bossing is crucial for ensuring the strength and durability of the hull, particularly in areas subjected to high stress and pressure.

Bow The bow of a ship is the forward-most part of its hull, designed to cut through water efficiently and reduce resistance. It influences the vessel’s maneuverability, stability, and hydrodynamic performance. The shape and construction of the bow vary based on the ship’s purpose, optimizing its ability to navigate various sea conditions and maintain speed.

Bow door A bow door on a vessel is a large, hinged opening located at the forward end of the ship’s hull, designed for efficient loading and unloading of cargo or vehicles directly onto docks or ramps. It facilitates quick deployment and retrieval of goods or equipment during maritime operations, especially in roll-on/roll-off (Ro-Ro) ferries and cargo ships. Bow doors are crucial for enhancing efficiency and reducing turnaround times in port operations.

Bow thruster A bow thruster is a maneuvering device mounted in the forward section (bow) of a ship’s hull, typically at the sides near the waterline. It provides lateral thrust to aid in maneuvering the vessel sideways, enhancing its agility and reducing reliance on tugs in tight spaces or adverse weather conditions. Bow thrusters improve safety during docking and berthing operations, allowing for precise movements without the need for significant forward or reverse propulsion.

Bracket In maritime terminology, a bracket refers to a structural component used to support or attach various equipment, fixtures, or fittings on a ship’s deck or hull. It provides stability and reinforcement, ensuring secure mounting of items such as navigation lights, antennas, or safety equipment. Brackets are designed to withstand marine environments and the stresses encountered during vessel operations, contributing to the overall functionality and safety of the ship.

Breadth Breadth in marine terms refers to the width of a ship at its widest point, measured horizontally across the hull. It is a critical dimension that influences the vessel’s stability, cargo capacity, and maneuverability. Breadth plays a significant role in determining the ship’s overall dimensions and its ability to navigate through narrow passages or dock in ports with restricted space.

Breasthook A breasthook is a structural component in a ship’s bow that reinforces and connects the forward ends of the hull planking or frames. It provides additional strength and support to the bow structure, helping to withstand the forces encountered at sea. Breasthooks are essential for maintaining the overall integrity and shape of the vessel’s bow, contributing to its stability and seaworthiness.

Bridge The bridge on a ship is the command center and navigation hub, typically located above the main deck and forward part of the vessel. It houses the wheelhouse, where the ship’s steering controls and navigational equipment are located. The bridge allows the crew to oversee and control the ship’s operations, ensuring safe navigation and communication with other vessels and shore facilities.

Bridge wing(s) Bridge wings are extensions of the ship’s bridge structure, located on either side of the main navigation area. They provide additional vantage points for the officers to oversee ship operations, especially during docking, maneuvering, and navigating in narrow channels. Bridge wings enhance visibility and communication with the crew stationed on deck, ensuring safe and precise ship handling in various maritime conditions.

Bulk cargo Bulk cargo refers to loose, unpackaged commodities or materials that are transported in large quantities, typically loaded directly into a ship’s hold without individual packaging. Examples include coal, grain, ore, and petroleum products. Handling bulk cargo efficiently involves specialized equipment and procedures to ensure safe loading, transportation, and unloading at ports or terminals worldwide.

Bulk carrier A bulk carrier is a specialized merchant vessel designed for transporting bulk cargo such as grain, coal, ore, and cement in large quantities. It features a spacious cargo hold without internal divisions, optimized for efficient loading and unloading through hatches on deck. Bulk carriers vary in size and configuration to accommodate different types of bulk cargo, playing a crucial role in global trade and logistics by transporting commodities between ports worldwide.

Bulkhead A bulkhead in marine engineering refers to a vertical partition or wall within a ship’s hull, designed to separate compartments and provide structural support. It enhances the vessel’s strength, stability, and safety by preventing the spread of water in case of leaks or collisions. Bulkheads also contribute to the ship’s buoyancy and help maintain its trim and stability during loading and unloading operations.

Bulkhead deck A bulkhead deck on a ship is a horizontal partition or platform that serves as a structural division between different compartments or levels within the vessel’s superstructure. It reinforces the ship’s hull integrity, providing support and stability while also compartmentalizing the internal space. Bulkhead decks contribute to the vessel’s safety by containing potential hazards and preventing the spread of fire or flooding in case of emergencies at sea.

Bulwark A bulwark on a ship is a raised protective wall or structure along the sides of the main deck, extending above the ship’s hull. It shields the deck and crew from waves, wind, and spray, enhancing safety and comfort during navigation. Bulwarks also serve as a barrier to prevent cargo and equipment from falling overboard, contributing to the overall security of the vessel.

Bureau Veritas Bureau Veritas is a global leader in testing, inspection, and certification services, specializing in ensuring safety, quality, and sustainability across various industries, including maritime. It provides classification and certification services to ships and offshore structures, verifying compliance with international regulations and standards. Bureau Veritas plays a critical role in enhancing operational efficiency and safety for marine operators worldwide.

Buttock line In naval architecture, a buttock line is a theoretical line running vertically through a ship’s hull, representing the intersection of a vertical plane with the hull surface. It helps designers and engineers visualize the shape and curvature of the ship’s hull in side view. Buttock lines are essential for assessing hydrodynamic performance, stability, and overall hull shape during the ship design and construction phases.

Butt weld A butt weld is a type of weld used in shipbuilding and marine engineering where two pieces of metal are joined together end-to-end along a single plane. It provides a strong and smooth connection, essential for maintaining the structural integrity and watertightness of the vessel’s hull and components. Butt welding is widely used in constructing ship hulls, tanks, and pipelines to ensure reliability and durability in marine environments.

Maritime Glossary: C

Cabin A cabin on a ship refers to a private room or living space allocated for passengers or crew members. It provides accommodations, including sleeping quarters and personal storage, designed for comfort during voyages. Cabins vary in size and amenities, ranging from basic berths to luxurious suites, depending on the type of vessel and passenger requirements.

Cable layer A cable layer is a specialized vessel designed for laying underwater cables, such as telecommunications and power cables, on the seabed. Equipped with advanced machinery and technology for precision placement, these ships play a crucial role in establishing and maintaining global communication networks and power distribution systems. Cable layers are essential for connecting continents, islands, and offshore installations, ensuring reliable and efficient data and power transmission.

Cable locker A cable locker on a ship is a compartment used to store the anchor chain or cable when it is not in use. Located near the bow, this area ensures the anchor chain is neatly coiled and readily accessible for deployment and retrieval. The cable locker helps maintain order and safety on deck by preventing the chain from becoming tangled or causing obstructions.

CAD/CAM CAD/CAM in marine engineering stands for Computer-Aided Design and Computer-Aided Manufacturing. CAD involves using software to create precise 2D and 3D models of ship components and structures, enhancing design accuracy and efficiency. CAM translates these designs into manufacturing instructions, guiding automated machinery to produce parts with high precision. Together, CAD/CAM streamline the design and construction processes, reducing errors and improving the quality and performance of marine vessels.

Camber Camber in marine design refers to the slight upward curvature of a ship’s deck from the centerline towards the sides. This design feature allows water to drain off the deck more efficiently, enhancing safety and preventing water accumulation. Camber contributes to the structural strength of the deck and improves the overall seaworthiness of the vessel.

Cant frame A cant frame is a structural component in a ship’s hull, positioned at an angle to the keel near the bow or stern. Unlike regular transverse frames, cant frames are inclined to follow the curved contours of these areas, providing additional support and shaping. They are essential for maintaining the structural integrity and hydrodynamic efficiency of the vessel in these complex, curved sections.

Capstan A capstan is a vertical, spool-shaped mechanical device on a ship used for handling heavy ropes, cables, and chains. It is primarily utilized for tasks such as raising anchors, hoisting sails, and mooring. Operated manually or powered by an engine, the capstan provides the necessary leverage to manage heavy loads efficiently and safely on deck.

Car carrier Cargo door A car carrier cargo door is a large, hinged or sliding door on a specialized vessel designed for transporting vehicles. Located at the stern or side of the ship, this door provides access to ramps and decks, facilitating the efficient loading and unloading of cars and other vehicles. It is engineered to handle the weight and dimensions of vehicles, ensuring safe and secure transfer during port operations.

Casing A casing on a ship refers to an enclosed structure that surrounds and protects machinery, equipment, or structural elements. Commonly found around engine rooms, exhaust stacks, or ventilation systems, casings provide protection from the elements and reduce noise levels. They also contribute to the vessel’s overall safety by containing potential hazards and facilitating maintenance access.

Cathodic protection Cathodic protection is a corrosion prevention technique used on ships and marine structures to protect metal surfaces submerged in water. It works by making the metal surface the cathode of an electrochemical cell, typically through the use of sacrificial anodes or impressed current systems. This method effectively prevents rust and deterioration, extending the lifespan of the ship’s hull and underwater components.

CCS CCS, or China Classification Society, is a non-profit organization dedicated to providing classification and certification services to ships and offshore installations. It ensures compliance with international maritime safety and environmental standards, supporting safe and sustainable maritime operations. CCS plays a vital role in promoting maritime safety and contributing to the development of China’s shipping industry.

Cellular container ship A cellular container ship is a specialized vessel designed with a series of vertical cells or slots to efficiently transport standard shipping containers. These containers fit precisely into the ship’s cargo holds, stacked in rows and columns. Cellular container ships are integral to global trade, facilitating the transport of goods in a standardized and secure manner across international waters. Their design maximizes cargo capacity and allows for efficient loading, unloading, and transportation of containers between ports worldwide.

Centreline The centreline of a ship refers to an imaginary line running longitudinally along its keel, dividing the vessel into port (left) and starboard (right) halves. It serves as a crucial reference point for structural alignment, stability calculations, and symmetrical placement of equipment and compartments. The centreline is fundamental in ship design and navigation, ensuring balanced weight distribution and optimal performance at sea.

Chain locker A chain locker on a ship is a compartment or storage area located near the bow where the anchor chain is stowed when not in use. It ensures the anchor chain is neatly stored and ready for deployment and retrieval during anchoring operations. The chain locker also helps prevent the chain from causing clutter or hazards on deck, maintaining safety and efficiency aboard the vessel.

Chemical carrier (Tanker) A chemical carrier, also known as a chemical tanker, is a specialized vessel designed for transporting liquid chemicals in bulk. These tankers are equipped with segregated tanks and advanced cargo handling systems to ensure safe and efficient transportation of various chemical cargoes. They adhere to strict safety and environmental regulations, including measures to prevent contamination and leakage, making them essential for the global chemical industry and maintaining maritime safety standards.

Classification societies Classification societies are independent organizations that establish and apply technical standards for the design, construction, and maintenance of ships and offshore structures. They conduct inspections, surveys, and certification to verify compliance with international regulations and industry standards, ensuring safety, reliability, and environmental protection. Classification societies play a critical role in enhancing maritime safety, facilitating global trade, and promoting sustainable practices in the shipping industry.

Coaming A coaming on a ship refers to a raised edge or border around a hatch, opening, or compartment on the deck. It helps contain water and prevent it from entering the enclosed area during rough seas or inclement weather. Coamings also provide structural support and serve as a barrier to protect cargo, equipment, and personnel from exposure to elements such as waves, spray, and rain.

Cofferdam A cofferdam on a ship is a watertight enclosure or compartment used to isolate and contain liquids or gases, providing protection and safety for onboard operations. It serves as a barrier between different areas of the vessel, preventing leaks or spills from spreading to other compartments. Cofferdams are crucial in maintaining the structural integrity of the ship and ensuring environmental safety by minimizing the risk of pollution or contamination at sea.

Collision bulkhead A collision bulkhead is a reinforced partition located at the forward end of a ship’s hull, designed to absorb and minimize the impact of collisions or accidents. It enhances the vessel’s safety by preventing the penetration of water into other compartments during emergencies. Collision bulkheads are strategically positioned to protect critical areas and ensure the ship remains seaworthy and operational in adverse conditions.

Compartment A compartment on a ship refers to a separate section or room enclosed by bulkheads, typically serving specific purposes such as accommodation, machinery housing, or storage. It helps organize and compartmentalize the ship’s interior for efficient use of space and facilitates maintenance and safety management. Compartments are essential for ensuring the functionality, safety, and operational readiness of the vessel during maritime operations.

Complement The complement of a ship refers to the total number of crew members required to operate the vessel effectively during normal operations. It includes officers, engineers, deck crew, and other personnel essential for navigation, maintenance, and cargo handling. The complement size varies depending on the ship’s size, type, and operational requirements, ensuring all tasks and responsibilities aboard the ship are adequately managed and performed.

Container vessel A container vessel is a specialized ship designed for efficiently transporting standard shipping containers between ports worldwide. These vessels feature large cargo holds and a series of vertical cells or slots to accommodate containers of various sizes stacked securely on deck. Container vessels play a pivotal role in global trade, facilitating the transportation of goods in a standardized and efficient manner. They are equipped with advanced cargo handling systems and adhere to strict safety and operational standards to ensure reliable and timely delivery of cargo.

Continuous welding Continuous welding in marine engineering refers to a welding technique where the welding process is uninterrupted along the entire length of the joint. This method ensures a continuous and strong bond between metal components, enhancing structural integrity and durability. Continuous welding is commonly used in constructing ship hulls, pipelines, and other critical components to achieve uniformity and reliability in strength and performance.

Counter In naval architecture, the counter refers to the aft, or rear, part of a ship’s hull above the waterline. It typically extends beyond the waterline and contributes to the vessel’s overall aesthetics and hydrodynamic performance. The counter may feature decorative elements or serve functional purposes such as housing rudders, stern gear, or accommodating crew spaces.

Crew boat A crew boat is a small, fast vessel designed to transport personnel and light cargo to and from offshore platforms, ships, or installations. These boats are equipped with seating and safety features to accommodate crew members, ensuring efficient crew transfer and support during offshore operations. Crew boats play a vital role in the oil and gas industry and maritime logistics, providing essential transportation services in offshore environments.

Maritime Glossary: D

Davit(s) Davits are mechanical devices installed on a ship’s deck used for raising, lowering, and storing lifeboats, tenders, or other small vessels. They consist of a pair of pivoting arms equipped with winches and cables, enabling safe and efficient launching and recovery of boats. Davits are crucial for emergency preparedness and routine operations, ensuring quick deployment and secure handling of lifeboats and other auxiliary craft.

Deadlight A deadlight is a strong, fixed cover or shutter fitted over a porthole or window on a ship. It is used to provide extra protection against heavy seas, preventing water from entering the vessel during rough weather conditions. Deadlights are typically made of metal and are secured in place to enhance the ship’s safety and watertight integrity.

Deadrise Deadrise in marine terminology refers to the angle between the horizontal plane of a boat’s hull and the surface of its bottom, measured at the centerline or keel. It indicates how much the hull slopes upwards from the keel towards the sides. A higher deadrise angle typically results in a deeper V-shaped hull, which can improve performance in rough seas by providing a smoother ride. Conversely, a lower deadrise angle results in a flatter bottom, which can enhance stability and speed in calm waters.

Deck height Deck height refers to the vertical distance between the bottom of a ship’s hull (the keel) and the deck, or the height of a specific deck above the base line or another reference point on the vessel. It is a critical measurement in ship design and construction, influencing the ship’s overall stability, cargo capacity, and structural integrity. Proper deck height ensures adequate headroom and accessibility for crew and passengers, as well as efficient space utilization for cargo and equipment.

Deck stringer A deck stringer is a longitudinal structural member running along the outer edge of a ship’s deck, providing support and reinforcement. It connects the deck plating to the hull structure, enhancing the deck’s strength and rigidity. Deck stringers are crucial for maintaining the structural integrity of the ship, distributing loads, and ensuring the durability of the deck under various operational conditions.

Deep tank A deep tank on a ship is a large, enclosed tank that extends from the bottom of the vessel up to the main deck, used for storing ballast water, fuel, or liquid cargo. These tanks are integral to the ship’s stability and trim, allowing for adjustments in weight distribution as needed. Deep tanks enhance the vessel’s operational flexibility by providing additional storage capacity for essential liquids during voyages.

Derrick A derrick is a lifting device on a ship, typically consisting of a mast, boom, and associated rigging, used for loading and unloading cargo. It provides a mechanical advantage for hoisting heavy loads onto or off the vessel, particularly in locations where shore-based cranes are unavailable. Derricks are essential for handling cargo efficiently and safely, contributing to the overall productivity of maritime operations.

Design draft The design draft of a ship refers to the vertical distance between the waterline and the lowest point of the hull (keel) when the ship is fully loaded to its designed capacity. This measurement is crucial for determining the vessel’s buoyancy, stability, and safe navigation in various water depths. The design draft ensures the ship operates efficiently and safely within its intended load and operational parameters.

Det norske Veritas Det Norske Veritas (DNV) is an international classification society headquartered in Norway, providing services for risk management and quality assurance to the maritime, oil and gas, and renewable energy industries. DNV establishes technical standards for the design, construction, and operation of ships and offshore structures, ensuring safety, reliability, and environmental sustainability. It conducts inspections, certifications, and research to promote best practices and innovation in maritime operations globally.

Diesel generator A diesel generator on a ship is a crucial piece of machinery that converts diesel fuel into electrical power, ensuring a reliable energy supply for various onboard systems and equipment. It provides electricity for propulsion, lighting, navigation, communication, and other essential operations, particularly when the ship is not connected to shore power. Diesel generators are designed for efficiency, durability, and safety, supporting the continuous and smooth functioning of maritime vessels.

Displacement Displacement in maritime terms refers to the weight of water displaced by a ship’s hull when it is floating or submerged in water. It is a fundamental measurement used to determine the ship’s buoyancy and load-carrying capacity. Displacement includes the weight of the ship, cargo, fuel, crew, and any other onboard items. This measurement is critical for assessing the vessel’s stability, performance, and operational characteristics.

Docking plan A docking plan in maritime operations is a detailed strategy outlining procedures and preparations for safely docking a ship at a pier, wharf, or dockyard. It includes factors such as approach angle, speed adjustments, mooring arrangements, and communication protocols with port authorities and tugboats. The docking plan ensures efficient and safe maneuvering of the vessel during arrival and departure from ports, minimizing risks and optimizing turnaround times for maritime operations.

Double bottom A double bottom in maritime engineering refers to a structural feature of a ship’s hull where there are two layers of watertight compartments or spaces between the bottom of the hull and the innermost surface of the ship’s bottom plating. This design provides additional protection against water ingress and enhances the vessel’s structural integrity and buoyancy. Double bottoms are commonly used to store ballast water, fuel, or fresh water, and they serve as a safety measure to mitigate the risk of hull damage from grounding or collisions.

Double skin Double skin in marine terminology refers to a hull construction design where there are two layers of hull plating separated by a space or void. This configuration enhances the ship’s structural strength and provides additional protection against hull damage from external impacts or corrosion. Double skin hulls are commonly found in modern ships, especially oil tankers and chemical carriers, to meet stringent safety and environmental regulations governing the transportation of hazardous cargoes.

Draft (or draught) Draft (or draught) in maritime terms refers to the vertical distance between the waterline and the deepest part of a ship’s hull, typically measured from the keel to the waterline when the ship is fully loaded. It is a crucial measurement for determining the ship’s buoyancy, stability, and ability to navigate safely in various water depths. Draft affects the ship’s maneuverability, cargo capacity, and overall performance, making it an essential consideration in ship design, operation, and navigation planning.

Draft marks Draft marks on a ship are numerical markings or lines painted on the bow (forward) and stern (aft) of the hull to indicate the ship’s draft or depth in the water. These marks help determine the vessel’s loaded condition and ensure it maintains proper trim and stability. Draft marks are essential for monitoring and recording changes in draft due to loading, fuel consumption, or water density variations during voyages.

Dredger A dredger is a specialized vessel or equipment used for excavating and removing sediment or debris from the bottom of rivers, harbors, and other water bodies. It is equipped with powerful pumps, suction devices, or mechanical tools to loosen and extract materials, facilitating deepening of channels, harbor maintenance, and land reclamation projects. Dredgers play a crucial role in maintaining navigable waterways, improving water quality, and supporting infrastructure development in coastal and inland regions.

Drill ship A drill ship is a specialized vessel equipped with drilling equipment and facilities for offshore exploration and production of oil and gas. It typically features a derrick or drilling rig capable of drilling deep into the seabed to extract oil or gas deposits. Drill ships are mobile platforms capable of operating in deep waters, providing flexibility for exploration and development activities in remote offshore locations. They play a pivotal role in offshore drilling operations, contributing to the global energy industry’s exploration and production efforts.

Dry bulk Dry bulk refers to commodities or materials that are transported in large quantities without packaging, typically loaded directly into a ship’s hold. Examples include grains, coal, iron ore, and cement. Ships designed for transporting dry bulk cargo are called dry bulk carriers, which feature large, open holds to accommodate bulk commodities. Dry bulk shipping plays a vital role in global trade, facilitating the efficient transport of essential raw materials between producers and consumers worldwide.

Dry dock A dry dock is a large structure, typically made of concrete or steel, used for docking, maintaining, and repairing ships. It is designed to be flooded and then drained to allow ships to be floated in and out, exposing their hulls for inspection, maintenance, and repair work. Dry docks provide a controlled environment for ship maintenance, ensuring efficient and safe servicing of vessels without the need for them to remain in the water.

Duct In maritime terms, a duct refers to a channel or conduit on a ship used for directing air, fluids, or electrical cables between different compartments or areas. Ducts are essential for ventilation systems, cooling mechanisms, and ensuring the efficient flow of essential services throughout the vessel. They contribute to maintaining optimal operating conditions and safety aboard ships by regulating air circulation and preventing overheating of equipment.

Duct keel A duct keel in ship construction refers to a longitudinal structure or channel integrated into the bottom of the ship’s hull. It serves multiple purposes such as providing a pathway for cables, pipes, and other systems running along the length of the vessel. Additionally, the duct keel reinforces the ship’s structure and enhances its overall stiffness and strength, contributing to its seaworthiness and structural integrity.

Maritime Glossary: E

 

Electro-hydraulic Electro-hydraulic systems in marine applications utilize electricity to control hydraulic machinery and equipment aboard ships. These systems efficiently convert electrical energy into hydraulic power, enabling precise and reliable operation of functions such as steering mechanisms, stabilizers, and cargo handling equipment. Electro-hydraulic systems enhance operational efficiency and safety by providing responsive control over critical shipboard functions, contributing to overall maritime performance and reliability.

Endurance Endurance in marine terminology refers to the maximum duration or distance a ship can travel on a single supply of fuel and provisions without refueling or resupplying. It is a measure of the ship’s capability to sustain operations at sea, indicating its range and self-sufficiency. Endurance is influenced by factors such as fuel capacity, engine efficiency, and the crew’s provisions, essential for prolonged voyages and maritime missions.

Engine control room The engine control room on a ship is a dedicated space where engineers monitor and manage the operation of the vessel’s propulsion system and auxiliary machinery. It houses control panels, monitoring displays, and communication equipment essential for overseeing engine performance, fuel consumption, and power distribution. The engine control room ensures efficient and safe operation of the ship’s engines, contributing to optimal performance, reliability, and safety during maritime operations.

Engine room The engine room on a ship is a vital compartment where the main propulsion engines and auxiliary machinery are housed and operated. It contains engines, generators, pumps, and other essential equipment necessary for power generation, propulsion, and various onboard systems. The engine room is carefully designed to optimize space, ensure efficient operation, and maintain safety standards, playing a critical role in the vessel’s overall performance and reliability at sea.

Ergonomic In a maritime context, ergonomic principles focus on designing shipboard environments and equipment to optimize safety, efficiency, and comfort for crew members. This includes the layout of workspaces, seating arrangements, and the design of controls and interfaces to minimize physical strain and fatigue. Ergonomic considerations are crucial for enhancing crew performance, reducing the risk of injury, and promoting overall well-being during maritime operations.

Even keel “Even keel” refers to the state of a ship when it is floating levelly in the water without any significant list or trim. It indicates that the vessel is properly balanced, with the bow and stern at equal heights above the waterline. Maintaining an even keel is essential for stability and efficiency during navigation, ensuring optimal performance and comfort for crew and passengers alike.

Maritime Glossary: F

 

Factory ship A factory ship is a large vessel equipped with extensive facilities for processing and preserving fish or other marine resources directly on board. These ships can catch, process, package, and freeze seafood, allowing them to stay at sea for extended periods. Factory ships enhance efficiency in the fishing industry by combining harvesting and processing operations, enabling immediate preservation of the catch and reducing the need for shore-based processing facilities.

Fender A fender is a protective device used on ships and boats to absorb impact and prevent damage when mooring, docking, or coming alongside another vessel. Made from materials such as rubber, foam, or plastic, fenders are placed between the ship’s hull and the dock or another vessel to cushion the contact. They play a crucial role in maintaining the structural integrity of the vessel and ensuring safe and secure mooring operations.

Ferry A ferry is a vessel designed to transport passengers, vehicles, and goods across bodies of water, typically between fixed points on a regular schedule. Ferries vary in size and capacity, ranging from small boats for short crossings to large ships capable of carrying hundreds of passengers and vehicles over longer distances. They play a vital role in public transportation, providing essential links in coastal, island, and riverine areas where bridges or tunnels are impractical.

Flag State A Flag State refers to the country under whose laws a ship is registered and whose flag the ship is entitled to fly. The Flag State has jurisdiction over the vessel and is responsible for enforcing regulations concerning safety, crew welfare, and environmental standards. This includes conducting inspections, certifying vessels, and ensuring compliance with international maritime conventions and laws.

Flange A flange in maritime engineering is a projecting rim or edge, typically used to strengthen or attach one component to another. Commonly found in piping systems, flanges connect pipes, valves, pumps, and other equipment, ensuring a secure and leak-proof joint. They are essential for maintaining the integrity and efficiency of onboard systems, facilitating maintenance and assembly by allowing easy disconnection and reconnection of components.

Flare In maritime terminology, a flare refers to the outward curvature or widening of a ship’s hull towards the upper sections, typically found in the bow or stern areas. This design feature helps improve the vessel’s stability and performance in rough seas by reducing pitching and enhancing wave deflection. Flares also contribute to the ship’s aesthetic appearance and can serve practical purposes such as providing additional buoyancy and reducing spray on deck.

Floor In maritime construction, a floor refers to a transverse structural member that supports the bottom of a ship’s hull frames. Floors are essential for distributing loads and reinforcing the hull’s structural integrity against bending and twisting forces encountered at sea. They span between the keel and the frames, contributing to the overall strength and stability of the vessel’s hull structure.

Flush deck hatch A flush deck hatch on a ship is a watertight opening in the deck that lies flush with the surrounding surface when closed. It provides access to compartments below deck for cargo handling, equipment maintenance, or storage. Flush deck hatches are designed to maintain the integrity of the deck structure while allowing easy and secure access when needed, contributing to efficient operations and safety aboard the vessel.

Flush deck ship A flush deck ship is a vessel with a continuous, unbroken main deck that extends from bow to stern without any raised structures or superstructures above it. This design provides a flat and open deck space, which can be advantageous for certain types of cargo handling and operations. Flush deck ships are typically seen in smaller vessels or historical designs where simplicity and practicality in deck usage are prioritized.

Focsle The forecastle (fo’c’sle) on a ship is the forward part of the main deck, located near the bow, and often includes crew accommodations and storage spaces. It serves as a working area for handling anchors and mooring lines, as well as providing essential housing for crew members. Additionally, it helps to improve the ship’s buoyancy by adding a volume to the front of the ship

Forebody The forebody of a ship refers to the front section of its hull, extending from the bow to amidships. It includes the forwardmost part of the vessel’s structure and is critical for shaping its hydrodynamic performance, stability, and maneuverability. The forebody typically houses compartments such as crew accommodations, storage areas, and sometimes specialized equipment or machinery essential for the ship’s operations.

Forecastle The forecastle (often abbreviated as fo’c’sle) on a ship is the forward part of the main deck, situated near the bow. Historically, it served as a raised platform for observation and defense in sailing vessels. In modern ships, the forecastle may house crew accommodations, storage areas, and sometimes machinery or equipment essential for ship operations. It also serves as a working area for handling anchors, mooring lines, and other deck operations.

Foredeck The foredeck on a ship is the forward part of the main deck, extending from the bow towards amidships. It is typically a flat or slightly raised platform used for various operations, including handling anchors, mooring lines, and cargo. The foredeck provides essential workspace for crew members during docking, anchoring, and other deck activities, contributing to the efficient and safe operation of the vessel.

Forefoot The forefoot of a ship refers to the forward-most part of the hull where the keel and the stem intersect. It plays a critical role in cutting through the water and influencing the ship’s hydrodynamic performance, stability, and maneuverability. The design and shape of the forefoot impact the vessel’s ability to navigate efficiently and maintain directional stability, making it an essential feature in ship construction and naval architecture.

Fore peak tank The fore peak tank on a ship is a compartment located at the forward-most part of the vessel’s hull, near the bow. It is used primarily for storing ballast water, which helps adjust the ship’s trim and stability. Additionally, the fore peak tank serves as a safety measure to prevent water ingress into other compartments in case of damage to the bow. It is an integral part of the ship’s hull structure, contributing to its overall buoyancy and seaworthiness.

Forest product carrier A forest product carrier is a specialized vessel designed for transporting various forestry-related products such as logs, lumber, wood chips, and pulp. These ships are equipped with specific cargo handling facilities and storage areas tailored to handle different types of timber and wood products. Forest product carriers play a crucial role in the global timber trade, facilitating the efficient transportation of raw materials and finished wood products between production areas and consumer markets worldwide.

Forward “Forward” in maritime terminology refers to the direction or area towards the bow (front) of the ship. It is used to describe the location of objects, compartments, or movements relative to the vessel’s front end. For example, “forward deck” indicates the deck area near the bow, and “move forward” means to proceed towards the bow. This term helps in navigation, communication, and operational activities aboard a ship.

FPSO FPSO stands for Floating Production Storage and Offloading. It is a type of floating vessel used in offshore oil and gas production. FPSOs are equipped with processing facilities to extract, process, store, and offload oil and gas extracted from subsea wells. They serve as mobile production units, capable of operating in remote offshore locations where fixed platforms are not feasible. FPSOs play a crucial role in the offshore oil industry by facilitating efficient and cost-effective production and transportation of hydrocarbons to shore facilities.

Frame In maritime construction, a frame refers to a transverse structural member that runs perpendicular to the ship’s longitudinal axis, providing support and strength to the hull. Frames are spaced along the length of the vessel and help to maintain the shape and integrity of the hull structure. They play a critical role in distributing loads and stresses evenly throughout the ship, enhancing its stability, rigidity, and overall seaworthiness. Frames are typically spaced at regular intervals and are connected to the keel, hull plating, and other structural components to form the skeletal framework of the ship.

Frame station(s) Frame stations on a ship refer to specific points along the hull’s longitudinal axis where frames or structural members are located and numbered for reference. These stations are marked at regular intervals along the length of the vessel, typically from the forward (bow) to the aft (stern). Frame stations are essential for shipbuilding and maintenance, providing standardized locations for measuring hull dimensions, assessing structural integrity, and conducting inspections or repairs. They serve as crucial reference points for ship designers, builders, and engineers throughout the lifecycle of the vessel.

Freeboard Freeboard on a ship is the vertical distance between the waterline and the main deck level, measured amidships (at the midpoint of the ship’s length). It represents the margin of safety and buoyancy above the waterline, helping to prevent water from entering the ship’s hull during normal operating conditions and ensuring adequate stability and seaworthiness. Freeboard is a critical design consideration in shipbuilding, influenced by factors such as vessel type, cargo load, and international regulations governing safety at sea.

Freeboard deck The freeboard deck on a ship is the uppermost continuous deck that provides a margin of safety above the waterline, ensuring adequate buoyancy and stability. It serves as a working platform for crew activities, cargo handling, and navigation equipment. The height of the freeboard deck above the waterline is determined by the ship’s design, intended load conditions, and regulatory requirements to maintain safety and seaworthiness at sea.

FRP FRP stands for Fiber Reinforced Plastic, commonly known as fiberglass. In marine applications, FRP refers to composite materials made of a polymer matrix reinforced with fibers, typically glass fibers. These materials are lightweight, strong, and resistant to corrosion, making them ideal for constructing boat hulls, decks, and other marine structures. FRP is valued for its durability, versatility, and ease of maintenance, offering advantages such as reduced weight, improved fuel efficiency, and extended service life in marine environments.

Funnel A funnel on a ship is a vertical structure used to expel exhaust gases from the ship’s engines and provide ventilation for the engine room and other compartments. It is typically located on the upper deck or superstructure and can vary in size and design depending on the ship’s propulsion system and operational requirements. The funnel also serves as a distinctive feature of the ship’s profile, often adorned with the vessel’s insignia or colors, and is a recognizable element in maritime aesthetics.

Maritime Glossary: G

Galley

The galley is the kitchen area on a ship where food is prepared for the crew. It is usually located near or on the same deck as the messroom, where meals are served, and is equipped with ovens, stoves, and other cooking appliances suited for use at sea.

Galvanizing

Galvanizing is a protective process where a layer of zinc is applied to steel or iron parts to prevent rust and corrosion. It’s commonly used on ship structures and components exposed to moisture and saltwater.

Gangway

A gangway is a portable bridge or ramp used to connect a ship to the shore, allowing safe boarding and disembarkation. It often includes handrails and can be adjusted for tide levels.

Garbage

Garbage refers to all types of domestic, food, and operational waste generated on a ship, such as packaging, food scraps, paper, and maintenance-related refuse. It excludes cargo residues and hazardous substances.

Garbage collection craft (BATELLO ECOLOGICO)

A garbage collection craft, such as the BATELLO ECOLOGICO, is a vessel designed to collect waste from ships, particularly in ports and harbors, to help maintain marine cleanliness and prevent pollution.

Garbage Management Plan

Ships of 100 gross tonnage or more, or those certified to carry more than 15 persons, must have a Garbage Management Plan. This document outlines how shipboard waste is handled, stored, and disposed of in compliance with MARPOL regulations.

Garbage processing equipment

These are onboard devices like incinerators, compactors, and shredders (communiters), used to reduce the volume of waste or make it suitable for discharge or storage, as part of a ship’s waste management system.

Garbage Record Book

The Garbage Record Book is a mandatory logbook on ships with a Garbage Management Plan. It records all garbage handling activities, such as discharge at sea, delivery to port reception, or onboard incineration.

Gas carrier

A gas carrier is a specialized ship designed to transport liquefied gases such as LPG (liquefied petroleum gas) or LNG (liquefied natural gas) in insulated tanks under pressure or at low temperatures.

Gas carrier cargo handling

This involves the complete process of preparing tanks, loading, transporting, and unloading liquefied gas cargoes. It includes multiple steps like drying, inerting, cooling, and warming up of the system to ensure safety and cargo quality.

Drying

Drying is the process of removing moisture from cargo tanks and piping systems before loading liquefied gas to prevent ice formation and maintain the purity of the gas.

Inerting

Inerting is the procedure of filling cargo tanks and pipelines with inert gas (like nitrogen) to reduce oxygen levels and prevent fire or explosion when carrying flammable gases.

Cooling down

Before loading cryogenic liquefied gases, the tanks and lines are gradually cooled to prevent damage from thermal shock and to minimize vapor formation during loading.

Loading

Loading is the process of transferring liquefied gas from shore-based terminals into the ship’s cargo tanks through designated liquid lines, typically using pumps and controlled systems.

Laden voyage

During the voyage with cargo onboard, gas carriers (except pressure types) carefully control temperature and pressure of the cargo using insulation and refrigeration to maintain safety and cargo quality.

Unloading

Unloading involves discharging the liquefied gas cargo using onboard pumps. The system often includes vapor return lines to balance pressure between the ship and shore terminal.

Stripping

Stripping is the process of removing the last remnants of cargo from tanks after unloading, using pumps or stripping ejectors, to prepare the system for cleaning or gas-freeing.

Warming up

Warming up gradually raises the temperature of cargo tanks and piping after unloading cold cargoes, preparing the system for maintenance, inspection, or a different type of cargo.

Gas carrier standards

These are construction and operational requirements outlined in the International Gas Carrier (IGC) Code, covering design, materials, safety systems, and equipment for ships that carry liquefied gases.

Gas cylinder

A gas cylinder is a pressurized container, typically up to 150 liters, used to store and transport gases in liquid or compressed form for industrial or onboard use.

Gas engine

A gas engine is an internal combustion engine that operates on gas fuels like natural gas or biogas. It is used on some ships for auxiliary power or propulsion due to lower emissions compared to diesel engines.

Gas free

A space is considered gas free when it has been ventilated sufficiently to remove all flammable and toxic gases, making it safe for human entry and hot work like welding or maintenance.

Gas freeing

Gas freeing is the process of removing flammable or toxic gases from the inside of a tank, compartment, or pipeline by ventilating it with fresh air. This is done to make the space safe for crew entry, inspection, or maintenance, especially before hot work.

Gas indicators

Gas indicators are portable devices used on ships to detect and measure the concentration of hydrocarbon or other gases in the atmosphere. These tools help ensure safe working conditions, particularly in confined or enclosed spaces.

