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    More details on UT737L for Island Offshore

    Vessel & ROV News // September 12, 2002
    Rolls-Royce has revealed more details of the UT737L that is being built for Island Offshore.

    The 106m long vessel - now under construction - can undertake a variety of offshore support tasks including sub sea installation; well intervention; ROV operations; diving support and supply work.

    UT737L is the first design to be built to the DNV rules for ship-shaped well intervention units for worldwide service and also meets NMD requirements for Mobile Offshore Units.

    It builds on experience from more than 400 UT series offshore service vessels and is a development of the Island Offshore's UT737 Normand Flower.

    The first UT737L, Island Frontier, is now being built for Island Offshore at the Søviknes shipyard in Norway for delivery in 2003. It has been designed from the outset as a DP3 class vessel with full redundancy and logically planned subdivision, and is to a standard well in excess of 'comfort' and 'clean' class notations.

    Two moonpools are provided, with the 7m x 7m main pool optimally positioned for minimum motions. Operations such as module handling, sub sea lubrication and wire-lining will use this moonpool, while the pool further forward is for inspection and ROV work.

    The hull is 106m long overall and has a beam of 21m. A deadweight of about 4,600 tonnes is available on a draught of 6.2m, of which about 3,400 tonnes can be taken on deck. Tank testing indicates extremely low motions, helped by the roll reduction systemusing four passive tanks. High freeboard and full height rails ensure good working conditions on deck. A pumped anti-heeling system is fitted, independent of the roll-reduction tanks, to counteract the heeling effect of the 100 tonne long-outreach offshore crane which is installed on the starboard side of the working deck.

    In view of the many modes of operation, a diesel electric propulsion system has been selected, using four of the new Bergen C25:33 engines each rated at 2,100kW to power the generators. Two electric azimuth thrusters are used for main propulsion, supplemented by 883kW Ulstein Aquamaster swing up azimuth thrusters fore and aft and two super silent tunnel bow thrusters. Frequency control is used throughout to give speed control while minimising energy use, and very large amounts of electric power are available on deck.

    Accommodation to a high standard is provided for a total of 64 people in single and twin berth outside cabins in the Island Offshore UT 737L. The main public spaces also have windows or ports. Floating decks and other noise control measures ensure quietness. A reserve accommodation with five 4-man cabins can also be used, except when in well intervention mode. If required, the accommodation in the generic UT737L design can be extended by fitting an air-conditioned module for 44 people above the ROV hangar.

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