The FRS Accommodation Support Vessel below is one of the latest breed of all-in vessels, designed to provide all the logistics required for an offshore wind farm in one package, providing accommodation, workshops, storage and options for transfer to turbines. At 72 metres long, its sheer scale helps manage the harsher conditions and longer distances.
This model offers accommodation for up to 38 personnel, with cabins providing integral bathrooms, TVs and internet access. People would typically work on a three-shift system over 24 hours. And, when unusually high numbers of technicians are required, such as at the peak service period, additional accommodation in containers on deck can bring the capacity to 50 people.
The design incorporates facilities for personal and business needs, and include a gym, sauna, TV room, client office, conference room, workshops and storage areas, and a fully-equipped hospital.
Access to and from turbines would be via a smaller transfer vessel, motion-compensated platform, or helicopter. This vessel offers a winch zone, and other large service vessels and motherships feature helidecks to enable helicopters to land.
MULTI-USE SWATH: EXAMPLE FOB SWATH
Used for personnel transfer, work continues on achieving speed plus stability while stationary. The FOB SWATH 1 is a catamaran in transit that converts to a Small Waterplane Area Twin Hull with deeper draft for better stability when static. Work on later versions of the model aims to produce a design that removes much movement when static.
LONG-LEGGED JACK-UP BARGE: EXAMPLE JACK-UP BARGE JB-117
Deep-water sites require self-elevating platforms with long legs for lifting. With Bard Engineering and Vestas both reported to be looking into turbine foundations for water depths of 45m and 50m respectively, and with the potential for jack-up legs penetrating 10m into the seabed, the need for longer legs goes on. This jack-up barge, currently working at North Sea wind farms, can operate in waters up to 45m deep, and in wave heights over 3m.
SITE PREPARATION: EXAMPLES GARDLINE OCEAN RESEARCHER AND NEXANS SKAGERRAK
Distances for site preparation will also require bigger vessels if nothing else. The 69m long Ocean Researcher is one of the larger marine investigation vessels, capable of operating in higher wave conditions, and can carry up to 35 personnel for up to a month at a time. The Skagerrak has been reconfigured for further-shore work, with an extra 12.5m centre section added to enable it to carry more cable.
PREASSEMBLED INSTALLATION: EXAMPLE WIND TURBINE SHUTTLE
Using onshore facilities to assemble the offshore wind turbine means less time offshore for personnel and fewer trips out to the site, saving fuel and time. The Wind Turbine Shuttle concept, completed and with Norwegian maritime DNV approval, is designed to be able to operate in up to 3.5m wave height, and deliver completed wind turbines for installation without a transition piece. It can also replace wind turbines, install complete jacket-type and monopile foundations, and would be able to operate all year round in the North Sea.