Gas processing

Gas processing refers to the separation of natural gas from oil and the removal of impurities like water, sulfur compounds, and gas condensates. The cleaned gas is then suitable for storage, transportation, or use as fuel.

Gas tanker (CLIPPER VIKING)

The CLIPPER VIKING is a specific example of a gas tanker, a type of ship designed to carry liquefied gases such as LPG or LNG in specialized, pressurized, or refrigerated tanks.

Gas Reformer

The Wärtsilä GasReformer is an onboard system that converts low-quality or variable-composition gaseous fuels into a consistent, clean fuel suitable for marine engines, helping to meet emissions and efficiency standards.

Gas treatment

Gas treatment involves purifying natural gas by removing contaminants such as water vapor, carbon dioxide, hydrogen sulfide, and other impurities to ensure the gas meets safety and quality standards for use or sale.

Gas turbine

A gas turbine is a type of internal combustion engine that generates power through the expansion of high-pressure gas. It consists of an air intake, compressor, combustion chamber, turbine, and exhaust, and is used for ship propulsion or electricity generation.

Gasket

A gasket is a flexible sealing material placed between two surfaces—such as flanges, doors, or hatches—to prevent leakage of fluids or gases. Gaskets help maintain pressure and prevent contamination or spillage.

Gate valve

A gate valve is a type of stop valve that uses a sliding gate mechanism to either allow full flow or completely stop fluid movement in a pipeline. It is commonly used when straight-line flow and minimal restriction are desired.

Gauge

A gauge is a measuring device used to monitor and display a physical quantity such as pressure, temperature, or level. It provides critical information to ensure systems are operating within safe parameters.

Diaphragm gauge

A diaphragm gauge measures pressure using a thin, flexible membrane that deflects under pressure. The amount of deflection is proportional to the pressure applied and is used in low-pressure applications.

Pressure gauge

A pressure gauge is a tool used to display the internal pressure of a system or container, commonly found on boilers, pipelines, and engines, helping to monitor system performance and safety.

Gauge glass

A gauge glass is a transparent tube or set of glass plates attached to a tank or boiler, providing a visual indication of the liquid level inside. It is vital for monitoring water or fuel levels onboard.

Closed gauging device

This device allows measurement of tank contents without releasing gases or vapors into the atmosphere. It maintains a sealed environment, enhancing safety by minimizing exposure to hazardous substances.

Indirect gauging device

An indirect gauging device determines the level or quantity of liquid inside a tank without direct contact. It may use weight measurements, pressure readings, or ultrasonic sensors to calculate volume.

Open gauging device

An open gauging device allows direct measurement by inserting tools (like sounding rods or tapes) into a tank through an open access point, which may expose the tank’s atmosphere to the outside.

Restricted gauging device

This type of gauging device penetrates the tank but is designed to minimize the release of vapors during measurement. It provides more control and safety than open gauging while allowing direct contact with the cargo.

Gauging systems

Gauging systems are installed onboard ships, especially tankers, to measure the quantity, level, temperature, and sometimes pressure of liquid cargo in tanks. These systems may be manual or automated and include components like sensors, radar or ultrasonic devices, temperature probes, and interface units. Gauging systems help ensure safe cargo operations, accurate loading and unloading, and compliance with safety and environmental regulations. They also play a key role in preventing overfilling, monitoring tank conditions, and maintaining proper documentation for cargo handling.

Electro-pneumatic system

This system involves blowing air down a pipe to the liquid in the tank. The back pressure is used to determine the liquid level.

Hydrostatic pressure system

The gauge sensor indicates the liquid level by measuring the pressure exerted by the liquid column.

Radar tank gauging system

A radar transmitter is installed at the top of each cargo tank to measure the distance to the liquid surface, providing accurate level measurement.

TankRadar system

A radar-based tank monitoring system developed by Saab Marine Electronics, used for precise level measurement and inventory control.

Gear pump

A type of positive displacement pump consisting of two intermeshing gear wheels within a casing. It is used for pumping viscous liquids

Geared

Refers to a vessel that is equipped with its own cargo handling equipment, such as cranes or derricks.

Gearless

Refers to a vessel that does not have its own cargo handling gear and depends on shore-based equipment for loading and unloading.

General cargo ship

A type of ship designed to carry various types of cargo, often packaged in boxes, barrels, or pallets, and usually equipped with multiple decks.

General emergency alarm

A signal composed of seven short blasts followed by one prolonged blast, used to alert crew and passengers to an emergency.

General radio communications

Radio communication used for operational purposes and public correspondence, excluding distress and safety traffic.

Generator

A machine that converts mechanical energy into electrical energy, typically a 3-phase alternator used for supplying power on ships.

Geophysical

Pertains to the use of scientific techniques (electrical, gravitational, magnetic, seismic) to study the physical properties of the earth, often used in marine surveys.

Geotechnical ships

Vessels designed for seabed and subsurface investigations to detect underwater conditions, often used in offshore construction or oil exploration.

Girder

A major structural component that supports weight and provides stiffness. Girders run longitudinally or transversely throughout the vessel.

Deck girder

Double bottom girder – A vertical longitudinal plate within the double bottom, extending from the outer shell to the tank top, adding strength and subdividing spaces.

Hull girder

The components of a ship’s hull structure that contribute to its overall strength when subjected to longitudinal bending forces, such as in waves.

Gland

A device used to prevent leakage at a mechanical joint, especially where a rotating or reciprocating shaft passes through a housing.

Glare

The sensation of discomfort or reduced visibility caused by excessive brightness within the visual field.

Glass crushing

The process of breaking down glass waste into smaller pieces for recycling. It’s preferred because it avoids the issues of incineration and allows reuse.

Glass reinforced plastic (GRP)

A strong, lightweight material made of glass fibres embedded in plastic resin, commonly used in shipbuilding and lifeboats.

Global Positioning System (GPS)

A satellite-based navigation system operated by the U.S. government that provides accurate position and time information worldwide.

Global warming potential (GWP)

A measure of how much heat a greenhouse gas traps in the atmosphere relative to carbon dioxide (CO₂), which has a GWP of 1.

Globe valve

A type of valve with a spherical body and a moveable disc-type element, used for regulating flow in a pipeline.

GMDSS (Global Maritime Distress and Safety System)

A worldwide radio system designed to improve emergency communications for ships, using satellite and terrestrial technology.

Gouging

A technique used to remove metal from a weld joint, typically in preparation for a back pass or re-welding.

Grab

A cargo handling device that uses a bucket with two hinged jaws to pick up bulk materials like coal or ore.

Grab handling

The use of grab buckets to load or unload bulk cargo, especially in ports lacking automated systems.

Grain

Refers to dry bulk cargoes like wheat, maize, rice, barley, and seeds, either whole or processed.

Grain capacity

The total volume of a cargo hold, measured to the inside shell plating, which represents the maximum capacity when carrying grain.

Grain hatch

A small hatch used during grain loading to monitor the level of cargo and assist in safe loading.

Grating

An open-work floor or walkway made of metal or other material, allowing light, air, and liquid to pass through.

Gravel

Small stones used as aggregate in construction and road making, sometimes shipped in bulk by sea.

Gravity drain system

A system where liquid flows through pipes due to gravity alone, without the use of pumps.

Gravity welder

A type of automatic welding machine that moves by gravity along a guide rail, ensuring consistent welds.

Grease

A thick lubricant used to minimize friction between moving parts, especially in bearings or gears.

Grease separator

A device installed in galley drain systems to remove oil and grease from wastewater before discharge or treatment.

Great Lakes ports

Ports located on the North American Great Lakes, serving as major hubs for the transport of bulk goods like grain, coal, and iron ore.

Great Lakes ship

Vessels specifically built to navigate the locks and ports of the Great Lakes, often long and narrow in design.

Greenhouse gases (GHGs)

Gases such as CO₂, CH₄, and N₂O that trap heat in the Earth’s atmosphere, contributing to global warming.

Green sea

Seawater that washes over a vessel’s deck in solid mass (not spray), usually caused by heavy seas or storm conditions.

Grim vane wheel

A type of power-saving device installed behind the propeller to recover energy from the propeller’s rotational flow and improve efficiency.

Gripes

Ropes or wires used to secure lifeboats in their davits when stowed, preventing unwanted movement.

Grothues spoilers

Streamlined fins installed ahead of the propeller near the sternpost to optimize flow into the propeller and improve propulsion efficiency.

Grounded

In electrical terms, connected to the earth or an equivalent conducting body, like a ship’s hull, to prevent shock or damage.

Grounding

The event in which a vessel unintentionally comes into contact with the seabed or shore. Groundings can cause significant hull damage and environmental impact, especially in sensitive areas.

Gudgeon

A metal fitting, usually attached to the sternpost, which contains holes to receive the pintles of the rudder, allowing it to pivot.

Gunwale

Pronounced “gunnel,” this is the upper edge of a ship’s or boat’s side, forming the junction between the deck and the hull.

Gusset

A triangular or similarly shaped plate used to reinforce joints or corners in structures, especially to help distribute loads evenly at a connection point.

Gymnasium

A designated space onboard larger vessels (like cruise ships or naval ships) equipped with fitness machines and gear for physical exercise.

Gyroscope

A spinning device used in navigational systems to maintain orientation and stability. It detects changes in direction, helping ships and aircraft maintain a set course.

Maritime Glossary: H

Habitability

Habitability refers to the suitability of a ship or offshore structure for human living, ensuring comfortable living conditions such as ventilation, temperature control, lighting, sanitation, and noise levels.

Habitat

A habitat in maritime and offshore operations typically refers to a temporary, enclosed workspace used during activities like welding, which protects workers from environmental hazards and contains dangerous gases or sparks.

Halon

Halon is a fire-extinguishing agent used in shipboard fire suppression systems; it effectively interrupts the chemical reaction of fire but has been phased out in many areas due to its harmful environmental effects, particularly on the ozone layer.

HAM (Humid Air Motor) method

The HAM method involves adding moisture to the intake air of a diesel engine, reducing nitrogen oxide (NOx) emissions and improving engine efficiency by lowering combustion temperatures.

Hampered vessel

A hampered vessel is a ship that, due to its work or conditions like towing, dredging, or restricted maneuverability, cannot easily deviate from its course and must be given special consideration under navigation rules.

Handbook

A handbook is a compact reference manual containing essential information, procedures, and guidelines for operations, safety, or equipment, frequently used by maritime crew and engineers.

Handing over

Handing over is the process where responsibility and authority for a vessel, equipment, or duty is formally transferred from one person or team to another, often with a checklist or briefing to ensure continuity.

Handrail

A handrail is a protective rail designed to be grasped by the hand for support, installed along walkways, stairs, and decks aboard ships to ensure crew safety during movement, especially in rough seas.

Harbour dues

Harbour dues are charges levied by port authorities on ships entering a port, typically based on the ship’s size, tonnage, or type of cargo, to cover the maintenance and administration of port facilities.

Harbour master

The harbour master is the official responsible for overseeing the safe navigation, docking, anchoring, and general administration of ships within a port or harbour area, often coordinating with pilots and port services.

Hard coating

Hard coatings are tough, protective layers applied to a ship’s steel surfaces, especially in ballast tanks and cargo holds, to resist corrosion, mechanical damage, and chemical attacks over long periods.

Hardener

A hardener is a chemical substance mixed with another material, such as paint or epoxy, to trigger or accelerate the curing process, resulting in a hard, durable finish essential for marine protection.

Hardening

Hardening refers to the process of increasing the hardness of a material, typically metal, through heat treatment or chemical processes, to improve its strength and resistance to wear in maritime structures and machinery.

Harmonics

In marine electrical systems, harmonics are voltage or current distortions at multiples of the fundamental frequency, caused by non-linear loads, which can lead to equipment overheating and reduced efficiency.

Hatch, hatchway

A hatch or hatchway is an opening in the deck of a ship providing access to the cargo hold or spaces below; it is typically covered and sealed to protect against weather and water ingress.

Hatch coaming

A hatch coaming is the raised, vertical boundary around the edge of a hatchway, designed to prevent water from entering the cargo hold or lower decks and to support the hatch covers.

Hatch cover

A hatch cover is a watertight or weathertight closure placed over a hatchway to protect cargo and ship interiors from the sea, rain, and external elements, critical for vessel safety and cargo integrity.

Folding hatch covers

Folding hatch covers are sectional panels that fold together on deck via hinges when opened, allowing quick and efficient access to cargo holds and saving space compared to traditional removable covers.

Lift-and-roll Piggy-Back covers

Lift-and-roll Piggy-Back covers are a type of hatch cover system where panels are lifted vertically and then rolled horizontally to stack on each other, providing fast and mechanized opening and closing of cargo spaces.

Lift-away hatch covers

Lift-away hatch covers are individual panels that are completely removed from the hatch opening, typically using cranes, allowing full access to cargo holds and offering a simple design without complex moving parts.

Pontoon hatch covers

Pontoon hatch covers are heavy, detachable panels, shaped like pontoons, used mainly on bulk carriers; they are lifted off the hatchway and stored separately to provide large, unobstructed openings for cargo handling.

Rolling hatch covers

Rolling hatch covers are panels that move horizontally along rails when opening or closing, often used on cargo ships to allow quick and easy access to holds while minimizing space usage on deck.

Double rubber lip seal

A double rubber lip seal provides enhanced watertight protection for hatch covers or doors by using two flexible rubber lips that press against the sealing surface, preventing water or air from entering.

Swing-seals

Swing-seals are flexible sealing devices attached to hatch covers that move or swing into position when the hatch is closed, ensuring a secure, watertight closure even if there are slight movements or misalignments.

Hatch rubber

Hatch rubber refers to the rubber gaskets fitted around the edges of hatch covers to create a watertight seal, preventing water from leaking into the cargo hold and protecting cargo during voyages.

Hatch cover seals

Hatch cover seals are essential components made of rubber or similar materials that sit between the hatch cover and coaming, ensuring that hatchways remain watertight and preventing cargo damage from water ingress.

CAT profile

CAT profile refers to a specific cross-sectional shape of hatch rubber seals that looks like a cat’s ear; this design helps maintain effective watertight integrity even under compression and movement during a voyage.

FlexSeal

FlexSeal is a flexible, high-performance sealing system used for hatch covers and other marine applications, offering excellent resilience, durability, and watertight protection even under extreme ship motions and loads.

Hatch rubber

(Repeated) Hatch rubber is the rubberized sealing material attached to hatch covers to ensure watertight closure, protecting cargo holds from seawater ingress during operations or rough sea conditions.

Hatch sealing tape

Hatch sealing tape is an adhesive tape used as a temporary or additional measure to improve hatch cover sealing, particularly during bad weather or when rubber seals are worn out, preventing water leaks.

Hatchcoverless container ship NORASIA FRIBOURG

NORASIA FRIBOURG was one of the first hatchcoverless container ships, designed without traditional hatch covers; instead, containers were stacked in deep holds and secured by advanced lashing systems, simplifying operations and reducing turnaround time.

Hatchrails

Hatchrails are rails installed along hatchways that guide and support the movement of rolling hatch covers, allowing them to slide open and closed smoothly and securely.

Hawser

A hawser is a thick, heavy rope or cable used for mooring or towing ships; it is designed to handle enormous stresses and is often made from synthetic fibers or steel wire for strength and durability.

Hazardous air pollutants (HAPs)

Hazardous air pollutants (HAPs) are toxic chemicals released into the air from industrial processes, ship exhausts, or cargo operations, which can cause serious health effects and environmental damage.

Hazardous area

A hazardous area is any location onboard a ship or offshore platform where flammable gases, vapors, or dust may exist, requiring special equipment and precautions to prevent fires or explosions.

Hazardous substances

Hazardous substances are materials that pose risks to health, safety, or the environment due to their chemical nature; on ships, these include fuels, chemicals, and certain types of cargo requiring special handling.

Header tank

A header tank is a small tank located at the highest point of a system, like an engine cooling system, used to maintain pressure, provide fluid reserves, and allow for thermal expansion.

Heat balance

Heat balance refers to the accounting of all heat inputs and outputs within a system, such as a ship’s engine room, ensuring that energy conservation principles are met and helping improve efficiency and performance.

Heat detector

A heat detector is a fire safety device installed on ships that senses abnormal increases in temperature and triggers an alarm, helping in early detection of fires in enclosed spaces.

Heat exchanger

A heat exchanger is a device used on ships to transfer heat between two fluids without mixing them, commonly used in engine cooling systems, air conditioning, and other thermal management systems.

Plate heat exchanger

A plate heat exchanger consists of multiple thin, corrugated metal plates stacked together, allowing efficient heat transfer between fluids while occupying less space, making them ideal for marine engine and HVAC systems.

Shell-and-tube heat exchanger

A shell-and-tube heat exchanger consists of a series of tubes enclosed within a larger shell, where one fluid flows inside the tubes and another outside, widely used in marine engineering for its robustness.

Heating

Heating on ships involves the use of various systems like steam, electrical heaters, or fuel-fired heaters to maintain required temperatures for machinery operation, crew comfort, or cargo requirements.

Heating coils

Heating coils are pipe arrangements usually installed in tanks or engine rooms, where hot fluid circulates through the coils to maintain the temperature of liquids like fuel oils or to provide space heating.

Heaving

Heaving refers to the vertical up-and-down movement of a ship in the water, typically caused by wave action, and is one of the six degrees of freedom in ship motion.

Heaving line

A heaving line is a lightweight rope with a weighted end, thrown across a gap (like ship to shore) to pull across a heavier mooring line or cable needed for docking or towing.

Heavy lift derrick

A heavy lift derrick is a large, powerful lifting device fitted on ships to handle extremely heavy cargoes like engines, containers, or industrial components, allowing vessels to load and unload without specialized port cranes.

Heavy lift ships

Heavy lift ships are specialized vessels designed to transport extremely heavy or oversized cargoes, like machinery or offshore structures, which cannot fit into standard containers, often equipped with their own heavy-duty cranes.

Heavy lift carrier FAIRPLAYER

The FAIRPLAYER is a well-known heavy lift vessel operated by Jumbo Shipping, capable of transporting massive, non-standard cargoes using its twin 900-ton cranes and advanced stability systems.

Project cargo ships

Project cargo ships are relatively small vessels featuring large box-shaped holds, ideal for carrying complex, high-value, or oversized cargo that often requires careful handling and customized loading plans.

Open deck cargo ships

Open deck cargo ships are Ro-Ro (roll-on/roll-off) type vessels with the superstructure positioned forward, offering an extended open deck space suitable for transporting large or awkwardly shaped items.

Semi-submersible ships

Semi-submersible ships can partially submerge themselves by taking in water ballast, allowing cargo such as oil rigs or heavy platforms to float aboard before they de-ballast to lift the cargo above the water.

Heavy load transportation system (STS)

The Ship Transfer System (STS) is a method used for moving large ship modules, like hull sections, within shipyards by rolling them over tracks using hydraulic power and special trolleys.

Heavy running of the fixed pitch propeller

Heavy running of a fixed pitch propeller occurs when the propeller faces more resistance than usual, often due to fouling or rough seas, causing increased engine load and reduced efficiency.

Heavy weather damage

Heavy weather damage refers to structural damage a ship sustains during storms or rough sea conditions, such as hull dents, cracked fittings, damaged cargo, or even broken equipment.

Heel

Heel is the inclination of a ship to one side, either temporarily due to wind, waves, or turning forces, or permanently because of loading issues; it differs from “list,” which is a permanent tilt.

Heickel coefficient

The Heickel coefficient is used in marine engineering to compare propulsion efficiencies between ships operating at the same Froude number, helping to assess and improve ship performance.

Helicopter facility

A helicopter facility on a ship includes a helideck for landing and take-off, as well as any associated fuel storage, firefighting systems, and sometimes a hangar for helicopter maintenance, especially on offshore vessels.

Helideck

A helideck is a purpose-built platform, usually located on offshore vessels or ships, equipped with firefighting and safety gear, providing a landing area for helicopters supporting offshore operations or emergencies.

Helm

The helm is the steering equipment of a ship, usually a wheel or tiller located on the bridge or in the wheelhouse, which controls the rudder to direct the ship’s course.

Helmsman

The helmsman is the crew member responsible for steering the ship under the command of the officer on watch, adjusting the vessel’s course manually or as directed.

Helmsman’s workstation (workstation for manual steering)

This workstation is the area around the ship’s helm, designed ergonomically to allow the helmsman to steer efficiently, with easy access to navigational displays and communication devices.

HERO (Habitat Environment Repair Option)

The HERO system is an underwater maintenance method allowing the dry replacement of stern seals without dry-docking the ship, minimizing downtime and maintenance costs.

HiBuoy

HiBuoy is an innovative mono-buoy mooring concept developed by Hitec Marine AS, offering a flexible and efficient solution for mooring vessels in offshore fields, especially where traditional mooring is challenging.

HI-FOG system

HI-FOG is a high-pressure water mist fire-fighting system created by Marioff, using fine water mist to cool fire zones, suppress flames, and displace oxygen efficiently while minimizing water damage compared to conventional sprinklers.

HI-FOG MT4

HI-FOG MT4 is a specific modular version of the HI-FOG fire suppression system, offering compact design and efficient protection, particularly for machinery spaces and engine rooms on ships.

High expansion foam

High expansion foam is a fire-fighting material that rapidly expands to many times its liquid volume, filling large spaces quickly to smother fires by cutting off the oxygen supply.

High heat tanker BITFLOWER

The BITFLOWER is a tanker vessel designed to transport high-temperature cargoes like molten sulphur or bitumen, equipped with special heating systems to maintain cargo fluidity during transit.

High heat value

High heat value (HHV) refers to the total amount of heat released when a fuel is completely burned, including the heat recovered from the condensation of water vapor, providing a full measure of energy content.

High-lift cylinders

High-lift cylinders are powerful hydraulic actuators used on ships to raise and lower stacking hatch covers, facilitating easier and safer access to cargo holds during loading and unloading.

High-pressure waterjet abrasive cutting

High-pressure waterjet abrasive cutting is a technique that uses a fine jet of water mixed with abrasive particles at extremely high pressures to cut through metals and other hard materials, often used for ship repairs.

HiLoad System

The HiLoad System, developed by Hitec Marine AS, is an offshore loading solution involving a dynamically positioned buoy that attaches to the hull of an FPSO or tanker for efficient cargo transfer without the need for traditional turret systems.

Hogging

Hogging is the upward bending of a ship’s hull at the center (amidships) caused by uneven weight distribution or wave action, creating stress that must be carefully managed in ship design and operation.

Hoist

A hoist is a cable system used by helicopters to lift or lower people or equipment during operations at sea or in emergencies; it can also refer to lifting devices aboard ships.

Hold

The hold is a large enclosed space below a ship’s deck where cargo is stored; it’s typically the lowest cargo compartment.

Hold space

Hold space refers to the structural area inside the ship where independent cargo tanks are housed, separate from the main cargo hold, often used in tankers.

Hold space of gas carrier

In gas carriers, the hold space is the area within the hull where insulated or independent cargo tanks are installed to safely transport liquefied gases.

Holding tank

A holding tank is used for collecting and temporarily storing sewage or greywater onboard ships before it can be properly treated or discharged, as per MARPOL regulations.

Holding-down bolts

These are large bolts used to secure main machinery, like engines or generators, firmly to the ship’s structure to prevent movement during operation.

Homogeniser

A homogeniser is a machine with concentric, cone-shaped gears used to mix and break down substances evenly, such as in the processing of emulsions or sludge.

Hopper barge

A hopper barge is a type of non-self-propelled vessel that collects dredged material dumped into it and releases it through bottom doors or splits open when it’s time to discharge.

Hopper side tanks

These are side compartments located in the lower part of a ship’s hull that can be used for ballast water or for adding stability when carrying certain bulk cargoes.

Hopper unit

A hopper unit is a ship designed for transporting dredged or spoil material; in split hopper units, the hull opens down the center to dump cargo directly overboard.

Horizontal fixed position (pipe welding)

This is a pipe welding position where the pipe remains stationary with its axis horizontal, requiring skilled welding along the sides of the joint.

Horizontal rotated position (pipe welding)

In this welding position, the pipe is horizontal and rotates during welding, making it easier to achieve uniform welds around the pipe circumference.

Horizontal welding position (fillet weld)

A welding position where the weld is applied horizontally along the intersection of two surfaces, usually requiring precision to avoid sagging.

Hose assembly

A hose assembly is a complete hose unit, either metallic or non-metallic, fitted with end connectors or couplings, ready for installation in piping or fluid systems.

Hose testing

Hose testing ensures tightness and integrity of hoses or parts like bulkheads or deck seals by pressurizing them with water or air to check for leaks.

Hot work

Any activity such as welding, cutting, or grinding that generates heat or sparks and poses a fire risk is considered “hot work” and requires special safety precautions onboard ships.

HSVA Speed Trial Analysis

Developed by the Hamburg Ship Model Basin, this method analyzes ship speed trial data, correcting for external factors like wind and current to evaluate true ship performance.

Hull

The hull is the main body of a ship, providing buoyancy and structural support, and includes components such as the keel, decks, frames, and outer shell plating.

Hull appendages

These are parts attached to the hull below the waterline—like rudders, bilge keels, shafts, and propeller brackets—that influence hydrodynamics and vessel control.

Hull efficiency

Hull efficiency is the ratio of the power delivered by the propeller (thrust power) to the effective power needed to overcome resistance, measuring how well the hull design transmits force.

Hull roughness

Hull roughness refers to the surface condition of a ship’s hull caused by biofouling, paint deterioration, or corrosion, which increases drag and reduces fuel efficiency.

Hull-stress monitoring system

This is a shipboard system that continuously measures stresses and strains in a vessel’s structure, helping operators avoid overloading or damage during rough seas or heavy loading.

Humidity

Humidity is the amount of water vapor present in the air; on ships, it affects cargo storage, crew comfort, and equipment performance.

Hundred-year storm

A design benchmark used in offshore construction, representing a storm so severe it statistically occurs once in 100 years, used to define safety limits for structures like oil rigs.

Hungry horse deflections

These are noticeable deflections or buckling in ship plating between structural supports (like beams or frames), resembling a hungry horse’s ribcage, and usually indicate stress or insufficient support.

Hydrant

A hydrant is a fixed water outlet, typically part of a ship’s fire main system, where hoses can be connected for firefighting.

Hydraulic motor

A hydraulic motor converts fluid pressure into mechanical motion and is commonly used on ships to power equipment such as winches, cranes, or steering gear.

Hydraulic rack and pinion

This is a mechanism powered by hydraulic pressure that uses a gear (pinion) and toothed rail (rack) to open or close hatch covers or move other shipboard equipment.

Hydrochlorofluorocarbons (HCFCs)

These are refrigerant gases made of hydrogen, chlorine, fluorine, and carbon, used in ship air conditioning systems, but phased out under environmental regulations due to ozone depletion.

Hydroblasting

Hydroblasting is a surface-cleaning method that uses high-pressure water jets to remove rust, paint, or other contaminants before painting or repairs.

Hydrocarbons

Hydrocarbons are organic chemical compounds made of hydrogen and carbon, found in fuels like oil and gas, and are key energy sources in the marine industry.

Hydrodynamics

Hydrodynamics is the study of how fluids, particularly water, move around objects like ships or propellers, critical in ship design and performance optimization.

Hydrofoil Small Waterplane Area Ship (HYSWAS)

A type of hydrofoil vessel that combines a submerged small waterplane hull with lifting foils; the hull rides mostly below the water surface, reducing resistance and improving stability at high speeds.

Hydrographic survey vessel

A ship equipped with sonar, echo-sounders, and other hydrographic instruments to measure and map underwater features such as seabed contours, depths, and hazards for navigation or research.

Hydrostatic curves

Graphs used in ship design and stability analysis that show relationships between draft, displacement, center of buoyancy, and other hydrostatic properties across a range of loading conditions.

Hydrostatic release unit (HRU)

A device used in life raft or EPIRB installations that automatically cuts the securing strap and allows release of the equipment when submerged at a certain depth, typically during a sinking.

Hydrostatically-balanced loading (HBL)

A loading technique for oil tankers where the cargo tanks are nearly full (98%) and the pressure at the tank bottom is balanced with the external seawater pressure to minimize oil outflow in case of grounding damage.

HYKAT

An advanced hydrodynamic and cavitation tunnel facility at the Hamburg Ship Model Basin (HSVA), used to test ship models and propellers under controlled water flow conditions to study performance and cavitation.

Hyperbaric evacuation system

A specialized system used on diving support vessels allowing divers who are under pressure to be evacuated safely in a pressurized environment during emergencies.

Hyperbaric facility

A structure containing one or more pressure chambers where occupants can safely remain at pressures higher than atmospheric, used in saturation diving or medical decompression treatments.

Hyperbaric lifeboat

A self-propelled, enclosed lifeboat capable of maintaining a pressurized environment for occupants undergoing saturation diving, ensuring their safety and continued decompression during emergencies.

Hyperbaric rescue capsule

A free-floating chamber designed to evacuate saturation divers in emergencies; it maintains internal pressure and allows for transfer to a hyperbaric facility for controlled decompression.

Maritime Glossary: I

IBC Code (International Bulk Chemical Code)

The International Bulk Chemical Code (IBC Code) is a set of regulations established by the International Maritime Organization (IMO) to ensure the safe transport of dangerous liquid chemicals in bulk by sea. It outlines construction and equipment standards for ships carrying these chemicals, focusing on ship design, cargo containment, environmental protection, and crew safety.

Ice belt

The ice belt refers to the reinforced region of a ship’s outer shell plating, typically located along the waterline in the forward section. This area is strengthened with thicker steel and additional structural support to withstand the pressure and abrasion from sea ice during navigation in icy waters.

Ice class

Ice class is a classification assigned to ships that have been specially built or modified with extra strength and features to operate in ice-covered waters. The class, assigned by classification societies, determines the level of ice thickness and severity the vessel can handle safely without assistance.

Ice class rules

Ice class rules are technical guidelines developed by classification societies, such as the Finnish-Swedish Ice Class Rules (FSICR), which define the design and operational standards for ships navigating in ice-prone areas like the Baltic Sea. These rules help ensure vessel safety, structural integrity, and environmental compliance in icy conditions.

Ice strengthening

Ice strengthening involves reinforcing a ship’s hull and propulsion system to resist the mechanical forces exerted by ice. This includes using thicker plating, installing ice knives, strengthening rudders and propellers, and reinforcing the bow and stern sections to reduce the risk of hull damage in ice-infested waters.

Ice thickness

Ice thickness refers to the vertical measurement of an ice sheet from its surface to its base. It is a critical parameter in assessing the navigability of ice-covered waters, ship routing decisions, and the structural requirements of ice-strengthened or icebreaking vessels operating in polar regions.

Icebreaker

An icebreaker is a specially designed vessel capable of navigating through and breaking sea ice to clear and maintain open shipping routes. These ships have powerful engines, reinforced hulls, and unique bow shapes that allow them to crush ice and provide passage for other ships in frozen waterways.

Icebreaking PSV VITUS BERING

The VITUS BERING is an advanced icebreaking Platform Supply Vessel (PSV) designed to operate in harsh Arctic environments. It supports offshore oil and gas activities by supplying equipment and cargo while navigating through thick sea ice using its reinforced hull and powerful propulsion systems.

ICEPOD

ICEPOD is an azimuthing, pulling-type thruster system developed by Wärtsilä for vessels operating in ice. Designed to meet the 1A Super Ice Class requirements, ICEPOD enhances maneuverability and icebreaking capability by enabling ships to move more effectively through thick ice using directional thrust.

Icing

Icing on ships occurs when freezing sea spray, rain, or snow accumulates and forms layers of ice on exposed surfaces like decks, railings, and equipment. This buildup can affect stability, block access, and pose safety hazards to the crew, particularly in polar and subpolar navigation zones.

Icon

An icon is a visual symbol used in user interfaces or diagrams to represent commands, features, or functions in a simplified graphic form. Icons improve navigation and communication by offering quick visual references that users can easily recognize and understand.

I-core panels

I-core panels are lightweight, laser-welded steel sandwich panels developed for shipbuilding by Macor Neptun and Meyer Werft. They feature an “I” shaped internal core structure between two plates, providing strength and stiffness while reducing weight—ideal for decks and bulkheads in modern ships.

Ignition

Ignition is the process of setting an air-fuel mixture on fire, typically inside an internal combustion engine’s cylinder. This controlled explosion drives the piston and generates mechanical power to move the ship or operate machinery.

Ignition delay

Ignition delay is the brief time period between the start of fuel injection into an engine cylinder and the actual ignition of the fuel-air mixture. It affects engine performance, efficiency, and emissions, and is a key parameter in diesel engine combustion analysis.

Red or low-level white illuminance

This refers to dim lighting used on ships at night to preserve crew members’ night vision. Red or low-intensity white lights are commonly used in bridge areas to allow watchkeepers to read instruments without impairing their ability to see outside in the dark.

Immersion

Immersion is the change in a ship’s draught (depth below the waterline) due to the loading or unloading of weight, such as cargo, fuel, or ballast. Greater immersion means the ship sits deeper in the water, affecting stability and maneuverability.

IMO (International Maritime Organization)

The International Maritime Organization is a specialized agency of the United Nations responsible for setting global standards for the safety, security, and environmental performance of international shipping through conventions, codes, and regulations.

IMO Instruments

IMO instruments are official documents such as conventions, protocols, codes, and guidelines adopted by the IMO. These instruments, including SOLAS and MARPOL, set the legal framework for safe and environmentally responsible maritime operations.

Impeller

An impeller is a rotating component found in pumps, fans, turbines, or propulsion systems. It uses centrifugal force to move fluids or gases by spinning, and is essential in ship systems such as cooling pumps or waterjets.

Impressed current cathodic protection (ICCP)

ICCP is a method of protecting a ship’s hull from corrosion by using an external electrical current. It works by making the hull a cathode in an electrochemical cell, preventing it from losing metal due to galvanic action in seawater.

In water survey (IWS)

An in-water survey is a hull inspection carried out while the ship remains afloat, often using divers or remotely operated vehicles (ROVs). It allows certain surveys to be done without drydocking, saving time and cost, while meeting classification requirements.

Inclining test

The inclining test is a stability test performed by shifting known weights across a ship to measure how it tilts. The data collected is used to calculate the ship’s vertical center of gravity, essential for assessing stability and compliance.

In service inclining test system (ISITS):

ISITS is onboard equipment that continuously monitors a ship’s stability by collecting real-time data on weight distribution and trim. It helps ensure operational safety without requiring a formal inclining test during service conditions.

Indent

An indent is a deformation in a ship’s structural element, such as plating or beams, caused by out-of-plane forces like bottom impact or docking accidents. It can affect structural strength and may require inspection or repair.

Independent

In maritime terminology, “independent” refers to a system—like piping or venting—that is completely separate and not interconnected with any other system. This ensures redundancy and avoids cross-contamination or interference between functions.

Independent tank

An independent tank is a cargo tank that is structurally self-supporting and does not form part of the ship’s hull. Commonly used on gas carriers, these tanks are insulated and built to strict standards for transporting liquefied gases or chemicals.

Indicated power

Indicated power is the theoretical power developed within an engine’s cylinder, calculated using pressure-volume data. It does not account for mechanical losses, and is used to evaluate engine performance and efficiency.

Indicator diagram

An indicator diagram is a graph showing the pressure inside an engine cylinder over the course of the piston’s stroke. It helps engineers analyze engine efficiency and diagnose problems by revealing how combustion occurs in real-time.

Indirect expansion system

This refrigeration system uses a secondary coolant (like brine or glycol), which is cooled by a primary refrigerant and then circulated to cool cargo spaces or machinery. It offers better control and safety, especially for sensitive cargo.

Indirect injection engine

In an indirect injection engine, fuel is first injected into a pre-combustion chamber, where it mixes with air and starts burning before entering the main cylinder. This method improves combustion smoothness and is used in some diesel engines.

Industrial vessels

Industrial vessels are specialized ships designed to perform specific marine functions beyond transportation, such as fishing, dredging, cable-laying, and oil exploration. Their structures and systems are tailored to support these industrial tasks efficiently.

Inert condition

An inert condition refers to the state inside a tank where the oxygen level is low enough to prevent combustion. This is achieved by filling the tank with inert gas, and is critical for the safe carriage of flammable cargoes.

Inert gas

Inert gas is a non-flammable gas (such as nitrogen or exhaust gas) used to displace oxygen in cargo tanks, reducing the risk of fire or explosion. It’s an essential part of safety systems on oil and chemical tankers.

Inert gas blower

An inert gas blower is used to push scrubbed (cleaned) flue gas into a ship’s cargo tanks. This helps create a non-explosive environment by reducing oxygen levels, which is essential on oil and chemical tankers.

Inert gas generator (IGG)

An inert gas generator is a device similar to a boiler that burns fuel to produce exhaust gas with very low oxygen. This gas is cooled and cleaned before being used to inert cargo tanks and prevent fires or explosions.

Flue gas system

The flue gas system collects exhaust gases from a ship’s boilers or generators, cools and cleans them, and directs them for use in inert gas systems or releases them safely into the atmosphere.

