The world’s first large, powered trimaran, Triton, was recently launched provoking much interest from the leading naval powers. The 1200 grt research vessel has been commissioned by the United Kingdom’s Defence Research and Evaluation Agency (DERA) as a two-thirds scale frigate prototype to investigate this can be a possible future combat vessel design. The £13 million project offers great promise for future naval trimarans.

Analysis by DERA established that the trimaran’s slender hull form would give a 20 % reduction in resistance compared with an equivalent monohull, and that this would permit a reduced machinery fit leading to lower lifetime costs. The side hulls would offer better stability, and the ability to mount above-water sensors high up providing earlier detection of incoming missiles; the configuration also offered 40 % more deck area for weapon fits and helicopters.

United Kingdom naval shipbuilder Vosper Thornycroft (VT) was chosen to design and build the 100 m long demonstrator. VT in turn selected Det Norske Veritas to provide classification services because of the experience DNV had already amassed with its classification of high-speed craft, and the introduction of DNV’s Rules for classification of High Speed, Light Craft and Naval Surface Craft. The size of a new trimaran such as Triton called for special consideration of design loads, sea-keeping behaviour and structural response.

RV Triton will be handed over in August this year to embark on a rigorous 18-month programme of sea trials that is already attracting the interest of navies around the world, most notably the United States. Indeed, the US Department of Defense has signed a Memorandum of Agreement with the UK and is investing in the project. The Naval Sea Systems Command (NAVSEA) in the US will be involved in the initial sea trials.

The 98m. long vessel is the world's biggest sea-going trimaran and, in the UK, will be evaluated with a view to becoming a potential design basis for the Future Surface Combatant, the successor to the Royal Navy's Type 22 and Type 23 frigates.

The perceived ability of the trimaran to maintain higher speeds in sea states that would normally require monohulls to reduce speed or to alter course to reduce damage will be one area where the spotlight will focus quite heavily during the trials programme.

Building such an innovative hull form has led to a new approach to safety issues with several features, ranging from ship evacuation to pilot embarkation requiring a completely new approach. Throughout the project, VT has worked closely with the UK Maritime and Coastguard Agency and the classification society Det Norske Veritas. This has been particularly significant with future Royal Navy warships set to be built to the construction rules of commercial classification societies.

VT is also using the hull form as a platform for its latest platform management systems, supplied by Vosper Thornycroft Controls. VTC will supply the package of diesel electric propulsion and associated platform management system, taking total responsibility for the system.

Building such an innovative hull form has led to a new approach to safety issues with several features, ranging from ship evacuation to pilot embarkation requiring a completely new approach. Throughout the project, VT has worked closely with the UK Maritime and Coastguard Agency and the classification society Det Norske Veritas. This has been particularly significant with future Royal Navy warships set to be built to the construction rules of commercial classification societies.

Accuracy of the cut was also critical in the challenge to align the three lender hulls, both in perpendicular and longitudinal positions. Tolerances are critical in areas such as the knuckle between the hulls where stresses will be extremely high. In addition, the trimaran has given VT the chance to develop new construction techniques which can be applied to all future projects. Most notable has been the use of mega-blocks weighing up to 200 tonnes each. Five of these blocks, the biggest to be used in shipbuilding at VT, were included in the trimaran and experience in this methodology will be invaluable for future projects such as the Royal Navy's Type 45 destroyer. Pre-outfitted cabin modules for up to 24 personnel who will crew the trimaran have been another timesaving area, which has enabled VT to complete the build in some 16 months since the first steel was cut.

More Information:Vosper Thornycroft