Customized 600 t rope for offshore installation

In offshore operations, efficiency, reliability, and safety during anchor handling and mooring operations are critical. That’s why many operators rely on high-performance ropes made with Dyneema^® fibre, offering a clear operational advantage over traditional steel wire ropes and mooring lines.

For external turret mooring applications, Dynamica Ropes has developed and supplied 96 mm ropes with a Minimum Breaking Load (MBL) of 600 tons, demonstrating the strength and reliability required for the most demanding offshore environmental conditions - including operations in challenging water depths as well as exposure to strong wind loads and powerful waves.

This rope was significantly lighter and easier to handle, reducing physical strain on deck crews while improving control and safety during demanding offshore operations. The procedure was to pull the anchor chains to the required height and securely hold them in place while the crew completed the locking procedure.

Dynamica rope, with a 12-strand core, was made from high-strength, low-stretch Dyneema^® fibres. The protective heavy-duty jacket was applied to the eyes and the splice area to avoid abrasion during the operation.

To further enhance operational efficiency, the ropes are manufactured with strategically placed color-coded sections at predefined lengths. These visual markers allow crews to instantly identify key positions during chain retrieval, enabling better preparation, smoother coordination, and faster execution during critical stages of the operation.

The result is improved safety on deck, greater operational efficiency, and dependable performance when it matters most.

Proof-load and ABS surveillance

The presence of a third-party surveyor transformed a proof load test to a fully certified validation—providing the level of trust and traceability required for critical offshore mooring components.

The Proof load conducted in the Netherlands was demanding due to the length of the ropes.

Proof load testing of long, high-capacity offshore ropes is a critical step in ensuring the turret mooring system performs safely and reliably once installed offshore. In this case, the test was particularly demanding due to the rope length of 180 meters and the high loads involved.

Although the system is designed for a maximum operational tension of 200 tons, the ropes were proof-loaded to 400 tons in a basket configuration. Testing at twice the operational load provides a strong safety margin and confirms that the rope can withstand the extreme forces it may encounter in service.

Equally important is the presence of an independent third-party surveyor from the American Bureau of Shipping (ABS). In offshore oil and gas projects, independent verification is essential to ensure transparency, compliance, and confidence in the testing process.

What is a turret mooring system of FPSO?

A mooring turret is installed at the centre of the ship, where all anchoring lines terminate and around which the ship can rotate freely, enabling it to select a favourable heading for the environment. This free rotation is essential for safe offloading operations, as it allows the vessel to maintain a stable position during water-to-vessel transfer regardless of environment. The mooring forces applied to the vessel are introduced and accommodated by the turret components contained within the hull, supported by bearings that enable smooth and continuous rotation.

The turret mooring system of the FPDSO consists of an array of anchor legs, connected at their lower end to an anchor point on the seabed and at their upper end to the turret.

The turret cylinder accommodates the anchor-leg and riser entry points at its lower end. At its upper end, there is an anchor leg tensioning system with chain lockers and the riser support structures. These are the chains that are pulled in with Dynamica ropes in the turret. The chains are accommodated in tubes with flared trumpets that exit at their lower end.

The turret at its upper deck supports up to 16 individual chain lockers, which accommodate the additional lengths of chain that are paid out or pulled in when the vessel is relocated above each drilling template.