Flue gas system with topping up generator

This is a system that uses flue gas from boilers as the primary source of inert gas, and includes a separate generator to produce additional inert gas if needed to maintain safe tank conditions.

Inert gas generator systems:

These are complete systems onboard ships that produce, clean, and distribute inert gas to cargo tanks. They ensure the tanks are kept in a non-flammable atmosphere, especially during loading or unloading of oil or chemicals.

Inert gas system

An inert gas system prevents explosions in cargo tanks by filling them with gas that has very low oxygen content, usually from exhaust or an inert gas generator. This makes the environment inside the tank non-combustible.

Inerting

Inerting is the process of replacing the air in cargo tanks or void spaces with inert gas to prevent the possibility of fire or explosion, particularly important when handling flammable cargo.

Inflatable appliance

An inflatable appliance is a safety device, such as a life raft, that depends on gas-filled, flexible chambers for buoyancy and function. These are compact until needed and inflate automatically or manually.

Inflated appliance

This is an inflatable safety device that has already been filled with gas and is in its fully expanded, working condition—ready for use during emergencies such as ship evacuation.

Injection

Injection refers to the process where fuel is sprayed into an engine cylinder under high pressure by an injector. This atomized fuel mixes with air and ignites, powering the engine.

Injector, fuel valve

A fuel injector or valve is a device that precisely sprays high-pressure fuel into the engine cylinder in fine droplets. This allows efficient combustion and smooth engine operation.

INMARSAT

INMARSAT (International Maritime Satellite Organization) is a global network providing satellite communication for ships. It enables reliable voice and data services for safety and operational purposes at sea.

Inner hull

The inner hull is the internal structure of a double-hulled ship, forming a second protective skin inside the outer hull. It adds safety by providing an extra barrier against leaks or damage.

In-Sea Equipment

In-sea equipment includes any tools or devices deployed into the water from a vessel for tasks like surveying, sampling, or underwater inspection. These can be towed or remotely operated.

Insert plate

An insert plate is a thicker steel plate welded into an area of the ship’s structure that experiences higher stress or wear. It reinforces that part to prevent damage or deformation.

Instantaneous rate of discharge of oil content:

This is a measurement of how much oil (in liters) is being discharged into the sea per hour, based on the ship’s speed and location. It must be controlled to meet pollution regulations.

Instrument:

An instrument is a tool or device that measures and displays values like pressure, temperature, or speed. Ships use many instruments to monitor systems and ensure safe operation.

Instrument air:

Instrument air is clean, dry compressed air used in shipboard systems for controlling valves and instruments. It ensures accurate and reliable operation of automated and pneumatic systems.

Instrumentation

Instrumentation refers to the collection of sensors, displays, and systems used to monitor and control various ship functions—such as engine performance, tank levels, and environmental data.

Insulated container

An insulated container is a shipping container with built-in insulation in the walls, roof, and floor. It helps keep internal temperatures stable and is used for transporting temperature-sensitive cargo.

Insulated container tank

This is a tank enclosed in a standard container frame and equipped with thermal insulation to maintain the temperature of its liquid cargo—commonly used for chemicals or food-grade products.

Insulating flange

An insulating flange is a joint that prevents electrical current from passing between connected pipes or fittings. It uses gaskets and sleeves to provide electrical isolation, protecting systems from corrosion.

Insulation of ship structures

Insulation on decks, walls, and bulkheads helps control temperatures and noise inside ships. It also improves energy efficiency and protects the crew from hot or cold surfaces.

Insulation material

Materials like rockwool, polyurethane, Styrofoam, or fiberglass are used on ships to insulate hot or cold surfaces, reduce heat loss, and improve safety and comfort for crew and cargo.

Insulation of cargo spaces

Cargo spaces on refrigerated ships (like trawlers or reefers) are insulated to keep cargo cold during transport. This ensures the freshness of perishable goods like fish, meat, or produce.

Insulation of hot surfaces

Any surface that might get hot enough to burn a person—such as engine parts or steam pipes—is covered with insulation to protect crew from accidental contact and improve heat efficiency.

Insulation space of gas carrier

This is the space in a gas carrier that provides insulation around the cargo tanks. It may also be used as a safety buffer between inner and outer barriers to help prevent gas leaks and maintain temperature.

Intact stability criteria

These are guidelines based on past ship behavior that help ensure a vessel remains stable and upright under normal (undamaged) conditions, even in rough seas.

INTAKEMATIC

INTAKEMATIC is a system created by Wilson Taylor that protects seawater intake systems from marine growth using electrolytic anti-fouling technology, reducing maintenance needs.

Integrated bridge systems (IBS)

An IBS is a ship’s control center where navigation, radar, engine monitoring, and communication systems are all displayed on connected screens, allowing easier, safer ship operations.

Integrated Full Electric Propulsion (IFEP)

IFEP uses a single power source—usually electric—to run both the ship’s propulsion and other onboard systems. It allows flexible power use, reduced noise, and increased efficiency.

Integrated monitoring system

This is a centralized system that combines different control panels and instruments (like for engines, power, and alarms) into one interface to simplify ship operations and diagnostics.

Integrated Propulsion Package (IPP):

An IPP includes the controllable pitch (CP) propeller, shaft, gearbox, and engine—all designed to work together efficiently as one propulsion system.

Integrated system

This refers to a setup where multiple computer-based systems on a ship are connected and work together as a single unit for better performance and monitoring.

Interbarrier space of gas carrier

This is the area between a gas carrier’s primary and secondary barriers (tank walls). It acts as an extra safety layer in case the inner tank leaks and can also hold insulation.

Intercooler

An intercooler is a heat exchanger placed between compression stages in an air compressor. It cools the air between stages, improving efficiency and reducing load on the compressor.

Intercostal:

“Intercostal” means placed or built between main structural parts, like between ship frames or beams. It’s the opposite of a continuous structure, often used to allow flexibility or access.

Interface detector

This is an electrical device used to find the boundary where two liquids meet—like the line between oil and water in a tank. It helps in safe pumping and avoiding contamination.

Intering™ Anti-heeling Systems:

These are automatic systems (using air or pumps) that quickly correct a ship’s tilt (heel) to improve stability and safety, especially during loading or rough sea conditions.

Intering™ Stability Test System (ISTS)

Developed by Hoppe, this is an automatic onboard system that performs inclining tests to measure and monitor a ship’s stability in real time, without needing to go to port.

Intermediate shafting

This is the section of the propulsion shaft located between the engine and the propeller shaft. It transmits engine power to the propeller to move the ship.

Intermediate bulk container (IBC)

An IBC is a large container used to transport or store liquids or powders in bulk. It’s portable, reusable, and often seen in industries like chemicals or food.

Intermittent weld

This is a welding technique where sections are left unwelded between welds, forming a pattern. It saves time and materials while still offering enough strength for the purpose.

INTERMODESHIP

INTERMODESHIP is a project aimed at making river-sea-river transport more efficient by using trailers that can easily shift between ships and trucks, improving logistics.

Internal combustion engine

This engine burns fuel (like diesel or gasoline) inside a cylinder to produce power. It’s the type commonly used in cars, small boats, and auxiliary ship machinery.

Spark-ignition engine

A spark-ignition engine is a type of internal combustion engine that uses a spark plug to ignite fuel, typically running on gasoline or natural gas.

Internal watertight integrity

This means that internal parts of a ship (like compartments and doors) are built to be watertight, preventing water from spreading in case of damage or flooding.

International Association of Classification Societies (IACS)

IACS is a group formed in 1968 that includes major classification societies. It sets standards for ship safety, design, and construction to ensure global maritime safety.

International Association of Dry Cargo Shipowners (INTERCARGO)

INTERCARGO represents the global dry bulk shipping industry and works to improve safety, environmental performance, and regulatory policies affecting bulk cargo ships.

International Bulk Chemical Code (IBC Code):

The IBC Code sets international safety standards for building and operating ships that carry dangerous chemicals in bulk, ensuring protection for crew, cargo, and the environment.

International Chamber of Shipping (ICS):

The ICS is a leading global trade association for shipowners and operators. It works to represent the industry’s interests in matters of safety, regulation, and sustainability.

International Code on Intact Stability, 2008 (2008 IS Code):

This code provides updated rules and technical criteria to ensure ships remain stable under normal conditions. It helps designers and operators maintain safe vessel operations.

International Convention for the Prevention of Pollution from Ships (MARPOL 73/78):

Known as MARPOL, this international treaty helps prevent pollution from ships, covering oil, chemicals, garbage, sewage, and air emissions.

International Convention on Load Lines 1966 (ICLL 1966):

This agreement sets rules on how low a ship can sit in the water when loaded, ensuring safety by preventing overloading.

International Convention on Load Lines; Positions:

For load line rules, ships have two important positions marked—Summer and Winter load lines—which show how deep a ship can safely go into the water depending on the season and region.

International Convention on Tonnage Measurement of Ships 1969 (TONNAGE 1969):

This treaty provides a standard way to measure the size (gross and net tonnage) of ships for safety, port fees, and regulations.

International Gas Carrier Code (IGC Code):

This code sets safety rules for building and operating ships that carry liquefied gases in bulk, like LNG or LPG.

International Grain Code:

This code ensures the safe loading of grain in bulk, preventing it from shifting and causing ship instability during transport.

International Institute of Marine Surveyors (IIMS):

Founded in 1991 in London, IIMS is a global professional body for marine surveyors who inspect ships and cargo to ensure safety and compliance.

International Labour Organization (ILO):

A part of the UN, the ILO sets global labor standards, including seafarers’ rights, working conditions, and safety at sea.

International Life-Saving Appliance Code (LSA Code):

This code provides rules for life-saving equipment on ships, like lifeboats, life jackets, and emergency beacons.

International Marine Contractors Association (IMCA):

IMCA represents companies involved in offshore marine construction, promoting safety, training, and standard practices.

International Maritime Dangerous Goods Code (IMDG Code):

This code governs the transport of dangerous goods (e.g., flammable or toxic materials) by sea to ensure safety for ships, crews, and the environment.

International Maritime Organization (IMO):

A UN agency responsible for global maritime safety, pollution prevention, and setting international shipping regulations.

International NAVTEX service:

A worldwide system that sends automatic weather and safety messages to ships on 518 kHz, helping mariners stay updated during voyages.

International Oil Pollution Compensation Fund (IOPC Fund):

This fund pays compensation to those affected by oil spills when shipowners’ insurance is not enough to cover the damage.

International Oil Pollution Prevention Certificate (IOPP Certificate)

A mandatory certificate proving that a ship follows MARPOL rules to prevent oil pollution at sea.

International Safety Management Code (ISM Code):

This code sets safety procedures and management rules to reduce accidents, environmental harm, and human errors on ships.

International Ship and Port Facility Security Code (ISPS Code):

A global security standard created after 9/11 to protect ships and ports from terrorism and other unlawful acts.

International Ship Suppliers Association (ISSA):

Formed in 1955, ISSA is a global trade association representing companies that supply goods and services to ships.

International Shipping Federation (ISF):

The ISF represents shipowners in labor issues, working with the ILO and others to protect seafarers’ rights and conditions.

International shore connection:

This is a standard connection (flange with bolts and nuts) allowing fire hoses from port facilities to be linked to a ship’s system during emergencies.

International Towing Tank Conference (ITTC):

A worldwide group of ship model testing labs that share research and methods to improve ship design and performance.

ITTC Recommended Procedures:

These are standardized testing methods developed by the ITTC for measuring ship performance in model basins and towing tanks.

INTERTANKO

The International Association of Independent Tanker Owners — a global trade association that represents the interests of independent tanker owners and promotes safe, environmentally sound, and efficient shipping.

Intrinsically safe

An electrical circuit is considered “intrinsically safe” if it’s designed so that any spark or heat it might produce is too weak to ignite flammable gases or vapors — crucial in hazardous ship areas like fuel tanks.

Invar

A special metal alloy made of 36% nickel and steel, known for barely expanding or contracting with temperature changes — often used in precision instruments on ships.

Inverter

A device that converts DC (direct current) electricity into AC (alternating current) — commonly used on ships to power AC devices from DC sources like batteries.

Iron

A strong, gray metal known for its excellent magnetic properties and its use in ship construction and machinery due to its strength and ductility.

Iron ore

A heavy cargo material with a stowage factor of about 0.4 to 0.5 m³ per ton — one of the densest and most commonly shipped bulk commodities.

IRONSAILOR

An automatic mooring system developed in New Zealand that helps ships moor (tie up) safely and efficiently without human intervention.

Itinerary:

A list of the ports a ship plans to visit during its voyage — used in planning, scheduling, and customs documentation.

ITTC Performance Prediction Method (1978)

A standard method developed by the International Towing Tank Conference for predicting the performance (like speed and fuel use) of full-scale ships based on model test data.

Maritime Glossary: J

Jack

A mechanical device used to lift heavy objects or apply strong force — often used on ships for lifting parts during maintenance or repairs.

Jacket

An outer protective covering, often used to refer to insulation or the casing around equipment, pipes, or a cylinder in an engine.

Jacket cooling water system

A system that circulates water around engine cylinders to absorb and carry away heat, keeping the engine at a safe operating temperature.

Jalousie

A type of shutter or cover made with angled slats (louvers) that allows air to flow through while keeping out rain, sunlight, or debris — commonly used in ship ventilation systems.

Jettison of cargo

The emergency act of throwing cargo or equipment overboard (called “jetsam”) to lighten the ship and improve safety during danger.

Joiner arrangement

Construction plans showing how interior ship structures like walls, ceilings, and panels are combined and connected — especially for accommodation areas.

Joule-Thomson effect:

A physical effect where a gas cools down when it expands without doing external work — used in refrigeration and gas liquefaction systems on ships.

Maritime Glossary: K

KAPPEL propeller

An advanced, curved-edge screw propeller designed to be more efficient and quieter than traditional ones, improving fuel economy and reducing cavitation.

Keel

The main structural backbone of a ship, running along the center bottom from front to back, supporting the entire hull structure.

Duct keel

A tunnel-like structure built along the centerline of the double bottom of a ship, used to carry pipes and cables safely through the hull.

Keel blocks

Heavy blocks (often made of wood or concrete) placed under a ship’s keel to support it in dry dock during construction or repair.

Kelly

A square or hexagonal pipe used in oil drilling, connecting the rotary table to the drill pipe to transfer rotation and allow vertical movement.

Key

A small, solid metal bar used to connect rotating machine parts (like gears or pulleys) to a shaft, ensuring they turn together.

Keyless fitting of fixed pitch propeller:

A method of mounting a propeller directly onto a shaft without using a key, by press-fitting it tightly to ensure secure, balanced rotation.

Keyway

The slot or groove in a shaft or hub where a key fits, enabling mechanical parts to rotate together without slipping.

Kinematic viscosity

A measure of how easily a fluid flows under gravity, calculated by dividing its internal resistance (viscosity) by its density.

Kingston valve

A sea valve installed at the hull’s bottom, used to control the intake or discharge of seawater, often for ballast or firefighting systems.

Knocking

A damaging engine condition where the fuel-air mix in a spark-ignition engine burns unevenly or too early, causing noise and performance loss.

Knot

A unit of speed used at sea, equal to one nautical mile per hour (1 knot ≈ 1.852 km/h or 1.15 mph).

Knuckle:

A sharp bend or angle in a ship’s structure, such as in the hull plating or at the junction of different parts (e.g., deck and side).

Kort nozzle

A circular shroud around a ship’s propeller that boosts thrust, especially useful for tugboats and slow-speed vessels needing high maneuverability.

KOTUG Rotor Tug

A type of advanced tugboat with three azimuth thrusters that allow 360° maneuvering, offering excellent control and pulling power from any angle.

Maritime Glossary: L

Ladder

Steps used on ships instead of stairs. A vertical ladder is very steep, almost straight up and down, used where space is limited.

Lagging

Insulating material wrapped around hot surfaces like steam pipes or boiler parts to reduce heat loss and protect crew from burns.

Laid-up tonnage

Ships that are temporarily out of service—either stored, waiting for repairs, or not in use due to economic or other reasons.

Laker:

A cargo ship designed for use only in the Great Lakes of North America. These ships usually transport bulk materials like iron ore or grain.

Laminar flow

A smooth, orderly flow of liquid or gas in parallel layers, with minimal mixing between them—common in low-speed flow conditions.

Lamination

A structural defect in metal where thin, flat, non-metallic inclusions are layered inside, weakening the material and reducing safety.

Landmarks

Visible objects on land such as towers, mountains, or buildings used by sailors for navigation and position fixing.

Lap joint

A method of joining two pieces of material (often metal) by overlapping them and then welding or bolting them together.

LASH (Lighter Aboard Ship)

A transport system where small barges (lighters) are loaded onto a larger ship, allowing cargo to move between inland waterways and the sea.

Lashing

Chains, straps, or ropes used to tie down and secure cargo to prevent movement during a voyage. Especially important for containers.

Lashing bridge

A strong steel platform between hatch covers where containers are secured and lashed to prevent movement at sea.

Latent heat

The energy needed to change the state of a substance (like melting ice or boiling water) without changing its temperature.

Launch

A small motorboat used for transport in harbors or near the shore, not meant for open sea or rough waters.

Launch and recovery system of the underwater unit

Equipment used to safely lower and lift underwater vehicles or systems (like ROVs) from the ship to the sea and back.

Launching

The process of transferring a ship from land into the water, often by sliding it down a ramp or using a mechanical lift.

Launching appliance or arrangement:

Equipment used to lower survival craft (like lifeboats or rescue boats) from a ship into the water safely and quickly in an emergency.

Launching ramp angle

The angle between the launch rails (or track) and the horizontal surface. This affects how easily a boat slides into the water.

Launching ramp length

The total distance from the back of a lifeboat (stern) to the end of the ramp where it enters the water.

Layout

The arrangement or placement of equipment and machinery in areas like engine rooms or control spaces for safety and efficiency.

Laytime

The agreed amount of time a ship is allowed to load or unload cargo at a port under a charter party. Extra time may incur penalties (demurrage).

Lay-up

When a ship is taken out of service temporarily due to low demand or high operating costs. The ship is usually anchored or moored safely.

Leading pair

The first set of folding hatch cover panels on a cargo hold that move during opening or closing.

Leak

An unintended escape of fluid (like water, oil, or gas) through a crack, hole, or seal failure on a ship.

Lean burn engine

An engine that runs with more air than fuel in the mixture, improving fuel efficiency and reducing emissions.

Length (L) of the ship

Different ship lengths are measured depending on purpose—such as for design, loading, or legal compliance.

Length on waterline

The length of the ship measured along the waterline from the bow (front) to stern (back). Important for hydrodynamic calculations.

Length overall (LOA)

The total length of the ship from the foremost to the aftmost points, including any extensions.

Level gauging system of the oil tanker UNITED GRACE

A system used on the tanker UNITED GRACE to monitor how much liquid (oil) is in the cargo tanks, often electronically.

Lifeboat

A motor-propelled survival craft carried by a ship for use in emergencies. A ship should be equipped with a sufficient number of lifeboats to accommodate all persons onboard in case of evacuation.

Lifeboat Davits

Lifeboat davits are mechanical devices used to lower lifeboats from the deck to the sea. They must be capable of turning out the lifeboats against an adverse heel of up to 20°, ensuring operability even when the ship is listing.

Lifeboat Station

A designated place on the ship where crew and passengers must assemble during emergency drills or actual abandon-ship situations. Each person is assigned to a specific station.

Lifebuoy

A ring-shaped floating life preserver thrown overboard to assist someone who has fallen into the water. Lifebuoys are equipped with reflective tape, grab lines, and may include a self-igniting light or smoke signal.

Lifejacket

A personal flotation device designed to keep an individual afloat and maintain their airway above water, even if the person is unconscious. Lifejackets are mandatory for all persons on board.

Liferaft

A rigid or inflatable raft designed to carry people abandoning ship. Liferafts can be automatically or manually deployed and typically include survival equipment.

Davit-Launched Liferaft

A type of liferaft that is connected to a davit system, allowing it to be lowered into the sea from the ship’s deck in a controlled manner, especially useful when quick and safe launching is needed.

Reversible Liferaft

A liferaft designed to function regardless of which side it lands on in the water. It provides canopy protection in either orientation, eliminating the need to right it manually.

Self-Righting Liferaft

A liferaft that automatically turns from a capsized position to an upright position, enhancing safety in rough sea conditions.

Throw-Over Liferaft

A liferaft that is manually thrown overboard from its cradle. It inflates upon contact with the water, allowing occupants to board it from the water or by ladder.

Liferaft Equipment (SOLAS A Pack)

Liferafts are equipped with survival gear as per SOLAS regulations. A “SOLAS A” pack includes more extensive equipment for long voyages, such as food rations, water, flares, fishing gear, and medical supplies.

Liferaft Painter System

A line that connects the liferaft to the ship. When pulled, it triggers the inflation of the liferaft. It also ensures the raft remains tethered to the ship during deployment.

Life-Saving System

A comprehensive system onboard that includes lifeboats, liferafts, lifejackets, lifebuoys, and emergency escape routes. It ensures all personnel can evacuate the ship safely in an emergency.

Lift-and-Roll Cover

A type of hatch cover lifted using hydraulic jacks or wheel lifts. Once elevated, it rolls to the side to provide access to cargo holds.

Lift-Away Cover

A hatch cover removed entirely from the coaming using shipboard or shore-based cranes. It provides full overhead access to cargo spaces.

Lifting Beam

A structural beam, typically of H-section, used in cargo handling. It helps distribute weight evenly when lifting heavy or awkwardly shaped items with cranes.

Lighthouses

Tall, solid towers located along coastlines. By day, they act as navigation landmarks, and by night, they display lights to guide mariners and warn of dangerous areas.

Lightening Hole

A hole cut into structural members (like girders or frames) to reduce overall weight without significantly affecting strength.

Lighter

A flat-bottomed barge used to transfer cargo between a ship and the shore, especially where port facilities are not available for large vessels.

Lighterage

The process of transporting cargo using lighters. It also refers to the fee charged for such transportation.

Lightest Seagoing Condition

A ship’s loading condition where it is on an even keel with no cargo, ballast, consumables, or crew on board. It is used for stability calculations and inspections.

Lighting

Lighting in crew and work areas should be sufficient to perform tasks safely and effectively. It should also contribute to crew comfort and well-being.

General Lighting

Lighting designed to provide a uniform level of illuminance throughout an area, ensuring adequate visibility for general tasks and safe movement.

Task Lighting

Lighting provided to meet the illuminance requirements of a specific task. It enhances visibility for detailed work such as chart reading, maintenance, or inspections.

Lightship

A specially constructed ship or vessel without any cargo, ballast, fuel, crew, or provisions. It serves as a reference for weight and stability calculations.

Lightship Draught

The mean draught (depth below the waterline) of a vessel in its lightship condition, i.e., when it is empty of cargo, ballast, fuel, etc.

Lightship Mass

The mass of the vessel, in metric tons, excluding cargo, fuel, lubricants, ballast water, stores, and crew. It includes the structure, machinery, and equipment.

Lightship Mass Coefficient

A parameter used in ship design to estimate the lightship mass during the preliminary design phase. It plays a crucial role in stability and performance predictions.

Lightships

Red-painted ships anchored in hazardous areas such as rocks or reefs. They act as floating lighthouses, equipped with lights and sound signals to warn ships.

Limber Hole

A small hole cut in a structural member, such as a frame or plate, near the base to allow water to drain through to the bilge for pumping out.

Line Throwing Appliance

A device (gun or rocket-based) designed to throw a light line between ships or from ship to shore. It is essential for emergency towing or rescue operations.

Liner Conference

An agreement among shipping companies operating on the same trade routes to coordinate schedules, tariffs, and service conditions for efficiency and fair competition.

Liner Service

A shipping service provided by cargo ships operating on fixed routes and regular schedules, offering consistent service between specified ports.

Linkspan

An adjustable bridge ramp at a ro-ro (roll-on/roll-off) berth that connects the vessel to the shore, allowing vehicles to roll on and off the ship efficiently.

Double-Level Linkspan

A specially designed linkspan with two or more levels to accommodate ro-ro ferries with multiple vehicle decks, enabling faster and more flexible loading.

Lip Seal

A type of shaft seal used to prevent seawater from entering and oil from leaking out of the stern tube. It helps maintain propulsion system integrity.

Liquefaction

The process of converting a gas into a liquid state, typically through cooling or pressure. In shipping, it refers to liquefying gases for easier transport.

Liquefied CO₂ Carrier – CORAL CARBONIC

A specialized ship designed to transport liquefied carbon dioxide (CO₂) under pressure and low temperatures. The CORAL CARBONIC is a known example.

Liquefied Natural Gas (LNG)

Natural gas cooled to -162°C to become a liquid for easier storage and transportation. It is mainly composed of methane and used as a cleaner fuel alternative.

Liquefied Petroleum Gas (LPG)

A hydrocarbon gas liquefied through pressurization, typically propane or butane. It is a by-product of natural gas processing and crude oil refining.

Liquid Cargo

Any cargo with a vapor pressure below 2.75 bar absolute at 37.8°C. It includes products like crude oil, chemicals, and fuel oils.

Liquid Cargo Ships

Also known as tankers, these vessels are designed to carry liquid cargo in bulk, using special tanks and pumping systems.

Liquid Chemical Waste

Hazardous waste in liquid form, often transported for disposal or recycling. It must be handled according to strict environmental regulations.

Liquid Penetrant Inspection

A non-destructive testing (NDT) method used for surface inspection of welds or materials. It involves applying a liquid dye to reveal surface cracks or defects.

Liquid Pitch Carrier – SUNBIRD ARROW

A specialized vessel designed to transport hot liquid pitch (a tar-like substance). The SUNBIRD ARROW is an example of such a carrier.

Liquid Transfer Operations

Operations involving the loading or discharging of liquid cargo, including ballast management. These are conducted under strict safety protocols.

List

A condition where a ship leans to one side (port or starboard) due to uneven weight distribution. It affects stability and can indicate a serious problem.

List Indication Lights

Lights installed on the deck that show visually when the vessel is listing and to what degree. They help crew monitor the ship’s stability.

Livestock Carriers

Ships specially designed to transport live animals. They include ventilation, drainage, and feeding systems to ensure the well-being of the livestock.

LNG Cargo Containment Systems

Systems within LNG carriers used to safely contain liquefied natural gas. Key types include membrane tanks and spherical Moss-type tanks, ensuring insulation and pressure control.

LNG Re-gasification Vessel – GDF SUEZ NEPTUNE

A floating terminal capable of receiving LNG, converting it back to gas (re-gasification), and delivering it to shore. GDF SUEZ NEPTUNE is a notable example.

LNG Reliquefaction System

A system onboard LNG carriers that re-condenses boil-off gas from LNG back into liquid form for storage, reducing cargo loss and improving efficiency.

LNG RV (LNG Re-gasification Vessel)

A specialized LNG tanker equipped with onboard systems to convert LNG back into gaseous form and deliver it directly to shore-based gas grids.

LNG Tanker

A highly specialized gas carrier designed to transport liquefied natural gas (LNG). These tankers feature advanced insulation and containment systems to maintain cryogenic temperatures.

LNG Tanker – BRITISH EMERALD

An LNG carrier known for its advanced cargo containment systems and energy-efficient design, part of the new generation of LNG ships.

LNG Tanker – GAZ DE FRANCE ENERGY

An LNG carrier operated under the Gaz de France fleet, designed to transport LNG with high safety and efficiency standards.

Load Line Convention

See: International Convention on Load Lines, 1966 – a treaty setting standards for ship load lines to ensure vessel stability and safety.

Load Line Mark

A mark located amidships on both sides of a vessel indicating the maximum depth to which the ship can be safely loaded under various conditions.

Loader

Shore-based mechanical equipment (e.g., conveyors, cranes) used to load cargo into the holds of a ship efficiently.

Loading and Stability Manual

A manual required under the SOLAS Convention for passenger ships and cargo vessels, containing instructions on safe loading, ballasting, and stability.

Loading Arms

Articulated mechanical arms used at port terminals to connect to ships and transfer liquid or gas cargo during loading and unloading operations.

Alternate Hold Loading Condition

A cargo loading method where every other cargo hold is filled (e.g., for iron ore), used to reduce stress on the ship’s structure.

Block Hold Loading Condition

A loading pattern in which contiguous cargo holds are loaded with cargo, usually at the center of the ship, to balance structural loads.

Homogeneous Hold Loading Condition

A loading method where all cargo holds are loaded with similar cargo type and weight to maintain uniform distribution and balance.

Loading Instrument

An onboard device or software used to calculate and monitor the ship’s stability, stress conditions, and compliance with loading limits.

Loading Overall

The process of loading cargo or ballast directly from above using open-ended pipes or other top-filling methods.

Loading Rate

The speed at which cargo is loaded into the ship, typically measured in tons per hour, dependent on the equipment and cargo type.

Loads (on Ships)

A ship experiences several types of loads at sea, such as wave impact, cargo weight, wind, and internal structural stress.

Bending Load

A force that causes bending stresses within a ship’s structure, such as hogging and sagging in waves.

Critical Load

The maximum load that a structure can bear before undergoing a significant change, such as structural failure or buckling.

Distributed Load

A load that results in motion or acceleration of the ship or its parts, caused by waves, vibration, or engine thrust.

Environmental Load

Forces from environmental sources like wind, waves, current, and ice acting on the ship’s structure.

Static Load

A stationary or constant load that causes internal stresses without motion, such as the ship’s deadweight.

Local Fire Protection

Fire protection requirements specific to areas on board, such as engine rooms or accommodation areas, especially in larger vessels (500GT+ for passengers; 2000GT+ for cargo).

Location

The act of determining the position of ships, aircraft, or persons in distress, essential in search and rescue operations.

Lock

An enclosed chamber in canals or rivers with gates that raise or lower ships by filling or draining water, enabling navigation between different water levels.

Lofting

A shipbuilding process where full-scale templates of ship components are drawn out to ensure accurate construction of the hull and parts.

Log

A navigational device used to measure the speed and distance traveled by a ship through water.

Log Book

An official record maintained by the ship’s master, documenting navigation details, operations, weather, incidents, and daily activity.

Longitudinals

Structural members running lengthwise along the ship, providing strength to resist bending and improve overall hull integrity.

Longliner

A fishing vessel using a long fishing line with many baited hooks, suspended from buoys and deployed over long distances.

Louver

A slatted opening, often in a ventilation system, designed to allow air flow while preventing the entry of rain or debris.

Low Flame-Spread

A characteristic of materials that limits the speed at which flames spread over the surface, crucial for fire safety onboard.

Low Heat Value (LHV)

The energy content of fuel excluding the heat of vaporization of water formed during combustion. It reflects the usable energy output.

Low NOx Combustion

A combustion process developed (e.g., by Wärtsilä) to minimize nitrogen oxide (NOx) emissions, improving engine environmental performance.

Low Loss Concept

A design and operational strategy aimed at minimizing energy loss in marine electrical systems, enhancing efficiency and reducing emissions.

LPG Reliquefaction Plant

An onboard system in LPG tankers that re-condenses boil-off gas from liquefied petroleum gas (LPG) cargo back into liquid form, ensuring minimal product loss during transport.

LPG Tanker

A gas carrier specifically designed to transport liquefied petroleum gases (such as propane and butane) in bulk. These vessels are equipped with pressurized, semi-pressurized, or fully refrigerated cargo containment systems.

LPG Tanker – CELANOVA

A named LPG carrier, part of a fleet transporting petroleum gases globally, typically featuring advanced cargo handling and reliquefaction technology.

Lubricating Oil

A product derived from crude oil refining, used in machinery and engines to reduce friction and wear between moving parts, improve efficiency, and dissipate heat.

Lubrication

The act of applying lubricants to moving parts in engines or machinery to reduce friction, prevent wear, and enhance performance and longevity.

Luff (to)

A verb used in crane and derrick operations, meaning to raise or lower the boom or jib vertically in order to position the lifting gear correctly.

Lumber Carrier

A specialized cargo ship designed to transport lumber, timber, and other wood-based products. These vessels often have large, unobstructed cargo holds and are equipped for deck cargo.

Luminaire

A complete lighting fixture, including one or more lamps (bulbs), along with components such as reflectors, lenses, and housings, designed to distribute and support lighting effectively.

Luminance

A measure of the brightness of a light source or the light reflected from a surface, typically expressed in candelas per square meter (cd/m²).

Maritime Glossary: M

Machinery spaces

Machinery spaces refer to the compartments onboard a ship that house various machines and equipment necessary for operation, including engines, pumps, and generators. These spaces are often categorized for safety and fire protection and must be properly ventilated and monitored to ensure smooth ship operations.

Unmanned machinery space (UMS)

Unmanned Machinery Space is a setup where engine rooms and related spaces are operated without the constant presence of personnel, being monitored and controlled remotely from the ship’s bridge using automated systems and alarms.

Machinery spaces of category A

These are specific machinery spaces containing internal combustion engines or boilers used for propulsion or other heavy-duty purposes. Due to the risk of fire, these spaces have strict safety regulations, including fire suppression and detection systems.

Magna flux

Magna flux, short for magnetic flux inspection, is a non-destructive testing method used to detect surface and near-surface flaws in ferromagnetic materials like steel. It involves magnetizing the material and applying iron particles to reveal cracks or discontinuities.

Magnetic particle test

This test uses magnetic fields and fine iron particles to detect cracks in metals. When the particles are applied to a magnetized surface, they accumulate at discontinuities, making invisible flaws visible to inspectors without damaging the material.

Maiden voyage

A maiden voyage is the very first journey undertaken by a newly built ship after it has been delivered to its owner. It is often a ceremonial event, sometimes including VIP guests, media coverage, and public interest, marking the ship’s entry into active service.

Main engine lubricating oil system

This system is essential for supplying lubricating oil to key parts of the main engine, such as bearings and pistons. It reduces friction, cools components, and helps prevent wear and tear, ensuring efficient and long-lasting engine performance.

Main generating station

The main generating station is the area on the ship where the primary electricity-generating equipment is located. It typically includes generators powered by diesel engines that supply power for all onboard systems and operations.

Main propulsion power:

This refers to the total amount of energy delivered by the ship’s main engines to propel the vessel forward. It is a critical metric in ship design and operation, directly influencing speed, fuel consumption, and engine sizing.

Main source of electrical power

The main source of electrical power on a ship is the primary electrical generation system that powers essential equipment, lighting, navigation systems, and other onboard operations. It usually consists of multiple generators to ensure redundancy.

Main vertical zones

These are vertical sections of a ship divided by fire-resistant bulkheads, designed to contain fires and prevent them from spreading vertically through the vessel, contributing to safer evacuation and firefighting.

Maintainability

Maintainability is the measure of how quickly and efficiently a ship’s systems or equipment can be restored to full function after a fault, which depends on system design, ease of access, availability of tools, and crew training.

Maintenance

Maintenance includes all procedures and actions taken to keep a ship’s equipment and systems running reliably. It involves routine inspections, cleaning, part replacements, and repairs to prevent breakdowns and ensure safety.

Breakdown maintenance

This type of maintenance is performed only after equipment fails or breaks down. While it may seem cost-saving initially, it can lead to higher repair costs, downtime, and operational risks in the long run.

Condition based maintenance (CBM)

CBM uses sensors and monitoring equipment to assess the real-time condition of machinery. Maintenance is only performed when data indicates signs of wear or performance issues, increasing efficiency and reducing unnecessary repairs.

Planned maintenance

Planned maintenance involves scheduling routine checks, servicing, and part replacements at set intervals to prevent equipment failure. It is a proactive approach that helps improve reliability and extend the service life of systems.

Maintenance costs

These are the expenses involved in performing maintenance activities, including spare parts, labor, tools, and downtime costs. Effective maintenance planning aims to keep these costs low while ensuring high equipment reliability.

Maintenance of class:

Ships are regularly surveyed by classification societies to ensure they meet the required technical standards. Maintaining class certification is essential for legal operation, insurance, and port entry permissions.

Maintenance work

Any task carried out to fix, restore, or service a ship’s system or equipment falls under maintenance work. It can range from simple checks and lubrication to complex overhauls and part replacements.

Maintenance tools

Specialized tools are often required for maintaining different onboard systems. These may include torque wrenches, diagnostic meters, hydraulic jacks, and manufacturer-specific kits designed for precise and safe servicing.

Major failure of tanker

This refers to a significant structural issue, such as a rupture or deformation in a cargo tank, often due to collision, grounding, or design failure. Such incidents pose serious safety, environmental, and financial risks.

Mandel shackle

A mandel shackle is a strong, specially-designed connector used to join a wire rope (mooring line) to a synthetic tail. It provides flexibility and strength needed during berthing and mooring operations.

Manhole

A manhole is an access opening, often circular or oval, in tanks, pipelines, or compartments, allowing crew to enter enclosed spaces for inspection, cleaning, or maintenance. Low-positioned manholes may require crouching or crawling.

Manifold

A manifold is a central pipe assembly used to connect various pipelines and valves. On tankers, the cargo manifold is where hoses or loading arms connect for the transfer of oil or chemicals.

Manipulator

A manipulator is a robotic or remote-controlled arm used for tasks in hazardous or hard-to-reach areas, such as underwater repairs, welding, or nuclear inspections, enhancing crew safety and precision.

