Bibby Marine Services Limited, part of Bibby Line Group, signed a contract with the Damen Shipyards Group for delivery of its first Service Operations Vessel (SOV) with walk-to-work access. The vessel, 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 and aims to maximise working time and staff retention. The design guarantees fast, safe and comfortable access to turbines, at lower cost, up to 80% of the time, including in worst case scenario Central North Sea conditions, resulting in a vessel capable of providing access up to 3.1 metre Hs.
In line with wind farms being constructed farther from shore, the 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 15 crew members.
Dedicated to the job in hand
The attention to detail can be seen throughout the design. For example, the hull, at 90 metres, 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 offers significantly reduced slamming and facilitates inclusion and improved offshore operation of the bow thrusters.
The aft ship has been adapted specifically to the tasks that the vessel is designed for, including stern to waves operations. The most pronounced features that have been included 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 design.
Comfort onboard stems also from ergonomic design application, which sees interior spaces grouped together into similar task areas. This not only separates ‘clean’ and ‘dirty’ tasks, but ensures short lines of communication and smooth workflow. The accommodation has been placed midships for additional comfort – the location reducing vertical acceleration by as much as 15%.
Efficiency is another key feature. The design includes a diesel-electric main propulsion system, which powers twin azimuth thrusters. Thanks to careful development, the vessel requires less installed power than a conventional PSV. This results from two factors – a symmetrical wind profile and use of a four split main switchboard.
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.
Proven to Master the weather
The DP capabilities have already been proven, with a first-of-its-kind scale model test at the Netherlands-based leading 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 30-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.
The vessel exceeded all expectations, as Dr Joop Helder, MARIN Project Manager Offshore attested: “The results clearly showed Damen’s vessel performing very nicely. Especially in the wave conditions – there was hardly any rolling. I think these tests give a lot of confidence.”
Flexible & versatile
The vessel will be used by Bibby Marine Services to serve the offshore wind industry although the design can just as easily be applied to the offshore oil and gas sectors.
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.