Reading an IRS Class Certificate: A Practical Guide to IRS Class Notations
Why class notations matter
A string such as “SUL, BULK CARRIER ESP, Load Comp (4)” on a class certificate is a compact record of what a ship is, where it may trade, how it is surveyed and which extra standards it meets. The Indian Register of Shipping (IRS) uses a consistent set of symbols, characters of class and notations for this, and its Handbook of Notations (July 2021 edition) collects them in one table.
This article is a reading guide to that system. It follows the handbook’s own grouping, explains what each family of notations tells you, and then decodes six typical notation strings.
Two cautions before starting. The handbook is a summary: the online IRS Rules, Classification Notes and Guidelines, together with their Rule Change Notices, are the authoritative text if the two ever differ. And the exact requirements behind each notation sit in Part 1, Chapter 1 and the chapters named alongside each notation, so check those before relying on any detail here.
How a notation string is built
A notation string is read left to right as a stack of layers, each answering a different question. In general a ship can carry any combination of distinguishing marks, characters of classification, ship type, cargo, special feature and service restriction notations, plus class notations for hull and machinery.
| Layer | Question it answers | Example |
|---|---|---|
| Distinguishing mark | How was the ship built and admitted to class? | The IRS swastika mark (or one of its two variants) |
| Character of class, hull | Does the hull meet the Rules, and how complete is the equipment? | SUL, SU (-), SU |
| Ship type | What kind of ship is it? | BULK CARRIER, OIL TANKER, TUG |
| Additional hull notations | Survey, stability, strength, ice and similar features | ESP, Load Comp (4), SFA |
| Character of class, machinery | Does the machinery installation meet the Rules? | IY |
| Machinery and system notations | How is the plant controlled, maintained and supported? | SYJ, CCS, PMS-CBM, DP (3) |
| Environment, comfort, cyber | Pollution, habitability and cyber practice | BWT, EP, CMF(Cy-c-l), CyS-II |
Hull items normally appear on the first line of the certificate string and machinery items on the second, as the handbook’s worked examples show.
Characters of class
Characters of class are the foundation of the string: they state whether the hull, and separately the machinery, meet IRS requirements.
| Symbol | Expanded form | What it means |
|---|---|---|
| SUL | Sarvoutam Langer | Hull and appendages meet the Rules, and so does the equipment (anchors, chain cables, hawsers) |
| SU (-) | Sarvoutam (-) | Hull and appendages meet the Rules, but equipment is not supplied or maintained to the Rules; IRS accepts it for the particular service |
| SU | Sarvoutam | Hull and appendages meet the Rules, but the ship’s purpose or service means normal equipment may be unnecessary |
| IY | Indian Yantra | For self-propelled seagoing vessels: the machinery installation complies with the applicable IRS requirements |
| [ ] | Square brackets | The notation is enclosed in brackets: the arrangements exist on board, but the notation is temporarily suspended |
Distinguishing marks
A distinguishing mark placed before the character of class records how the ship came into class. There are three versions:
- Plain mark. New vessels whose hull, appendages, equipment and machinery (as appropriate) were built under IRS special survey, in compliance with the Rules.
- First variant. Vessels admitted to IRS class during construction, having been surveyed by an IACS society.
- Second variant. Vessels admitted to IRS class at delivery, having been built under the survey of an IACS society.
The mark is mandatory for newly constructed vessels. A vessel taken into class later, after construction and delivery, does not receive it.
Hull notations
Hull notations describe where the ship may operate, how strong it is against ice, how its stability and loading are managed, and which special structural features or analyses apply. The handbook splits them into six groups.
Service restriction
These limit the ship to a defined type of water or trade. The geographical limits form part of the notation itself.
| Notation | Scope |
|---|---|
| Sheltered Water Service | Sheltered water near sand banks, reefs, breakwaters or other coastal features, and between islands |
| Restricted Water Service | Sheltered waters plus short distances beyond them, generally under 15 nautical miles, in reasonable weather |
| Specified Coastal Service | Along a coast, never more than 20 nautical miles from the nearest land, and may cross gulfs or similar features recognised locally as part of coastal service. Example: “Indian Coastal Service” |
| Specified Route Service | Between two or more named points or geographical features |
| Specified Operating Area Service | Within one or more named areas |
The handbook also lists wording templates, such as operation within a named port limit, in a maximum water depth, wave height or wind speed, in fair weather only, or outside emission control areas.