Manned facility

A manned facility refers to a structure, such as an offshore platform or ship, that includes living accommodations and is permanently occupied by personnel for operational or safety purposes.

Manning

Manning refers to the number and composition of crew members assigned to a vessel, determined by ship size, type, and international regulations to ensure safe and efficient operation.

Manoeuvring characteristics

These are the behavioral traits of a ship while turning, stopping, or changing course. They depend on hull shape, rudder design, propeller type, and sea conditions and are critical for safe navigation and docking.

Inherent dynamic stability

This term describes a ship’s natural tendency to return to a straight course after a small disturbance, without requiring corrective steering, reflecting the vessel’s stability in dynamic sea conditions.

Course-keeping ability

This is the ship’s capacity to maintain a steady course with minimal rudder input, and it serves as a key indicator of directional stability during navigation.

Initial turning/course-changing ability

This refers to how quickly and effectively a ship can begin turning once the rudder is applied, measured by the rate of heading change early in the manoeuvre.

Yaw checking ability

Yaw checking ability measures a ship’s capability to stabilize itself and return to a steady course after an oversteering movement, indicating its responsiveness and course control.

Turning ability

Turning ability defines how well a ship can perform a full turn using maximum rudder angle, often measured through the tactical diameter and advance during turning circle tests.

Stopping ability

A ship’s stopping ability is assessed by how far and how long it takes to come to a complete stop (dead in water) after full astern is applied from a given speed, known as track reach and stopping time.

Manoeuvring criteria

These are internationally recognized benchmarks used to assess whether a vessel meets acceptable manoeuvring standards, such as turning diameter, advance, and zig-zag response.

Manoeuvring Information

Includes key ship handling data such as the pilot card, wheelhouse poster, and manoeuvring booklet, all of which help bridge officers and pilots during navigation.

Pilot card

Provided to the pilot upon boarding, the pilot card contains essential data about the ship’s handling characteristics, propulsion, and steering systems for safe and efficient control.

Wheelhouse poster

A permanent display in the ship’s bridge area, the wheelhouse poster summarizes the ship’s manoeuvring performance and characteristics for quick reference by officers.

Manoeuvring booklet

This document provides detailed test results and operational limits for a ship’s manoeuvring capabilities, required to be onboard for reference and safety compliance.

Advance

The advance is the distance a ship moves forward in the original course direction during a turn, measured from the point the rudder is first applied until the ship is 90° off its original heading.

Tactical diameter

Tactical diameter is the distance a ship’s midship point travels along the original course direction during a 180° turn using full rudder.

Test speed’

A designated speed, typically 90% of the vessel’s speed at 85% of maximum engine power, used during sea trials to evaluate manoeuvring performance.

Track reach

This is the distance the ship travels along its path from the moment full astern is applied until the ship comes to a complete stop (dead in water).

Manoeuvring speed

This refers to the reduced speed maintained by a vessel when navigating in constrained waters such as harbors, canals, or nearshore areas.

Manoeuvring tests

These full-scale trials, conducted during sea trials, assess a ship’s handling characteristics, including turning, stopping, and yaw response.

Man-overboard manoeuvre (Williamson turn)

A specific turn used when someone falls overboard, the Williamson turn brings the vessel back on a reciprocal course to aid search and recovery.

Pull-out manoeuvre

After completing a steady turning circle, the rudder is centered to assess how the ship exits the turn and returns to a straight path, testing stability and yaw checking.

Turning circle manoeuvre

This test involves applying the rudder hard over from straight motion at test speed to determine the ship’s turning diameter and advance.

Zig-zag test

In this test, the rudder is alternated in 10° increments to each side to assess how quickly the ship changes heading and stabilizes, measuring yaw response and course stability.

Manoeuvring stations

These are designated operational areas onboard a ship such as the forecastle, stern, pilot boarding station, and muster stations, where crew perform specific duties during manoeuvres.

Margin line

A safety-related horizontal line drawn at least 76 mm below the upper surface of the bulkhead deck, used to determine intact stability and subdivision requirements.

Margin plate

The outermost plating of a ship’s inner bottom structure, running alongside the tank top and providing structural support near the ship’s side shell.

MARIN

The Maritime Research Institute Netherlands, established in 1929, is a world-leading research facility in maritime technology and hydrodynamic studies.

MARIN ARK

A ship evacuation system developed by RFD, MARIN ARK facilitates safe and rapid evacuation using inflatable liferafts and slides in marine emergencies.

Marine evacuation systems (MES)

These are rapid-deployment systems, often including slides and liferafts, designed to quickly evacuate passengers and crew from a ship to the sea.

Dry shod marine rapid evacuation system

Developed by Dunlop-Beaufort, this MES allows people to evacuate a vessel without getting wet, using enclosed slides and rafts.

Rigid evacuation slide

A fixed or semi-fixed evacuation slide system introduced by Marine Safety of Norway for rapid and stable disembarkation in emergencies.

Twin-track-slide marine evacuation system

This system uses two inflatable slides side-by-side to ensure faster and safer evacuation during emergencies, often connected to life rafts.

Vertical escape chute system

Introduced by Selantic Safety AS, this vertical evacuation method uses a chute and life raft to allow personnel to descend safely in limited deck space.

Marine fuel oils

These are heavy residual fuels, including HFO (heavy fuel oil), widely used in ship engines due to their high energy content and cost-efficiency despite environmental concerns.

Marine riser

A large, flexible pipe that connects subsea blowout preventers on the sea floor to surface drilling platforms, allowing fluid transfer during offshore drilling operations.

Maritime Safety Committee (MSC)

A top-level technical committee of the IMO, the MSC is responsible for developing regulations related to maritime safety, navigation, and ship construction.

Maritime industrial organizations

These include international bodies and associations representing shipping companies, maritime workers, and industry stakeholders that advocate for safety, regulation, and industry standards.

International Association of Dry Cargo Shipowners (INTERCARGO)

This organization represents dry bulk shipowners, focusing on safe, efficient, and environmentally sound dry cargo shipping.

Baltic International Maritime Council (BIMCO)

One of the largest international shipping associations, BIMCO provides contracts, advice, and policy support to shipping companies worldwide.

Chamber of Shipping (ICS)

The International Chamber of Shipping is a global trade association that represents the interests of merchant shipowners and operators across all sectors.

International Shipping Federation (ISF)

This federation advocates on behalf of shipowners on labor and employment issues, especially in relation to the International Labour Organization (ILO).

Society of Gas as Marine Fuel (SGMF)

SGMF promotes safe and efficient use of gas as a marine fuel by setting operational guidelines and supporting technical innovation in the field.

Society of International Gas Tankers and Terminal Operators (SIGTTO)

SIGTTO is an industry body that develops safety and operational standards for the gas shipping and terminal industry.

Maritime inquiry

A maritime inquiry is conducted by authorized maritime and legal bodies following a marine accident or incident to determine the cause, assess liability, and recommend safety measures to prevent future occurrences.

Maritime safety information

Maritime safety information includes navigational warnings, weather forecasts, storm alerts, and other data essential for the safe navigation of vessels, often broadcast via radio and satellite systems.

Mark III system

The Technigaz Mark III LNG cargo containment system features a primary barrier made of 1.2 mm thick stainless steel supported by insulation panels to minimize heat ingress and maintain LNG at cryogenic temperatures.

MARPOL 73/78

The MARPOL 73/78 Convention is the main global agreement for preventing marine pollution from ships due to operational or accidental causes, covering oil, chemicals, sewage, garbage, and air emissions.

MARPOL 73/78 Annex I

Annex I addresses oil pollution prevention, requiring ships to have oil filtering equipment, oil discharge monitoring systems, and procedures to manage oil spills and bilge discharges.

MARPOL 73/78 Annex II

Annex II controls the discharge of noxious liquid substances in bulk, requiring tank washing procedures, discharge criteria, and mandatory cargo record books for chemical tankers.

Packaged Form

Dangerous goods carried in packaged form account for about 15% of marine cargo and are regulated to prevent accidents and environmental damage during transport by sea.

MARPOL 73/78 Annex III

Annex III sets out guidelines for labeling, documentation, packaging, and stowage of harmful substances carried in packaged form to prevent marine pollution during shipping.

MARPOL 73/78 Annex IV

This annex provides regulations for controlling sewage discharge from ships, mandating treatment plants or holding tanks and restricting discharge near coastal areas and ports.

MARPOL 73/78 Annex V

Annex V focuses on garbage management, prohibiting the dumping of plastics at sea and restricting other types of waste depending on the ship’s location and distance from land.

MARPOL 73/78 Annex VI

Annex VI limits air pollution from ships by regulating sulphur content in fuel, controlling nitrogen oxide emissions, and setting energy efficiency standards for vessels.

MARSEC

MARSEC (Maritime Security) levels are used by the U.S. Coast Guard to define the security status of ships and port facilities, with escalating measures at Levels 1, 2, and 3 based on threat level.

MARVS

The Maximum Allowable Relief Valve Setting (MARVS) is the highest pressure at which a cargo tank’s safety valve can open, as specified under the International Gas Carrier (IGC) Code.

Mass disease

A mass disease outbreak involves an infectious illness affecting more than two people aboard a ship, which can trigger health protocols and quarantine measures.

Mast

A mast is a steel structure on a ship used to mount navigational and communication equipment like radar, lights, antennas, and signal flags, contributing to safe operations.

Master controller

In a cascade control system, a master controller regulates a primary variable by generating a setpoint for a secondary controller, helping maintain stable system performance.

Maximum ahead service speed

This refers to the top continuous speed a ship can sustain under normal service conditions when moving forward, typically used for voyage planning.

Maximum astern speed

This is the highest speed a ship can achieve in reverse using full astern propulsion, important during emergency maneuvers or docking operations.

Maximum continuous rating (MCR) of engine

The MCR is the highest power output an engine can safely operate at continuously under specified conditions without causing damage.

Mayday

“Mayday” is the internationally recognized radio distress signal used in life-threatening emergencies at sea, requiring immediate assistance.

MCF

MCF stands for 1,000 cubic feet, a unit commonly used to measure volumes of natural gas, equal to approximately 28.3168 cubic meters.

Mean time between failures

This is a reliability metric indicating the average time a system or component operates before failing, useful in assessing equipment performance and maintenance needs.

Means of rescue (MOR)

Means of rescue refers to equipment or systems onboard that allow for quick and safe retrieval of people from the water, especially during emergencies.

AB Welin’s MOR system

This rescue system uses a floating rigid platform to recover survivors from water and can be launched quickly from the ship’s side to facilitate safe boarding.

Mechanical efficiency

Mechanical efficiency is the ratio of output shaft power to input power in an engine, showing how effectively an engine converts fuel energy into mechanical work.

Mechanical seal

A mechanical seal replaces the traditional stuffing box in pumps, providing a tight seal around a rotating shaft to prevent leaks and reduce maintenance.

Medium-speed engine

These engines operate between 250 and 900 revolutions per minute (RPM) and are widely used in marine applications due to their fuel efficiency and durability.

Melting

Melting is the physical process of a solid changing into a liquid when heated to its melting point, such as ice turning into water or metal liquefying in a furnace.

Membrane BioReactor (MBR)

Wärtsilä Hamworthy’s MBR is an advanced sewage treatment system combining biological treatment and membrane filtration to meet strict effluent standards at sea.

Membrane containment system of HANJIN MUSCAT

This refers to the LNG containment technology used aboard the HANJIN MUSCAT, likely featuring a membrane-based design to safely store cryogenic LNG.

Membrane technology

In marine applications, membrane technology is used for filtration, LNG storage, and gas generation, providing lightweight and space-efficient solutions.

Membrane-type LNG cargo containment system

This system uses a thin metal membrane supported by insulation to store LNG within the ship’s double hull, reducing heat ingress and maintaining cryogenic conditions.

Membrane type Nitrogen Generator System

This system separates nitrogen from air using semi-permeable membranes, supplying inert gas for tank blanketing and fire prevention on tankers.

Memorandum of Understanding on Port State Control (MOU)

These agreements between countries enhance maritime safety by ensuring foreign ships comply with international regulations through inspections at ports.

Mermaid propulsion unit

Developed by Rolls-Royce, the Mermaid is a podded propulsion system combining an electric motor and steerable propeller to improve maneuverability and fuel efficiency.

Messenger line

A messenger line is a lightweight rope used to pull heavier mooring lines or hawsers ashore during berthing, making it easier to secure a ship to a dock.

Metacentre M (initial transverse metacentre)

The metacentre is a key point used in ship stability calculations; its position relative to the center of gravity determines whether a ship is stable when tilted.

Metacentric height

The metacentric height is the vertical distance between a ship’s center of gravity (G) and its metacenter (M). It is a key indicator of a vessel’s initial stability; a greater metacentric height generally means better stability and a quicker return to upright position after being heeled by wind or waves.

Methane hydrate

Methane hydrate is a solid, ice-like substance composed of water and methane. Found in ocean sediments and permafrost areas, it consists of methane molecules trapped within a lattice of water ice, forming under high pressure and low temperature, and is considered a potential future energy source.

Methanol carrier MILLENNIUM EXPLORER

The MILLENNIUM EXPLORER is a methanol carrier designed to safely transport methanol, a toxic and flammable chemical. These specialized vessels are equipped with advanced containment and ventilation systems to handle methanol’s hazards, ensuring both safety and efficiency during voyages.

Mevis duct – see POWER-SAVING DEVICES

The Mevis duct is a power-saving device installed ahead of a ship’s propeller. It optimizes water flow into the propeller, improving propulsion efficiency and reducing fuel consumption by creating a more uniform wake field.

Mezzanine decks

Mezzanine decks are lightweight, movable platforms commonly used on fast ferries to accommodate additional vehicles or freight. When traffic primarily consists of freight vehicles, these decks can be adjusted or folded to maximize space and improve loading efficiency.

Midship section

The midship section is the cross-sectional area of a ship taken at the midpoint of its length. It is crucial for analyzing structural strength and stability, as it represents the part of the hull subjected to the highest stresses during operation.

Midship section modulus

The midship section modulus refers to the structural strength of a ship’s hull at the midship area. It is a measure of the resistance to bending forces, and a higher section modulus indicates a more robust hull structure.

Mill scale

Mill scale is a flaky surface layer of iron oxide that forms on hot steel during production. While often removed before painting or coating, it can provide temporary protection against corrosion during storage and handling.

Miller timing

In Wärtsilä engines, Miller timing refers to the early closing of the intake valves, just before the piston reaches the bottom of its intake stroke. This improves engine efficiency and reduces nitrogen oxide (NOx) emissions by lowering peak combustion temperatures.

Mimic diagram

A mimic diagram is a simplified visual representation of a ship’s piping system or machinery layout. It uses symbols and lines to show connections and flow, helping operators monitor and control shipboard systems efficiently.

Minimum breaking load of a mooring line (MBL)

The minimum breaking load is the lowest force at which a mooring line will break. It is a critical safety factor in mooring operations, ensuring the line can withstand environmental and operational loads without failure.

Minimum comfortable condition of habitability

This refers to the baseline living conditions on a ship where essential services—such as lighting, water, and air conditioning—are maintained to support crew well-being and operational effectiveness, even in emergency or degraded scenarios.

Minor failure of tanker

A minor failure in a tanker refers to a localized structural defect, such as a small fracture or crack in a tank boundary weld. Though not catastrophic, it requires inspection and repair to prevent potential leaks or escalation.

Misalignment

Misalignment occurs when the rotational axes of two connected shafts do not line up perfectly. In marine machinery, this can lead to vibrations, increased wear, and potential mechanical failure if not corrected through proper alignment.

Mitsubishi Stator Fin

The Mitsubishi Stator Fin is an energy-saving device installed near the ship’s propeller. It enhances propulsion by redirecting water flow to reduce turbulence and rotational loss, thereby increasing fuel efficiency.

Mixed stowage

Mixed stowage refers to the method of placing 20-foot containers into 40-foot container cell guides on a ship. This approach maximizes cargo space utilization, especially when there is an imbalance in container sizes during loading.

MMBTU

MMBTU stands for one million British Thermal Units, a unit of energy used in natural gas and other energy-related industries. One BTU is the amount of energy needed to heat one pound of water by one degree Fahrenheit.

MMSCFD

MMSCFD means Million Standard Cubic Feet per Day, a volume measurement used primarily in the natural gas industry. It represents the amount of gas produced, processed, or transported in standardized conditions over a 24-hour period.

MOB RETRIEVAL EQUIPMENT

Man Overboard (MOB) retrieval equipment includes devices and systems used to recover individuals who have fallen into the water. Types range from throw ropes and ladders to mechanical recovery devices used in various sea states.

Cosalt Personnel Recovery Device (PRD)

The Cosalt PRD is a compact, safety-approved device designed to recover people from the water in MOB situations. It helps lift a person quickly and safely back onto the vessel without requiring additional crew to enter the water.

Dacon Rescue Frame

The Dacon Rescue Frame is a man-overboard recovery system that meets UKOOA 1997 guidelines. Approved by Norway’s Maritime Directorate, it enables the safe lifting of unconscious or injured persons from the water using a net-like cradle.

Double loop RLS

Developed at the University of Applied Sciences, the double loop Rescue Lifting System (RLS) is a new MOB device that secures a person in two loops for stable and safe vertical lifting from the water, even in rough conditions.

Rescue basket

A rescue basket is a metal frame with buoyant materials used for lifting people from the water, especially during helicopter rescues. The person climbs in or is placed in the basket, which is then hoisted aboard safely.

Mobdock

A Mobdock is a mobile, mini drydock system shaped like a steel box. It allows access to a ship’s hull below the waterline through an access hatch, enabling underwater repairs or inspections without docking the entire vessel.

MOBILE OFFSHORE DRILLING UNIT (MODUs)

MODUs are floating or mobile structures used to explore or extract oil and gas beneath the seabed. These include drillships, jack-ups, and semi-submersibles, each suited to different water depths and environmental conditions.

Drillship

A drillship is a vessel equipped with drilling equipment used to explore subsea oil and gas reserves. It remains on station using dynamic positioning or anchors and is ideal for deepwater exploration due to its mobility and onboard storage.

Mobile Offshore Units

Mobile Offshore Units are floating structures such as jack-up rigs or semi-submersibles used in oil exploration. Unlike MODUs, these units may not have full drilling capability and can be used for production, accommodation, or maintenance support.

Accommodation Unit

This type of offshore unit provides living quarters for crew working on offshore platforms. It includes sleeping areas, dining facilities, and safety equipment, and can be moored next to platforms during maintenance or construction work.

Construction and Maintenance Unit

These offshore units are used for construction, installation, or repair work on oil rigs, subsea pipelines, or wind farms. Equipped with cranes and workshops, they serve as mobile support bases at sea.

Crane Unit

A crane unit is a type of offshore platform designed specifically for heavy lifting operations. It is used to install or remove large structures like modules or equipment on offshore platforms or subsea foundations.

Drilling Tender

A drilling tender supports offshore drilling by supplying equipment, personnel, and storage. It is usually stationed next to a fixed platform or floating structure and provides logistics and technical backup during drilling operations.

Wind Turbine IMR Unit

This mobile offshore unit is designed for Installation, Maintenance, and Repair (IMR) of wind turbines at sea. It includes lifting gear and specialized tools to handle complex offshore wind infrastructure tasks safely and efficiently.

Model testing tanks

These are large, specialized basins used to conduct physical tests of ship models. They simulate real sea conditions to evaluate vessel resistance, propulsion, and seakeeping performance, often used alongside computer simulations.

Manoeuvring basin of UK Defence Evaluation and Research Agency (DERA)

This maneuvering basin is a controlled environment where ship models undergo tests for steering and maneuverability. It helps researchers understand ship behavior in tight navigation scenarios.

Model towing tank of UK Defence Evaluation and Research Agency (DERA)

This towing tank allows detailed study of a ship model’s resistance and propulsion under controlled water flow. It is part of the UK DERA’s efforts to support naval architecture and marine engineering research.

MODEL TESTS

Model tests are physical experiments carried out on scale models of ships to evaluate hydrodynamic performance. These tests complement computational fluid dynamics (CFD) simulations and provide essential data for ship design validation.

Resistance tests

Resistance tests determine how much drag a vessel experiences when moving through water. These are critical in designing energy-efficient hull forms by measuring forces acting on a model to estimate real-world fuel consumption.

Self-propulsion tests

In a self-propulsion test, the ship model is towed at specific speeds to simulate real operating conditions and determine the model’s propulsion characteristics. This helps estimate the full-scale ship’s performance by analyzing thrust, torque, and efficiency of the propulsion system under realistic flow conditions.

Propeller open water test

In this test, the propeller operates in uniform flow, separate from the hull, to evaluate its performance in ideal conditions. Though real-life operation involves non-uniform flow, the test provides vital data like thrust and torque curves to assess propeller efficiency independently.

Model tests of the 57,300 DWT bulk carrier at HSVA

Hydrodynamic model tests for a 57,300 DWT bulk carrier conducted at HSVA (Hamburg Ship Model Basin) are used to evaluate ship resistance, propulsion efficiency, and seakeeping performance. These tests help validate and optimize the vessel’s design before full-scale construction.

Modified atmosphere

Modified atmosphere involves controlling the composition of gases, such as increasing nitrogen levels, during the transport of fruits and vegetables. This technique slows down respiration and decay, thereby extending the shelf life of perishables during long voyages.

Molten sulphur/bitumen tanker FS CHARLOTTE

FS CHARLOTTE is a specialized tanker built to safely transport high-temperature cargoes like molten sulphur or bitumen. These vessels are designed with heated tanks and insulation systems to maintain cargo in liquid state during transit.

Moment

A moment is the turning effect of a force applied at a distance from a pivot point. It is calculated as the product of the force and its perpendicular distance from the point of rotation, commonly used in ship stability and structural calculations.

Moment of statical stability

This refers to the righting moment that attempts to restore a ship to its upright position after being heeled by external forces. It is a key indicator of a vessel’s initial stability and is vital for ensuring safe operations at sea.

Monitoring

Monitoring involves continuous observation of equipment and the surrounding environment to promptly detect any irregularities, malfunctions, or hazardous conditions, thus ensuring safe and efficient operation on ships and offshore platforms.

Monitoring system

A monitoring system is an integrated setup designed to track the operational status of shipboard machinery, providing real-time data and alerts to prevent failures and improve maintenance planning.

Monitoring workstation

A monitoring workstation is a dedicated area equipped with displays and controls where operators oversee the functioning of ship systems and environmental parameters, enabling timely decision-making and safety assurance.

Montreal Protocol

The Montreal Protocol is a global agreement signed in 1987 to phase out substances that deplete the ozone layer, such as CFCs and halons. It has played a significant role in protecting the environment and human health from harmful UV radiation.

Moonpool

A moonpool is a large vertical opening that extends through the hull of a vessel, allowing safe deployment and retrieval of subsea equipment in offshore drilling and research vessels without exposing personnel to harsh sea conditions.

Mooring

Mooring is the process of securing a ship to a fixed or floating object like a pier, buoy, or anchor using ropes, chains, or cables. This prevents movement due to wind, current, or tides while the vessel is stationary.

Multi-Buoy Moorings (MBM), conventional buoy moorings

MBM is a mooring setup where a tanker is held in position by multiple buoys and mooring lines, allowing safe loading and unloading operations offshore, especially in areas without dock infrastructure.

Single Point Mooring (SPM)

SPM is a floating buoy anchored offshore that allows tankers to moor by the bow and transfer cargo via flexible hoses. It enables large vessels to offload oil and gas without entering shallow ports.

Mooring and Towing Manual

This manual contains detailed information on the ship’s mooring and towing arrangements, including diagrams, equipment specifications, and operational procedures, serving as a vital guide for safe port operations.

Mooring drums

Mooring drums are cylindrical components of winches used to wind and store mooring lines. They can be split or non-split types, and their configuration affects how tension and storage of lines are managed during mooring operations.

Non-split type mooring drum

A non-split mooring drum is a single-piece drum used to store mooring lines. It is commonly found on smaller ships and offers a simpler design, though it may lack flexibility in separating line tensioning and storage functions.

Mooring equipment

Mooring equipment comprises all the tools necessary for securing a vessel, such as mooring winches, bollards, fairleads, bitts, and windlasses. These ensure that the vessel remains safely in position at a berth or offshore facility.

Mooring lines

Mooring lines are ropes or steel cables used to tie a ship securely to a quay, jetty, or buoy. They must be strong, flexible, and properly arranged to resist environmental forces and keep the vessel stable and secure.

Breast lines

Breast lines are mooring lines that extend perpendicularly from the ship to the shore, providing lateral restraint and limiting side-to-side movement of the vessel while moored.

Head lines

Head lines run from the forward part of a ship to the shore and are primarily responsible for preventing aft movement, helping keep the bow aligned and secure.

Spring lines

Spring lines are mooring lines that run diagonally, forward or aft from the ship to the berth. They control longitudinal movement, preventing the vessel from surging fore or aft while docked.

Stern lines

Stern lines run from the aft end of the ship to the quay and prevent the vessel from moving forward. These are critical for maintaining the vessel’s position and ensuring safe mooring at the stern.

Mooring restrain

Mooring restrain refers to the ability of the mooring system to counteract external forces such as wind, current, or wave action that attempt to move the vessel from its secured position.

Mooring retention

Mooring retention indicates the effectiveness of a mooring system, measured by the cumulative breaking strength of all lines used to keep the ship in place under extreme conditions.

Mooring trials

Mooring trials are conducted to test the ship’s main propulsion and control systems while the vessel is stationary at berth. These trials help ensure systems are operating correctly before sea trials begin.

Mooring winch

A mooring winch is a mechanical device used to handle mooring lines. It enables crew to pull in, let out, or hold lines under tension, ensuring precise control of the ship’s position during docking.

Mooring winch brake

The mooring winch brake is a critical safety feature that holds the mooring line in place once tensioned. It must be strong enough to prevent slippage under high loads, ensuring the vessel remains secure.

Band brakes

Band brakes use a friction band wrapped around a rotating drum. When the band tightens, it generates braking force through friction, similar to tying a rope around a capstan to control tension.

Mooring winches

Mooring winches are machines used to haul, store, and tension mooring lines. They come in different types and configurations and are essential for the safe and efficient docking of ships.

Manual tension mooring winch

This type of winch requires manual input to operate. It is typically used on smaller vessels or where automation is not necessary, relying on human power for line tensioning and adjustment.

Non-split drum mooring winch

A winch with an undivided drum, where tensioning and storing of the mooring line happen on the same drum surface. These are simple in design and found in smaller vessels.

Split drum mooring winch

A split drum winch features a central flange dividing the drum into two parts: one for line tensioning and the other for storage. This allows for more precise control and management of mooring lines.

Mooring winches drives

These drives power the winch systems and can vary in technology, such as electric or hydraulic. The choice depends on factors like vessel size, energy efficiency, and operational needs.

Frequency converter drive

This is a modern electric drive system that allows variable speed and torque control, offering high precision, energy savings, and smooth operation for mooring winches.

High-pressure drive

Operating at pressures between 200 to 280 bar, high-pressure hydraulic drives provide strong, responsive performance. They are compact and efficient, suitable for demanding winch operations.

Low-pressure drive

Low-pressure drives are easier to install and maintain, offering quieter operation and dynamic braking capabilities. These are often preferred in applications where noise and simplicity are key factors.

Three speed pole-change drive

The three-speed pole-change drive is an advanced electric motor that provides flexible speed options with minimal maintenance. By altering the number of magnetic poles in the stator winding, it enables the motor to operate at three different fixed speeds, making it suitable for marine applications where varying loads and energy efficiency are important.

Moss Rosenberg system

The Moss Rosenberg system is a spherical LNG cargo containment technology developed in Norway. This system uses independent, self-supporting spherical tanks that are mounted within the hull of the ship, offering safety, reliability, and ease of inspection and maintenance for transporting liquefied natural gas.

Motor enclosures

Motor enclosures are protective housings designed based on the environment in which the motor operates. Types include flameproof enclosures for hazardous areas, splash-proof for marine use, and totally enclosed designs to protect against dust and moisture, thereby ensuring motor safety and prolonged service life.

Motor starter

A motor starter is an electronic or electromechanical device used to safely start, stop, and protect motors. It controls the electrical power delivered to the motor, allowing smooth acceleration from rest to full speed while preventing overcurrent conditions that could damage the motor.

Moulded breadth extreme

The moulded breadth extreme is the widest horizontal measurement of a ship’s hull at any frame, excluding any external structure. It is a crucial design dimension used for stability analysis, classification, and ensuring compliance with port and docking restrictions.

Moulded depth

Moulded depth refers to the vertical distance measured from the top of the keel to the underside of the main deck at side, at the ship’s midsection. This dimension helps define the hull’s overall profile and is vital for hydrostatic calculations and structural design.

Moulded lines

Moulded lines are the set of curves used to represent the internal surface shape of a ship’s hull in design drawings. These lines are crucial for creating the form of the vessel and for planning construction without including the thickness of the outer plating or shell.

Multifunctional Subsea Operation Vessels

Multifunctional Subsea Operation Vessels are specially designed ships that support underwater activities such as pipeline inspections, maintenance, and remote-operated vehicle (ROV) deployment. These vessels are equipped with dynamic positioning systems and advanced deck equipment for versatile subsea tasks.

Multiple-container lifting

Multiple-container lifting is a port operation technique that uses spreaders capable of lifting two or three containers simultaneously. This significantly reduces container handling time, increases crane productivity, and improves the overall efficiency of container terminals.

Multi-purpose carrier NEPTUN TRADER

The NEPTUN TRADER is a versatile multi-purpose cargo ship capable of handling a wide variety of cargo types, from breakbulk and containers to heavy lifts. It is equipped with flexible cargo handling gear and adaptable holds, making it suitable for global trade routes.

Multi-purpose dry cargo vessel

A multi-purpose dry cargo vessel is generally a smaller ship with box-shaped holds that can carry a mix of cargo types such as containers, steel, or grain. Its design allows for greater flexibility in ports with different loading and discharge requirements.

Multi-purpose dry cargo vessel INNOGY SPRITE

The INNOGY SPRITE is a dry cargo vessel built to handle a wide range of freight, often operating on regional routes. Its box-shaped holds and efficient cargo gear enable it to transport everything from bulk commodities to packaged goods with ease.

Multi-purpose/forest product carrier SUOMIGRACHT

The SUOMIGRACHT is a specialized multi-purpose carrier designed to transport forest products such as logs, paper rolls, and pulp, along with general cargo. It features reinforced holds, cargo handling cranes, and weather-protected deck areas for sensitive cargoes.

Musketeer door

The Musketeer door, developed by the WINEL Company, is a marine-grade door featuring a unique locking mechanism for enhanced watertight integrity and operational safety. It is commonly used in ship compartments requiring secure closure in harsh maritime environments.

Mussel cutter CORNELIA YE-157

The CORNELIA YE-157 is a mussel fishing vessel highlighted in HSB International (June 1998) for its efficient harvesting design. It is equipped with specialized cutting and cleaning systems tailored for shellfish farming, ensuring sustainable and productive marine aquaculture operations.

Maritime Glossary: N

National authorities

National authorities refer to the government or maritime administration of a country where a ship is registered. They are responsible for ensuring compliance with international maritime laws, safety regulations, certification, and inspection standards applicable to vessels flying their flag.

Natural gas (dry)

Dry natural gas is a form of natural gas that has been processed to remove all liquid hydrocarbons and impurities. It consists mainly of methane and remains in a gaseous state under standard temperature and pressure, making it suitable for pipeline transport and as a clean-burning energy source.

Natural gas fuel

As stricter emission control regulations come into effect, natural gas has emerged as a promising marine fuel. It significantly reduces emissions of sulfur oxides (SOx), nitrogen oxides (NOx), and particulate matter, offering a cleaner alternative to traditional marine diesel.

Natural gas-fuelled ferry GLUTRA

The GLUTRA is a pioneering Norwegian ferry that became the world’s first vessel to operate entirely on liquefied natural gas (LNG). It demonstrated the feasibility of using LNG as a marine fuel, setting the stage for cleaner and more sustainable ferry operations.

Natural gas-fuelled ferry VIKING GRACE

The VIKING GRACE is a modern cruise ferry operating in the Baltic Sea that uses LNG as its primary fuel. Built with advanced environmental technologies, it produces significantly lower emissions and sets a benchmark for eco-friendly passenger transport.

Nautical chart

A nautical chart is a detailed graphic representation of maritime areas and adjacent coastal regions. It provides crucial information such as water depths, navigation hazards, coastlines, and aids to navigation, ensuring safe and efficient passage planning.

Nautical mile

A nautical mile is a unit of distance used in maritime and air navigation, equivalent to one minute of latitude or exactly 1,852 meters. It provides a standardized measurement crucial for global marine navigation and chart plotting.

Naval architecture

Naval architecture is the science and art of designing ships and marine structures. It includes aspects such as hydrodynamics, structural integrity, stability, propulsion, and overall performance to ensure the vessel operates safely and efficiently.

Navigation

Navigation encompasses all processes involved in directing a ship’s movement from one point to another. This includes route planning, monitoring the ship’s position, making course corrections, and ensuring the vessel follows a safe and efficient path.

Navigation aids

Navigation aids are instruments and systems that help in determining a ship’s position and direction. Common examples include magnetic compasses, gyrocompasses, radar, echo sounders, and rudder angle indicators, all of which assist the crew in safe navigation.

Navigation aids vessel

A navigation aids vessel is a specialized ship designed for handling and maintaining marine aids such as buoys, beacons, and lightships. These vessels are equipped with cranes and other gear to position and retrieve navigation markers safely.

Navigating and manoeuvring workstation

Located on a ship’s bridge, the navigating and manoeuvring workstation is the central area for controlling the vessel’s speed, heading, and course. It is equipped with key instruments like radar, autopilot, ECDIS, and engine controls.

Navigation lights

Navigation lights are mandatory on all sea-going vessels to indicate their position, heading, and operational status during darkness or poor visibility. These lights prevent collisions by making ships visible and recognizable at night.

Running lights

Running lights are standard navigational lights that include sidelights (green for starboard and red for port), masthead lights (white), and a stern light (white). These indicate a ship’s direction of movement and position to nearby vessels.

Signal lights

Signal lights are specialized lights used to communicate a vessel’s status or condition, such as anchor lights, not-under-command lights, towing lights, and restricted maneuverability signals, helping others identify special operating situations.

All-round light

An all-round light is a white or colored light visible from any direction in a 360-degree arc. It is used for various operational signals, such as anchor lights or navigation status indicators on different types of vessels.

Flashing light

A flashing light emits bursts of light at regular intervals, with a frequency of 120 flashes or more per minute. These are typically used in lighthouses, buoys, or other navigation aids to attract attention and convey navigational information.

Masthead light

A masthead light is a white light positioned over the centerline of a vessel, shining forward and to each side over a 225-degree arc. It indicates the presence and direction of power-driven vessels under way.

Sidelights

Sidelights consist of a green light on the starboard side and a red light on the port side, each visible over a 112.5-degree arc. These help vessels determine the relative angle and direction of approaching ships.

Sternlight

The sternlight is a white light placed near the rear of a ship, shining in a 135-degree arc astern. It indicates the back of a vessel to nearby ships, especially in crowded or narrow waterways.

Towing light

A towing light is a yellow light with the same characteristics as a sternlight and is placed at the rear of a towing vessel. It signals that the ship is engaged in towing operations, warning nearby traffic.

Navigator

The navigator is a key crew member responsible for planning and executing the ship’s voyage. They operate bridge equipment, monitor environmental conditions, and ensure safe maneuvering and compliance with navigation rules.

NAVTEX

NAVTEX is an international maritime broadcast system that automatically delivers navigational and meteorological warnings to ships. Sponsored by IMO and IHO, it operates through telex-format transmissions, ensuring mariners receive up-to-date safety information.

Necking effect

The necking effect describes localized corrosion or thinning at the junction between a ship’s plating and its structural stiffeners. This weakness is often due to stress concentration or poor protective coating and can compromise structural integrity.

Net pick-up

A net pick-up is an ancillary safety device shaped like a U-section ring that supports trawl nets. It protects propellers and rudders from entanglement, ensuring smooth fishing operations and preventing mechanical damage.

Net cutters

Net cutters are sharp, stainless-steel blades mounted on a vessel’s rope guard. They are designed to slice through fishing nets or ropes that may become entangled in the ship’s propeller, enhancing safety during fishing or passage.

Nitrile rubber

Nitrile rubber is a synthetic copolymer made from acrylonitrile and butadiene. It is known for its excellent resistance to oils, fuels, and chemicals, making it ideal for seals, hoses, and gaskets in marine and industrial applications.

Nitrogen generator

A nitrogen generator is a critical onboard system used on tankers and reefer ships to produce clean, dry nitrogen. It is essential for inerting cargo tanks, preventing fire hazards, and preserving sensitive cargo.

Membrane technology

Membrane technology is used to separate gases by passing air through a semi-permeable membrane. In maritime applications, this process generates nitrogen by filtering out oxygen, providing a safe and efficient inerting solution.

