VESSEL REVIEW | CRC Walrus – Amphibious crewboat to support UK offshore wind operations

UK boatbuilder Diverse Marine recently delivered a new windfarm crewboat with amphibious capability to safely transfer technicians and cargo to offshore wind turbines in shallow and drying areas.

CRC Walrus will be operated by Commercial RIB Charter (CRC) at the Scroby Sands wind farm in the UK North Sea under a charter contract with German energy company RWE. The vessel was designed in cooperation with naval architecture firm Chartwell Marine to combine the safety and comfort of a standard crewboat with the capabilities of amphibious open rigid inflatable boats (RIBs) currently available.

The 12- by four-metre crewboat features many of the elements typically found in CRC's fleet of catamarans and cabin RIBs such as MCA Category II coding, push-on bow fendering, suspension seating, chart plotters, radar, galley facilities including a microwave and a refrigerator, a toilet, and full safety equipment such as an MOB recovery davit and a fall arrest system.

The foredeck is fitted with several stowage and mounting points for cargo along with inspection hatches for the amphibious gear, enabling maintenance to be carried out whilst afloat if required. A three-metre extendable gangway is fitted on the bow as a means for technicians to safely bridge the scour pools typically found around offshore installations, providing handrails and wide access.

CRC Walrus boasts a wide and spacious saloon for two crewmembers and 10 passengers with the additional benefit of still being a road transportable vessel thanks to its narrow beam. The vessel can be mobilised quickly anywhere in Europe, and up to 1,000 kilograms of assorted cargo can also be carried.

The vessel features a bespoke hydraulics system run by an air-cooled Kubota 37kW hydraulic power unit that provides all-wheel drive to three wheels through a joystick control system mounted on the dashboard. Running all-terrain tyres on rims, the vessel can smoothly travel at speeds of over three knots on land across surfaces including compact sand, light shingle, and dry mud. Installation of the controls for the amphibious hydraulic drive was done by N-Tech Engineering Solutions.

CRC Walrus can transition smoothly from displacement to amphibious mode within minutes. An air-cooled HPU and 240V generator ensures there is no loss of comfort or equipment when out of the water. This also guarantees that operating time on land is in excess of the 30 minutes typically found with smaller amphibious open RIBs. When in the water, the vessel has a draught of only 0.8 metre.

The twin OXE 223kW diesel outboards operate in conjunction with a bow thruster to provide excellent close-quarters manoeuvrability. A high freeboard and large foredeck ensures improved seakeeping when cruising speeds of up to 20 knots and transferring personnel in wave heights of 1.5 metres. The vessel can also reach a maximum speed of 24 knots.

The passengers and the crew are seated on Grammer seats in the cabin.

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