Ice class
Two families exist. The Baltic-style notations are for first-year ice in the Northern Baltic in winter, or similar areas, and are defined by the thickest unbroken level ice they can handle.
| Notation | Meaning | Level ice limit |
|---|---|---|
| HAT(B) | Hima Atitivra (B) | 1.0 m |
| HT(B) | Hima Tivra (B) | 0.8 m |
| HM(B) | Hima Madhyam (B) | 0.6 m |
| Ha(B) | Hima Alpa (B) | 0.4 m |
| Ha | Hima Alpa | Light first-year ice in areas other than the Northern Baltic |
For polar work, the POLAR notation points to Part 5, Chapter 36, with the ice strength itself covered by the Polar Class notations PC1 to PC7 under Part 5, Chapter 32. PC1 is year-round operation in all polar waters; PC7 is summer and autumn operation in thin first-year ice. Ships with a Polar Class that meet the specific requirements may also carry the ICEBREAKER notation, which implies an escort or ice management role with the power and dimensions for aggressive operations in ice.
Stability and loading computers
- STS (Samatarana Sthiratva) shows compliance with the survival capability (damaged floatability) requirements of Chapter 3 of IMO Resolution MSC.235(82).
- Load Comp (1) is a loading computer that checks still-water hull girder loads against permissible limits.
- Load Comp (2) adds intact stability calculations.
- Load Comp (3) builds on (2) by adding damaged stability calculations.
- Load Comp (4) builds on (2) by adding both stability and strength calculations in the damaged condition.
Special features, arrangements and equipment
This group records design choices the owner has asked for or the cargo demands. Examples include strengthening for heavy cargoes (with a note where specified holds may be empty), deck strengthening stated in t/m² and by frame range, equipment for carriage of containers, owner’s additional thickness for extra corrosion margin, and arrangements for crane operation with spuds on a barge or pontoon.
Shorter coded entries in the group are HELDK (helicopter deck, Part 5, Chapter 27), ETA (emergency towing arrangement), SPM (single point mooring, Part 5, Chapter 28) and DWA (anchoring in deep and unsheltered waters). DOUBLE HULL is appended for bulk carriers, oil tankers and combination carriers built double hull throughout the cargo area, while DOUBLE SIDE SKIN applies to double-side-skin bulk carriers.
Survey related
- ESP shows compliance with the Enhanced Survey Programme. It applies to bulk carriers, ore carriers, oil tankers, combination carriers and asphalt carriers with integral tanks, and is also assigned to chemical tankers.
- INWATER SURVEY allows the bottom survey to be done afloat.
- EDD (X) denotes fitness for an extended dry-docking interval of X years, under the IRS Classification Note on Extended Dry-Docking Scheme.
Special analysis
SFA ( ) means the design fatigue life was assessed under IRS spectral fatigue analysis guidelines. The figure in brackets is the number of years assessed.
Machinery notations
Machinery notations sit on the second line of the string, after IY. They cover how the plant is controlled and maintained, and the specialist systems fitted. Many carry the Hindi-derived names IRS uses for its characters.
| Notation | Meaning | Rule reference |
|---|---|---|
| CCS | Centralized Control Station: propulsion and auxiliary machinery controlled and monitored under continuous supervision from one station | Part 4, Ch. 7 |
| SYJ | Swachalit Yantrik Jahaz: machinery spaces can be operated unattended | Part 5, Ch. 22 |
| HY | Himikar Yantra: refrigerated cargo installation meets the Rules | Part 5, Ch. 23 |
| HY* | Refrigerated installation able to cool down fruit in general or a catch of fish | Part 5, Ch. 23 |
| HY(LGC) | Re-liquefaction or refrigeration plant on a liquefied gas carrier for cargo temperature and pressure control | Part 5, Ch. 4 |
| NV | Niprabhav Vashpa: cargo spaces on oil or chemical tankers can be inerted by an approved inert gas system | Relevant Rules |
| AGNI 1, 2, 3 | Fire-fighting capability: AGNI 1 for early-stage fire fighting and rescue close to structures; AGNI 2 for continuous fighting of large fires and cooling; AGNI 3 the same at greater capacity. All include self-protection | Part 5, Ch. 25 for offshore support vessels |
| DP (0) to DP (3) | Dynamic positioning, from automatic control with no joystick back-up up to full redundancy with physical separation of components in different compartments | Part 5, Ch. 24 |
| BD, BDS | Bridge design (ergonomic layout) and bridge design plus navigation equipment and related systems | Part 5, Ch. 31 |
| IBS | Integrated Bridge System for navigation, manoeuvring, communication and monitoring of other functions | Part 5, Ch. 31 |
| DSV, DIV-SURF, DIV-SAT | Diving support vessel; surface diving systems; saturation diving systems | Part 5, Ch. 26 |
| TCM | Tailshaft Condition Monitoring based on service records and oil and water sample analysis | Part 1, Ch. 2; Part 4, Ch. 4 |
| FT | Fuel oil treatment system and equipment meeting the IRS Classification Note on fuel oil treatment | Classification Note |
| BATTERY PROP | Battery systems used for propulsion, per the IRS guidelines on battery powered vessels | Guidelines |
| HVSCS | High Voltage Shore Connection Systems, for ships powered by shore alone at berth (voltages above 1 kV) | Guidelines |
The planned maintenance family
Three notations show how far a ship’s maintenance regime goes beyond routine surveys:
- PMS: machinery is subject to a planned maintenance system and surveys (Part 1, Chapter 2, Section 14).