PSA-type nitrogen generator

A PSA (Pressure Swing Adsorption) nitrogen generator uses a bed of adsorbent material to separate nitrogen from compressed air. It is a common and reliable method for producing nitrogen on ships, especially on tankers.

Nitrogen oxides (NOx)

Nitrogen oxides, including nitric oxide (NO) and nitrogen dioxide (NO2), are harmful gases formed during high-temperature combustion. NOx contributes to air pollution and acid rain, making it a key target of emission reduction regulations in shipping.

Nitrous oxide

Nitrous oxide (N₂O), also known as laughing gas, is a greenhouse gas that can be emitted from certain combustion processes. Unlike NO and NO₂, it is not directly involved in smog formation but contributes significantly to global warming.

Noise Code

The IMO Noise Code is a mandatory regulation aimed at protecting seafarers from harmful noise exposure onboard. It sets acceptable noise levels in various shipboard spaces and promotes design features to reduce acoustic hazards.

Non-combustible material

A non-combustible material does not ignite or emit flammable vapors when exposed to fire. These materials are crucial in ship construction, especially for bulkheads, ceilings, and deck insulation, to enhance fire safety.

Nondestructive test (NDT)

Nondestructive testing refers to inspection techniques used to evaluate materials or structures without causing damage. These tests are essential for detecting flaws in ship components and ensuring structural reliability.

Nondestructive testing methods of hull welds

Hull welds are inspected using NDT techniques such as ultrasonic testing, radiography, magnetic particle inspection, and dye penetrant testing. These ensure weld quality without compromising structural integrity.

Non-organic grease

Non-organic grease is a specialized lubricant that does not chemically react with sealing materials. It is ideal for use in sensitive marine equipment, where compatibility with rubber seals and extreme conditions is required.

Non-return valve

A non-return valve, also known as a check valve, allows fluid to flow in only one direction. It automatically closes to prevent backflow, protecting pumps, pipelines, and other onboard systems from damage or contamination.

Non-volatile petroleum

Non-volatile petroleum includes fuels and oils with a flash point of 60°C or higher. These are less likely to ignite under normal conditions and are categorized separately in maritime safety and handling regulations.

Normal operational and habitable condition

This term describes the state in which a ship and its onboard systems function correctly, providing safe living and working conditions for crew. It includes operational propulsion, ventilation, power supply, and habitability.

Normalising

Normalising is a heat treatment process where steel is heated to a specific temperature range (850–950°C) and then air-cooled. This treatment refines the grain structure, enhances mechanical properties, and reduces internal stresses in shipbuilding steel.

Not under command (NUC)

A vessel is classified as “Not Under Command” (NUC) when it cannot maneuver due to exceptional circumstances such as engine failure. NUC vessels must display specific lights and shapes to alert other ships of their status.

Notch ductility

Notch ductility is a material’s ability to absorb stress and deform plastically around a notch or defect without fracturing. This property is critical in shipbuilding materials, particularly in low temperatures or under impact loads.

NOx emissions

NOx emissions refer to nitrogen oxides released during the combustion of fossil fuels in ship engines. These emissions contribute to air pollution and are regulated under MARPOL Annex VI, prompting the use of cleaner fuels and engine technologies.

NOx Reducer System

A NOx reducer system is an emission control technology installed on ships to reduce nitrogen oxide (NOx) emissions produced during fuel combustion in engines. These systems include methods like Selective Catalytic Reduction (SCR) and Exhaust Gas Recirculation (EGR), which help meet international environmental standards by converting NOx into harmless nitrogen and water before it is released into the atmosphere.

NOx Technical Code

The NOx Technical Code is a set of international guidelines developed by the International Maritime Organization (IMO) to regulate the emissions of nitrogen oxides (NOx) from marine diesel engines. It sets testing, certification, and compliance requirements under MARPOL Annex VI to ensure that ship engines meet the specified emission limits based on their build date and operating conditions.

Nylon

Nylon is a synthetic polymer known for its high strength, flexibility, and resistance to wear and chemicals. In the maritime industry, nylon is commonly used for ropes, nets, gaskets, and various fittings because it performs well in marine environments, offering durability and resistance to erosion and impingement from water flow and suspended particles.

Maritime Glossary: O

OBO

An abbreviation for Oil/Bulk/Ore carrier, OBO refers to a type of combination vessel designed to carry oil, dry bulk cargoes such as coal or grain, and ores. These versatile ships maximize cargo-carrying flexibility and reduce ballast voyages by switching between different cargo types depending on demand.

Ocean Area Coverage

Ocean area coverage refers to the extent or range of oceanic zones monitored, studied, or serviced for maritime operations, navigation, weather reporting, or satellite communications. It plays a crucial role in global maritime safety and logistics planning.

Ocean Areas

These are vast regions of the sea located beyond the limits of territorial waters, where maritime operations are governed by international laws. In these areas, vessels enjoy the freedom of navigation under UNCLOS (United Nations Convention on the Law of the Sea).

Oceanographic Research Vessel RRS JAMES COOK

The RRS James Cook is a UK-based oceanographic research ship operated by the National Oceanography Centre. Equipped with cutting-edge scientific equipment, it conducts studies on deep-sea ecosystems, geology, and climate change across the world’s oceans.

Octopus Onboard System

Developed by Amarcon BV, the Octopus system is a modular decision support tool installed on ships. It collects real-time data and provides navigational and operational guidance, helping vessels improve safety, performance, and fuel efficiency, particularly in challenging sea conditions.

Officer

An officer on a ship is a certificated crew member who holds specific responsibilities for the safe operation of the vessel. Under the authority of the ship’s master, officers oversee navigation, engineering, and safety, depending on their department.

Offset Table

An offset table is a document listing the measurements taken from a faired lines plan of a vessel. It provides detailed coordinates of the hull’s shape, which are essential for shipbuilding and stability calculations.

Offsets

Offsets refer to the numerical coordinates or dimensions used to define the shape and structure of a ship, including hull form, deck heights, and structural frames. These values guide both the design and construction phases of shipbuilding.

Offshore

Offshore refers to industrial activities conducted at sea, such as oil and gas exploration, drilling, and wind farm installation. These operations typically take place far from the coast and require specialized vessels and equipment.

Offshore Construction and Anchor Handling Vessel NORMAND INSTALLER

The Normand Installer is a specialized offshore vessel designed for heavy construction and anchor handling tasks. It supports subsea installations and towing operations in deep-sea energy projects.

Offshore Production and Storage Installations

These are stationary or floating structures used in oil and gas fields to extract, process, and store hydrocarbons. Examples include FPSOs (Floating Production Storage and Offloading units) and fixed platforms.

Offshore Support Vessels (OSVs)

OSVs are specially designed ships that support offshore exploration and production activities. Their roles include transporting supplies, handling anchors, conducting subsea operations, and accommodating crew and technicians.

Seismic Survey Ship

A seismic survey ship uses air guns or similar devices to send sound waves into the seabed. By analyzing the reflected waves, geologists can map the underwater rock formations, which is essential for oil and gas exploration.

Platform Supply Vessel (PSV)

PSVs are workhorses of the offshore oil and gas industry. These vessels transport essential supplies such as drilling mud, cement, fuel, and provisions from shore bases to offshore rigs and platforms.

Anchor Handling Tug Supply Vessel (AHTS)

AHTS vessels are multipurpose ships combining towing, anchor handling, and supply capabilities. They are used to tow oil rigs to position, anchor them, and provide logistical support in remote offshore locations.

Construction Support Vessels

These vessels are DP3-rated and feature expansive open decks and heavy-lift cranes. They are used for complex offshore construction tasks like subsea installation, pipe laying, and cable deployment in deep-sea environments.

Diving Support Vessel (DSV)

DSVs are specially outfitted for underwater diving operations. They come equipped with diving bells, saturation diving systems, and hyperbaric chambers, enabling commercial divers to perform maintenance and repairs on underwater structures.

Inspection Maintenance and Repair (IMR) Vessel

An IMR vessel is a dynamically positioned ship that performs regular inspections, maintenance, and repairs of subsea infrastructure such as pipelines, risers, and oilfield installations to ensure operational integrity.

ROV Support Vessels

These are DP-capable vessels designed to deploy and operate Remotely Operated Vehicles (ROVs) for subsea tasks. They are widely used in offshore oil and gas fields for inspections, surveys, and maintenance at great depths where human diving is impractical.

Offshore Unit

An offshore unit includes any floating or fixed structure, such as platforms, rigs, or barges, designed for energy extraction, processing, or storage in offshore locations. These units support long-term operations in challenging marine environments.

Oil

In maritime and offshore contexts, oil refers to any petroleum-based substance, including crude oil, refined products, sludge, and waste oil. Its handling, transport, and potential spillage are subject to strict international safety and environmental regulations.

Oil Companies International Marine Forum (OCIMF)

The OCIMF is a voluntary association of oil companies with an interest in the safe and environmentally responsible operation of oil tankers and offshore vessels. It develops best practices and standards to enhance safety, security, and pollution prevention in the marine oil industry.

Oil distribution shaft

This is a hollow propulsion shaft with internal bores and radial holes used for delivering oil to lubricate internal engine components. It plays a crucial role in ensuring smooth operation and reducing wear in marine engines.

Oil-in-water monitor 

This instrument continuously measures the concentration of oil in bilge water or other discharge streams. It’s essential for compliance with environmental regulations and preventing marine pollution.

Oil Pollution Act (OPA)

Enacted in the U.S. in 1990, the OPA was created to prevent and respond to catastrophic oil spills. It outlines safety measures, liability, and response protocols for vessels transporting hydrocarbons by sea.

Oil Record Book

Required under MARPOL 73/78, this logbook records all operations involving oil on a ship, including discharges, transfers, and sludge handling. It ensures transparency and environmental compliance.

Oil recovery and sludge treatment system

These systems process oil sludge collected during vessel operations, separating recoverable oil and treating waste to minimize environmental impact and comply with regulations.

Oil recovery system of HAVEN HORNBILL

The HAVEN HORNBILL is equipped with advanced systems designed for the effective recovery of oil in case of spills, contributing to rapid and efficient containment and cleanup.

Oil spill combatment vessel ARCA

The ARCA is a specialized vessel built to combat oil spills. It is equipped with containment booms, skimmers, and storage facilities for recovered oil, playing a vital role in marine environmental protection.

Oil slick

An oil slick refers to a thin layer of oil floating on the sea surface, usually the result of accidental discharges or spills. It poses a severe threat to marine ecosystems and requires immediate response.

Oil spill response vessel (OSRV)

These vessels are specifically designed to support oil spill cleanup operations. They are equipped with specialized tools such as booms, skimmers, and dispersant spray systems.

Oil spill response vessel ARKONA

The ARKONA is a German OSRV designed to assist in oil spill containment in the Baltic Sea. It plays a key role in protecting the marine environment from pollution.

Oil tanker

An oil tanker is a ship primarily built to transport large volumes of oil in bulk. These vessels are vital to global energy transport and are subject to strict design and safety standards.

Oil treatment

This process involves the purification of fuel or lubricating oils to remove water and contaminants before use in marine engines, improving efficiency and protecting machinery.

Oil/water interface detector

Used in slop tanks of oil tankers, this sensor identifies the boundary between oil and water layers, helping operators manage waste discharge in compliance with pollution control regulations.

Oily mixture

A mixture that contains any amount of oil, usually from bilge water, fuel residues, or operational discharges. It must be treated before disposal to avoid environmental harm.

Oily rags

Rags saturated with oil, often used in engine rooms or maintenance areas. These must be stored and disposed of carefully to avoid fire hazards and environmental contamination.

15 ppm bilge separator

This equipment separates oil from water in bilge discharges, ensuring that the effluent has less than 15 parts per million (ppm) of oil before being released overboard, meeting MARPOL standards.

One compartment subdivision

A structural safety design where the ship is divided into watertight compartments, allowing it to remain afloat if any one compartment is flooded.

On-hire/off-hire surveys

Inspections conducted to document the condition of a ship before it’s chartered (on-hire) or after it returns (off-hire). These surveys determine responsibility for any damage or maintenance issues.

On-load release hooks

Mechanisms used on lifeboats that allow them to be released from davits even when under load, essential during emergency evacuations.

On-scene commander (OSC)

The designated leader of a rescue or emergency operation who coordinates all activities and communication at the incident site.

Open bell

A diving chamber at ambient sea pressure that allows divers to enter or exit underwater environments without pressure equalization, commonly used in shallow-water operations.

Open-top container vessel RIJNBORG

The RIJNBORG is a vessel designed to carry containers without overhead decks, enabling the transport of oversized cargo that cannot fit in standard containers.

Open-top reefer container vessel DOLE COLOMBIA

This ship carries refrigerated (reefer) containers with an open-top design, allowing the transport of perishable goods while accommodating oversized or non-stackable cargo.

Open water efficiency

This is a measure of the propulsion system’s effectiveness in open water, calculated as the ratio between thrust power and absorbed power, crucial for evaluating fuel efficiency.

Openings

These refer to various external openings on a ship such as doors, windows, hatches, and vents. Their design must ensure watertight integrity and structural safety.

Operation manual

A guide provided by manufacturers that outlines how to operate, maintain, and troubleshoot a particular machine or system onboard a vessel.

Operational

A term indicating that a machine, system, or vessel is fully functional and ready for immediate use in its intended application.

Operational design

This refers to the phase in the design process focused on ensuring that systems and components can operate reliably under all expected conditions throughout their service life.

Operator

A person, company, or agency responsible for managing the operation of a vessel, including its crewing, maintenance, and regulatory compliance.

Ore carrier

A type of bulk carrier designed specifically for transporting dense cargoes like iron ore. These vessels are usually single-deck with reinforced hulls for high-density loads.

Ore/oil carrier

A hybrid vessel capable of carrying both ore and oil cargoes, designed with structural reinforcements and internal configurations to accommodate these different types of cargo.

Orimulsion

A fuel composed of 70% bitumen and 30% water with emulsifying agents. It is used in power generation and presents challenges for marine transport due to its high viscosity.

Osmosis

A natural process where a solvent passes through a semi-permeable membrane from a low to a high solute concentration. In ships, it’s a concern in fiberglass hulls, where water seeps in and causes blisters.

Reverse osmosis

A water purification method that uses pressure to force seawater through a membrane, removing salts and impurities to produce fresh water on ships.

Outboard

A direction pointing away from the centerline of the ship, often used when referring to the positioning of equipment, structures, or personnel.

Overall survey

A detailed inspection assessing the general condition of a ship’s hull, machinery, and equipment. It is a key part of classification society and regulatory compliance.

Overflow 

The accidental escape of oil from a tank during filling operations when the tank becomes too full, often due to operator error or pump failure.

Overflow pipes

Pipes designed to safely direct excess fluid from tanks to prevent over-pressurization or accidental spills during filling operations.

Overhead welding position

A difficult welding posture where the welder must work from below the joint, with the weld pool above them, often requiring extra care and skill.

Overload

A situation where equipment or a structure is subjected to a load greater than its rated capacity, risking damage or failure.

Overload protection

A safety mechanism in electrical systems that automatically stops current flow when it exceeds safe limits, preventing overheating and fire hazards.

Override

A manual control function that allows operators to bypass automated systems, often used during emergencies or testing.

Overspeed protective device

A safety mechanism that shuts down or disengages a propulsion engine if it exceeds its maximum safe speed, protecting it from damage.

Oxygen

A vital gas making up around 20% of Earth’s atmosphere. In marine applications, it’s essential for combustion in engines and life support in enclosed spaces.

Oxygen analyser/meter

A device used to measure the concentration of oxygen in tanks or enclosed spaces, crucial for safety during tank entry and gas freeing.

Oxygen cutting

A metal cutting method using a high-temperature flame and a jet of oxygen to oxidize and remove metal, widely used in shipbuilding and repair.

Oxygen gouging

A variation of oxygen cutting used to create grooves or remove welds and defects from metal surfaces in preparation for repair or further processing.

Ozone depleting substances (ODS)

Man-made chemicals like CFCs and halons that damage the ozone layer. Their use is heavily regulated in marine refrigerants and fire suppression systems.

Ozone depletion potential (ODP)

A rating system that measures how much a substance can degrade the ozone layer compared to a reference substance, typically CFC-11.

Maritime Glossary: P

Pad gas

Pad gas is an inert gas, such as nitrogen, introduced into the vapor space above a liquid cargo in a tank to create a protective atmosphere. This helps prevent the formation of flammable or explosive mixtures, reduces oxidation, and maintains cargo stability during storage or transit.

Padding

Padding refers to the process of charging an inert gas, typically nitrogen, into the space above liquid cargo. This is done to preserve cargo quality and prevent contamination or chemical reactions that could result from contact with atmospheric oxygen or moisture.

Paint

Paint is a liquid substance applied to surfaces for protective, decorative, or functional purposes. Once applied, it dries into a solid film that shields the substrate from corrosion, environmental damage, and wear, especially important in marine environments.

Paint cracking

Paint cracking occurs when the dried paint film fractures and separates, often due to aging, improper application, or environmental stress. These cracks can expose the underlying material to corrosion and damage, requiring timely maintenance.

Paint system

A paint system refers to the full sequence and combination of paint layers, including primers, intermediate coats, and topcoats, used to protect a surface. It encompasses the materials, number of coats, and application procedures necessary for effective surface protection.

Pallet

A pallet is a flat, portable platform made of wood, metal, or plastic, used for stacking, storing, and transporting goods. It allows for efficient handling by forklifts and cranes and is a staple in maritime and logistics operations.

Pallet swinger

A pallet swinger is a specialized crane attachment or device designed to handle pallets efficiently, especially on refrigerated cargo vessels. It aids in the rapid and safe movement of palletized goods between ship and shore.

Panama Canal

The Panama Canal is a vital artificial waterway that links the Atlantic and Pacific Oceans, allowing ships to avoid the long journey around South America. It significantly shortens transit times and supports international maritime trade.

Panama Canal SOPEP

The Panama Canal Shipboard Oil Pollution Emergency Plan (SOPEP) is a requirement for vessels transiting the canal. It outlines response procedures and equipment in the event of an oil spill, aligning with international pollution control standards.

Panel

In maritime context, a panel is a single hatch cover section used to seal the cargo hold. Multiple panels work together to form a complete hatch cover system that protects cargo from water ingress and environmental exposure.

Panting

Panting describes the rhythmic inward and outward movement of a ship’s hull plating, especially in the bow and stern, due to pressure changes as the ship pitches in waves. This structural stress requires reinforcement to prevent fatigue and damage.

Parallel mid-body

The parallel mid-body is the central portion of a ship’s hull with a uniform cross-section. It contributes to the vessel’s cargo-carrying capacity and simplifies the shipbuilding process due to its consistent structure.

Parallel Side Loader

The Parallel Side Loader is a gantry-style shipboard crane system designed for rapid and efficient cargo handling. Developed by Wijnne & Barends, it allows parallel loading and unloading operations, improving turnaround times.

Parametric roll resonance

Parametric roll resonance is a dangerous phenomenon where a ship in longitudinal waves experiences large rolling motions due to periodic variations in stability. It can cause structural damage and cargo loss if not mitigated.

Parametric roll prevention system (IPRP)

The IPRP is an anti-rolling system designed to prevent parametric rolling in ships. Developed by German engineers, it works by actively controlling ballast and heel to stabilize the vessel in challenging sea conditions.

Parametric rolling

Parametric rolling occurs when a ship’s righting moment varies cyclically due to changes in hull geometry as it moves through longitudinal waves. This can lead to large, dangerous roll angles, especially in container ships.

Paravane

A paravane is a towed underwater device used to maintain lateral separation from a ship. It is often employed in mine-sweeping, sonar operations, or towing underwater survey equipment to ensure stability and control.

Partially weathertight hatch covers

These hatch covers offer limited resistance to water ingress and are not fully sealed. They are typically used where complete watertight integrity is not required, such as in sheltered cargo holds.

Passenger

A passenger is any person aboard a vessel who is not part of the crew or command team. Passengers are carried for travel or leisure, and their safety and comfort are regulated under specific maritime laws.

Passenger/cargo ship FINNMARKEN

The FINNMARKEN is a passenger/cargo vessel designed for mixed-use service, offering comfortable passenger amenities along with space for freight. Such ships are common in coastal and regional service routes.

Passenger spaces

Passenger spaces are designated areas on a ship for use by travelers, including cabins, lounges, dining rooms, and recreational facilities. These areas must meet safety and comfort standards under international maritime regulations.

Payload

Payload refers to the total weight of cargo that a ship can transport after accounting for its own weight and fuel. It is a critical metric in determining a vessel’s commercial efficiency and profitability.

Pelagic freezer trawler AFRIKA

The AFRIKA is a specialized pelagic freezer trawler designed for catching and processing fish at sea. It targets species like mackerel and herring, freezing the catch onboard to preserve quality.

Pelagic species

Pelagic species are fish that inhabit the open water column, away from the sea floor. Examples include tuna, mackerel, and sardines, which are often targeted by commercial fishing vessels operating in midwater zones.

Pentamaran

The Pentamaran is a unique vessel design featuring five narrow hulls for enhanced stability and reduced drag. Developed by Nigel Gee and Associates, it offers improved performance and fuel efficiency in various marine applications.

Performance Standards for Protective Coatings (PSPC)

PSPC outlines the minimum requirements for protective coatings in ballast tanks and other areas on ships. These standards help ensure long-term corrosion protection and structural integrity.

Period of roll

The period of roll is the time it takes for a ship to complete one full rolling cycle. It is influenced by the vessel’s size, shape, and loading conditions and is critical in understanding ship stability.

Periodical hull surveys

These surveys assess the condition of a ship’s hull at regular intervals, including annual, intermediate, and special inspections. They are vital for ensuring safety and compliance with classification society rules.

Permanent magnet motor

A permanent magnet motor uses magnets instead of electromagnetic windings to generate motion. These motors are compact, energy-efficient, and gaining popularity in marine propulsion systems.

Permeability of the space

Permeability refers to the volume percentage of a ship compartment that can be occupied by water if it floods. It’s crucial in damage stability calculations to assess the risk of sinking or capsizing.

Personnel evacuation system

A personnel evacuation system is a critical safety mechanism designed to evacuate individuals from oil rigs during extreme weather conditions. It typically includes life capsules, lifeboats, or escape chutes that can be deployed quickly and safely, even in high winds and rough seas, ensuring crew members can abandon the rig if an emergency arises.

Petroleum

Petroleum is a naturally occurring liquid found beneath the Earth’s surface, composed mainly of hydrocarbons. It serves as the raw material for many products, including gasoline, diesel, lubricants, and petrochemicals, making it one of the most valuable global energy resources.

Petroleum gas

Petroleum gas refers to the gaseous hydrocarbons that are released during petroleum refining or directly from oil wells. The primary components of petroleum gases include propane and butane, commonly known as LPG (liquefied petroleum gas), which are widely used for heating, cooking, and fuel.

Petroleum products

Petroleum products are refined outputs from crude oil and are classified as black (such as fuel oils and bitumen) or white/clean products (such as kerosene, gasoline, and lubricants). These products serve a wide range of industrial, domestic, and transportation needs.

Physically drying paints

Physically drying paints are coatings that cure through the simple evaporation of solvents, leaving behind a dry film of binder and pigments. These paints do not undergo any chemical changes during drying and are commonly used in quick-drying applications.

PICKUPCAT concept

The PICKUPCAT concept involves designing a vessel with two independently operating hulls that can separate or reconnect as needed. This design provides operational flexibility, allowing for easy maintenance, cargo handling, and modular usage across various marine tasks.

Pier

A pier is a man-made structure built perpendicular to the shoreline, extending into the water to serve as a docking point for ships. It facilitates the loading and unloading of cargo and passengers and can be equipped with utilities and equipment for ship servicing.

Piggy-back cover

A piggy-back cover is a hatch cover design where one panel can ride on top of another via a wheeled mechanism. This allows for efficient opening and closing of cargo holds, especially on container or general cargo ships.

Pigments (painting)

Pigments are finely ground solid particles added to paint to provide color, opacity, and protection. These insoluble powders also influence the paint’s durability, reflectivity, and finish, playing a vital role in both aesthetics and functionality.

Pile

A pile is a long, hollow steel or concrete cylinder driven deep into the seabed to provide foundational support for offshore structures, piers, or jetties. Installation methods include hammering or using vibratory drivers depending on the ground conditions.

Pillar

A pillar is a vertical structural element on a ship that supports deck loads and distributes them to the lower structures. Found throughout the ship, pillars help maintain hull integrity and bear the weight of upper decks and equipment.

Pilot

A pilot is a trained and certified maritime professional who assists the ship’s master in navigating through restricted or congested waters such as harbors, rivers, or canals. Their local knowledge ensures the vessel’s safe and efficient passage.

Pilot ladder

A pilot ladder is a flexible rope ladder with wooden or synthetic rungs used by pilots to board or disembark from a vessel. It is lowered from the ship’s deck to the waterline, meeting strict safety and design standards for secure boarding.A pilot ladder is a flexible rope ladder with wooden or synthetic rungs used by pilots to board or disembark from a vessel. It is lowered from the ship’s deck to the waterline, meeting strict safety and design standards for secure boarding.

Pilot mechanical hoist

A pilot mechanical hoist is a powered device used to lift and lower pilots between a ship and a smaller boat or dock. Operated by a winch system, it enhances boarding safety in rough seas or high freeboard conditions.

Pilot shelter platforms

Pilot shelter platforms are covered areas on ships, especially those passing through the Panama Canal, that provide protection and space for pilots while navigating. These platforms are mandatory as per navigation regulations in certain waterways.

Pilotage

Pilotage is the act of navigating a vessel through hazardous or congested waters with the help of a pilot. This service is often mandatory in certain ports and straits to minimize the risk of accidents due to local navigational challenges.

Pinholes

Pinholes are minute holes that penetrate the entire paint layer down to the surface beneath. These defects often occur during application and can lead to corrosion or coating failure if not addressed properly.

Pinpoint rusting

Pinpoint rusting refers to localized corrosion that occurs at small defects such as pinholes or scratches in a paint coating. Though small in appearance, these rust spots can grow and compromise the protective layer over time.

Pintles

Pintles are the vertical pins or bolts that hinge the rudder to the ship’s sternpost via gudgeons. They form a crucial part of the steering gear mechanism, allowing the rudder to swing for directional control of the vessel.

Pipe fittings

Pipe fittings are connectors used to join pipe sections or redirect fluid flow. These include elbows, tees, flanges, and reducers, and are essential in constructing and modifying piping systems onboard ships and offshore structures.

Pipe joints

Pipe joints are the methods used to connect pipes in a system. Common types include butt-welded, socket-welded, flanged, and slip-on welded joints, all chosen based on pressure requirements and fluid characteristics.

Pipe schedules

Pipe schedules refer to standardized classifications that specify the wall thickness of pipes. These are essential in system design to ensure the pipe can handle the required pressure, with Schedule 40 and Schedule 80 being common examples.

Pipe tunnel

A pipe tunnel is an enclosed space running longitudinally through the midship section of a vessel, used for housing essential pipelines. It allows for inspection and maintenance without disturbing cargo or structural components.

Pipelay/Heavy Lift vessel SEVEN BOREALIS

The SEVEN BOREALIS is a specialized offshore vessel designed for both heavy lifting and pipelaying operations. Equipped with advanced cranes and pipelay systems, it plays a critical role in subsea construction and energy projects.

Pipelay methods: J-lay method

In the J-lay method, the pipeline is lowered vertically into the sea, forming a “J” shape. This method is ideal for deepwater pipelaying as it reduces stress on the pipe and allows for more precise placement on the seabed.

Pipelay methods: Reel-lay method

The reel-lay method involves spooling pre-welded pipelines onto a large reel aboard a vessel. At the installation site, the pipe is unspooled and straightened, making it a fast and efficient method for small to medium pipeline projects.

Pipelay methods: Combination of Reel-lay and J-lay

This hybrid approach combines the speed of reel-lay with the deepwater capabilities of J-lay. It enables flexible operations in varying seabed conditions and pipeline requirements.

Pipelaying system of the MIDNIGHT EXPRESS

The MIDNIGHT EXPRESS uses a sophisticated pipelaying system combining real-time monitoring, tensioners, and dynamic positioning. Its versatile setup allows it to handle complex offshore pipeline installations.

Pipeline

A pipeline is a long, usually horizontal conduit that transports oil, gas, or other fluids across large distances. Pipelines may lie on the seabed or be buried beneath it, and are crucial for connecting offshore production sites to onshore facilities.

Pipeline bundles

Pipeline bundles are groupings of two or more pipelines laid together along the seabed. This arrangement reduces installation costs and seabed footprint while allowing multiple fluid types to be transported simultaneously.

Pipeline End Terminations (PLET)

PLETs are critical connectors located at the ends of subsea pipelines. They provide structural support and connection points to subsea facilities, requiring precise installation and integration by pipelay vessels.

Pipeline system

A pipeline system is an integrated network of subsea pipelines and associated components like risers, PLETs, and manifolds. It enables the efficient and controlled transport of oil, gas, or chemicals from offshore production sites to processing units.

Pipes

Pipes are cylindrical tubes made of metal or plastic, used to carry fluids under pressure. On ships and rigs, they serve in systems like fuel, ballast, freshwater, or cooling circuits, and are designed to withstand specific operating conditions.

Piping components

Piping components encompass all elements used in a piping system, including pipes, valves, fittings, flanges, gaskets, bolts, and hoses. These components are selected based on fluid type, temperature, and pressure demands.

Piping system

A piping system is a coordinated arrangement of pipes and components designed to transport fluids efficiently. It includes elements for controlling flow, pressure, temperature, and direction, tailored to the specific function it serves onboard a vessel or offshore platform.

Piston

A piston is a cylindrical metal component that moves up and down within an engine cylinder. It converts the energy generated from combustion into mechanical work by pushing against a crankshaft, thereby enabling the movement of the engine’s components and ultimately driving machinery or vehicles.

Piston ring

A piston ring is a split ring fitted around the piston of an engine. Made of cast iron, it ensures a seal between the piston and the cylinder wall to contain combustion gases, control oil consumption, and transfer heat from the piston to the cylinder.

Piston skirt

The piston skirt is the lower portion of a piston that extends downward to maintain alignment within the cylinder and reduce side-to-side movement. It also helps distribute side thrust and reduces wear between the piston and cylinder wall.

Pitquard anode

A Pitquard anode is a sacrificial anode installed just above a tank bottom to prevent localized corrosion. By corroding in place of the tank structure, it protects the metal surfaces from rusting and ensures the structural integrity of the tank over time.

Planking

Planking refers to the wooden boards used to cover the decks or other surfaces of a ship. Traditionally used in wooden shipbuilding, it provides a walking surface and can be aesthetically finished while offering a degree of weather protection.

Planning craft

A planning craft is a vessel designed to lift most or all of its hull out of the water at speed, reducing drag and increasing efficiency. Its specially shaped hull creates hydrodynamic lift, enabling high-speed navigation especially in smaller boats.

Planning terminal

A planning terminal is a bridge workstation used for voyage planning and route optimization. It is situated remotely from the ship’s main operational controls and enables officers to analyze navigation data and prepare routes in advance.

Plasma-arc cutting

Plasma-arc cutting is a method for slicing through electrically conductive metals using a jet of hot plasma. This precise and efficient technique is widely used in shipbuilding and metal fabrication for cutting steel components.

Plastic

Plastic is a synthetic material made of high polymers that can be molded into various shapes. It’s lightweight, durable, and used across industries, including shipbuilding, for insulation, piping, and components due to its resistance to corrosion.

Plasticity

Plasticity is the ability of a material to undergo significant and permanent deformation without breaking. This property is important in metals used in shipbuilding, as it allows them to absorb stress and strain without cracking.

Platform supply vessel VIKING ENERGY

The VIKING ENERGY is a modern platform supply vessel designed to transport essential supplies like fuel, water, and equipment to offshore oil platforms. It often features advanced propulsion systems and dynamic positioning.

Plating

Plating refers to the metal sheets that form the hull, deck, and bulkheads of a ship. These plates are welded together to create the watertight and structural body of the vessel, providing strength and resistance against sea pressure.

Plough

A cable plough is a seabed tool used in subsea cable laying. It digs trenches in the seabed and lays cables within them while backfilling to protect the cables from damage, ensuring long-term durability of underwater cable systems.

Plug

A plug is an electrical connector inserted into a socket to draw power. On ships, plugs are used for connecting various electrical equipment to onboard power supplies for safe and reliable operation.

Pneumatic control valve

A pneumatic control valve regulates the flow of gases or liquids in a system. Controlled by air pressure, it can be operated remotely and is essential in automated ship systems for efficient process control.

Pneumatic conveyor system

A pneumatic conveyor system moves powdered materials like cement or fly ash using air pressure. Common on specialized ships, it enables efficient and dust-free loading or unloading of dry bulk cargoes.

Pod

A pod is a propulsion unit combining an electric motor with a rudder and propeller in one pod-shaped unit. It provides increased maneuverability, fuel efficiency, and compact installation on ships, especially in modern vessels.

Polar orbiting satellite service

This service uses satellites that orbit the Earth from pole to pole, collecting data over the entire planet. It is vital for weather forecasting, environmental monitoring, and global maritime navigation.

Pollutant

A pollutant is a substance that contaminates the air, water, or soil, posing a threat to health and the environment. In marine operations, pollutants can include oil, chemicals, and waste discharged into the sea.

Pollution

Pollution is the act of introducing harmful substances into the environment, leading to contamination of air, water, and land. Maritime pollution includes oil spills, sewage discharge, and emissions from ships.

Pollution and accident control ship NEUWERK

The NEUWERK is a multi-purpose German vessel designed for pollution response and accident control. It handles tasks like oil spill recovery, emergency towing, firefighting, and search and rescue operations.

Pollutant recovery

Pollutant recovery involves capturing and removing harmful substances like oil from water or surfaces. Specialized equipment is used to contain and pump these pollutants for safe disposal, reducing environmental impact.

Underwater search

Underwater search operations involve using divers, sonar, or remotely operated vehicles (ROVs) to locate objects or debris beneath the sea surface, often as part of rescue missions or incident investigations.

Firefighting off- and onboard

Firefighting off-board refers to tackling fires on other vessels or structures, while onboard firefighting deals with blazes on the ship itself. Specialized equipment and trained crews are essential for both.

Buoy tender operations

These involve the maintenance and replacement of navigational buoys. Vessels conducting these tasks are equipped to lift, inspect, and deploy buoys to ensure safe maritime navigation.

Emergency towing

Emergency towing is the act of assisting a disabled vessel by towing it to safety. Specialized ships are equipped with powerful winches and towing gear to handle such operations in rough conditions.

Maritime Glossary: Q

Q.M.E.D. (Qualified Members of the Engine Department)

Q.M.E.D.s are certified seafarers trained to perform various technical duties in the engine department, such as operating and maintaining machinery. This category includes roles like pumpman and electrician, who are essential for the safe and efficient functioning of shipboard mechanical and electrical systems. They work under the supervision of licensed engineers and are often cross-trained for multiple support tasks.

Quarter deck

The quarter deck is a raised section of the upper deck located at the aft (rear) part of a ship. Historically used as the command and ceremonial area, it is often still treated with a degree of formality on naval and merchant vessels. On smaller ships, it may serve practical functions, such as providing access to the bridge or housing equipment and lifeboats.

Quay

A quay is a man-made, solid structure built along or into the shore of a harbor or port. It allows ships to dock securely for loading and unloading cargo or passengers. Quays are often equipped with cranes, bollards, and fenders and are critical for the smooth operation of maritime trade and logistics.

Maritime Glossary: R

Rack

A rack is a straight bar with cut teeth that mesh with those on a pinion gear. When the pinion rotates, it converts rotary motion into linear motion of the rack. This rack-and-pinion system is widely used in ship steering and machinery for precise mechanical control.

Rack wire

The rack wire system is a modified version of the rack and pinion mechanism. In this setup, only one hatch cover or panel is moved by the wire-driven mechanism, offering simpler and more compact automation for opening or closing ship components.

Racking

Racking refers to the structural distortion or deformation of a ship’s frame due to torsional stresses when rolling or flexing. It’s a crucial design consideration in shipbuilding to ensure hull integrity and long-term durability under various sea conditions.

Radar (radio detection and ranging)

Radar is a crucial navigation tool that emits radio waves and analyzes the reflected signals to detect objects like ships, landmasses, or obstacles. It helps mariners maintain situational awareness, especially in poor visibility conditions.

Radar plotting

Radar plotting is the process of tracking targets detected by radar, calculating their speed, course, and closest point of approach. This helps navigators avoid collisions and make informed maneuvering decisions in traffic-heavy or foggy areas.

Radio

Radio communication uses electromagnetic waves to send and receive signals between ships or with shore stations. It forms the backbone of maritime communication, enabling routine operations, emergency signaling, and coordination across long distances.

Radio direction finder

A radio direction finder (RDF) helps locate the direction of a radio signal source. Onboard ships, it is vital for navigation, allowing vessels to determine their bearing relative to shore stations or distress signals during search and rescue.

Radio operator

A radio operator is responsible for managing all shipboard radio communications, including sending and receiving distress signals, maintaining contact with coastal stations, and logging all transmissions as per maritime safety regulations.

