Performance of the propulsion solutions supplied by the technology group Wärtsilä exceeded the design specification and contributed to the success of the sea trials for the world’s largest semi-submersible crane vessel (SSCV). The ‘Sleipnir’ was built at Sembcorp Marine’s Tuas Boulevard Yard in Singapore for the Dutch offshore contractor Heerema Offshore Services (HOS). It was delivered from the yard in July.
The huge vessel is designed for heavy lifting operations and is fitted with two cranes, each with a lifting capacity of 10,000 metric tonnes. The reinforced deck area measures 180 metres by 98 metres. Dynamic positioning is critical to its operations and to ensure this, Wärtsilä developed specifically for this project four 5500 kW forward retractable WST-65RU thrusters that are the world’s largest retractable thrusters ever made. They feature a unique combination of retractable and underwater mountable functionality. The thrusters installed at the aft of the vessel are 5500 kW Wärtsilä WST-65U underwater mountable steerable thrusters.
The underwater demounting capability of all eight thrusters means that neither dry docking, nor the use of a habitat is necessary should the thrusters need to be exchanged. They are equipped with Wärtsilä anti-pollution face type shaft seals, which have been selected primarily because of the challenging environments in which the thrusters will operate. The outboard parts of the thrusters are completely interchangeable.
“These are the largest thrusters in our portfolio, and we are particularly pleased with the impressive first-installation performance of the WST-65RU retractable thrusters, which were designed in close cooperation with our customer Heerema Offshore Services especially for this SSCV. The eight-degrees tilted propeller shaft solution, that is a feature of our underwater mountable thrusters, significantly reduces the interaction between the thrusters and the hull, and by exceeding the design specifications during the sea trials, we demonstrated the efficiency of this solution,” says Lauri Tiainen, Director, Thrusters and Propulsion Control Systems, Wärtsilä Marine.
“Wärtsilä’s execution of the development and delivery of these thrusters specifically for the Sleipnir project and the performance of the thrusters demonstrated during the sea trials completely met our expectations. They also ensure accurate positioning, which is a must for a vessel of this size. Wärtsilä’s support and professionalism throughout this project have been first-class.” says Heerema’s Project Director for Sleipnir, Sipke Schuurmans.
In addition to the thrusters, Wärtsilä also supplied auxiliaries for steering and lubrication, the control units, and Wärtsilä’s comprehensive Propulsion Condition Monitoring Service (PCMS).