OSD-IMT, a division of Offshore Ship Designers, has secured a design contract for two IMT 965 seismic support vessels (SSV's) with a bollard pull in excess of 50 tonnes for China Oilfield Services Ltd (COSL), Beijing.
The vessels will be used to provide a range of support activities to larger seismic vessels which operate continuously for months when conducting seismic surveys. Designed to have a multi-role capability in support of the mother ship, they can be used for re-fuelling, fresh water replenishment, the provision of refrigerated stores and dry provisions, the supply of spares and general stores, emergency towing, and escort support and guard duties.
The IMT 965 carries 980 cubic metres of cargo oil for refuelling the mother ship, either alongside or ahead. Fuel is pumped to the mother ship from a deck-mounted fuel supply module located on the working deck of the IMT 965. Up to 500 cubic metres of fresh water can be supplied in a similar way.
Cold stores and dry provisions totalling 80 cubic metres can be accessed directly from the working deck of the IMT 965, providing easy access for transfer to the mother ship, either by the ship’s crane or by a crane mounted on the mother ship.
The operating cycle for the IMT 965 requires it to be on station shadowing the mother ship for prolonged periods. During this time the IMT 965’s activities include keeping passing vessels clear of the streamer arrays, and ensuring that there is a traffic-free area ahead of the mother ship.
The vessel is classed with a DP1 notation which will allow it to shadow the mother ship at a pre-set distance for long periods.
The main IMT 965 propulsion arrangement is a hybrid system, comprising twin CP propellers, each driven by a medium-speed diesel engine. A PTO/PTI alternator/motor is connected to each main gearbox, and two 360 kWe diesel generators are also provided. The system is arranged such that one main engine can drive both propellers for maximum fuel economy.
The seismic survey support vessel has accommodation for a total of 48 persons, including cabins for mother ship relief personnel.