Rolls-Royce provides update on well intervention shipVessel & ROV News // May 28, 2004
Among the main design drivers were stability, motions, deck area, deadweight and high quality quiet accommodation. A module handling system can be installed on the working deck over the main moonpool so that Island Frontier can carry out well intervention such as wirelining, and also deploy a sub sea lubricator. It is planned that the vessel can operate in this mode in the North Sea for about nine months of the year.
It is the first vessel to meet the new DNV 'Ship Shaped Well Intervention Unit' rules and is also classed as a Mobile Offshore Unit under Norwegian Maritime Directorate regulations. Strict requirements, particularly for damaged stability, involve doublehull construction with 1.5m wide wing compartments.
Island Frontier, owned by Island Offshore in Norway, is a development of the UT737 design, lengthened to 106m. The extra length allowed increased deck area, accommodation spaces and better ship motion characteristics.
Accommodation is provided for 64 people in single and twin berth outside cabins. A firewall is fitted between the accommodation and the ROV hangar, and air pressure inside is maintained at a higher level than outside to prevent gas being drawn into the living quarters. A reserve block of five 4-berth cabins is located at main deck level, but will not be used when the vessel is operating under MOU rules. To improve logistics, two provisions containers can be latched to the superstructure on top of the ROV hangar. Two accesses are provided for every compartment, with two gangways the whole way under deck. Staircases are provided as far as possible instead of escape ladders.
DP3 class is the starting point for the layout of Island Offshore's vessel and its propulsion system. In view of the many modes of operation, a diesel electric propulsion system was been selected, using four Bergen C25:33 engines each rated at 2,100kW topower the generators plus 2x1190kW auxiliary gensets. Two electric pod thrusters are used for main propulsion, supplemented by 883kW swing up azimuth thrusters fore and aft and two tunnel bow thrusters. Frequency control is used throughout to give speedcontrol while minimising energy use, and very large amounts of electric power are available on deck.
The UT737L Island Frontier can work in a variety of roles. Apart from well intervention, the ship is an effective platform for sub sea support and for inspection and maintenance, having also supply capacity. It recently returned to its builder, Søviknesyard in Norway, for the offshore crane and the foundation for the module handling tower to be installed.