Radio Regulations

The Radio Regulations are a global legal framework governing the use of radio frequencies and equipment. Enforced by the International Telecommunication Union (ITU), these rules ensure interference-free communication and safe maritime operations.

Radiobeacon

A radiobeacon is a shore-based station that emits regular radio signals for navigation. Ships use these signals to determine their position, especially during poor visibility or when electronic navigation systems are used for position fixing.

Radiocommunication workstation

A radiocommunication workstation on board is a dedicated control area where communication systems are operated. It includes equipment like VHF, MF/HF radios, satellite terminals, and emergency distress alert systems.

Rail

In a maritime context, a rail can refer to the safety barrier or edge guard running along the sides of a deck. It ensures crew safety by preventing falls and may also serve as a support for ropes or gear.

Rail/vehicle ferry ARATERE

The ARATERE is a rail and vehicle ferry that transports trains and cars across water bodies. Designed with roll-on/roll-off capabilities, it streamlines cargo and passenger transport between islands or across bays.

Rain shelters

Rain shelters are lightweight covers used on hatchcoverless container ships. They offer temporary protection against rain or sea spray during cargo operations, helping prevent water damage and maintaining dry working conditions.

Raised quarterdeck

A raised quarterdeck is an elevated structure on the aft part of a vessel extending forward. It provides extra space below deck for equipment or accommodations and helps improve ship balance and visibility from the bridge.

Rake

Rake refers to the tilt or slant of structures like masts, funnels, or stems from the vertical. A raked structure, such as a forward-leaning mast, can be both functional and aesthetic, aiding in aerodynamics or load balance.

Rake of keel

The rake of the keel is the angle or slope of the keel line from the aft (rear) toward the bow (front). It influences the vessel’s hydrodynamic profile, contributing to smoother movement and improved sea-keeping performance.

Ram

A ram in maritime systems typically refers to a mechanical actuator used in hydraulic systems, such as steering gears. It moves back and forth (reciprocates) to apply force or transfer motion, often in rudder or ramp operations.

Ramform hull

The ramform hull is a distinctive, triangle-shaped hull design with a wide stern, developed for seismic survey vessels. It provides exceptional stability and deck space, making it ideal for equipment-heavy offshore operations.

RAMFORM TITAN

The RAMFORM TITAN is a seismic survey vessel with the ramform hull design. Known for its broad stern and massive equipment capacity, it plays a key role in marine geophysical exploration and offshore resource mapping.

Ramps

Ramps are sturdy, inclined surfaces used for loading and unloading rolling cargo like vehicles and trailers. Found on ferries and RoRo ships, they connect the ship deck with the quay or between decks internally.

External ramps

External ramps, such as stern ramps, are installed outside the ship to enable direct loading and unloading of vehicles from the dock. They are commonly used on RoRo and ferry vessels for efficient cargo flow.

Stern quarter ramp

A stern quarter ramp is a ramp located at an angle on the aft side of a ship, typically between 30° and 45°, allowing vehicles to load and discharge even when docked at an angle or side of a quay.

Slewing ramp

A slewing ramp is a movable stern ramp that can swivel or rotate up to about 40° to align with shore facilities. It increases flexibility in port operations, especially where dock positioning is irregular.

Internal ramps

Internal ramps are built within the ship to allow movement of rolling cargo between different decks. They may be fixed or hinged and are key in multi-deck vehicle carriers for efficient cargo circulation.

Spiral ramp

A spiral ramp is a circular or helical-shaped internal ramp, designed to save space while connecting different levels. Introduced by Gdansk Shipyard, it’s especially useful on car carriers with limited deck room.

Tiltable ramp

A tiltable ramp is a single-section internal ramp equipped with flaps and hydraulic controls. It can be lifted or lowered to connect decks at different heights, offering versatile loading configurations for cars and trailers.

Rapson’s slide

Rapson’s slide is a steering gear mechanism used in ram-type steering systems. It enables precise and responsive rudder movement by guiding the tiller or crosshead along a defined track.

Raster navigational chart (RNC)

An RNC is a scanned image of a traditional paper nautical chart, used in electronic navigation systems. Though it’s not interactive like vector charts, it provides familiar visuals for navigators.

Rated speed of engine

The rated speed of an engine is the crankshaft speed, in revolutions per minute (RPM), at which the engine delivers its maximum continuous power. It defines the operational efficiency and power output standard.

Receiving point

A receiving point is a designated location where a vessel must report for permission to enter or transit a specific port or area. It ensures controlled traffic flow and coordination with port authorities.

Reciprocate

To reciprocate means to move back and forth repeatedly along a fixed path. In ships, this motion is often found in piston engines, pumps, and some steering mechanisms.

Recognized Security Organization (RSO)

An RSO is an external entity authorized by a flag state to perform security-related duties on behalf of the government. RSOs audit, certify, and assess ships under the ISPS Code.

Rectifier

A rectifier is an electronic device or circuit that converts alternating current (AC) into direct current (DC). It’s essential on ships to supply stable DC power to various equipment and control systems.

Reducing valve

A reducing valve automatically lowers and maintains fluid pressure at a constant, pre-set level on the outlet side. It is used in ship systems where precise pressure control is necessary for safety and efficiency.

Redundancy

Redundancy in marine systems refers to the provision of extra equipment or components that serve as backups to ensure continued operation if the primary system fails. This increases the safety, reliability, and survivability of the vessel under critical circumstances.

Level of redundancy

The level of redundancy classifies how well-separated and independently powered the duplicate systems are—mechanically, electrically, and spatially. Higher levels indicate greater separation and independence, reducing the risk of simultaneous failure.

Redundancy of propulsion

This involves the duplication of propulsion-related machinery and systems, such as multiple engines or separate fuel supplies, to maintain maneuverability in case one system fails.

Redwood seconds

Redwood seconds are units used to measure the kinematic viscosity of liquids. In this method, the time taken for a set volume of fluid to flow through a Redwood viscometer under specified conditions is recorded in seconds.

Reefer/container vessel CARMEL ECOFRESH

The CARMEL ECOFRESH is a modern reefer container ship designed for energy-efficient transport of temperature-sensitive goods, equipped with state-of-the-art refrigeration and monitoring systems.

Reefer vessel LOMBOK STRAIT

The LOMBOK STRAIT is a refrigerated cargo vessel designed to transport perishable items such as fruits, vegetables, or seafood under controlled temperature conditions across long distances.

REFCON system

The REFCON system is an advanced monitoring and alarm system used aboard reefer ships to track temperature, power, and alarms of individual containers, ensuring cargo integrity throughout the voyage.

Reference line

On radar screens, the reference line is a virtual line indicating the centerline of the navigational fairway, helping distinguish between inbound and outbound lanes for safer ship movement.

Refit

A refit refers to a comprehensive overhaul of a vessel, involving maintenance, repairs, and upgrades to extend its operational life or to comply with updated standards and technologies.

Refractory

Refractory materials are heat-resistant substances, often in brick form, that line boilers or furnaces aboard ships. They protect the structure from high temperatures and maintain thermal efficiency.

Refrigerant

A refrigerant is the working fluid used in refrigeration systems, absorbing and releasing heat as it circulates through various phases to maintain low temperatures in cooled spaces.

Refrigerated container

These are insulated shipping containers equipped with built-in refrigeration units, used to transport perishable cargo such as dairy, meat, or pharmaceuticals over long distances.

Refrigerated fish carriers

These vessels are designed for transporting freshly caught or processed fish under refrigeration. They include processing ships, fishing boats, and mother vessels with chilled holds.

Refrigerated storage spaces

These are temperature-controlled compartments on ships used to store perishable cargo, often equipped with insulation and active cooling systems.

Refrigeration

Refrigeration is the process of reducing and maintaining the temperature of a space or cargo to preserve perishable goods and prevent spoilage during storage or transit.

Cargo refrigeration

In reefer ships, cargo refrigeration systems are crucial for maintaining a controlled environment to keep goods like fruits or pharmaceuticals fresh throughout the voyage.

Refrigeration machinery spaces

These spaces house the compressors, motors, and related equipment required for operating the ship’s refrigeration systems, and are often located near the cargo holds.

Refrigeration unit

A refrigeration unit typically includes a compressor, condenser, evaporator, and expansion valve, all working together to cool air or liquid for maintaining low temperatures.

Refrigeration system

This system comprises one or more refrigeration units, along with associated piping, ducting, and controls, to ensure efficient and uniform cooling of specific areas or cargo.

Relative density of liquid

Also known as specific gravity, it is the ratio of a liquid’s mass to that of an equal volume of water at a specified temperature, often used in cargo calculations.

Relative humidity

Relative humidity indicates the percentage of water vapor in the air relative to the maximum it can hold at a given temperature, impacting cargo storage and onboard climate control.

Reliability

Reliability is the probability that a machine or system will perform its intended function without failure under specified conditions for a defined period of time.

Relief valve

A relief valve is a safety device that automatically opens to release excess pressure in a pipe or vessel, preventing damage or explosions from overpressure.

Remotely-operated vehicle (ROV)

ROVs are tethered underwater robots used for deep-sea inspection, maintenance, and exploration, often deployed in offshore oil, gas, and marine research operations.

Remotely-operated vehicle Sealion 3000

The Sealion 3000 is a high-performance ROV capable of deep-sea missions, equipped with robotic arms, cameras, and sensors for complex underwater tasks.

Removable tweendeck

A removable tweendeck is a temporary deck inserted between the hold and the main deck of a cargo vessel, allowing for flexible stowage of mixed cargo.

Rendez-vous

A rendez-vous in maritime operations is a scheduled meeting between vessels, often coordinated by radio communication, for transferring personnel, supplies, or conducting inspections.

Required free-fall height

This refers to the minimum vertical distance from the still water surface to the release point of a lifeboat during a free-fall launch, ensuring safe and effective deployment.

Representative spaces

These are selected compartments on a vessel that are used for inspection or testing, with the assumption that their condition reflects the status of similar spaces on board.

RESCUBE evacuation system

RESCUBE is an innovative emergency evacuation system designed for rapid and safe disembarkation of large groups of people from ships, particularly during critical situations.

Rescue boat davits

Rescue boat davits are mechanical arms, often hydraulic, used for lowering and retrieving rescue boats swiftly and safely, especially during emergencies at sea.

Dock-launched fast rescue boat

This patented system uses a floating dock to launch high-speed rescue boats efficiently, minimizing deployment time and enhancing life-saving capabilities.

Rescue boat davits (repeated)

These davits are typically pivoting or slewing types, hydraulically powered, designed for quick deployment and recovery of rescue boats from ship decks.

Rescue co-ordination centre (RCC)

A Rescue Co-ordination Centre (RCC) is a shore-based authority responsible for managing and coordinating search and rescue (SAR) operations. It receives distress alerts, organizes appropriate rescue assets, and ensures communication between involved parties to carry out maritime or aeronautical rescues effectively.

Rescue team

A rescue team is a designated group of trained crew members ready to act during emergencies onboard. They are equipped and prepared to perform tasks such as firefighting, man-overboard recovery, or first aid, ensuring rapid response and passenger safety.

Research ships

Research ships are specialized vessels outfitted for scientific studies of oceans, marine life, and underwater geology. These ships carry laboratories, sonar systems, and other scientific instruments to support exploration, data collection, and marine environment monitoring.

Reserve buoyancy

Reserve buoyancy refers to the volume of enclosed, watertight space above the waterline that contributes to a ship’s ability to remain afloat. It ensures the vessel maintains positive buoyancy and stability even when part of the hull is damaged or flooded.

Residual stability

Residual stability is the remaining ability of a vessel to right itself after sustaining damage, often expressed through the remaining area under the righting arm (GZ) curve. It is crucial in assessing ship safety after incidents like hull breaches.

Resilient mountings

Resilient mountings are machine supports that include springs or rubber-like materials to absorb vibration and noise. They reduce the transmission of mechanical vibrations from engines and machinery to the ship’s structure, enhancing onboard comfort and equipment lifespan.

Resin

Resin is a solid or semi-solid organic substance that is insoluble in water and often used in coatings, adhesives, and composite materials. It provides a durable, protective layer and is valued for its chemical resistance and binding properties.

Epoxy resin

Epoxy resin is a type of synthetic resin known for its strong adhesive properties and durability. It is widely used in marine coatings, flooring, and composites, and can be cured at room temperature to form a hard, chemical-resistant finish.

Resonance thickness measurement (RTM)

RTM is a non-destructive technique for measuring the thickness of metal structures. It uses resonance frequency analysis to determine wall thickness, allowing inspections without removing coatings or causing damage.

Restricted area

A restricted area on a vessel is a location that is off-limits to unauthorized personnel due to safety, security, or operational concerns. Access is usually controlled to prevent accidents, contamination, or interference with essential operations.

Restricted visibility

Restricted visibility refers to any situation where a vessel’s view is significantly limited due to environmental factors such as fog, heavy rain, or snow. Navigating under these conditions requires special precautions and adherence to COLREGs.

Reverse current protection

Reverse current protection involves a relay or diode that prevents electrical current from flowing in the wrong direction, especially between generators and switchboards. This protects equipment from damage and ensures proper power flow.

Ride control system

A ride control system is an advanced stabilization system that minimizes the effects of wave-induced motions in high-speed vessels. By adjusting fins, foils, or trim tabs, it improves passenger comfort and operational efficiency in rough seas.

Rig move

A rig move refers to the relocation of an oil drilling rig or platform from one site to another. This operation requires careful planning and coordination to ensure safe transport and reassembly at the new location, often involving tugs and support vessels.

Rigging

Rigging encompasses all ropes, wires, masts, booms, and other fittings used to support and control the ship’s sails or cargo-handling equipment. Proper rigging is essential for maintaining structural integrity and handling ship operations.

Righting arm GZ 

The righting arm (GZ) is the horizontal distance between the center of gravity and the center of buoyancy when a ship is heeled. It represents the leverage that causes a vessel to return to upright after being tilted by external forces.

Rigid pipelaying vessel SEVEN OCEANS

SEVEN OCEANS is a specialized rigid pipelaying vessel used in offshore oil and gas projects. It lays subsea pipelines on the ocean floor using a vertical lay system and advanced dynamic positioning for accuracy and efficiency.

Rim-Driven Permanent Magnet Motor Propulsor (RDP)

The RDP is a next-generation propulsion technology that integrates the motor into the propeller rim. Offering high efficiency, reduced noise, and compact design, it is ideal for modern, eco-friendly vessels.

Rise of floor

Rise of floor is the upward curve of a ship’s bottom from the keel outward toward the bilge. This design feature improves hull strength and affects the vessel’s stability and cargo hold configuration

Riser

A riser is a vertical pipe or conduit that connects subsea oil or gas wells to surface facilities or floating production units. It allows the safe transfer of fluids and can be rigid or flexible, depending on the installation depth and environmental conditions.

River/sea vessel, river/sea trader

River/sea traders are versatile, low-profile vessels designed for both inland waterways and coastal sea routes. Their shallow draft and compact design make them ideal for transporting cargo between ports with limited access.

Road tank-vehicle

A road tank-vehicle is a wheeled transport unit equipped with one or more tanks for carrying bulk liquids or gases, such as fuel, chemicals, or food-grade liquids. These vehicles must comply with safety and environmental transport regulations.

Road vehicle

A road vehicle refers to any motorized unit such as trucks, trailers, or semi-trailers used for overland cargo transport. These are key components of intermodal logistics, moving goods to and from ports and terminals.

Rock damping

Rock damping involves placing rocks over subsea pipelines to protect them from currents, fishing gear, and other external impacts. This method helps stabilize the pipeline and prevent damage in dynamic underwater environments.

Roll call

Roll call is the procedure of checking and confirming the presence of all passengers and crew, particularly during emergencies, drills, or evacuations. It ensures accountability and aids in safe and organized operations.

Roll reduction

Roll reduction measures the decrease in a vessel’s side-to-side motion due to the use of stabilizers or other damping systems. Effective roll reduction improves comfort, cargo safety, and vessel performance in rough sea conditions.

Roll stabilisation

Roll stabilisation includes systems like fins, gyros, or tanks designed to reduce the rolling motion of ships. These systems are essential for passenger ships, naval vessels, and cargo carriers operating in high seas.

Roll-on/roll-off system

The roll-on/roll-off (Ro-Ro) system allows vehicles and wheeled cargo to be driven directly on and off ships via ramps. It streamlines loading and unloading, reducing turnaround time at ports and increasing operational efficiency.

Ro-lo vessel

A Ro-Lo (Roll-on/Lift-off) vessel combines features of Ro-Ro and Lo-Lo ships, enabling both drive-on cargo and crane-lifted containers. This hybrid design increases cargo handling flexibility and adaptability across diverse port facilities.

Ro-lo forest product carriers from Gdynia Shipyard

These specialized Ro-Lo vessels, built at Gdynia Shipyard, are designed to transport forest products like paper, timber, and pulp. They feature cargo ramps and hold configurations optimized for roll-on and lift-off operations.

Rolling freight

Rolling freight refers to wheeled cargo such as trucks, trailers, or machinery transported on Ro-Ro vessels. It can be quickly loaded and unloaded without cranes, making it ideal for time-sensitive and intermodal logistics.

Side-loading system

A side-loading system allows cargo to be loaded from the vessel’s sides using ramps or cranes. It is useful in ports with limited stern access or in multipurpose vessels handling various cargo types.

Folding hatch covers

Folding hatch covers are movable panels that provide access to cargo holds. When open, they fold neatly to the side, allowing efficient use of deck space and quick opening and closing during cargo operations.

Rolux wheelless cassette system

The Rolux system, developed in Finland, is a cargo handling method that uses flat, wheelless cassettes moved by specialized transporters. It improves loading efficiency and reduces the need for multiple vehicle types.

Ropax

Ropax vessels are ships that combine roll-on/roll-off cargo capacity with passenger accommodations. These are commonly used in short sea routes and ferry services, offering fast, reliable transportation of both people and vehicles.

RoPax NILS HOLGERSSON

NILS HOLGERSSON is a modern RoPax ferry known for combining high passenger capacity with vehicle decks. It operates on European routes, providing efficient transport for travelers and freight across short sea passages.

Bow ramp/door

A bow ramp/door is a hinged or liftable section at the front of a Ro-Ro vessel, allowing vehicles to drive on or off the ship. It must be structurally secure and watertight to maintain vessel integrity during voyages.

Tiltable ramp

A tiltable ramp is an adjustable ramp that can be inclined to match different deck levels or port facilities. It enhances flexibility during cargo operations, especially for multi-deck Ro-Ro vessels.

Rope guard

A rope guard is a protective two-part metal covering installed on the propeller hub of a ship, designed to prevent ropes, fishing nets, or debris from entangling the propeller shaft, thereby reducing damage and maintaining propulsion efficiency.

Ro-ro

“Ro-ro” stands for Roll-on/Roll-off, referring to a type of vessel specially designed to carry wheeled cargo such as cars, trucks, and trailers, which are driven on and off the ship using built-in ramps.

Ro-ro cargo securing equipment

Equipment used to secure rolling cargo includes trailer trestles for elevation, support jacks for stability, speedlash systems for rapid lashing, and wheel chocks to prevent vehicle movement during transit.

Open ro-ro cargo spaces

Open Ro-ro spaces are either open at both ends for through traffic or at one end with permanent openings in the side walls, allowing better ventilation but requiring extra precautions against water ingress.

Closed ro-ro cargo spaces

These are fully enclosed and weather-protected compartments within a Ro-ro vessel, lacking the permanent end openings of open spaces, and are typically equipped with fire suppression and ventilation systems.

Ro-ro carrier SPAARNERBORG

The SPAARNERBORG is a notable Ro-ro cargo carrier designed for transporting large volumes of wheeled cargo across sea routes, featuring efficient loading systems and a strong cargo deck structure.

Ro-ro freighter TOR MAGNOLIA

TOR MAGNOLIA is a dedicated Ro-ro freight vessel known for its robust build and efficient vehicle-loading capabilities, often used in short-sea shipping across Northern Europe.

Ro-ro passenger ship

A Ro-ro passenger ship combines facilities for vehicle transportation with accommodations for passengers, enabling efficient transport of both people and vehicles on popular ferry routes.

Rotary bow rudder system

The rotary bow rudder system enhances ship maneuverability by applying a rotating force at the bow, often used in combination with azimuth thrusters to improve turning performance in confined waters.

Rotary pump

A rotary pump is a type of positive displacement pump that moves a fixed amount of fluid with each rotation, providing steady, pulse-free flow ideal for lubricating or hydraulic systems.A rotary pump is a type of positive displacement pump that moves a fixed amount of fluid with each rotation, providing steady, pulse-free flow ideal for lubricating or hydraulic systems.

Gear pump

The gear pump uses two intermeshing gears to transport fluid between the gear teeth and pump casing, offering reliable performance in applications involving lubricating oils or fuels.

Rotary vane pumps

These pumps use a rotor with vanes that slide in and out of slots to maintain close contact with the pump housing, allowing fluid to be trapped and moved efficiently through the system.

Screw pump

A screw pump uses one or more helical screws to transport fluid along the screw axis, especially suitable for high-viscosity liquids and low-pulsation flow in marine fuel and oil systems.

Rotary table

The rotary table is a rotating platform found on drilling rigs, used to apply torque to the drill string and facilitate drilling into the seabed or rock formations for oil and gas extraction.

Royal Institution of Naval Architects (RINA)

RINA is a prestigious British professional body established in 1860, promoting excellence in naval architecture and marine engineering through research, certification, and global standards.

Rudder

The rudder is a vital steering component of a vessel, typically mounted aft and shaped like a hydrofoil, which directs water flow to control the ship’s heading.

Balanced rudder

This rudder type places part of its area forward of the turning axis, reducing the effort needed to steer the ship and enhancing response at higher speeds.

Becker rudder

The Becker rudder features a hinged flap that moves independently from the main blade, significantly improving lift and maneuverability, especially at low speeds or tight turns.

Flap rudder

Developed for enhanced steering control, the flap rudder has a movable trailing edge flap that increases lift and decreases turning radius, particularly effective for large vessels.

Flettner rudder

The Flettner rudder incorporates dual trailing-edge flaps, designed for greater lift and improved handling, commonly used on older vessels and in special maneuvering applications.

Semi-spade rudder with simple pintle

This rudder is partially supported by a horn and connected with a pintle, offering a balance between structural support and hydrodynamic efficiency.

Rudder actuator

The rudder actuator is a hydraulic or electro-mechanical device that converts power into motion to control the rudder’s position, playing a key role in a vessel’s steering system.

Semi-balanced rudder

A semi-balanced rudder places only a portion of the blade forward of the rudder stock, combining some of the benefits of reduced steering torque with structural simplicity.

Spade rudder

Spade rudders are unsupported at the bottom and fully hinged on a stock, offering high responsiveness and excellent steering performance at various rudder angles.

TLKSR rudder

Developed by Becker Marine Systems, the TLKSR is a high-efficiency spade rudder with an advanced twisted design that minimizes cavitation and improves maneuvering at high loads.

Twisted leading edge rudder

This innovative rudder design features a twisted blade that optimizes water flow across its surface, enhancing lift and reducing drag and vibration.

Rudder angle indicator

This device displays the real-time position of the rudder in degrees, allowing the ship’s crew to monitor steering input and response during operations.

Rudder blade

The rudder blade is the primary surface that interacts with water to create directional force, allowing the ship to change course effectively when steered.

Rudder blade area

While there are no strict international rules for rudder size, the blade area is crucial for maneuverability, often determined by vessel type, size, and intended use.

Rudder carrier

The rudder carrier is a structural fitting mounted inboard on the steering gear deck, designed to support the weight of the rudder and its stock when not fully submerged.

Rudder horn

The rudder horn is a robust, often welded structure that helps support semi-spade rudders by providing a pivot point and mechanical strength from the hull.

Rudder propeller

A rudder propeller is a combined propulsion and steering unit capable of 360-degree rotation, often used in tugs and offshore vessels for enhanced maneuverability.

Rudder roll stabilisation 

This system uses the ship’s existing steering gear to counteract rolling motions caused by waves, thereby improving comfort and safety in rough seas.

Rudder sole cavitation

Rudder sole cavitation occurs when the rudder blade has a sharp front lower edge, causing water flow to separate and form vapor bubbles. These bubbles collapse violently, leading to pitting and erosion of the rudder surface, which can reduce steering efficiency and damage the rudder over time.

Rudderstock

The rudderstock is the vertical shaft that connects the rudder blade to the steering gear. It transmits the turning force from the steering mechanism to the rudder, enabling directional control of the vessel. Made of strong materials, it must withstand high torque and bending stresses.

Rudder stop

A rudder stop is a mechanical limit, either on the stern frame or as brackets beside the rudder quadrant on deck, designed to restrict the rudder’s movement within safe angles. This prevents over-rotation and damage to the steering gear or rudder components.

RULFINDER

RULFINDER is a PC-based interactive software developed by Lloyd’s Register to assist with fatigue assessments of ship structures. It helps ship designers and engineers estimate the Remaining Useful Life (RUL) of components under operational stress, enhancing maintenance planning and structural safety.

Rule of thumb

A “rule of thumb” refers to a practical method or rough estimate based on experience rather than strict calculations or scientific principles. In maritime practice, it often guides quick decision-making, though it may lack precision.

Rust

Rust is the reddish-brown corrosion product that forms when iron or steel reacts with oxygen and moisture. Composed mainly of hydrated iron oxides, rust weakens metal structures over time, making it a serious concern for ships and offshore installations without proper maintenance and protective coatings.

Maritime Glossary: S

S-57 Standard Format

The S-57 standard format is a digital data standard used for Electronic Navigational Charts (ENCs) in marine navigation systems. Developed by the International Hydrographic Organization (IHO), it ensures consistent and accurate charting information is available for safe ship navigation worldwide.

Sacrificial anode

A sacrificial anode is a metal component, typically made of zinc, aluminum, or magnesium, used in cathodic protection systems. It corrodes instead of the protected steel structure, such as a ship’s hull or underwater piping, thereby extending the service life of the main components.

Sacrificial anode cathodic protection

This protection method involves attaching a less noble metal (the sacrificial anode) to a steel structure, which then becomes the cathode in an electrochemical cell. The anode corrodes over time, protecting the steel from corrosion by diverting the electrochemical reactions.

Safe Anchor Handling System (SAHS)

SAHS refers to specialized equipment and procedures designed for the safe and efficient handling of rig anchors, especially on anchor handling tug supply (AHTS) vessels. This system minimizes crew risk and improves operational performance in offshore anchoring tasks.

Safe Return to Port (SRtP)

Following incidents like the Costa Concordia capsizing and engine room fires, the SRtP concept ensures that passenger ships maintain basic safety functions, such as propulsion, fire protection, and life-support systems, allowing them to safely return to port under their own power.

Safe speed

Safe speed is the speed at which a vessel can operate while still being able to take proper and effective action to avoid collisions and safely stop within a suitable distance under prevailing conditions such as visibility, traffic, and maneuverability.

Safe Working Load (SWL)

SWL is the maximum load that lifting gear, cranes, or rigging can safely handle under normal operating conditions. It is a critical safety parameter marked on shipboard equipment to prevent overloading and reduce the risk of accidents or equipment failure.

Safe working practice

This term refers to standardized procedures and behavior that ensure the safety of personnel while working on ships or in industrial environments. These practices include wearing personal protective equipment (PPE), following safety protocols, and using machinery correctly.

Safe working pressure

The safe working pressure is the highest pressure that equipment like cargo hoses or pipelines can handle during normal operations without risk of failure or leakage. It is determined through design specifications and safety testing.

Safety head

A safety head is a pressure relief device used in tanks or pipelines to expel gas or fluid when internal pressure exceeds safe limits. It ensures controlled release at high velocities, preventing equipment damage or explosions.

Safety system

A safety system is an automated control mechanism designed to monitor and manage shipboard or industrial operations. It activates alarms or shutdowns during abnormal conditions, helping to maintain operational safety and protect personnel and equipment.

Safety workstation

Found on a ship’s bridge, a safety workstation is a designated area equipped with displays and controls for navigation, communication, and emergency systems. It allows officers to quickly monitor and respond to safety-related events.

Safety zone

The safety zone around an offshore platform extends 500 meters in all directions from the installation. Unauthorized vessels are prohibited from entering this area to prevent collisions and ensure the safety of offshore operations and workers.

Sagging

Sagging is a structural stress condition where the ship’s midsection bends downward due to buoyant support at the bow and stern. This can occur in heavy seas or uneven loading and needs to be considered during ship design and loading.

Sags

In painting, sags are defects caused by excess paint running down a vertical surface, forming uneven runs or curtains. These reduce coating effectiveness and visual appeal, requiring careful surface preparation and paint application techniques.

Saimaa Canal

The Saimaa Canal connects Lake Saimaa in Finland to the Gulf of Finland, passing partly through Russian territory. It provides a vital waterway for cargo traffic between inland Finland and the Baltic Sea, supporting regional trade.

Salinity

Salinity refers to the concentration of dissolved salts in water, typically measured in parts per million (PPM). In marine environments, salinity affects buoyancy, corrosion rates, and engine cooling systems, making it a key parameter for ship operations.

Salinometer

A salinometer is an instrument that measures the salt content (usually sodium chloride) in water. It is commonly used in ship boilers and desalination systems to monitor and control water purity for operational efficiency and safety.

Salvage

Salvage is the compensation paid to those who voluntarily assist in recovering a ship or cargo from danger at sea. It is a recognized maritime practice governed by international law and often involves professional salvage companies.

Salvage Association

The Salvage Association is an organization that, through its surveyors, assesses maritime incidents to determine causes and advise on claims. It plays a key role in supporting marine insurers and coordinating salvage responses.

Salvage operation

This term encompasses all activities undertaken to rescue a vessel, cargo, or marine property from peril. Operations may include refloating grounded ships, firefighting, or recovering sunken cargo, often under time-sensitive and hazardous conditions.

Sand blasting

Sand blasting is a surface preparation method where abrasive materials like sand are blasted at high speed to clean or roughen steel surfaces. It is commonly used before painting to ensure strong adhesion and remove rust or scale.

Sanitary discharges

These are waste fluids from onboard sources like toilets, showers, and kitchens. Proper management and treatment of sanitary discharges are essential for marine hygiene and environmental compliance under MARPOL regulations.

Sanitary pump

A sanitary pump delivers seawater to shipboard toilets for flushing. These pumps are typically part of the vessel’s plumbing system and must be reliable to ensure hygienic operation throughout the voyage.

Saturated steam

Saturated steam is steam that exists at the boiling point of water at a given pressure, containing no superheat. It is widely used in marine and industrial boilers where consistent energy transfer is essential.

Saturation

Saturation in meteorological or HVAC terms describes air that contains the maximum amount of water vapor possible at a given temperature. Further cooling of saturated air typically results in condensation, affecting shipboard climate control.

Scale

Scale refers to a measurement factor that translates observed or instrument values into real-world quantities. In ship design or navigation, scale is crucial for interpreting charts, plans, or engineering drawings.

Loose scale

Loose scale consists of rust or oxide flakes that easily fall off steel surfaces when struck. Surveyors use tools like hammers to detect these weak spots, which often indicate underlying corrosion problems needing maintenance.

Mill scale

Mill scale is a thick, hard oxide layer formed on hot-rolled steel surfaces. Although it can offer temporary protection, it must be removed before painting or welding, as it may interfere with adhesion or structural integrity.

Scallop

A scallop is a cut-out or notch in a stiffener or frame that allows a continuous weld to be made along a plate seam. It facilitates better structural bonding and reduces stress concentration during welding.

Scantlings

Scantlings refer to the dimensions and strength characteristics of a ship’s structural elements, such as beams, plates, and girders. They are determined by classification society rules to ensure the vessel’s safety and durability.

Reduced scantlings

Reduced scantlings are allowed in certain non-critical ship areas where corrosion-protective measures are in place. These lower dimensions still meet structural safety standards but help reduce material costs and weight.

Scavenge Air System

This system supplies compressed air to the main engine’s scavenging ports, helping to clear out exhaust gases from the cylinder and fill it with fresh air for the next combustion cycle, improving engine efficiency.

Scavenge fire

A scavenge fire is a hazardous condition where unburned fuel, carbon deposits, and oil residue in the scavenging space ignite. It is dangerous and requires immediate fire suppression measures to prevent engine damage or explosion.

Scavenging

Scavenging is the process of removing exhaust gases from an engine cylinder by introducing fresh air. This ensures complete combustion in the next cycle and is crucial for the performance of two-stroke marine engines.

Scavenging methods

Different engine designs use cross-flow, loop, or uniflow scavenging methods. Each technique has a specific air flow pattern to efficiently clear exhaust gases and supply fresh air for combustion.

Uniflow scavenging

In uniflow scavenging, fresh air enters from the bottom while exhaust gases exit through top exhaust valves, creating a smooth, unidirectional flow. This method provides high scavenging efficiency in large two-stroke engines.

Scene

In maritime safety and emergency response, a “scene” refers to the physical area where an incident, such as an accident, fire, or grounding, has occurred. It is the focus of rescue, investigation, and recovery efforts.

Schneekluth duct

A Schneekluth duct is a power-saving device fitted ahead of a ship’s propeller to improve water flow and reduce fuel consumption. It guides water into the propeller more efficiently, enhancing propulsion performance.

Scissors platform lift

A scissors platform lift uses a crisscrossing set of levers to raise or lower a platform. Common on ships for maintenance or cargo access, these lifts are stable and can be easily adjusted to desired working heights.

SCOLD

The SCOLD (Shipping Container Location Device) is a compact radio beacon used to monitor and track containers. It helps identify misplaced or lost units in large container yards or ships, improving logistics and inventory management.

Scoop cooling

Scoop cooling is a passive seawater cooling system that uses the ship’s forward motion to direct seawater through an opening in the hull, which then flows through heat exchangers before exiting, requiring minimal pumping energy.

SCOT concept

The SCOT (Safe Concept of Tanker) design involves building tankers with redundant propulsion, steering, and power systems. This enhances safety by ensuring the vessel can remain operational in case of critical system failure.

Scraper ring

A scraper ring is a type of piston ring located at the lower end of a piston in an engine. Its primary function is to remove excess lubricating oil from the cylinder walls and return it to the crankcase, ensuring proper lubrication without oil entering the combustion chamber.

Screen plate

A screen plate is a heat-resistant metal plate installed in boilers. It acts as a shield, through which superheater tubes pass, protecting them from direct exposure to intense radiant heat and promoting efficient heat distribution.

Screw aperture

The screw aperture is the opening in the stern frame of a ship where the propeller, also known as the “screw,” is housed and rotates. This area must be carefully designed to allow smooth water flow and minimize resistance for effective propulsion.

Screw down non-return valve

A screw down non-return valve is a type of check valve with a disc that is not connected to the spindle. When fluid flows in the correct direction, the disc lifts, but it closes automatically to prevent backflow when flow reverses.

Screw effect

The screw effect refers to the sideways thrust created by a rotating propeller. This can cause a vessel’s stern to swing in a specific direction depending on the propeller’s rotation, especially during maneuvering or reversing.

Screw lift valve

A screw lift valve features a disc that is directly attached to the spindle. It allows precise manual control over the valve’s opening, enabling the disc to be locked in any position to regulate fluid flow.

Scum valve

A scum valve is a boiler fitting used to remove impurities or scum that float on the water surface. Located at the boiler’s water level, it helps maintain water purity and boiler efficiency by allowing surface contaminants to be drained off.

Scuppers

Scuppers are drainage openings on a ship’s deck that allow rainwater, wash water, or condensation to drain off, preventing water accumulation and maintaining safe, dry surfaces on the deck.

Scuttle

A scuttle is a small, typically circular or oval opening in a ship’s deck or bulkhead, fitted with a cover or hatch. It is used for ventilation, access, or drainage, and is designed to be watertight when closed.

SEA-Arrow bow

The SEA-Arrow bow, or Sharp Entrance Angle bow, is a modern hull design used in LPG carriers. It features a narrow, streamlined shape that reduces resistance and improves efficiency, particularly in heavy seas.

Sea Axe

The Sea Axe is an innovative bow design resembling the shape of an axe, developed to improve seakeeping, reduce vertical acceleration, and increase fuel efficiency. It is commonly used on fast patrol vessels and offshore service ships.

Sea-going vessel 

A sea-going vessel is a ship designed and equipped to operate on the open sea, as opposed to rivers or sheltered coastal areas. These vessels must meet higher structural and operational standards to ensure safety and performance.

Maritime Glossary: T

Tack welder

A tack welder is typically a fitter or someone working under a fitter’s guidance who performs small, temporary welds known as “tack welds.” These welds hold components in place during the assembly process until final, continuous welds are applied. This ensures proper alignment and prevents movement of parts during the final welding stages.

Tactical diameter

The tactical diameter is a ship manoeuvring parameter that refers to the distance a vessel travels perpendicular to its original course when it completes a 180° turn during a turning circle test. It is a key indicator of a ship’s turning ability and overall manoeuvrability.