- PMS-CM: adds condition monitoring (Section 21).
- PMS-CBM: adds condition based maintenance (Section 21).
Low flash point fuel and regasification
LFPF is for ships designed and built primarily to use low flash point fuel (Part 5, Chapter 35). Qualifiers state the fuel or engine type: NG (natural gas), EG (ethane), LPG, ML (methanol), SFE (single fuel engines) and DFE (dual fuel engines).
RV(LNG) is for LNG carriers fitted with regasification systems (Part 5, Chapter 38). They must also meet the liquefied gas carrier requirements in Part 5, Chapter 4.
Environmental notations
Environmental notations go beyond the baseline MARPOL and ballast water requirements, and they point to Part 5, Chapter 29 (vapour control), Chapter 30 (pollution) or Chapter 37 (ballast water) of the Rules.
Pollution prevention
| Notation | What it signals |
|---|---|
| VCS1 | Vapour control system meeting IMO MSC/Circ.585; for oil tankers, combination carriers and chemical tankers |
| VCS2 | Vapour control system meeting USCG regulations (CFR 46 Part 39); for oil tankers and chemical tankers |
| CLEAN-SEA | Construction and procedures that prevent sea pollution: MARPOL Annexes I to V, plus measures such as fuel and lube oil tanks kept above the double bottom and away from the side shell, bilge water separation, holding tanks for treated sewage and grey water, TBT-free antifouling, and proper storage of solid waste |
| CLEAN-AIR | Construction and procedures that prevent air pollution: MARPOL Annex VI, plus low-emission engines, low sulphur fuel and incinerators, refrigerants and fire-fighting media with zero ozone depletion potential, leak detection and evacuation systems, and recovery of vapours from dangerous liquid cargoes |
| EP | Environmental Protection: MARPOL Annexes I to VI plus controls on liquid, solid and gas releases, with a ship-specific Environmental Management Plan that considers IMO recycling requirements |
| Inventory of Hazardous Material | An inventory developed under IMO Resolution A.962(23), as amended, and kept on board for the ship’s life |
Two dependencies are worth remembering. For oil tankers, combination carriers, chemical tankers and liquefied gas carriers, VCS1 or VCS2 is a prerequisite for both CLEAN-AIR and EP. And the hazardous material inventory is a prerequisite for EP, although it can also be provided on ships without EP.
Ballast water
- BWE ( ) is assigned to ships that comply with the 2004 Ballast Water Management Convention and carry out ballast water exchange per Part 5, Chapter 37.
- BWT is assigned to ships fitted with a ballast water treatment system approved by an IMO member state, complying with the Convention, the IMO guidelines and Part 5, Chapter 37.
Ship type notations
The ship type notation names the ship’s primary function and sets which Part 5 chapter governs its design. Ship type notations are assigned mandatorily, as appropriate to the vessel.
