BMT Nigel Gee Ltd, a subsidiary of BMT Group Ltd, has announced further collaboration with Turbine Transfers, one of the leading providers of Windfarm Support Vessels (WSVs), on its latest unique development – the design of a 19m WSV utilising the Voith Linear Jet.
The Voith Linear Jet (VLJ) is an innovative propulsor unit developed by Voith that provides considerable advantages to the operator over both conventional propellers and waterjets. Voith has undertaken extensive numerical modelling and model testing of the propulsor but this will be the first application in a vessel. The VLJ is an advanced ducted propeller with a stator positioned in the duct aft of the propeller, in a similar arrangement to that of a waterjet. For the same installed power the VLJ is expected to provide a bollard pull approximately 50% higher than that of a waterjet and in excess of 30% higher than conventional propellers.
Bollard pull is important for the WSV operator in docking operations as a higher bollard pull could allow for personnel transfers in higher sea states. The advantage of the VLJ is that the increased bollard pull is provided without a requirement for increased installed power. Most importantly, since the VLJ has a torque curve similar to that of a waterjet, the torque limits of the engine do not impact the available bollard pull which can be the case with fixed pitch propellers. Model tests have shown that at speed the VLJ is capable of delivering efficiencies at least equal to, if not higher than, those achieved with fixed pitch propellers.
Voith is now undertaking extensive model tests in conjunction with BMT to optimise the VLJ design and to validate performance. The production of the first VLJ900 units is underway and construction of the vessel will start shortly at Holyhead Marine, for completion early next year.
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Offshore WIND staff, February 27, 2012; Image: BMT Nigel Gee