Take-me-home drive systems

These are emergency propulsion systems installed on ships, especially larger vessels, to provide limited mobility in case the main propulsion system fails. They help maintain vessel control and safety until repairs can be made or the ship reaches port.

Tank

In maritime terms, a tank is an enclosed space formed by the permanent structure of the ship, designed to hold liquids such as fuel, water, oil, or cargoes. Tanks play a critical role in the operation and stability of vessels.

Centre tank

A centre tank is a storage tank located inboard of a longitudinal bulkhead. These tanks are generally found in the middle of the ship and are important for maintaining stability and optimizing cargo distribution.

Slop tank

A slop tank is a designated tank used to collect residues such as tank drainings, washings, and other oily mixtures. These tanks are essential in preventing marine pollution by holding waste liquids for proper disposal or treatment.

Wing tank

Wing tanks are situated adjacent to the side shell plating of a ship and are often used for ballast or cargo storage. Their positioning helps with vessel balance and structural integrity.

Tank Arrangement Plan (TAP)

The Tank Arrangement Plan is a critical ship drawing that outlines the location, size, and purpose of all tanks onboard. It serves as an essential reference for design, operation, and emergency response.

Tank cleaning

Tank cleaning involves the removal of hydrocarbons, vapours, residues, or other substances from cargo tanks to prepare them for inspection, maintenance, or change of cargo. This ensures safety and compliance with environmental standards.

Tank cleaning machines

Also known as washing machines, these devices are installed inside cargo tanks to spray cleaning fluid in controlled patterns. They automate and improve the safety and efficiency of tank cleaning operations.

Tank cleaning validation (TCV) system

The TCV system is a software tool that monitors and records tank cleaning operations. It validates that proper cleaning procedures are followed and helps maintain compliance with regulatory and safety standards.

Tank cover

The tank cover is a structural element designed to protect a ship’s cargo containment system, particularly in gas carriers or other specialized tankers, by shielding it from mechanical damage and weather.

Tank dome

A tank dome is the raised portion on top of a cargo tank, typically found in below-deck tank configurations. It allows for tank access, pressure relief, and cargo loading/unloading.

Tank Space Information

This documentation includes detailed data on the ship’s tanks, such as size, capacity, location, coatings, and service type. It is vital for cargo planning, stability analysis, and maintenance.

Tank support system for high-temperature cargoes

These support systems are designed to hold cargo tanks carrying high-temperature substances. They allow for thermal expansion and maintain structural integrity under extreme conditions.

Parcel chemical tanker

A parcel chemical tanker is a specialized vessel designed to carry numerous types of chemical cargoes simultaneously. Each cargo is kept in separate tanks to avoid contamination, making them highly flexible and efficient.

Target useful life (painting)

This refers to the expected number of years a paint or coating system will last before requiring significant maintenance. It is a key factor in choosing protective coatings for ship structures.

Tarpaulin

A tarpaulin is a durable, waterproof fabric used to cover hatches and other areas for protection against weather and water ingress. It is commonly used in cargo handling and storage.

Taut wire system

This is a precise method of position fixing used in marine operations. It involves a wire anchored to the seabed with its angle measured to determine the ship’s position, often used in dynamic positioning systems.

Technical Data Sheet (painting)

Issued by paint manufacturers, this sheet includes critical product information such as composition, application methods, drying time, and safety precautions, aiding proper and safe use.

Technical file of an engine

This is a detailed record that includes all technical parameters, parts, settings, and emissions data of an engine. It is required for compliance with environmental regulations and performance monitoring.

Telecommunications cable

These are marine-grade cables used for undersea data transmission, varying in diameter from 10mm to 80mm. They play a crucial role in global communications infrastructure.

Tempering

Tempering is a heat treatment process applied to steel after quenching. It involves reheating the metal to a moderate temperature to improve its toughness and reduce brittleness.

Template

A template is a full-size pattern used as a guide to shape or fabricate parts like steel plates or pipes. It ensures consistency and accuracy in production and fitting.

Tensile strength

Tensile strength is the maximum stress a material can withstand when stretched. It is a key indicator of a material’s mechanical performance under load.

Tensile test

This is a standardized test in which a specially shaped specimen is pulled until it breaks, revealing the material’s strength, ductility, and elasticity characteristics.

Tension leg platform (TLP)

A type of floating offshore platform tethered to the seabed by vertical tendons. TLPs are commonly used for oil and gas production in deep waters due to their stability.

Terminal

A terminal is a shore-based facility where ships load or unload cargo or passengers. It includes necessary infrastructure for berthing, storage, customs, and transport connections.

Terminal/escort tug LAMNALCO SANA’A

The LAMNALCO SANA’A is a specialized tug used for escorting ships to terminals. It provides maneuvering assistance, particularly in confined or hazardous waters.

Terminal representative

A terminal representative is the person appointed by the port facility to liaise with visiting vessels, ensuring smooth and safe cargo operations and compliance with port regulations.

Terminal representative

A terminal representative is the person appointed by the port facility to liaise with visiting vessels, ensuring smooth and safe cargo operations and compliance with port regulations.

Test cock

A small valve used for sampling or checking system contents, such as pressure or fluid type, in pipelines or tanks. It allows for easy testing without system disassembly.

Thermal conductivity

This property defines how well a material conducts heat. Materials with high thermal conductivity are used in applications where rapid heat transfer is essential.

Thermal efficiency

Thermal efficiency measures how effectively an engine converts fuel energy into mechanical work. Higher efficiency means more useful energy output for the same amount of fuel.

Thermal protective aid

This is a lightweight, waterproof garment that helps conserve body heat in cold water. It is typically used in life-saving appliances like life rafts and survival suits.

Thermal trip

A thermal trip is a safety device that shuts down electrical equipment when temperatures rise above safe levels. It prevents overheating and potential fire hazards.

Thermoplastic

Thermoplastic materials soften when heated and harden when cooled, making them ideal for molding and forming into various shapes repeatedly without degrading their properties.

Thermostat

A thermostat is a device that detects and responds to temperature changes, often used to control heating or cooling systems by regulating fluid flow or electrical circuits.

Thinner

Thinners are volatile liquids added to paint to reduce viscosity, making it easier to apply by brush, roller, or spray, while also aiding in the coating’s penetration and adhesion.

Third Assistant Engineer

This is the entry-level licensed engineer on a ship responsible for managing machinery during the 8–12 watch, and assisting with daily engine operations and maintenance.

Third Mate

The Third Mate is the junior officer in the deck department, typically in charge of navigation during the 8–12 watch and safety equipment maintenance, including lifeboats and firefighting gear.

Threshold

In measurement systems, a threshold refers to the minimum level of input required to generate a detectable output or trigger a response in an instrument or control system.

Threshold limit value (TLV)

This value represents the acceptable average exposure level of a chemical substance over a workday. It is used to ensure the safety of personnel from toxic exposure.

Actual throat

In welding, the actual throat is the shortest distance from the weld root to the face of a fillet weld. It is a key parameter for assessing weld strength.

Theoretical throat

This is the calculated distance from the root of a joint to a point on the weld face, measured perpendicular to the weld leg, and is used in design for ensuring sufficient weld strength.

Thrust bearing

A thrust bearing absorbs and transfers axial forces from the propeller shaft to the ship’s hull structure, allowing smooth and safe transmission of thrust.

Thrust block

The thrust block is the complete assembly, including thrust bearings and shaft, designed to securely transfer the propeller’s thrust to the ship’s hull without movement or misalignment.

Thrust power

Thrust power is the product of propeller thrust and the vessel’s speed of advance. It indicates how effectively the propeller is converting rotational energy into forward movement.

Thrust shaft

This is a short section of shaft fitted with a thrust collar and flanges, which connects the main propulsion shaft to the thrust block, transmitting axial loads efficiently.

Thrusters

Thrusters are manoeuvring devices on ships that provide lateral or 360° directional thrust, enhancing ship handling during docking, undocking, and low-speed operations.

Azimuthing thruster

An azimuthing thruster is a steerable propeller unit that can rotate 360° horizontally, providing excellent manoeuvrability for dynamic positioning and harbor operations.

Continuous duty thruster

This thruster is built to operate continuously, such as in dynamic positioning systems, where precise and sustained thrust is required for station-keeping.

CRP thruster

A CRP (Contra-Rotating Propeller) thruster features two propellers rotating in opposite directions to improve thrust efficiency and reduce cavitation.

Intermittent duty thruster

This type of thruster is used occasionally, such as during docking or slow-speed navigation, and is not designed for prolonged operation.

Jet thruster

A jet thruster functions like a water jet pump, drawing water from below the hull and expelling it through nozzles to produce directional thrust for manoeuvring.

Outboard thruster

Mounted externally at the stern, an outboard thruster provides additional manoeuvring power and is often used in vessels with limited internal space for traditional systems.

Retractable thruster

A retractable thruster can be lowered into the water when needed and retracted when not in use, reducing drag and protecting the unit when sailing at higher speeds.

Rim drive thruster

This innovative thruster design uses a motor integrated into the rim of the propeller, reducing noise, improving efficiency, and minimizing maintenance.

Swing-up azimuth thruster

A dual-purpose unit that combines azimuthing movement with a vertical swing-up mechanism, allowing it to be retracted when not in use, ideal for shallow waters.

Titled thruster

A steerable thruster developed by Wärtsilä with a downward tilted propeller to reduce cavitation and improve hydrodynamic performance in challenging operating conditions.

Thyristor

A thyristor is a semiconductor device that allows current flow in one direction and is used in power electronics for controlling high-voltage AC or DC power efficiently.

Tidal energy

Tidal energy harnesses the kinetic and potential energy from ocean tides to generate electricity. It is a renewable and predictable source of energy with minimal environmental impact.

Tightness test

A tightness test verifies the integrity of a structure (e.g., a tank or hatch) by checking for leaks using air, water, or another medium to ensure it is properly sealed.

Air test

This test uses air pressure to check the tightness of ship structures such as compartments, tanks, or pipelines, detecting any leaks that may compromise safety or function.

Chalk test

A chalk test is used to determine the weathertightness of hatch covers or doors on ships. The method involves rubbing chalk on the contact surface of the seal and then closing the hatch. If the chalk transfers evenly onto the opposing surface, it indicates good contact and weathertight sealing.

Hose test

The hose test checks the tightness of a ship’s structure, especially hatch covers, by spraying a jet of water over the seals. Water penetration inside indicates leakage, making this a quick and simple method to assess potential points of failure in weathertight closures.

Hydropneumatic test

A hydropneumatic test combines both hydrostatic (liquid) and pneumatic (air) pressure to evaluate the integrity and tightness of a system. This method involves filling the component with liquid and applying air pressure to detect leaks and assess strength.

Hydrostatic test

A hydrostatic test assesses the structural integrity and leak tightness of tanks, piping, or pressure vessels. The system is filled with liquid, typically water, and pressurized to a specified level to ensure it can safely hold its operating pressure without deformation or leakage.

Tiller

A tiller is a lever attached directly to a vessel’s rudderstock, used to manually steer the rudder. Commonly found in smaller boats or as an emergency steering mechanism, it allows direct mechanical control of the vessel’s direction.

Timber

Timber refers to processed wood in forms like sawn lumber, logs, poles, and cants. In maritime shipping, timber can be carried as cargo and must be handled with care due to its bulk and potential for shifting during transit.

Timber deck cargo

Timber deck cargo consists of timber products transported on the open deck area of a vessel. Carriage of such cargo requires specific lashing and stowage methods to maintain vessel stability and prevent shifting in rough seas.

Timber load line

The timber load line is a special load line assigned to ships carrying deck loads of timber. It accounts for the unique buoyancy and safety considerations required when transporting timber on deck, permitting a deeper load draft under controlled conditions.

Tin

Tin is a corrosion-resistant, ductile metal often used to coat other metals such as steel to prevent rust. It plays a vital role in shipbuilding and packaging industries due to its protective qualities and non-toxic nature.

Titanium

Titanium is a lightweight, strong, and corrosion-resistant metal used in marine applications. Due to its excellent resistance to seawater, it’s often selected for hull plates, piping systems, and critical components in high-performance vessels.

T-joint

A T-joint is formed when two metal components intersect at a right angle, resembling the letter “T”. This type of weld joint is commonly used in structural assemblies in shipbuilding to connect beams and plates.

Toeboard

A toeboard is a safety feature installed along the edge of elevated platforms or walkways. It prevents tools, equipment, or personnel from slipping off the edge and is critical in ensuring workplace safety on ships and docks.

Tolerance

Tolerance refers to the allowable variation in dimensions, shape, or position of a manufactured part. In shipbuilding, strict tolerances are essential to ensure components fit and function correctly under operational stresses.

Gross tonnage

Gross tonnage (GT) is a measure of the overall internal volume of a ship, including all enclosed spaces. It is used internationally for regulatory purposes such as safety rules, port fees, and manning requirements.

Net tonnage

Net tonnage (NT) is derived from gross tonnage but only accounts for the cargo-carrying areas of a ship. It excludes spaces such as the engine room or crew quarters and is used for calculating port dues and canal transit fees.

Top drive

A top drive is a mechanical device mounted on the drilling derrick that rotates the drill string. Powered by electric or hydraulic motors, it improves the efficiency and safety of oil and gas drilling operations compared to traditional rotary tables.

Topping off

Topping off is the process of completing the final stage of loading a tank to reach the desired ullage or volume. This is done carefully to prevent overfilling and ensure safe containment of the liquid cargo.

Topping up

Topping up involves adding inert gas to a tank already in an inert state. This helps maintain a non-flammable atmosphere, especially in oil tanks, by preventing oxygen entry and reducing the risk of explosion or combustion.

Toppling

Toppling refers to the instability of a container or object causing it to tilt and potentially fall over. In shipping, preventing toppling is critical to cargo safety, especially during heavy seas or uneven stowage.

Torsion

Torsion is the twisting stress experienced by a component when subjected to a torque. In marine engineering, torsional loads are carefully considered in the design of shafts and hulls to avoid mechanical failure.

Torsional vibration

Torsional vibration is the oscillatory twisting of rotating parts like engine crankshafts or propeller shafts. If not properly dampened, these vibrations can cause damage, reduce efficiency, or lead to mechanical failure.

Total head

Total head in a pump system is the total pressure or energy difference between the suction and discharge points. It represents the capability of the pump to move fluid through the system and includes all resistance due to elevation and friction.

Total static head

Total static head is the vertical distance from the fluid source to the point of discharge. It reflects the height a pump must overcome to move liquid, not including frictional losses in the piping.

Total loss (marine insurance)

In marine insurance, a total loss refers to a situation where a vessel is completely destroyed, sunk, or so severely damaged that it is no longer economically viable to repair. It may be actual or constructive, depending on circumstances.

Towing and anchor handling equipment of TOR VIKING

The ice-class anchor handling tug supply vessel TOR VIKING is equipped with specialized towing and anchor handling gear, including powerful winches, shark jaws, and stern rollers, designed for offshore support in harsh Arctic conditions.

Towing gear

Towing gear includes the equipment used to connect and manage a tow, such as winches, towing hooks, tow bitts, and hawsers. These components must be robust and reliable to handle dynamic loads and ensure safe operations.

Towing gear of the Rotor tug RT INNOVATION

The RT INNOVATION, a Rotor Tug, features an advanced towing system with triple azimuth thrusters for superior maneuverability. Its towing gear includes high-performance winches and hooks designed for complex harbor and escort duties.

Towing gear of the standard type tug SAAM MEXICA

The standard tug SAAM MEXICA is equipped with conventional towing gear such as stern winches, towing hooks, and heavy-duty towlines. Its design supports general towing, harbor operations, and barge assistance.

Towing hook

A towing hook allows a quick and secure connection to a tow line. It is built to withstand high tensile forces and often includes a manual or remote-release mechanism for safety in emergencies.

Towing hook slipping device

This device enables the quick release (or slipping) of a towing hook in the event of an overload or emergency, preventing damage to the vessel or injury to crew by disconnecting the tow safely.

Towing tank

A towing tank is a large testing basin used to simulate ship movements through water. Scale ship models are towed along a track to evaluate hydrodynamic performance, resistance, and hull design characteristics.

Towing winch

A towing winch is a mechanical device used to control the tension and length of a towline. Essential for tugboats and anchor handling vessels, it allows precise control during towing operations and ensures safety.

Toxic fluids

Toxic fluids are substances that pose serious health risks if ingested, inhaled, or come into contact with skin. In shipping, the handling, storage, and transportation of toxic fluids require special containment and safety protocols.

Tracking

Tracking is the process of monitoring the position and movement of an object, such as a ship or aircraft, over time. In maritime operations, tracking systems use GPS and radar to ensure navigational accuracy and safety.

Trackways

Trackways are metal rails installed on the deck or coaming of cargo ships to guide and support hatch covers. They allow the hatch covers to roll or slide during opening and closing operations.

Traditional fuel injection

Traditional fuel injection systems are mechanically controlled, with each engine cylinder receiving fuel via its own injector. While effective, this system is being replaced by electronic fuel injection in modern engines for better control and efficiency.

Air shuttle trailer

Designed by Wallenius Wilhelmsen, the air shuttle trailer is built for transporting fully assembled vehicles. It features air suspension and efficient loading mechanisms for roll-on/roll-off (RoRo) shipping.

Samson heavy-lift trailer

The Samson trailer, also by Wallenius Wilhelmsen, is designed for small and medium-sized heavy-lift cargo. It provides flexibility in handling oversized industrial components with enhanced stability and load distribution.

Trailing suction hopper dredger VASCO DA GAMA

The VASCO DA GAMA is a large trailing suction hopper dredger used for seabed excavation. It collects sediments through suction pipes and stores them in onboard hoppers for disposal or land reclamation.

Dredging equipment

Dredging equipment includes suction pipes, cutter heads, hoppers, and pumps used for underwater excavation. This machinery is critical in maintaining navigable waterways, ports, and harbors.

Loading

Loading refers to the process of placing cargo onto a ship or vehicle in a secure and balanced manner. Proper loading ensures the vessel’s stability, safety, and compliance with cargo regulations.

Discharging

Discharging is the removal of cargo from a ship upon arrival at its destination. Efficient discharging is key for turnaround time in ports and requires coordinated equipment and labor.

Transport of bitumen products

Bitumen is transported at high temperatures in specially designed tankers. These tanks are insulated and sometimes heated to keep the bitumen molten and pumpable during transit.

Transport of molten sulphur

Molten sulphur is transported in a liquid state and must be maintained at temperatures around 130–155°C to stay fluid. Specially insulated and heated cargo tanks are used to keep the sulphur in its molten form, and safety measures are critical due to the risks of solidification and toxic gas emissions.

Transport of reefer containers

Reefer containers are used to carry perishable goods like fruits, vegetables, meat, and pharmaceuticals. These containers have built-in refrigeration systems and are carefully monitored during sea transport to maintain precise temperature and humidity levels.

Transverse

The term “transverse” refers to anything situated at a right angle to the ship’s centerline, extending from one side of the vessel to the other. Transverse structural members such as frames and bulkheads help provide lateral strength and stability to the ship.

Travelling block

The travelling block is a large, multi-sheave block that moves vertically within a drilling derrick. It supports the drill string and is part of the hoisting system, working in tandem with the crown block and drawworks to lift and lower heavy equipment.

Trawler/seiner VEA

The VEA is a modern fishing vessel designed to perform both trawling and purse seining operations. It combines versatility and advanced fishing technologies, making it suitable for targeting various fish species across different sea conditions.

Trawlers

Trawlers are fishing vessels that tow a conical or tunnel-shaped net called a trawl through the water. They are commonly used for catching fish living near the seabed or in mid-water, depending on whether bottom or pelagic trawling methods are used.

Trawling

Trawling is a method of fishing in which a net is dragged through the water to catch fish. This method can target fish at different depths, and bottom trawling is specifically used to collect species living close to or on the seabed.

Trencher

A trencher is a large underwater robot used in marine cable and pipeline installations. It injects water or air into the seabed to fluidize the soil, allowing cables or pipes to be buried securely and efficiently beneath the ocean floor.

TRIBON

TRIBON is an integrated computer-aided design system developed by Kockums Computer Systems for shipbuilding. It allows designers to manage and model complex ship structures, piping, and outfitting with high precision and integration across disciplines.

TriboPack technology

TriboPack is a package of advanced design features aimed at improving piston-running performance in diesel engines. It enhances lubrication, reduces wear and friction, and extends engine life, especially under heavy-duty operating conditions.

Tri-Cargo Carrier (TCC)

The TCC is a versatile Norwegian-developed ship type designed to transport dry bulk, liquid, and container cargoes. It allows operators to switch between cargo types efficiently, maximizing vessel utilization and reducing turnaround times.

Trim

Trim refers to the difference in the ship’s draft forward and aft. Proper trimming ensures that a vessel sails efficiently and safely, and adjustments are often made during loading or unloading to optimize fuel consumption and stability.

Trim and Stability Booklet

This booklet provides crucial information about a vessel’s stability characteristics and acceptable loading conditions. It includes guidelines for maintaining safe trim and stability during operations, as required by maritime safety regulations.

Trimaran ro-pax ferry BENCHIJIGUA EXPRESS

The BENCHIJIGUA EXPRESS is a high-speed trimaran ferry designed for both roll-on/roll-off cargo and passenger transport. Its unique triple-hull design offers superior stability, fuel efficiency, and passenger comfort in open-sea crossings.

Trimming (loading cargo)

Trimming during cargo loading involves leveling the cargo within the ship’s holds to distribute weight evenly and prevent shifting during the voyage. Proper trimming ensures vessel stability and reduces the risk of damage to both cargo and ship.

Trimming (unloading cargo)

When unloading, trimming refers to sweeping or shoveling remaining cargo to facilitate complete discharge. This step is often required for granular or bulk materials to prevent residue build-up that could impact future cargo operations.

Trimming (ship)

Ship trimming is the adjustment of onboard weight by adding, removing, or shifting ballast, fuel, or cargo to achieve a desired fore-and-aft draft. Correct trim enhances propulsion efficiency and ensures safer navigation, especially in shallow waters.

Tripping bracket

A tripping bracket is a reinforcing component fitted to stiffeners, beams, or deck girders. It helps prevent buckling by supporting the structural member against lateral forces, especially in areas subject to high stress or load changes.

Maritime Glossary: U

Ullage

Ullage refers to the empty space between the surface of a liquid (such as oil or fuel) in a tank and the top of that tank or hatch. This measurement is important in shipping and storage operations, as it helps determine how much liquid is in the tank and ensures that there’s enough space to allow for liquid expansion, preventing overfilling.

ULEPSI Tank Support System

The ULEPSI tank support system, developed by Beele Engineering of the Netherlands, is designed to provide advanced and secure support for storage tanks. It helps absorb movements and vibrations while maintaining a strong seal, ensuring structural integrity and safety in demanding marine and industrial environments.

Ultra Large Crude Carrier HELLESPONT ALHAMBRA

The HELLESPONT ALHAMBRA is one of the world’s largest crude oil tankers, classified as an Ultra Large Crude Carrier (ULCC). These massive vessels can carry millions of barrels of oil, offering efficient transport over long distances and playing a crucial role in global energy logistics.

Ultra Long Stroke Engine

An ultra long stroke engine is a slow-speed, two-stroke diesel engine characterized by a long piston stroke relative to its bore. This design increases fuel efficiency and reduces emissions, making it ideal for large vessels such as container ships and tankers that require powerful, continuous propulsion.

Ultra Low Sulphur Diesel

Ultra low sulphur diesel (ULSD) is a cleaner type of diesel fuel that contains just 15 parts per million (ppm) of sulphur. It is used to reduce harmful emissions from diesel engines and is mandated by environmental regulations for both marine and land-based transportation.

Ultrasonic Testing

Ultrasonic testing is a non-destructive inspection technique that uses high-frequency sound waves to detect internal flaws in materials or to measure thickness. Widely used in shipbuilding and engineering, it ensures structural integrity without damaging the component being tested.

Umbilical

An umbilical is a flexible cable or hose that connects a submersible unit or remotely operated vehicle (ROV) to a support vessel. It supplies power, communication, and life-support fluids, making it essential for underwater exploration, maintenance, and diving operations.

Undercut

Undercut is a welding defect where a groove is unintentionally melted into the base metal next to the weld. This weakens the joint and can lead to structural failures if not corrected, making it a critical flaw to identify and repair in marine and industrial welding processes.

Underwater Complex

An underwater complex consists of connected habitats, laboratories, or structures submerged under water. These complexes are used for marine research, deep-sea exploration, or military applications and allow personnel to live or work beneath the ocean surface for extended periods.

Underwater Container

An underwater container is an unmanned submersible vessel used to house equipment or supplies. These containers are often deployed in subsea operations and can be designed to withstand high-pressure environments on the seabed, storing tools or instruments for remote tasks.

Underwater System

An underwater system comprises various interconnected components like vehicles, sensors, communication lines, and support units, all functioning beneath the water. These systems are crucial for underwater exploration, oil and gas operations, and military applications.

Underwater Vehicles

Underwater vehicles are self-propelled crafts built to operate below the water’s surface. They may be manned or unmanned and are used in scientific research, subsea construction, salvage, and surveillance operations in both shallow and deep waters.

Remotely Operated Vehicles (ROVs)

ROVs are tethered, cable-controlled underwater robots used for exploring and working in the ocean, especially where it’s too deep or dangerous for divers. They are equipped with cameras, sensors, and tools for tasks like pipeline inspections and salvage operations.

Autonomous Underwater Vehicles (AUVs)

AUVs are fully autonomous subsea robots that operate without real-time human control. They are used for oceanographic surveys, seabed mapping, and environmental monitoring, often following pre-programmed routes and collecting data independently.

Underwriter

An underwriter is a person or organization that evaluates risks and provides insurance coverage, especially for ships and cargo in maritime transport. They play a key role in maritime insurance by ensuring that risks are adequately assessed and priced.

Underwriting

Underwriting refers to the process of evaluating and assuming risks by an insurer, typically for transport vessels, cargo, or marine operations. It involves setting premiums, terms of coverage, and determining the financial responsibility in case of loss or damage.

UNIC Davit

The UNIC davit is a space-saving lifeboat launching system developed by Schat-Harding for modern cruise vessels. It allows lifeboats to be stored and deployed efficiently within limited deck space, ensuring quick and safe evacuation in emergencies.

UNIC Engine Automation System

The UNIC engine automation system is a modular, embedded control system used to manage ship engine operations. It ensures efficient engine performance, safety, and reliability by monitoring and controlling key parameters automatically.

UNILOCK

UNILOCK is a universal twistlock developed by MacGregor, used for securing shipping containers. This semi-automatic locking device ensures containers remain firmly attached to each other and to the ship’s deck during transit, enhancing safety and efficiency.

Unsymmetrical Flooding

Unsymmetrical flooding occurs when water enters only one side of a ship’s compartment. This can cause the vessel to list or tilt dangerously, posing stability challenges and increasing the risk of capsizing if not promptly controlled.

Upper Flammable Limit (UFL), Upper Explosive Limit

The UFL, or upper explosive limit, is the highest concentration of a flammable gas or vapor in the air above which combustion will not occur. Knowing this limit is vital in preventing explosions in enclosed spaces onboard ships or offshore platforms.

Uptake

An uptake is a large-diameter duct or pipe that carries exhaust gases from ship engines or boilers to the funnel or smokestack. It helps safely vent combustion gases out of the ship, reducing heat buildup and maintaining air quality inside the vessel.

Urea

Urea is a widely used chemical compound (NH₂)₂CO, commonly used in agriculture as fertilizer and in marine systems like SCR (Selective Catalytic Reduction) units to reduce nitrogen oxide (NOx) emissions from ship engines by converting them into harmless nitrogen and water.

Maritime Glossary: V

Vacuum cleaners

Industrial vacuum cleaners are heavy-duty machines used in shipyards to efficiently remove debris such as dust, metal shavings, and hazardous particles, ensuring a clean and safe working environment for ongoing ship maintenance and construction.

Vacuum toilets

Vacuum toilets work on the principle of creating a vacuum to evacuate waste using minimal water, making them highly efficient and commonly used in ships and aircraft where water conservation and space are essential.

Valve

A valve is a critical component in piping systems aboard ships, allowing operators to control the flow of liquids or gases by opening, closing, or partially obstructing passageways depending on system requirements.

Ball valve

A ball valve uses a rotating ball with a bore through it to control flow; when the bore is aligned with the pipe, fluid flows, and when turned, the flow is stopped—providing a simple and reliable shutoff mechanism.

Gate valve

Gate valves function by raising or lowering a gate inside the valve body, making them ideal for fully open or fully closed positions in pipelines where minimal flow restriction is necessary.

Quick closing valve

Quick closing valves are fitted on oil tanks and can be shut rapidly from a distance in emergencies to prevent oil spills or fires, providing vital safety control in hazardous situations.

Pressure-reducing valves

These valves automatically maintain a constant downstream pressure regardless of upstream pressure fluctuations, helping to protect equipment and ensure system stability.

Relief valve

A relief valve is a safety device designed to open automatically when internal pressure exceeds safe limits, allowing fluid to escape and thereby preventing system overpressure damage.

Remote-operated valves

These valves can be controlled from a remote location, typically through hydraulic, pneumatic, or electric actuators, enhancing safety and operational efficiency in inaccessible or dangerous areas.

Safety valve

Safety valves are installed on pressure vessels and open automatically when the internal pressure becomes dangerously high, releasing pressure to prevent explosions or equipment failure.

Valve cage

A valve cage surrounds the valve plug and includes openings for fluid passage; it guides plug movement and controls fluid dynamics for consistent and efficient flow regulation.

Valve characteristics

These describe how flow rate changes in relation to valve lift, helping engineers design systems for specific control patterns like linear, equal-percentage, or quick-opening flow profiles.

Valve chests

Valve chests group several valves into a single block or manifold, streamlining complex piping systems by providing centralized control over multiple fluid paths.

Valve disc

The valve disc is the movable part inside a valve that regulates flow by varying the opening size; it’s crucial in throttling and sealing functions within a control valve.

Valve manifold

A valve manifold is a compact assembly that connects multiple valves, allowing selective routing of fluid from various sources to different destinations within the system.

Vapour emission control system

This system captures and processes vapors released from cargo tanks, especially in tankers, to prevent environmental pollution and comply with emission regulations.

Vapour lines

Vapour lines are vent pipes that connect cargo oil tanks to pressure or vacuum valves, ensuring safe release or intake of vapors to maintain tank pressure balance during loading and unloading.

Vapour lock system

This system allows accurate measurement and sampling from tanks without exposing the contents to atmospheric pressure, minimizing contamination and evaporation losses.

Vapour pressure

Vapour pressure refers to the pressure exerted by a vapor in equilibrium with its liquid at a given temperature, influencing evaporation rates and tank safety requirements.

Variable Injection Timing (VIT)

VIT is a fuel injection feature in Wärtsilä (Sulzer) engines that optimizes timing based on engine load, improving fuel efficiency and reducing emissions.

Variable Inlet Valve Closing (VIC)

VIC is an optional feature in Wärtsilä 46F engines that adjusts the closing time of inlet valves, improving performance and fuel economy across load ranges.

Ventilation

Ventilation involves circulating and refreshing air within enclosed spaces aboard a ship to ensure adequate oxygen supply and remove contaminants, enhancing crew safety and comfort.

Natural ventilation

Natural ventilation uses wind and temperature differences to move air through spaces without mechanical assistance, providing energy-efficient airflow on ships and in buildings.

Mechanical ventilation

Mechanical or forced ventilation uses fans and blowers to move large volumes of air through confined areas, crucial for engine rooms and other poorly ventilated ship spaces.

Ventilator

A ventilator is any structure, opening, or fitting—such as a grille or pipe—that allows air to enter or exit ship compartments, facilitating airflow and pressure equalization.

Ventilator coaming heights

These are the raised edges around ventilators as mandated by the Load Line Convention of 1966 to prevent seawater ingress during rough seas, enhancing vessel safety.

Ventilator head

The ventilator head is the weatherproof cover fitted to the top of a ventilator duct, designed to prevent rain, seawater, or debris from entering the ventilation system.

Controlled tank venting system

This system uses pressure/vacuum relief valves to safely release or admit air to cargo tanks, protecting them from over- or under-pressure conditions during operations.

Open tank venting system

An open system provides unrestricted airflow into or out of cargo tanks (except for basic friction losses), used in simpler configurations where pressure control is less critical.

Vertical welding position

In vertical welding, the weld is applied vertically, with the workpiece either ascending or descending; it requires skill due to gravity affecting molten metal flow.

Very high frequency (VHF)

VHF communication operates between 30 to 300 MHz, providing reliable short-range voice communication, especially for ship-to-ship or ship-to-shore operations.

Very large crude carrier (VLCC)

VLCCs are massive oil tankers with deadweights between 250,000 to 300,000 tonnes, capable of transporting vast quantities of crude oil across long distances efficiently.

Very large crude carrier FRONT CENTURY

The FRONT CENTURY is a Very Large Crude Carrier (VLCC), designed to transport massive volumes of crude oil across long distances. These vessels, including FRONT CENTURY, typically have a deadweight tonnage of around 300,000 tonnes and are used for intercontinental oil shipments, offering both operational efficiency and reduced transportation costs per barrel.

Vessel constrained by her draught

A vessel is considered constrained by her draught when her ability to deviate from her course is severely limited due to the shallow depth of water relative to her deep draught. These vessels must navigate carefully in narrow or shallow waterways and are given special consideration under navigation rules.

Vessel engaged in fishing

A vessel engaged in fishing refers to any ship actively using nets, lines, trawls, or other fishing gear that restricts its maneuverability. This classification excludes vessels using trolling lines or other gear that does not hamper their ability to move.

Vessel not under command

A vessel not under command is one that, due to exceptional circumstances such as equipment failure, is unable to maneuver as required and cannot follow the usual navigation rules, requiring other vessels to give way.

Vessel restricted in her ability to manoeuvre

This refers to ships performing operations like towing, dredging, or underwater surveys that limit their ability to deviate from their course, and such vessels display specific lights or signals to inform others of their restricted maneuverability.

VIBRATION

Vibration in marine environments is the oscillatory motion experienced by ship components or structures, often caused by machinery, propellers, or sea conditions. Excessive vibration can lead to discomfort, equipment failure, and structural fatigue.

Vibration measurements

Vibration measurements involve monitoring and recording the amplitude and frequency of vibrations on machinery or structures to detect abnormalities, ensure safety, and maintain performance efficiency through timely maintenance.

Vibration damper

A vibration damper is installed on an engine’s crankshaft to absorb torsional vibrations, protecting the engine from stress and preventing damage caused by resonant frequencies during operation.

Vigilance system

A vigilance system monitors the alertness of the officer of the watch by requiring periodic confirmations of presence or response. If no input is detected within a set interval, alarms are triggered to ensure safety.

VIKING EVACUATION MINI CHUTE

The VIKING Evacuation Mini Chute is a compact marine evacuation system designed for small passenger vessels, enabling rapid and safe descent into life rafts in emergency situations with minimal space requirements.

VIKING MARINE EVACUATION SYSTEM

The VIKING Marine Evacuation System is an advanced evacuation solution combining chutes, slides, and liferafts, facilitating fast, safe, and efficient evacuation from ships, especially ferries and cruise vessels.

Viscosity

Viscosity is a physical property of fuel that measures its resistance to flow. It affects fuel atomization, combustion quality, and pumpability, making it a key factor in marine engine performance and fuel handling.

Vital auxiliary pumps

Vital auxiliary pumps are essential shipboard pumps that support critical systems such as steering, bilge, firefighting, and cooling. Their operation is crucial for vessel safety, particularly during emergencies or main system failures.

V-Max tankers STENA VISION and STENA VICTORY

STENA VISION and STENA VICTORY are part of the V-Max tanker series, designed for efficient transport of large crude oil volumes. They feature twin-hull construction and advanced safety systems, offering higher speed and reduced environmental impact.

Void space

A void space is an empty compartment within a ship’s cargo area, located outside of the cargo tanks and not used for storage or accommodation. These spaces are crucial for structural strength and provide access for inspection and maintenance.

Voith Cycloidal Rudder

The Voith Cycloidal Rudder combines propulsion and steering into one unit. By adjusting the blade pitch and rotation, it provides excellent maneuverability and precision control, making it ideal for tugs and ferries.

Voith-Schneider Propulsor (VSP)

The Voith-Schneider Propulsor is a type of azimuthing propeller system where vertically oriented blades rotate around a vertical axis. The pitch of each blade is adjusted to generate thrust in any direction, offering exceptional control.

Voith Turbo Fin

The Voith Turbo Fin is a rotating fin installed on the skeg to reduce drag and improve steering efficiency. It enhances the hydrodynamic performance of the vessel and contributes to better fuel economy.

Voith Water Tractor

The Voith Water Tractor is a powerful tugboat that uses Voith-Schneider propellers at the bow for exceptional maneuverability, enabling precise movements and high thrust in all directions for docking and escorting large ships.

Volatile Organic Compounds (VOC) Recovery Systems

VOC Recovery Systems are installed on tankers to capture and process hydrocarbon vapors emitted during loading or unloading. These systems help reduce air pollution and improve operational safety.

