Wärtsilä thrusters have helped ensure successful sea trials for the world’s largest semi-submersible crane vessel (SSCV).
Dynamic positioning is critical to the operations of Heerema Offshore Services’ (HOS) SSCV Sleipnir and to ensure this, Wärtsilä specifically developed four 5500kW 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 5500kW Wärtsilä WST-65U underwater mountable steerable thrusters.
“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,” said Lauri Tiainen, director, thrusters and propulsion control systems at Wärtsilä Marine.
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.
In addition to the thrusters, Wärtsilä also supplied auxiliaries for steering and lubrication, the control units, and Wärtsilä’s Propulsion Condition Monitoring Service (PCMS).
The Sleipnir was built at Sembcorp Marine’s Tuas Boulevard Yard in Singapore. Deesigned for heavy lifting operations, it is fitted with two cranes, each with a lifting capacity of 10,000t.
By Rebecca Jeffrey