Dry bulk and tankers
| Notation | Meaning | Governing Rules |
|---|---|---|
| BULK CARRIER | Designed mainly for dry cargo in bulk, with cargo density of at least 0.8 t/m³ | Part 5, Ch. 1 |
| ORE CARRIER | Designed mainly to carry ore | Part 5, Ch. 1 |
| OIL TANKER | Carries oil in bulk. Where approved for oil with a flash point of 60°C or above, or other liquids, the notation is modified to show the cargo | Part 5, Ch. 2 |
| ORE OR OIL CARRIER; OIL OR BULK CARRIER | Combination carriers for dry bulk and, alternatively, oil. Simultaneous carriage of both is prohibited | Part 5, Ch. 2, Sec. 12 |
| ASPHALT CARRIER | Carries asphalt or bitumen, in integral tanks (ESP also assigned) or independent tanks, with maximum cargo temperature stated | Part 5, Ch. 2 |
| CHEMICAL TANKER | Designed mainly to carry chemicals in bulk; ESP is mandatory | Part 5, Ch. 3 |
Additional tanker qualifiers include FOR CARRIAGE OF (a specified cargo from the Appendix B list) and FOR CARRIAGE OF LIQUID HAVING F.P. EXCEEDING 60°C, for unheated cargoes above that flash point and cargoes heated to a temperature below, and not within 15°C of, their flash point.
Chemical tanker qualifiers
- Type 1, 2 or 3 grades the severity of environmental and safety hazard of the cargo: Type 1 needs maximum preventive measures to prevent escape, Type 2 significant measures, and Type 3 a moderate degree of containment to improve damaged survival.
- Independent Tank applies where tanks are independent.
- SG states a maximum permissible specific gravity above 1.025 (for example “SG 2.0”).
- PV states a relief valve setting above 0.21 bar (for example “PV + 0.4 bar gauge”).
- CR ( ) shows tanks of corrosion resistant material or lining, such as stainless steel or rubber lining.
- TC shows temperature control systems; with refrigeration the notation reads “TC HY(BC)”.
Liquefied gas carriers
LIQUEFIED GAS CARRIER covers ships carrying liquefied petroleum, natural or other gases under Part 5, Chapter 4. A gas carrier type states the level of preventive measures needed:
| Type | Level of measures to prevent cargo escape |
|---|---|
| 1G | Maximum |
| 2G | Significant |
| 2PG | Significant, for ships of 150 m or less with Type C independent tanks, MARVS of at least 7.0 bar gauge and design temperature of -55°C or above. Over 150 m, the ship is treated as 2G |
| 3G | Moderate |
The notation then lists the gases carried (for example Ethane), the maximum vapour pressure at sea and in harbour in pascals, the minimum and where needed maximum cargo temperature in °C, and design ambient temperatures for service in extreme climates.
Container, passenger and ferry types
- CONTAINER SHIP: built exclusively to carry containers in holds and on deck (Part 5, Ch. 5).
- PASSENGER SHIP: more than 12 passengers (Part 5, Ch. 6).
- FERRY: passengers and/or vehicles on regular scheduled service (Part 5, Ch. 6).
- Ro-Ro FERRY / TRAIN FERRY: passengers, vehicles and cargo in pallet or container form loaded by wheeled vehicles (Part 5, Ch. 6).
- Ro-Ro CARGO SHIP: carries roll-on/roll-off cargo on one or more decks. Part 3 (wheel loading, bow doors) and Part 6 (fire safety of ro-ro and vehicle spaces) also apply.
Tugs and offshore support
- TUG (Part 5, Ch. 7), with ESCORT (Fs, Fb, V) for escort tugs, where design steering force, braking force and escort speed are added to the notation.
- OFFSHORE SUPPORT VESSEL (Part 5, Ch. 8), or MULTIPURPOSE OFFSHORE SUPPORT VESSEL for several roles.
Offshore support vessels take role qualifiers:
| Qualifier | Role |
|---|---|
| SUPPLY | Transport of stores, materials, equipment and personnel to, from and between offshore installations (not crew boats) |
| STS | Damaged survival capability per IMO MSC.235(82), Ch. 3 |
| LHNS | Limited amounts of hazardous and noxious liquid substances in bulk |
| OCC | Hazardous and noxious liquids under the OSV Chemical Code (IMO Res. A.1122(30)) |
| AH | Anchor handling |
| TOW | Towing operations |
| SSR | Rescue and standby services |
| AGNI 1/2/3 | Fire fighting |
| DSV | Diving support |
| WSV | Well stimulation |
| OIL RECOVERY | Recovery, handling, storage and transport of spilled oil |
Fishing, dredging and non-propelled craft
- STERN TRAWLER, TRAWLER (side trawling) and FISHING VESSEL (no trawling gear): Part 5, Ch. 9.
