LORC tests and demonstrates technology for harvesting renewable energy offshore
Meeting industry’s needs for environmental testing of large components for offshore use is now one step closer with the ordering of a climatic chamber for a new LORC test centre.
Read more about the environmental testing of structures here
Length of hull: 25 / 30 / 35 m
Beam in waterline: 12 m
Draught (transit/service): 1.7/ 2.8 m
Deck cargo capacity: 10 / 20 / 30 tonnes
Propulsion: Two controllable pitch propellers
Transit speed: 25+ knots
Service speed: up to 15 knots
By Tea Tramontana
With a long and slender hull, the Norwegian WindServer will cut its way through the waves, making for a graceful and fuel-efficient vessel. What makes this trimaran special is its robustness, says the boat’s lead designer.
“It will have no moving parts underwater”, says naval architect Olav Kjetil Opheim, the man behind the WindServer from the Norwegian shipyard Fjellstrand on the shore of Hardangar Fjord. When asked to elaborate, he points out that this reduces the complexity of the system in comparison with active and computerized motiondamping systems, which add to the cost of both investment and maintenance.
Since it was awarded funding by the Carbon Trust competition on access systems in October 2011, Fjellstrand has been able to undertake advanced hydrodynamic analyses and computer simulations in order to optimize the hull concept in the range of 25 to 35 meters, the plan being to offer three different models – in lengths of 25, 30, and 35 meters.
“The hull has been modified”, reveals the chief architect, emphasizing the modification of the freeboard and roll damping plates on each side hull. “These plates reduce the roll and pitch motions of the vessel”.
Another big challenge is the stability of the vessel when stopped for transfer of personnel from the vessel to the turbine. Here, the combination of the slender hull, its large integrated hydrofoils, and the ballast tanks is central to providing stability and ensuring that the WindServer – though built in aluminium – behaves like a larger and heavier vessel. Compared with a “conventional” catamaran, preliminary model tests and computer simulations show that the motion reduction is substantial both when operated at high speed and when stopped.
Fjellstrand is building a prototype in scale 1:10 and is now moving the tests from computers and university labs to tanks. Turbine approach tests and resistance tests in large waves will be part of the schedule.
“The computer tests conducted so far indicate that WindServer can operate in waves of 3 meters significant height with a significant reduction in motion level relative to a comparable catamaran. In short, tests show that the vessel is designed to cope with rough weather conditions. But you must never forget that the motion of a vessel is also very much linked to the captain’s manoeuvring ability”, says Olav Kjetil Opheim.
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