Using two similar vessels, , a 21m support catamaran designed by BMT Nigel Gee named Treadurr Bay fixed with a Linear Jet system and a comparable South Boat’s catamaran fixed with traditional water jets, both vessels completed hundreds of crew journeys between Grimsby and a wind farm in order to gather data for a turbine transfer test.
After the successful completion of the journeys over four months, the efficiency of both vessels was calculated. Having clocked 629 hours at sea, Voith’s turbo marine manager Mark Harvey, confirmed that the vessel containing the VLJ system had used “dramatically” less fuel than the competing South Boat’s catamaran at 29 knots.
Anthony Robson, the turbine transfer’s captain was heard to say, “At 26 knots the South Boats’ CAT uses 460 litres of fuel an hour and here we are [VLJ] at the same speed with 320 litres an hour. It’s remarkable – that’s almost paid for the fuel for every fourth vessel.”
“The resourcefulness of the VLJ was also proven through a simulation using a coastguard cutter. The vessel completed a 1000 nautical mile mission in 52 hours 40 minutes,” continued Harvey. “The VLJ used 8.84 tonnes less fuel – 28.03 tonnes compared to 36.87 tonnes. That means that with fuel at around $500 a tonne the VLJ saves $4500 in a two day mission.”
In addition to the fuel savings, when using Treadurr, the VLJ also produced more thrust with less noise and vibration. However, this system has not just been designed to suit the smaller yacht/boat markets; vessels in the superyacht categories could stand to save a pretty penny.
Harvey explains, “The VLJ’s high efficiency figure compares favourably with screw propellers. At low speeds a good screw propeller will match the VLJ, but above 20 knots the VLJ starts to out-perform propellers in terms of efficiency”. This being the case, it is not a strong investment for superyachts with low cruising speeds, but for open sport vessels savings will be significant. However, what is most favourable for the superyacht market is the semi-integrated nature of the system. The semi-integration significantly shallows the vessels draft – ideal for areas such as Bermuda where shallow drafts are necessary to access the most desirable areas.
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