- DREDGER, HOPPER DREDGER, RECLAMATION CRAFT, HOPPER BARGE, SPLIT HOPPER BARGE: self-propelled or not, Part 5, Ch. 10.
- BARGE: non-propelled, manned or unmanned, carrying dry cargo in holds (Part 5, Ch. 11). OIL BARGE carries oil in bulk (Chapters 2 and 11). PONTOON carries non-perishable cargo or equipment on deck (Chapter 11).
- FLOATING DOCK: Part 5, Ch. 12.
Other specialist types
- WELL STIMULATION VESSEL (Part 5, Ch. 33), with OCC if it handles hazardous liquids under the OSV Chemical Code.
- OIL RECOVERY VESSEL (Part 5, Ch. 34), with FP 60C for recovering oils above that flash point.
- SPECIAL PURPOSE SHIP: meets the IMO SPS Code.
- LIVESTOCK CARRIER: Part 5, Ch. 40.
- MOORED OIL STORAGE TANKER at (Location): an existing double hull tanker used as storage at a fixed location.
- PASSENGER SUBMERSIBLE WITH MAX. OPERATING DEPTH OF ___ m: per MSC/Circ.981.
- PIPE LAYING / CABLE LAYING VESSEL or BARGE: Part 5, Ch. 13; barges also meet the BARGE rules.
- ACCOMMODATION BARGE / PONTOON: non-propelled accommodation for offshore personnel; pontoons keep all accommodation above the main deck.
- For carriage of cement in bulk: ships designed and built solely for that cargo.
Other class notations
General notations
| Notation | Meaning |
|---|---|
| SPECIAL GOVERNMENT SERVICE | Special purpose vessels built to arrangements and scantlings approved for that service |
| ADE (Alternative Design Evaluation) | An alternative design was used instead of the prescriptive Rules; details are shown on the class certificate |
| RA (Risk Assessment) | The design is risk based and accepted on that basis; the relevant aspects are shown on the certificate |
| DSA (Direct Strength Assessment) | A direct strength assessment was done under the IRS guidelines on direct seakeeping loads and on finite element structural assessment |
| FDA (Fatigue Design Assessment) | A fatigue assessment was done under the Rules and IRS guidelines. Mandatory for ships of 150 m and above, optional above 90 m. If assessed for more than 25 years or a specified area, it reads FDA (N, area) |
| ERS (Emergency Response Service) | The owner or manager opted into IRS’s computer-assisted analysis of a damaged ship’s stability and longitudinal strength after a casualty |
ADE and RA both draw on the IRS Guidelines on Alternative and Risk Based Design Evaluation.
Passenger and crew comfort
The CMF family (Part 5, Chapter 39) certifies noise and vibration, and optionally indoor climate and lighting, in accommodation spaces.
- CMF(Px) is for passenger spaces, where x is the noise and vibration comfort rating.
- CMF(Cy) is for crew spaces, where y is the rating.
- CMF(Px, Cy) covers both.
- Add -c for indoor climate and -l for lighting. For example, CMF(Cy-c-l) means crew spaces rated for noise and vibration, indoor climate and lighting.
Cyber safety
Both notations come from the IRS Guidelines on Maritime Cyber Safety.
- CyS-I (Informed Cyber Safety): the organisation assesses cyber safety issues and risks, has documented policies and applies minimum practices.
- CyS-II (Advanced Cyber Safety): policies and procedures are also reviewed periodically for continual improvement, and advanced practices are applied.
Worked examples: decoding six strings
The handbook closes with typical strings for six ship types. In each, [IRS mark] stands for the distinguishing mark that opens both lines. Read hull on line one and machinery on line two.
1. Bulk carrier
[IRS mark] SUL, BULK CARRIER ESP, Load Comp (4), CMF(Cy-c-l)
[IRS mark] IY, SYJ, IBS, TCM, PMS-CBM, BWT, CyS-II| Symbol | Layer | Reads as |
|---|---|---|
| SUL | Character of class, hull | Hull and equipment meet the Rules |
| BULK CARRIER | Ship type | Dry bulk carrier |
| ESP | Survey | Enhanced Survey Programme applies |
| Load Comp (4) | Stability | Loading computer that handles stability and strength in damaged condition |
| CMF(Cy-c-l) | Crew comfort | Noise and vibration, indoor climate and lighting rated for crew spaces |
| IY | Character of class, machinery | Machinery meets the Rules |
| SYJ | Machinery | Unattended machinery spaces |
| IBS | Machinery | Integrated bridge system |
| TCM | Machinery | Tailshaft condition monitoring |
| PMS-CBM | Machinery | Planned maintenance with condition based maintenance |
| BWT | Environment | Ballast water treatment |
| CyS-II | Cyber safety | Advanced cyber safety |
2. Oil tanker
[IRS mark] SUL, OIL TANKER ESP, Load Comp (4), CMF(Cy-c-l)
[IRS mark] IY, SYJ, IBS, CCS, TCM, VCS2, EP, PMS-CBM, BWT, CyS-IIThe hull line mirrors the bulk carrier, with OIL TANKER as the type. The machinery line adds CCS (centralized control station), VCS2 (USCG-standard vapour control) and EP (environmental protection). VCS2 is there because a vapour control notation is a prerequisite for EP on a tanker.
