“Benchijigua Express” is larger than any existing diesel-powered fast ferry and is the world’s largest all-aluminium commercial trimaran. The characteristics of this new vessel, with a length of 126.7 metres and beam of 30.4 metres, will improve overall efficiency in terms of passenger capacity, deadweight and freight lane metres by more than 35%. At the same time passenger comfort is expected to increase by 25% to 40%, according to the owner Fred Olsen S.A. This new trimaran, built by Austal, signals significant improvement in the fast sea transportation and opens up new markets beyond the ability of existing fast ferry design for both commercial and military operators.
During sea trials with operating ride control the vessel achieved a speed of 40.4 knots whilst carrying deadweight of 500 tonnes. Four MTU 20V 8000 diesel engines, each rated to 8,200kW, are arranged in two separate engine rooms in the trimaran’s central hull. Each of the two aft engines drives Kamewa 125 SII steerable waterjet from Rolls-Royce while the two forward engines deliver their combined power to a Kamewa 180 BII booster waterjet. All drivelines have Renk transmissions, with lightweight composite shafts fitted between the water jets and gearboxes and on the output shaft of the forward engines. The exhausts for the outboard aft engines are dry type exiting the vessel at the bridge deck through a funnel casing. The inboard engines have a wet exhaust system exiting between the hulls.
Vessel motions are controlled by the movement of three sets of control surfaces fitted to the centre hull. The system consists of a single T-foil forward, two anti-roll fin stabilisers at about two-thirds of the length aft and finally two interceptors at the transom. The vessel has a transverse metacentric height similar to a monohull ferry and therefore is fitted with a ballast and heel control system consisting of two ballast tanks and two heel control tanks. Both sets of tanks are designed to be filled as the vessel slows down on entering port. The tanks can be filled in about 5 minutes. The ballast tanks have been designed to cause parallel sinkage to lower the vessel into the water increasing the waterplane area and therefore the transverse stability. With the tanks filled upon arrival the control system senses any change in heel angle during loading and unloading and rapidly transfers ballast to maintain a level deck. When the vessel is loaded with vehicles and passengers the ballast and heel control tanks are pumped out.
The hull and superstructure are not protected by paint but by a self-adhesive film. Orca Marine’s Offshore Film is a pure vinyl product. The film has expected lifespan of 10-12 years of service, which compares to conventional paint coatings lifespan of 3-5 years under comparable conditions. The use of protective film on areas above the waterline is expected to deliver substantial economic benefits thanks to a significant reduction in work and time involved in application and reduction in routine maintenance costs by up to 50%.