Six Rolls-Royce waterjets propel jumbo catamaran ferry

15 February 2006

Virtu Ferries

The 68m catamaran Maria Dolores will shortly go into service with Malta-based Virtu Ferries on the company’s established Malta – Italy route, propelled by no fewer than six Kamewa waterjets, three in each hull.

A speed of about 36 knots with the engines running at 90 per cent of full load will link Valetta with Catania in three hours, with Pozallo in 90 minutes and provide a service to the Italian mainland at Reggio Calabria in four hours.

Maria Dolores was designed and built to a high standard by Austal in Western Australia to suit the owner’s requirement for a fast ferry capable of carrying trailers, coaches and other high vehicles together with cars and 600 passengers. The ferry will provide a scheduled freight service for Maltese industry while catering for an increasing tourist traffic. As well as having a 4.6m clear height in the vehicle deck, Maria Dolores also has a large water clearance height in the tunnel. In combination with T-foil and interceptor ride control, this will give the ferry the ability to operate its Mediterranean routes year-round.

Virtu Ferries wished to maintain engine compatibility with its existing fleet, and it was not easy to supply the power requirement with a conventional quadruple engine layout. A six jet solution has therefore been developed, with three engines in each hull, all connected to individual waterjets through reduction gears. This is thought to be the first sextuple waterjet installation in a fast ferry. Power per unit is 2,465kW and the waterjets chosen are the Kamewa 80 S II series from Rolls-Royce. To find space for three waterjets in the transom of a slim catamaran hull involved some interesting engineering of the intakes and drivelines. Two steerable and reversible water jets are installed side by side in each hull and a booster jet without steering is placed above and between the steerable units. The lower jets are driven by two engines in the forward engineroom, while the upper booster jet is coupled to an engine in the aft engine room which is raised to to give the correct driveline height.

The system provides operating flexibility and propulsion redundancy, as well as a high propulsive efficiency under different operating conditions. The four lower jets provide excellent manoeuvrability and mean that several economic speeds are available for off-peak operations, while the booster jets can be brought in to provide the power for the full loaded service speed.

Both Austal and Virtu Ferries are established users and specifiers of waterjets from Rolls-Royce. A recent Austal delivery was the innovative large trimaran fast ferry Benchijigua Express, now in service in the Canary Islands, which is fitted with three Kamewa waterjets in the centre hull – two steerable/reversible 125 SII units and a 180 BII booster jet giving the 126m long vessel a speed of 40 knots. Virtu Ferries operates the 51m catamaran ferry San Gwann on its Malta – Sicily service. This 39 knot fast ferry is equipped with four Kamewa 71 SII waterjets each handling 2,320kW.