Volatile petroleum

Volatile petroleum refers to fuels with a flash point below 60°C, making them highly flammable and subject to strict handling, storage, and transport regulations to prevent fire hazards.

Volume of displacement

The volume of displacement is the total amount of water displaced by a vessel when afloat, directly corresponding to the ship’s weight and used in calculating buoyancy and stability.

Voyage data recorder (VDR)

The VDR is a maritime black box that records essential operational data, including audio from the bridge, radar images, and navigational inputs, enabling analysis of ship operations and incident investigations.

Simplified Voyage Data Recorder (S-VDR)

The S-VDR is a cost-effective alternative to the full VDR, required on smaller vessels, which captures core voyage data like GPS, speed, radar, and bridge audio for safety and investigation purposes.

Maritime Glossary: W

Wake

When a ship moves forward through water, it creates turbulence and displacement behind it. This movement imparts forward momentum to the water at the stern, forming what is called the wake. The wake is a visible pattern of disturbed water trailing behind the ship. It is influenced by the ship’s hull shape, speed, and water conditions. Wake patterns are essential in naval architecture for performance analysis.

Wake equalization duct

A wake equalization duct is a propulsion-improving device placed ahead of the propeller. It is especially useful in full block ships like bulk carriers or tankers. This duct helps to straighten the wake flow and reduce rotational losses. By improving the flow to the propeller, it enhances thrust and reduces fuel consumption. These ducts are often customized based on the hull design.

Wake fraction coefficient

The wake fraction coefficient refers to the effect of the ship’s wake on the speed of water entering the propeller. It is a correction factor used to determine the actual speed of advance (VA) of the propeller relative to the surrounding water. This coefficient plays a crucial role in propeller performance calculations. A higher wake fraction generally reduces the effective thrust.

Wake-field

As the ship sails ahead, friction between the hull and the water creates a boundary layer. This layer distorts the flow of water towards the stern, forming what is known as the wake-field. It is a complex pattern of velocity distribution behind the ship. Understanding the wake-field is important for optimizing propeller design and placement. Advanced simulations are often used to model it accurately.

Wash

Wash refers to the waves, ripples, and turbulence created by a moving vessel. These disturbances radiate outward from the hull, especially near the bow and stern. Wash can affect nearby smaller boats, riverbanks, and marine ecosystems. Regulations in some regions limit excessive wash to reduce environmental impact. Managing wash is also part of good seamanship.

Wash bulkhead

A wash bulkhead is a perforated or slotted bulkhead found in cargo or deep tanks. Its primary purpose is to reduce the sloshing of liquid cargo during ship movement. By breaking up the flow of the liquid, it helps to stabilize the vessel. This is particularly important in partially filled tanks. It also adds structural strength to the tank.

Washing machines

In maritime operations, washing machines are devices used to clean the interior of tanks. These machines can be either fixed or portable and consist of rotating spray heads. They use high-pressure water jets to dislodge residues from tank surfaces. Washing machines are vital for maintaining tank hygiene, especially in oil and chemical tankers. Regular cleaning is necessary for safety and cargo integrity.

Waste

Waste on a ship includes any material that is no longer useful or needed. This could range from packaging materials to oil residues and used consumables. Proper management is crucial to prevent pollution and maintain hygiene. Burnable waste may be incinerated on board, while non-burnable waste is stored for disposal ashore. Waste categorization and handling are regulated under MARPOL.

Cargo-associated waste

Cargo-associated waste comprises materials generated during cargo operations. This includes residues, dunnage, packaging, and any spillage during loading or unloading. Such waste must be handled carefully to avoid contamination and comply with environmental rules. Ships must maintain records of this waste for regulatory compliance. Proper segregation is also important.

Domestic waste

Domestic waste is generated from the daily life of crew onboard the vessel. It includes food scraps, packaging, paper, plastics, and sanitary waste. This type of waste can attract pests and cause unpleasant odors if not managed properly. Ships have designated storage and disposal methods for such waste. Efficient waste segregation helps in proper disposal.

Food wastes

Food waste includes both spoiled and unspoiled food materials. Examples are fruits, vegetables, dairy products, and meat scraps discarded from the galley. These wastes decompose quickly and can lead to hygiene issues. International regulations like MARPOL restrict the discharge of food waste to protect marine life. Some ships have food waste macerators or composters.

Hazardous waste

Hazardous waste includes flammable, corrosive, or toxic substances used on ships. Common examples are cleaning solvents, expired chemicals, and batteries. These materials pose a risk to human health and the marine environment. Ships must store them securely in labeled containers and follow strict disposal protocols. Proper training of crew is essential for handling such waste.

Maintenance waste

Maintenance waste is generated during repair and upkeep of ship systems. It includes used oil filters, paint cans, rags, and broken parts. This waste needs careful handling due to the presence of contaminants. Regular checks and proper storage prevent accidental pollution. Disposal must be done as per port regulations.

Medical waste

Medical waste on ships includes used bandages, syringes, and infectious materials. It can be hazardous and requires special containers for disposal. International rules demand strict protocols for handling and storage. Medical waste must be segregated from regular waste. Often, it is handed over to authorized disposal services at ports.

Operational wastes

Operational waste includes a wide range of materials generated during daily ship activities. This encompasses maintenance waste, cargo residues, and other associated refuse. Efficient waste segregation and documentation are key to regulatory compliance. Onboard waste management plans outline the handling of such materials. Proper management prevents environmental harm.

Waste heat recovery (WHR)

Waste heat recovery systems utilize the heat from engine exhaust gases. This otherwise lost energy is used to generate steam or electricity. WHR systems improve fuel efficiency and reduce emissions. They are an important part of modern energy-saving designs. Many large ships now use WHR as part of their green initiatives.

Waste heat boiler

A waste heat boiler captures the heat from exhaust gases to produce steam. This steam can be used for heating or powering auxiliary systems. These boilers are passive and operate alongside the main engine. They contribute to overall energy efficiency on ships. Proper maintenance ensures consistent performance.

Waste management plan

A waste management plan is a documented procedure for handling waste onboard. It outlines methods for collection, segregation, treatment, and disposal. The plan ensures compliance with MARPOL and local port rules. Crew are trained to follow these procedures. Regular audits and records are required for verification.

Waste water

Waste water on ships includes any used water that is no longer fit for its original purpose. It comes from showers, toilets, kitchens, and machinery operations. Treatment before discharge is crucial to avoid marine pollution. Ships are equipped with systems to manage various types of waste water. Proper management is mandated by international law.

Black water

Black water is sewage generated from toilets and urinals. It contains pathogens and must be treated before discharge. Modern ships have sewage treatment plants onboard. Discharge regulations are strict and vary by location. Regular system maintenance ensures health safety and compliance.

Galley water

Galley water includes drainage from kitchens and food preparation areas. It often contains oils, fats, and detergents. This water must be processed before disposal due to its environmental impact. Ships have oil-water separators to treat such waste. Monitoring helps prevent pollution violations.

Grey water

Grey water is generated from showers, sinks, and laundry. Although less hazardous than black water, it still requires treatment. Detergents and cleaning agents in grey water can harm marine ecosystems. Ships often recycle or treat grey water before discharging. Systems vary by vessel type and regulations.

Waste water treatment systems

Waste water treatment systems process different types of waste water onboard. They include filters, separators, and biological treatment units. The aim is to remove harmful substances before discharge. These systems are essential for compliance with MARPOL. Crew must be trained to operate and maintain them.

Watch

In marine operations, a watch is a scheduled duty period for crew members. Typically lasting four hours, watches ensure continuous vessel monitoring. The ship’s day is divided into watch periods like 00-04, 04-08, and so on. Watchkeeping is vital for safety and operational continuity. A proper handover is essential between shifts.

Continuous watch

A continuous watch ensures constant monitoring of ship systems and communication. For radio operations, this means someone is always on duty to respond to messages. It is critical for safety, especially during emergencies. SOLAS requires specific equipment to support continuous watch. Automation has helped enhance the reliability of such watches.

Watch alarm

A watch alarm alerts the bridge if no activity is detected from the officer on watch. It is a safety feature to prevent accidents due to fatigue or inattention. If not reset within a set period, the alarm is transferred to the master or backup crew. It promotes alertness and compliance with watch duties. Many systems now include motion sensors and timers.

Watch alarm system

This system supports bridge team management by urging officers to confirm alertness periodically. If there is no acknowledgment within a set time, an alarm sounds and is escalated. Watch alarm systems are especially important in one-man bridge operations. They are standard on modern ships. Regular testing is part of maintenance routines.

Water-based local fire fighting system

According to SOLAS and IMO rules, certain ships must have water-based fire fighting systems. These systems use water sprays to suppress fires locally, often in machinery spaces. They are effective for specific fire hazards. Quick activation and accessibility are key features. Regular drills ensure readiness.

Water curtain

Some tankers use a fixed water curtain system as a protective barrier. This curtain acts between the deck and accommodation or cargo areas. It helps prevent the spread of fire or harmful vapors. Activation is usually automatic or through a remote control system. It’s part of advanced fire safety protocols.

Water fog

Water fog consists of finely divided water droplets sprayed into the air. It is used to cool fire zones and displace oxygen. Water fog is effective against oil fires and in enclosed spaces. The fine mist ensures minimal water damage. Ships carry portable and fixed fog systems.

Water level gauge

A water level gauge displays the water level inside boilers and tanks. Accurate readings help prevent boiler accidents due to dry operation or overfilling. There are sight glass types and electronic gauges. Operators monitor them regularly. Calibration ensures accuracy.

Water seal

A water seal is used in separators to prevent oil from leaking. It maintains pressure and flow balance in the system. The seal must be maintained and refilled as needed. Any disruption can lead to contamination. It’s a small but critical component in oil-water separation.

Water spray

Water spray systems release water in a dispersed form for cooling or fire suppression. These systems are used in engine rooms, around cargo tanks, and electrical equipment. The spray cools surfaces and helps control heat sources. They are part of the overall fire safety setup. Maintenance ensures nozzle performance.

Waterjet

A waterjet is a propulsion device that expels water to generate thrust. Water is drawn in through intakes and expelled at high speed through nozzles. It provides high maneuverability and is used in fast craft. Waterjets reduce the risk of damage from floating debris. They are efficient at shallow drafts.

Waterjet propulsion

Waterjet propulsion is an alternative to conventional screw propellers. It is especially popular for high-speed ferries and patrol boats. Waterjets allow rapid acceleration and agile turning. They are also safer for swimmers and marine animals. Maintenance is generally easier due to fewer moving parts.

Waterline

The waterline is an imaginary line around a ship’s hull where it meets the surface of the water. It changes with the vessel’s load and draft. Designers use waterlines to calculate buoyancy and stability. It is marked on the hull for reference. Regulatory drafts are often measured from the waterline.

Waterplane area

The waterplane area is the horizontal section of the hull at the waterline. It plays a key role in calculating stability and buoyancy. A wider waterplane area generally provides better initial stability. Naval architects analyze this during hull design. Changes affect the ship’s performance.

Watertight

A watertight structure prevents any water from passing through. This is essential in maintaining buoyancy and preventing flooding. Bulkheads, doors, and seals must be certified as watertight. Regular inspection and maintenance preserve their integrity. It’s critical for survival in case of hull breach

Watertight door

Watertight doors are fitted in ship bulkheads to contain flooding. They can be manually or hydraulically operated. Some close automatically in emergencies. These doors must pass pressure tests. Crews practice drills for operating them safely.

Watertight Integrity Plan

This is a detailed plan showing all watertight subdivisions of a ship. It includes main and secondary compartments, doors, and sealing points. The plan is essential for damage control operations. It helps in training and during inspections. Keeping it updated is mandatory.

Wave

A wave is a moving ridge on the surface of water caused by wind, currents, or ship movement. It consists of a crest and trough. Waves affect ship motion, stability, and navigation. Understanding wave behavior is vital for safe operation. Navigation systems often account for wave forecasts.

Wear

Wear is the gradual degradation of a surface due to friction or contact. It occurs in moving parts like engine components and bearings. Regular lubrication and inspection reduce wear. Excessive wear can lead to equipment failure. Replacement of worn parts is part of maintenance routines.

Weardown gauge

A weardown gauge is used to measure the erosion of the stern tube bearing. It is inserted into the stern frame boss to check the clearance. Monitoring this wear helps avoid serious damage. It is part of dry dock inspection routines. Accurate readings support preventive maintenance.

Weather deck

The weather deck is the uppermost deck exposed to open air and weather. It must be robust and watertight. Cargo handling and mooring operations often take place here. Coatings protect it from corrosion. Safety equipment is commonly stored on the weather deck.

Weathertight

A weathertight structure resists the entry of water from the outside in normal sea conditions. Unlike watertight, it doesn’t have to withstand full submersion. Deck hatches, doors, and windows are made weathertight. Regular checks prevent leaks during storms. Certification standards apply.

Weathertight door

A weathertight door is fitted above the freeboard deck and seals against sea spray and rain. It must withstand external water pressure without leakage. These doors are part of a ship’s environmental protection system. Proper sealing and maintenance are crucial. Inspection intervals are defined by class rules.

Web

A web is a vertical structural plate that adds strength to a ship’s framework. It is used in beams, girders, and other structural members. The web resists shear forces and bending. It is often reinforced with stiffeners. Correct design ensures structural integrity.

Web frame

A web frame is a large structural frame with flanged plates used to strengthen the hull. It is placed in key areas like the midship or engine room. These frames support longitudinal members and distribute loads. Web frames are essential in large vessels. Welding and inspection are crucial for their durability.

Weld defects

Weld defects are imperfections in welded joints that may weaken the structure. Common defects include cracks, porosity, and slag inclusions. Proper technique and inspection can prevent most defects. Non-destructive testing is used to identify them. Serious defects require repair or re-welding.

Cracks

Cracks in welds can occur during cooling or under stress. Hot cracks form during welding due to temperature gradients. Cold cracks appear later due to hydrogen embrittlement or stress. Cracks must be repaired immediately. They can compromise structural integrity.

Incomplete fusion

Incomplete fusion occurs when weld metal does not bond fully with the base metal. This creates weak spots in the weld joint. Causes include low heat input or poor technique. Visual and ultrasonic inspections can detect these defects. Re-welding may be required to fix them.

Porosity

Porosity in welds is caused by trapped gas bubbles during solidification. It weakens the weld and can lead to failure. Causes include damp electrodes or contamination. Porosity is visible as small holes or can be detected by X-ray. Quality control helps minimize it.

Slag inclusions

Slag inclusions are non-metallic particles trapped in weld metal. They result from poor cleaning between welding passes. These inclusions reduce the strength and durability of welds. Grinding and re-welding may be needed. Skilled welders can prevent them.

Undercut

Undercut refers to the groove melted into the base metal adjacent to the weld. It weakens the weld area and can lead to cracking. It may also refer to insufficient filler metal. Causes include excessive heat or poor angle control. Careful welding technique can avoid undercut.

Weld Metal Corrosion

Weld metal corrosion refers to the selective corrosion that occurs in the weld deposit due to an electrolytic difference between the weld metal and the base metal. This issue often arises when dissimilar metals are used or when the welding process creates microstructural variations. Environmental factors like moisture, temperature, and chemical exposure can accelerate the process. It is a common concern in marine environments where saltwater acts as a strong electrolyte. Regular inspection and use of compatible materials help in preventing this type of corrosion.

Weldability

Weldability is the ability of a material to be welded under specific conditions without causing defects or compromising its integrity. Factors influencing weldability include material composition, thickness, and the type of welding process used. High weldability ensures that the metal can be joined effectively and withstand operational stresses. Poor weldability may result in cracks, porosity, or reduced strength in the welded joint. Engineers often assess weldability before selecting materials for construction or repair.

Welder

A welder is a skilled tradesperson who performs manual or semi-automatic welding operations. They are responsible for preparing materials, setting up equipment, and creating strong, defect-free joints. The role requires precision, concentration, and knowledge of various welding techniques such as TIG, MIG, and arc welding. Welders play a critical role in industries like shipbuilding, construction, and manufacturing. Their craftsmanship ensures the structural integrity and safety of components.

Welder Certification

Welder certification is a formal document that verifies a welder’s ability to produce welds meeting predefined standards. This certification is issued by a recognized authority after successful completion of specific tests. It includes details such as the type of welding performed, positions tested, and materials used. Certification ensures consistency, quality, and compliance with safety regulations. It is a mandatory requirement in many critical industries, especially those involving pressure vessels and marine structures.

Welder Qualification Test

A welder qualification test is conducted to assess whether a welder possesses the necessary skills to create high-quality welds. These tests are performed under controlled conditions and follow standard procedures like AWS or ASME codes. The test may involve different welding positions, joint types, and materials. Successful completion results in certification, allowing the welder to work on specific projects. The qualification ensures that welds are structurally sound and meet design specifications.

Welding

Welding is a fabrication process that joins materials, typically metals or thermoplastics, by melting and fusing them together. The process may involve applying pressure, filler material, and protective gases. There are various welding methods, such as arc, MIG, TIG, and resistance welding, each suitable for different applications. Welding is widely used in shipbuilding, pipeline construction, and automotive industries. Proper technique and material compatibility are crucial for durable and defect-free joints.

Automatic Welding

Automatic welding is a process where welding operations are performed by machines with minimal human intervention. The equipment follows pre-programmed instructions to carry out the weld consistently and efficiently. This method is ideal for large-scale production where repeatability and speed are essential. Automatic welding improves quality, reduces labor costs, and minimizes human error. It is commonly used in manufacturing environments with high-volume output requirements.

Machine Welding

Machine welding involves using equipment that performs the welding operation under constant supervision but with mechanized movement. The welder may control settings but does not manipulate the torch or electrode directly. This technique offers higher precision and consistency than manual welding. It is suitable for repetitive welding tasks where uniformity is important. Machine welding bridges the gap between manual and fully automated processes.

Manual Welding

Manual welding is performed by a welder who controls the torch, gun, or electrode holder by hand. It requires a high level of skill and attention to detail to produce quality welds. The process allows for flexibility and adaptability, especially in complex or confined spaces. Manual welding is common in maintenance, repair, and field operations. The welder’s expertise significantly influences the strength and appearance of the final weld.

Welding Machine

A welding machine is the equipment used to generate the heat and control the electrical current required for welding operations. Common types include arc welders, MIG welders, TIG welders, and spot welders. These machines may be portable or fixed and vary in complexity based on their application. Proper calibration and maintenance of welding machines are essential for achieving desired weld quality. Safety features are also critical to protect the operator.

Welding Operator

A welding operator is someone who operates automated or semi-automated welding equipment. Unlike manual welders, operators oversee the machine’s performance and intervene when adjustments are needed. They must understand machine settings, material behavior, and safety protocols. Welding operators are vital in industrial settings where precision and efficiency are priorities. Their role helps streamline production while maintaining weld quality.

Welding Procedure

A welding procedure is a detailed, documented set of instructions for creating a specific type of weld. It includes information on joint design, materials, welding process, parameters, and pre- and post-weld treatments. Following a standard procedure ensures consistency and compliance with engineering and safety standards. Welding procedures are especially important in regulated industries like shipbuilding and pipeline construction. They help in achieving predictable and repeatable results.

Welding Sequence

Welding sequence refers to the order in which multiple welds are applied in a structure or assembly. Proper sequencing minimizes residual stresses, distortion, and potential weld defects. Engineers plan welding sequences to balance heat input and allow controlled cooling. This is especially important in large or complex structures like ship hulls and pressure vessels. An optimized welding sequence enhances strength, alignment, and overall integrity.

Welding Shrinkage

Welding shrinkage occurs due to the localized heating and cooling of the base metal during the welding process. As the metal expands with heat and contracts upon cooling, it can cause distortion in the welded components. This shrinkage may affect the dimensional accuracy and alignment of the assembly. Engineers must consider shrinkage during design and may use fixtures or sequence planning to mitigate its effects. Addressing shrinkage is essential for maintaining structural integrity.

Appraisal Well

An appraisal well is drilled near a previously successful discovery well to determine the extent, quality, and commercial viability of the hydrocarbon reservoir. It provides critical data about the subsurface geology and reservoir behavior. Information from appraisal wells guides investment decisions and field development planning. Multiple appraisal wells may be required to map out the full potential of the reservoir. They reduce uncertainty and help assess the economic feasibility of production.

Completed Wells

Completed wells are those that have been drilled, evaluated, and equipped with necessary infrastructure, such as Christmas trees and wellheads, to control the flow of oil or gas. These wells are ready for production and are connected to surface facilities. The completion process includes casing, cementing, perforation, and sometimes stimulation to enhance flow. Properly completed wells ensure efficient and safe extraction. They are a key milestone in the development of an oil or gas field.

Discovery Well

A discovery well is the first successful exploration well that confirms the presence of hydrocarbons in a new field or basin. This well marks the beginning of a potential new development area and attracts further exploration and investment. The results are used to estimate the size and value of the reservoir. Discovery wells often lead to appraisal drilling to determine the reservoir’s full potential. Their success is crucial in the energy industry.

Well Fluid Properties

Well fluid properties describe the physical and chemical characteristics of fluids within a well or reservoir, including temperature, pressure, viscosity, and composition. Understanding these properties is essential for designing production systems and predicting reservoir behavior. These properties influence equipment selection, flow rates, and recovery methods. Accurate measurement and modeling are key to efficient field operations. Well fluid analysis is conducted during exploration and production phases.

Well Intervention Vessel

A well intervention vessel is a dynamically positioned ship used to perform maintenance, repair, or enhancement operations on subsea wells. These vessels are equipped with specialized tools, cranes, and control systems to carry out tasks without removing the subsea infrastructure. They offer a cost-effective alternative to drilling rigs for non-drilling activities. Well intervention vessels help maintain production rates and prolong the life of wells. Their use is common in mature offshore fields.

Well Maintenance

Well maintenance involves regular inspection, repair, and optimization of existing wells to ensure continued safe and efficient operation. With over 3,000 subsea wells worldwide, proactive maintenance is essential for maximizing oil and gas recovery. Activities may include clearing blockages, replacing worn components, and monitoring pressure. Maintenance extends the well’s productive life and prevents costly downtime. It is a critical part of field management strategies.

Well Test Systems

Well test systems are essential setups installed on vessels or mobile offshore drilling units (MODUs) to evaluate the productivity and characteristics of an oil or gas well. These systems typically include separators, flow meters, safety valves, burners, and other equipment that handle the flow of hydrocarbons during the test phase. Their function is to measure reservoir performance, pressure, temperature, and flow rate, ensuring safe and effective analysis. Well testing helps operators make crucial decisions regarding field development and investment. This step is vital before full-scale production begins.

Wellhead

A wellhead is a critical component in oil and gas drilling operations, installed at the surface of a well to provide structural and pressure containment. It secures the casings and production tubing and serves as a mounting base for the Christmas tree or blowout preventer. Wellheads are designed to withstand extreme pressures and temperatures. They also allow access to the wellbore for intervention or maintenance activities. Proper installation and maintenance of the wellhead are crucial for ensuring operational safety and environmental protections.

WETPAC Humidification

WETPAC humidification is a nitrogen oxide (NOx) reduction technology developed by Wartsila. It functions by injecting humidified combustion air into the engine, thereby lowering the combustion temperature and reducing the formation of NOx emissions. Pressurized water is used to generate the humidified air. This environmentally friendly technology helps ships meet stringent IMO Tier III emission standards. It is especially beneficial for vessels operating in emission control areas (ECAs), where cleaner exhaust gases are required.

Wet Surface Hull Scanner (WSHS)

The Wet Surface Hull Scanner (WSHS) is an advanced technology that uses remotely operated vehicles (ROVs) to inspect and assess the condition of a vessel’s hull while it is still submerged. This device helps in detecting biofouling, corrosion, and other damage without requiring drydocking. The scanner collects data in real-time and allows for precise maintenance planning. By avoiding drydock, it saves both time and operational costs. This innovation improves hull maintenance efficiency and promotes sustainability in marine operations.

Wetted Surface

The wetted surface of a ship refers to the total area of the hull that is in direct contact with water when the vessel is floating at a given waterline. This surface plays a critical role in determining the hydrodynamic resistance of the ship as it moves through water. A larger wetted surface increases drag, requiring more power for propulsion. Therefore, naval architects strive to design hulls with optimal wetted areas for better fuel efficiency. Proper hull cleaning and coating also help in minimizing resistance.

Wide Tow

Wide tow is a seismic data acquisition technique used in offshore exploration, involving the deployment of multiple streamers with significant lateral separation. This setup allows for a broader swath of data to be collected in a single pass, improving survey efficiency and coverage. Wide tow systems often require specialized towing vessels and advanced positioning technologies. It enhances subsurface imaging, helping geologists and engineers locate hydrocarbon deposits more accurately. The technique is essential for modern, large-scale exploration projects.

Wind Turbine Installation Vessel INNOVATION

The Wind Turbine Installation Vessel INNOVATION is a purpose-built jack-up vessel designed for installing offshore wind turbines. Equipped with a heavy-duty crane, large deck space, and dynamic positioning systems, it can carry multiple turbine components at once. The vessel jacks itself out of the water to create a stable work platform, enabling precise and safe installations. INNOVATION plays a crucial role in advancing renewable energy infrastructure. It supports rapid and large-scale deployment of offshore wind farms.

Wheelhouse

The wheelhouse is an enclosed area on a ship from where it is steered and controlled. It contains essential navigation and communication equipment, including the main steering wheel, engine controls, radar, GPS, and electronic chart systems. Typically located on the bridge deck, it provides a clear view of the vessel’s surroundings. The wheelhouse is a crucial center for ship operations, particularly during maneuvering and docking. It is often manned by the officer on watch or the captain.

Whistle

A whistle is a sound signaling device used on ships to communicate intentions and ensure navigational safety, particularly in restricted visibility conditions. It can be operated by compressed air, steam, or electronically, and must be capable of producing prescribed blasts defined by international regulations. Whistles are used to signal turns, danger, and presence. They are mandatory on vessels of certain sizes under the COLREGs (International Regulations for Preventing Collisions at Sea). Proper functioning of the whistle is regularly checked for compliance.

White Metal

White metal is a tin-based alloy often used as a bearing material in marine engines. It may also contain small amounts of copper, lead, and antimony, providing excellent properties for wear resistance and load capacity. White metal is applied as a lining in journal and thrust bearings where lubrication and minimal friction are essential. It provides smooth surfaces for rotating components. Due to its softness and embeddability, it protects against damage from dirt or debris in the lubrication system.

White Petroleum Oils

White petroleum oils are refined hydrocarbon products including substances like benzene, kerosene, and gasoline. These oils are typically clean and clear, used for various purposes such as fuel, solvents, or industrial feedstock. They are flammable and require careful handling and storage to prevent fire hazards. White oils are subject to strict safety and environmental regulations, especially during transportation by sea. Their characteristics depend on the refining process and end-use application.

Winch

A winch is a mechanical device used to haul or lift heavy loads using a rope, cable, or chain wound around a rotating drum. On ships, winches are used for anchoring, mooring, and cargo handling operations. They can be powered manually, electrically, hydraulically, or pneumatically, depending on the size and function. Winches ensure safe and controlled movement of heavy equipment or lines. Regular maintenance is essential for safe operation, especially in marine environments where corrosion is common.

Wind and Water Strakes

Wind and water strakes are sections of the ship’s side shell plating located between the ballast and weather decks. These plates form part of the outer hull and are crucial for structural strength and watertight integrity. Positioned where wind and water forces are most active, these strakes are often thicker and more reinforced than other plating. They help maintain hull shape and resist the impact of waves and external forces. Damage in these areas requires immediate attention.

Wind Turbine Installation, Maintenance, and Repair Unit

This specialized mobile offshore unit is designed to handle the installation, maintenance, and repair of wind turbines at sea. It includes heavy-lift cranes, dynamic positioning systems, and living quarters for technicians. The unit supports sustainable energy development by enabling the efficient servicing of offshore wind farms. These vessels reduce downtime and increase the operational efficiency of wind turbines. They are essential to expanding the global capacity of renewable energy infrastructure.

Windlass

A windlass is a horizontal rotating machine used primarily for raising and lowering anchors on a ship. It consists of a drum or gypsy wheel around which the anchor chain is wound. Windlasses can be powered by manual effort, electricity, or hydraulics. They provide the necessary mechanical advantage to handle the heavy anchor and chain system safely. Windlass systems also include brakes and clutches for controlled operation. Testing and maintenance are vital for their reliability.

Windlass Trials

Windlass trials are conducted to ensure that the windlass system operates correctly under real working conditions after installation. These tests verify the windlass’s ability to raise and lower the anchor, engage the brakes, and withstand operational stresses. Trials are typically part of the ship’s sea trials or post-maintenance checks. Successful windlass trials confirm that the anchoring system meets safety and performance standards. Any issues discovered during trials must be rectified before certification.

Windows

In marine architecture, windows are restricted in certain areas such as superstructures or the ship’s hull due to safety and watertight requirements. Where permitted, they must meet strict regulations concerning material strength, visibility, and water resistance. Windows on ships are typically made from reinforced glass and designed to withstand wind and wave impacts. Their installation must ensure no compromise to the ship’s structural integrity. Improper placement or poor sealing can lead to flooding or structural failure.

Windward

Windward refers to the direction from which the wind is blowing. In navigation and sailing, knowing the windward direction is essential for course plotting, sail trimming, and anchoring decisions. Vessels typically point their bows into the wind when anchoring or maneuvering to maintain control. The opposite of windward is leeward, which denotes the downwind side. Understanding windward dynamics helps in reducing drift and ensuring safe vessel handling.

Wing in Ground-Effect Craft (WIG)

Wing in Ground-Effect Craft, also known as Ekranoplans, are high-speed vehicles that fly close to the water surface using aerodynamic ground effect. They combine features of aircraft and marine vessels, offering efficient transportation over water. WIG craft are often used for military, cargo, or passenger purposes in coastal and inland water regions. Their low-altitude operation reduces drag and fuel consumption. However, they require calm seas for safe operation.

Wire Winder

A wire winder is a circular guard or ring mounted on the propeller hub to prevent mooring lines or fishing nets from becoming entangled in the sterntube aft seal. This small but essential component reduces the risk of damage to the propulsion system and oil leaks. Wire winders are part of marine anti-entanglement solutions. They are particularly important in congested or fishing-heavy waters. Routine inspection ensures they remain intact and functional.

Wiring Diagram

A wiring diagram is a technical drawing that illustrates the electrical connections and layout of a ship’s systems. It shows how different components like switches, lights, motors, and circuit breakers are interconnected. Wiring diagrams are vital for installation, troubleshooting, and maintenance of electrical systems. They use standardized symbols to ensure clarity and consistency. Engineers and electricians rely heavily on these diagrams to maintain safety and functionality.

Workboat

A workboat is a small, sturdy vessel used for a variety of operational tasks in support of larger ships or offshore platforms. These boats perform duties such as towing, supply transport, crew transfer, and maintenance. Workboats are often designed with flat decks and powerful engines for maximum utility. Their construction emphasizes durability and reliability under harsh sea conditions. They play a critical role in port and offshore activities.

Workboat BELYRYAR

The Workboat BELYRYAR is a versatile and robust vessel built to perform various tasks in support of marine operations. With high maneuverability and strong towing capabilities, it can assist in harbor duties, offshore rig support, or general cargo movements. The boat is equipped with modern navigation and communication systems, ensuring efficient performance. It serves as a reliable asset for coastal and offshore work. Its compact size makes it ideal for confined operations.

Working Raft

A working raft is a small floating platform used for repair, painting, or cleaning work on a ship’s hull while afloat. These rafts provide safe and stable access to parts of the vessel that are hard to reach from the deck. Constructed from buoyant materials and often tethered for security, they are essential for maintenance without drydocking. Proper safety gear is always required when using these platforms. Their portability makes them practical for quick tasks.

Workmanship

Workmanship refers to the quality and skill demonstrated in the construction or repair of ship components and systems. It encompasses precision, finish, durability, and adherence to specifications. Good workmanship ensures safety, efficiency, and longevity of the vessel. Shipbuilding and repairs require highly skilled personnel to meet industry standards. Poor workmanship can lead to operational issues, safety hazards, and costly repairs. Quality assurance programs often monitor workmanship during projects.

Workover

A workover involves re-entering a completed well to carry out maintenance, modification, or repair. It may include operations like replacing tubing, sealing leaks, or enhancing production through stimulation techniques. Workovers are performed using specialized rigs or vessels and require detailed planning. These operations extend the life of the well and maximize hydrocarbon recovery. Workovers are critical for optimizing field output and ensuring well integrity.

Workshop

A workshop on a ship is a dedicated space equipped with tools and machinery for fabricating, modifying, or repairing components. Located in the engine or deck areas, workshops allow crew members to perform maintenance tasks onboard. These spaces include lathes, welding stations, grinders, and storage for spare parts. Workshops are vital for ensuring self-reliance during long voyages. Proper organization and safety practices are essential in these areas.

Workstation

A workstation refers to a designated area on a ship where specific tasks are performed, often equipped with relevant controls, tools, or computer systems. These may include positions for navigation, monitoring, or communication. Each workstation is designed for ergonomic efficiency and safety. The integration of modern technology enhances functionality. Workstations contribute to streamlined ship operations.

Manual Steering Workstation

The manual steering workstation is the area from which the ship can be steered using a wheel or tiller. It includes basic navigation instruments and is often used during critical operations such as docking or emergencies. Though autopilot is common, manual stations offer direct human control. Operators here must remain vigilant and responsive. The workstation is typically located on the bridge or nearby.

Monitoring Workstation

This workstation is dedicated to observing and analyzing shipboard systems and the surrounding environment. It includes displays for engine performance, fuel usage, weather conditions, and more. Real-time data collection enables prompt decision-making. Monitoring stations are essential for predictive maintenance and safety. They support efficient vessel operation.

Radiocommunication Workstation

The radiocommunication workstation handles all voice and digital communication with other ships, coastal stations, and satellites. It includes VHF, MF/HF radios, satellite phones, and emergency systems like GMDSS. This workstation ensures compliance with maritime communication protocols. It also plays a vital role during emergencies. Regular testing is essential.

Navigation and Manoeuvring Workstation

This is the primary control center for directing the ship’s course, speed, and maneuvers. Located on the bridge, it houses steering controls, radar, GPS, ECDIS, and other navigation aids. Officers here make navigational decisions, issue helm orders, and monitor traffic. It is a critical station for voyage safety and route compliance. Well-designed layout enhances operator awareness.

Route Planning Workstation

This is the designated area for charting the vessel’s voyage path. It utilizes electronic navigation charts, weather routing software, and performance data. Planners here aim to ensure safety, fuel efficiency, and regulatory compliance. The route is checked for hazards, restricted areas, and optimized timing. Proper planning helps in reducing voyage costs and delays.

Wreck

A wreck refers to a ship that has been destroyed or heavily damaged, often resting at the bottom of the sea or partially submerged. Wrecks can result from collisions, grounding, storms, or other marine accidents. They may pose hazards to navigation and are sometimes protected for historical or environmental reasons. Salvage operations may be launched to recover cargo or refloat the vessel. Maritime authorities chart wrecks and issue navigational warnings.

Yaw, Yawing – See Ship Motions

Yaw or yawing is one of the six primary motions of a ship and refers to the side-to-side rotation around the vessel’s vertical axis. When a ship yaws, its bow moves to the left or right, typically in response to wave action, wind, or steering inputs. Yawing can affect navigation accuracy and course-keeping, making it crucial for vessel control systems to monitor and adjust for it constantly. Excessive yaw can lead to increased fuel consumption and discomfort for those onboard. It is typically corrected using the rudder or automated navigation systems such as autopilot.

Yoke Arm

A yoke arm is a mechanical structure typically located at the aft or bow of a vessel, depending on its design, and is part of certain mooring or propulsion systems. It allows angular relative movement between connected components while restricting other types of motion. For example, in dynamic positioning systems or articulated tug-barge combinations, the yoke arm ensures controlled, pivot-like flexibility. This functionality is essential for maintaining stability and reducing structural stress during vessel operations. Yoke arms are often engineered to withstand high loads and harsh marine environments.

Zinc

Zinc is a hard, bluish-white metal known for its excellent resistance to atmospheric corrosion, making it highly valuable in marine applications. It is widely used in galvanizing steel to prevent rust, particularly on ship hulls, offshore structures, and fittings exposed to seawater. One of zinc’s most notable uses in maritime environments is as a sacrificial anode in cathodic protection systems, where it corrodes in place of more important metal parts. Zinc is also found in various alloys and coatings designed to enhance durability. Its anti-corrosive properties contribute significantly to extending the lifespan of marine infrastructure.

Zinc Silicate Paints

Zinc silicate paints are protective coatings that consist of zinc particles dispersed in an inorganic silicate binder. These paints are especially effective in providing corrosion resistance for steel surfaces in harsh environments, such as ship hulls, ballast tanks, and offshore platforms. Once cured, they form an extremely hard, durable layer that adheres well to the metal substrate. Zinc silicate coatings are often used as primers in multi-coat systems or as standalone coatings in specific marine applications. Their ability to resist chemicals, solvents, and high temperatures makes them ideal for long-term protection in marine and industrial settings.