Ad Hoc Marine Designs, based in the UK, has released details of its new 41-metre SWATH design specifically for the transportation of crew to oil platforms and servicing large wind turbines in offshore windfarms.
Servicing and supplying crew to offshore oil platforms requires safe and comfortable operation year round in all sea states. The sea states experienced at these offshore oil platform locations are of the same magnitude as those at offshore windfarms.
The seakeeping ability of SWATH-style vessels ensures safe and comfortable operations. The vessel's motions are further reduced by the use of an active ride control system, which enables year round operations in significant wave heights of up to 3.0 metres with service speeds up to 28 knots. Damping appendages are also integrated into the hull form to maintain comfort levels when stopped at station.
"The windfarm industry is maturing rapidly and the farms are being deployed further offshore," said Ad Hoc. "The existing range of windfarm vessel that service the windfarms are only suited for sheltered and inshore operations. However, with the growth of the farms being further offshore, and these farms expected to come "on-line" in the not too distance future, a safe reliable multipurpose workboat is required. The significant wave height in these future offshore farms, in the Irish Sea and North Sea regions, during the harsh winter months are regularly in the 3.0 to 4.0-metre band, and sometimes beyond. Designing a craft for high-speed operation in 3.0 metres significant wave height should allow 310 days a year safe operation."
The general arrangement of the 41-metre shown is in the oil platform crew transfer configuration and is designed to satisfy ISO 2631 sickness criteria in all service conditions and meets DNV's R2 Crew Boat rules and the HSC 2000 code.
In the windfarm role, the current method of crew transfer by stepping off the bow onto a vertical ladder is unlikely to be acceptable in these sea states. Hence a unique transfer system has been developed by Ad Hoc Marine Designs that would complement the SWATH's superior seakeeping ability.
The advantage of a SWATH in either role is simply that it can maintain a high speed in a sea state when conventional hull forms such as catamarans and monohulls have to slow down to displacement speeds and creep back to shelter.
