Feature 3 | ADVANCED HULLFORMS
Wave piercing monohull has a host of potential applications
NaviForm Consulting & Research Ltd in Vancouver, Canada has been developing a wave piercing monohull for a number of years, and believes that it has a number of potential applications in the naval, offshore vessel and commercial sectors
and military vessel design. Numerous attempts were – and are being – made to achieve that goal. Methods range from introducing very long and narrow bows, to an array of articulated trim, roll and pitch controlling devices, many of them computer controlled. All add capital and operating costs, and have a varying degree of success in reducing motions. In contrast, NaviForm believes that the
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SHARC Wave Piercing Monohull (SWPM) it has developed eliminates much of this added cost. It has no moving parts, and allows the hull to stay within standard proportions without resorting to long narrow hulls. Many current methods either ‘avoid’ interaction with waves (long narrow and tall bows) or attempt to counteract it (articulated fins or transom tabs), whereas the SWPM concept relies on interaction with waves. It has been extensively tested and compared to various hullforms, including model tests and full-scale vessel trials to ensure future applications present minimal risk.
Offshore sector Te SHARC SWPM was initially developed for commercial applications and has been subjected to more than 10 years of research involving computational fluid dynamics (CFD) and physical model testing. It was commercialised in the offshore drilling support field with three hulls presently in operation. The SWPM bow form is distinguished by using horizontal surfaces visually akin to fixed canard wings, which stabilise the hull in waves at the full range of speed. The impetus for the development of the hullform came in 1998 when a major
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educing hull motions in waves at speed has long been recognised as an important goal in commercial
NaviForm 66m standard military platform – wedge concept (2000)
oil company solicited proposals for an alternative mode of transporting crews to their drilling facilities in the Gulf of Mexico. The practice is to transport drilling rig crews by fast crewboats, in the 25+ knot speed range and carry up to 200 crew and small quantities of cargo. Tese Fast Supply Intervention Vessels (FSIVs) operating in the Gulf of Mexico are limited by weather conditions corresponding to Sea State 4 enforced by US Coast Guard. Above this operators have to utilise helicopters, at a cost significantly higher than FSIVs. Another economic consideration is the speed of FSIV and the corresponding transit time. As rigs move further offshore, crews spend more time onboard crew boats increasing cost in labour and fuel. The performance parameters in
the request for proposal were 50knots maximum speed in calm weather, 30knots in Sea State 4, and ability to operate below the 2 hour seasickness threshold in Sea
State 6, in waves of significant height of 6m. Operators sought proposals from designers of high-speed craft to meet this requirement. Four proposals of multihull designs, including well known wave piercing types, and one monohull were received. The monohull was the wave-piercing design from NaviForm based on the concept developed earlier for a major builder of US naval vessels, which focused primarily on a new type of propulsion plant utilising a combination of propellers and water jets, but also explored the ability to pierce through waves to avoid pitching motions that result in emergence of propellers and loss of speed – the original objective of that project. As Dave Longdale, Director, Business
Development at NaviForm and Peter van Diepen, President of the company explained in a paper originally presented at the INEC 2014 conference, after an exhaustive analysis of the proposals, it emerged that the wave piercing monohull
Warship Technology October 2014
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