BMT Nigel Gee Ltd., a subsidiary of BMT Group Ltd., is collaborating with offshore wind farm support vessel operator Turbine Transfers of Holyhead, Anglesey, U.K., on the design of a 19 m WSV catamaran utilizing the Voith Linear Jet.
This will be the first application in a vessel of the Voith Linear Jet (VLJ), an innovative propulsor unit designed by Voith Turbo to provides considerable advantages to the operator over both conventional propellers and waterjets. Voith has undertaken extensive numerical modeling 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 VLJ provides increased bollard pull 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, as 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 optimize 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.
February 27, 2012