The 1, 350 dwt IMT972 SOV is powered by two Steerprop SP25 or equal 1900 kWe fixed pitch azimuth propulsion units. There is also an option for fitting two 2.5 MW Voith Turbo main thrusters. Frequency-controlled electric motor-driven CPP thruster units are fitted forward, comprising two tunnel-type bow thrusters and one retractable bow thruster for station-keeping and high-dynamic performance under manoeuvring or DP conditions.
The IMT972 has a LOA of 72.20 m and conforms to the Clean Design classification requirements of DNV for wind-farm service operation vessels. It can provide accommodation for up to 60 persons, including 22 crew, and is able to operate for 30 to 45 days on station, and longer if replenished at sea.
The main features of the IMT972 include a heave-compensated turbine platform, and an aluminium access gangway arranged with a telescopic frame which facilitates the transfer of equipment to the platform. A back-up evacuation process is arranged by using the workboat to transfer technicians from the turbine access ladder in an emergency. The vessel has a small pallet lift and conveyor lift system for the loading and transfer of stores and spares, with access to/from a heated under-deck workshop and stores area. A mono-hull workboat is fitted with a heave-compensated single point lift davit for general wind turbine work duties as well as for emergency evacuation of technicians.
There are two boat-landing areas, one starboard and one at the stern of the vessel. There is a large deck area arranged for additional equipment or the retrofitting of an ROV system for turbine tower or seabed inspection.
The IMT972 has an electro-hydraulic 1.0 tonne SWL motion-compensated folding jib crane fitted on a pedestal on the main deck aft of the access gangway tower. It accesses the wind tower platform when the gangway is stowed and can also work over the stern, deck area or ship’s side.
The air-conditioned crew facilities include a mess room and recreation room. All accommodation will be fitted with an electronic identity access system, similar to the system used on passenger ships, to help locate personnel at any time.
In addition to its role as a wind farm maintenance SOV, the IMT972 can be used as a standby rescue vessel, command/control vessel, survey vessel and ROV support vessel.
Michiel Wijsmuller, managing director of OSD, says, “These new designs are based on the outcome of four years of extensive discussions with wind-farm developers, operators and maintenance companies. They fulfil the operational demands of the wind-farm maintenance industry and can also provide logistics support services to transformer platforms.”
*Offshore Ship Designers Group (OSD) is a global one-stop resource delivering naval architecture and marine engineering skills to the shipping and offshore energy industries. It draws on an experienced global workforce to provide high quality feasibility studies, conceptual and detailed designs for tugs and offshore support vessels of all types. OSD is based in IJmuiden, The Netherlands, and has offices in Dundee, York, Appledore, Shanghai and Singapore. www.offshoreshipdesigners.com