The world’s first large, powered trimaran, Triton, was launched on 6 May, 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 the feasibility of its basis as a future combat vessel design. The £13 million project offers great promise for future naval trimarans.
DERA issued invitations to tender for Triton in July 1997. 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 DNVs Rules for classification of High Speed Light Craft and Naval Surface Craft. Although DNV is accustomed to classifying new and novel ship designs, the size of a new trimaran such as Triton called for special consideration of design loads, sea-keeping behaviour and structural response.
Mathematical modelling
In addition to the normal plan approval process, the Triton project required additional input to the yard from DNVs Advisory Services in Oslo. A major contribution was the carrying out of mathematical simulations using DNVs hydrodynamic software SWAN. This computed 3-dimensional flow around the vessel, free surface elevation and pressure distribution on the hull. Classification and advisory services were co-ordinated through DNVs London offices.
The vessel has been constructed in steel to commercial standards and can be scaled-up to naval engineering standards. The side hulls are each 34.2 metres in length and the vessels overall beam is 22.5 metres. The diesel-electric propulsion system consists of two Paxman main generators supplying a 3.5MW electric motor driving a fixed-pitch propeller on a single centreline shaft. A 350kW electric motor drives a fixed thruster in each side hull.
Triton is capable of reaching 20 knots and has a range of 3000 nautical miles. Her prime task is to act as a research facility, and to this end the ship provides 47m2 of laboratory space. The trials instrumentation system has 560 channels and is being provided by the United States Department of Defense Naval Surface Warfare Center.
Rob Heather is Vosper Thornycrofts technical director for shipbuilding. He says, Close working relationships were critical if the very tight timescales were to be met and the project kept on budget. VT has been able to use new procedures such as large scale pre-construction outfitting to meet the contract requirements. This meant the use of megablock construction, the largest section weighing 200 tons. When launched Triton´s outfitting was 97% complete, the highest proportion so far achieved before launch.
Nine years of trials
The ship will be handed over to DERA on 31 August for the start of three sets of trials. The Phase 1 trials will last until March 2002 and are aimed at de-risking the hull form, confirming the general naval architectural performance, and recording structural loading data and seakeeping behaviour. Phase 2 provides the opportunity for Triton to be chartered for trials of emerging technology equipment, from masts to composite shafts. The final phase will commence after a mini refit in 2004, which will include enhancements to the trials capabilities of the ship.
Triton is a DERA-owned trials facility, and to justify the procurement of the ship a business case was prepared which showed that costs could be paid back over a nine-year period through its charter for trials to external clients.
DERAs applied research supports the future requirements of the U.K. Ministry of Defence. The results from the forthcoming trials will be critical in assessing a trimaran design for the Royal Navys Future Surface Combatant vessel. Indeed, Triton has been described as the most significant advance in warship hulls since the advent of the Ironclads. It is no surprise, therefore, that Bob Short, DERAs trimaran programme manager, says, We feel we are working with the navies of the world constantly looking over our shoulder.
Date: 2000-12-15