Anchor & Mooring Systems Aboard Bergesen’s LNG Tankers

Few shipowners shaped the modern LNG trade the way Bergesen d.y. did. Long before liquefied natural gas became a mainstream energy commodity, the Norwegian company was ordering Moss-type spherical tank carriers that pushed naval architecture to its limits. Behind those iconic tank domes sat a less glamorous but equally critical system: the anchor/mooring equipment of Bergesen’s LNG tankers, engineered to hold some of the largest gas carriers afloat steady against wind, current, and the punishing loads of terminal operations.

Engineering Behind the Anchor and Mooring Package

On a vessel the size of a Moss-type LNG carrier, displacing well over 90,000 tonnes fully laden, anchoring and mooring gear cannot be treated as an afterthought. Bergesen’s ships carried heavy-duty stockless anchors matched to chain cables sized several grades above what a conventional bulk carrier of similar length would require, reflecting the higher windage generated by those towering spherical tanks. The windlasses themselves were built for continuous high-torque service, with electro-hydraulic drive systems favored over purely electric units because hydraulics deliver smoother torque control when veering chain in deep anchorages or holding position during ship-to-ship transfers.

Mooring winches on these tankers were split-drum, tension-controlled units capable of automatic render-and-recover operation, a feature that became increasingly important as LNG terminals demanded tighter berthing tolerances. Self-tensioning mooring winches allow the vessel to compensate automatically for tidal movement and swell without constant manual adjustment from the crew, reducing the risk of parted lines during the loading or discharge window when a carrier is tethered for twenty-four hours or more alongside a jetty. Quick-release hooks, panama-style fairleads reinforced for higher line loads, and warping heads rounded out a package designed less for occasional use and more for near-constant deployment across a demanding trading pattern.

Why It Mattered on the LNG Trade Routes

LNG carriers do not behave like tankers or bulkers when it comes to berthing. The terminals they call at are often exposed, purpose-built jetties rather than sheltered docks, and the cargo itself demands zero tolerance for hull contact or excessive motion during cryogenic transfer. That reality placed enormous pressure on the anchor and mooring systems fitted to Bergesen’s fleet. A dragging anchor or a parted mooring line at a gas terminal is not simply an operational inconvenience; it is a safety event with the potential to interrupt loading arms, damage manifolds, or worse, compromise the integrity of a cargo system carrying gas at minus 162 degrees Celsius.

Bergesen’s engineering teams worked closely with equipment manufacturers to specify mooring winch brake holding capacities well above class society minimums, understanding that the real-world loads experienced during squally weather at an open berth routinely exceeded theoretical design figures. This conservative approach became something of a template for later generations of LNG carriers, influencing how classification societies and shipyards approached mooring equipment certification for the entire gas carrier segment.

Legacy and Influence on Modern LNG Newbuilds

Bergesen d.y. eventually folded into what became BW Gas and later BW LNG, but the operational philosophy around anchor and mooring equipment carried forward. Today’s membrane-type LNG carriers, far more numerous than the Moss spherical design Bergesen championed, still borrow heavily from the redundancy-first mooring philosophy those early ships demonstrated. Modern winches now incorporate load monitoring sensors feeding data directly to the bridge, an evolution from the manual tension gauges Bergesen’s crews once relied on, but the underlying engineering logic, oversized holding capacity paired with automatic tension management, remains largely unchanged.

Wärtsilä’s own encyclopedia entry on the subject reflects how influential this equipment configuration became as a reference point within the industry, cited by engineers and naval architects studying how mooring systems evolved alongside the growth of LNG shipping itself.

As LNG trade volumes keep climbing and terminals push toward faster turnaround times, the lessons embedded in Bergesen’s original anchor and mooring specifications still resonate. Robust holding power, intelligent tension control, and conservative safety margins were never just design preferences for these ships; they were operational necessities that continue to inform how the industry builds and equips the LNG carriers moving today’s energy supply.