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May 10, 2010

Next generation Austal trimaran nears completion

Austal's next generation 102 m high speed trimaran ferry is nearing completion. Based on the shipbuilder's second-generation trimaran hull form, it incorporates lessons learnt from the 2005 trimaran Benchijigua Express and the recently delivered Littoral Combat Ship USS Independence. Austal says it delivers "innovation without risk."

Austal Technical Manager James Bennett said that an outstanding features of Benchijigua Express has been her ability to deliver passengers to their destination in comfort no matter the weather conditions."

"We wanted the second generation trimaran to not only take passenger comfort to new levels but also to optimize performance, sea keeping, fuel efficiency and payload," he said.

Austal conducted a complete review of Benchijigua Express to establish where improvements could be made. This was followed by a detailed market study on the commercial ferry industry looking at the size and capacity of existing fleets.

Based on the data collected from this study, it was determined that 102 m, 1,165 passengers and 254 cars were the approximate specifications most applicable to the existing market.

As the vessel was being built on speculation, the design of the interior and the vehicle deck is at a level that will permits the eventual owner to easily modify the vessel to suit its particular market.

The final design achieved a number of key improvements:

Refined waterlines to improve sea keeping, passenger comfort and reduce resistance

A new and simplified ride control arrangement and operating system to deliver improved control over the vessel's motions and handling characteristics

Simplified, three engine power train

New series water jets with improved cavitation margins

The unique trimaran hull form combines the softer roll of monohulls with the low resistance, stability and carrying capacity of catamarans to deliver proven advantages over conventional designs. These, says Austal, include greater speed for the same installed power, an ability to operate in higher wave heights and maintain higher speeds in waves, greater resistance to damage and reduced wake which reduces impact on the environment.

The trimaran's lower roll speed means lower accelerations experienced by passengers, significantly reducing passenger sea sickness. Studies show that motion sickness on the trimaran will be approximately 56 per cent lower than on a 100 m catamaran operating in head seas. Even larger benefits are realized in other headings.

For operators, this means higher passenger satisfaction, greater customer loyalty and positive word of mouth marketing.

It also means higher revenue from onboard sales resulting from the ease of movement onboard and reduced sickness. Improved revenue potential from the trimaran's ability to sail in a larger range of sea conditions (fewer cancellations) is another significant advantage.

Increased comfort also provides operators with a competitive marketing advantage compared with other high speed craft.

The most immediately noticeable change to its predecessor is the existence of a straight-stem bow - designed to maximize the vessel's waterline length and deliver greater speed and efficiency.

Another significant improvement is the adoption of a three-engine propulsion train which combines with the trimaran's unique hydrodynamic hull form to deliver fuel efficiency across a range of operating conditions.

The three engine arrangement also means lower fuel consumption, less emissions and reduced maintenance compared to fast ferries of a similar that have four engines.

A speed of 39 knots (at 90% MCR) with 340 tonnes deadweight was achieved during sea trials, as well as a maximum speed of 45 knots, and a 760 nautical mile range (at 90% MCR) with fuel consumption of only 4.90 tonnes per hour.

Powering the vessel are three MTU 20V 8000 Series diesel engines, while propulsion is provided by three new-series Wartsila LJX 1300 water jets, chosen for their improved cavitation margin. Each water jet is driven through a ZF 53800 reduction gearbox.

Austal's focus on maximizing redundancy is evident throughout the vessel's machinery spaces, with two separate main fuel and day tanks and each of the vessel's three engines located in separate engine rooms. The vessel's four MTU S60 generators are split between the engine room and the starboard side of the main deck, again for redundancy.

The vessel's double retractable bow thruster arrangement delivers improved maneuverability in harbor along with redundancy in the event that one is damaged.

A new and simplified ride control arrangement and operating system delivers improved control over the vessel's motions and handling characteristics in all sea conditions. Along with a central T-foil on the main hull forward, the new ride control system includes T-foil roll control fins on each of the vessel's amahs. All foils have been designed to permit removal and servicing without the need to drydock the vessel.

The vessel has four decks - a main vehicle deck, mezzanine vehicle deck, upper passenger deck and bridge deck.

The main vehicle deck has space for 245 cars, or 190 truck lane m plus 145 cars.

The mezzanine deck is a mixture of fixed and hoistable decks that allow the carriage of up to 132 cars with a clear deck height of 2 m. When hoisted there is a height on the main deck below of 4.3 m and 2.3 m when lowered, and hoisted in two different sections at the same time.

This flexibility gives operators the capacity to change the traffic mix on a sailing by sailing basis.

A bow thruster hatch on the forward mezzanine deck allows the equipment to be serviced while the vessel is afloat. At the aft end of the main deck, where a large hydraulically operated hatch opens when the vessel is not operating, permitting access to the waterjet compartment and machinery spaces. Bolted hatches over the main engine rooms allow for machinery component removal.

The aft end of the vessel is strengthened to accept a conventional ramp, an optional bi-folding ramp or a shore based link span ramp. Spray curtains are installed on the main vehicle deck aft to protect vehicles from exposure to light sea spray.

Vehicle turnaround occurs at the front of both the main vehicle deck and mezzanine levels ensuring fast loading and unloading. The vehicle deck is designed to carry dangerous goods.

Passenger access is via staircases located both port and starboard of the vehicle deck, with an elevator for disabled persons on the port side.

To isolate noise and vibration, the entire superstructure has been resiliently mounted below the passenger deck. This important design feature provides a quieter, more comfortable passenger environment and allows for the large panoramic windows evident throughout the upper deck.

All passenger seating is on the upper deck, which is separated into three lounges and can be customized to seat between 950 and 1,165 passengers. Onboard amenities are designed to maximize accessibility and include wheelchair-accessible toilets, lift and four independent passenger entry points.

A business class lounge on the forward upper deck has Beurteaux Ocean Club seats and a dedicated bar and offers panoramic views over the bow.

Passenger and crew safety are assured with the availability of four Liferaft Systems Australia MES systems using twin track slides for faster and safer side-by-side passenger evacuation to canopied 100-person inflatable rafts.

Superior Control and Monitoring

The bridge deck includes separate engineer's console with MarineLink equipment monitoring system and CCTV to all vehicle and engineering spaces.

A dedicated aft facing control console with duplicated engine, waterjet and bow thruster controls allows stern docking maneuvers to be conducted safely.

Quality Alutech seating provides added comfort for the Captain, who is positioned with a 360 degree panoramic view around the vessel. The bridge features an ergonomic design housing state-of-the-art navigational equipment including Kelvin Hughes X-band and S-band radars, chart plotter, eco-sounder, gyrocompass, auto-pilot and night vision.

A separate work desk and GMDSS Area A3-compliant radio console are also located on the bridge deck.


Length overall 102.0 m

Length (waterline) 101.4 m

Beam (molded) 27.4 m

Hull depth (molded) 7.6 m

Hull draft (maximum) 4.5 m


Passengers 1,165 in 3 lounges

Cars 254 (4.5 x 2.35 m)

Truck lane meters 188 plus 145 cars

Hoistable mezzanine ramps

Stern ramp (optional)

Maximum deadweight 680 t


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