3. Liquefied gas carrier
[IRS mark] SUL, LIQUEFIED GAS CARRIER, 2G, Ethane, CMF(Cy), SFA
[IRS mark] IY, SYJ, IBS, CCS, TCM, PMS-CM, EP, BWT, CyS-IAfter the ship type come the gas carrier type (2G, significant preventive measures) and the cargo notation (Ethane). CMF(Cy) covers crew noise and vibration only. SFA shows a spectral fatigue analysis. On the machinery line, PMS-CM means condition monitoring rather than condition based maintenance, and CyS-I is the lower of the two cyber levels.
4. Passenger ship
[IRS mark] SUL, PASSENGER SHIP, CMF(Px-c-l, Cy-c-l), HELDK, SFA
[IRS mark] IY, SYJ, IBS, CCS, TCM, PMS-CBM, EP, BWT, CyS-IIThe comfort notation covers both passengers (Px) and crew (Cy), each with climate and lighting. HELDK shows a helicopter deck and SFA a spectral fatigue analysis.
5. Offshore supply vessel
[IRS mark] SUL, SUPPLY VESSEL, OCC, STS, HELDK, CMF(Cy-c)
[IRS mark] IY, SYJ, IBS, DP (3), CCS, TCM, PMS-CBM, EP CyS-IIOCC shows compliance with the OSV Chemical Code, STS shows damaged survival capability, and HELDK a helicopter deck. On the machinery line, DP (3) is the highest dynamic positioning level, with redundancy and physical separation of components.
6. Tug
[IRS mark] SUL, TUG, INDIAN COASTAL SERVICE, CMF(Cy-c)
[IRS mark] IY, SYJ, TCMThe shortest string. INDIAN COASTAL SERVICE is a Specified Coastal Service restriction, so the geographical limit is part of the notation. Crew comfort covers noise, vibration and indoor climate, and the machinery line carries only unattended spaces and tailshaft monitoring.
What is mandatory and what is optional
Not every item in a string is a choice. The handbook sorts them as follows.
| Category | Status |
|---|---|
| Distinguishing mark | Mandatory for newly constructed vessels; not given to ships taken into class after delivery |
| Hull character (SUL, SU or SU (-)) | Mandatory once compliance with the Rules is verified |
| Machinery character (IY) | Mandatory once compliance is verified |
| Ship type notation | Mandatory, as appropriate to the vessel |
| ESP | Mandatory where the ESP Code applies: bulk carriers, ore carriers, oil tankers, combination carriers, asphalt carriers with integral tanks, and chemical tankers |
| Everything else | Optional, assigned when requested by the owner and agreed by IRS, or when IRS considers it necessary, depending on special features, service restrictions and systems fitted |
Practical takeaways
- Start with the three fixed layers. Mark, character of class and ship type tell you the basics before any optional notation does.
- Look for dependencies. VCS1 or VCS2 before CLEAN-AIR or EP on tankers, the hazardous material inventory before EP, Polar Class before ICEBREAKER, and Load Comp levels that build on one another.
- Read brackets carefully. A notation in square brackets is not in force, even though the arrangements are on board.
- Check the qualifiers. Figures inside notations such as SFA ( ), EDD (X), FDA (N, area), SG and PV carry real design limits.
- Go to the Rules for requirements. The handbook says which chapter governs each notation. The current online Rules and Rule Change Notices are the final word.
Source
Based on the Indian Register of Shipping, Handbook of Notations: Rules and Regulations for the Construction and Classification of Steel Ships, July 2021, which is available through www.irclass.org. This article summarises and reorganises that handbook in new wording and is not a substitute for the Rules.
