Maria Dolores was designed and built by Austal in Western Australia to suit the owner's requirements 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 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, creating a challenge to supply the power requirement with a conventional quadruple engine layout. A six jet solution was therefore 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 waterjets 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 engine room while the upper booster jet is coupled to an engine in the aft engine room, which is raised to give the correct driveline height.

The system provides operational flexibility and propulsion redundancy as well as 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 fully loaded service speed.

MJ Information No: 21745