Bibby Marine Services Limited, part of Bibby Line Group, has signed a contract with the Damen Shipyards Group for delivery of its first Service Operations Vessel (SOV) with walk-to-work access.
The vessel, the Bibby WaveMaster 1, will undertake offshore wind project work in the North Sea. It is the first vessel purpose-built for the transfer and accommodation of offshore personnel. The design is capable of providing access up to 3.1 metre Hs. In line with wind farms being constructed farther from shore, the Damen SOV with walk-to-work access is able to remain at sea for periods up to one month. Accommodation is provided on board for up to 45 turbine maintenance personnel and fifteen crew members.
SOV Design
It is the first time that a wind farm operations and maintenance vessel has been designed exclusively for this purpose. The 90 metre hull is longer than that of a conventional platform supply vessel and the bow section has been lowered by 1.5 metres to create a V-shape. This feature reduces slamming and facilitates inclusion and improved offshore operation of the bow thrusters.
The aft ship has been adapted to the vessel’s tasks, including stern to waves operations. The most pronounced features are the strong V-shape in the frames in the aft ship to reduce the slamming occurrence and loads and the concentration of volume in the mid-ship region to achieve a slender aft ship. Both features should make stern to weather operations more comfortable than on a common PSV.
The accommodation has been placed amidships which reduces vertical acceleration by up to fifteen per cent.
Diesel-electric Propulsion
The design includes a diesel-electric main propulsion system, which powers twin azimuth thrusters. The vessel requires less installed power than a conventional PSV due to the symmetrical wind profile and use of a four split main switchboard.
The symmetric profile is created by locating the superstructure amidships instead of bow mounted. Because of this, the wind induced moment is less, resulting in lower required bow thruster power.
Due to the four split configuration of the main switchboard, the generator sets can be divided more efficiently than in conventional arrangements with two switchboards. In the event of a failure, only one of four switchboards would be out of action, as opposed to one of two. That leaves proportionally more power available, again requiring less total installed power.
Motion-compensated Gangway and Crane
A high-performance, motion-compensated access gangway and active heave compensated crane are located to port side, close to the centre of gravity. The management systems of both features are aligned with the vessel’s DP system.
Scale Model Test
The DP capabilities have already been proven, with a first-of-its-kind scale model test at the Netherlands-based research institute Marin. During these tests, the scale model of the vessel was pitted against North Sea wind, wave, swell and current simulations.
The target was a thirty-minute cycle, during which the vessel deploys the gangway and then transits in AutoTrack mode, several hundred metres, at speeds up to and beyond 6 knots to the following turbine without having to wait for an ideal weather window or having to rebuild the DP model at every turbine.
Other Options
A host of options are available for the vessel, including an additional deck crane with up to 24 tonnes capability, tanks arrangements suited to liquids such as glycols, tanks suited to low flashpoint liquids with separate delivery intakes and facilities for dive support and ROV operations.
