Feature 4 | ALTERNATIVE PROPULSION
Operators back pragmatism in new powering solutions
The soaring cost of bunker fuel and closer attention to vessel design efficiency, coupled with ever-growing environmental controls and expectations, have excited increased investment and the development of alternatives to conventional diesel mechanical propulsion, writes David Tinsley.
T
he manifold benefits of electric propulsion and functionally integrated shipboard electrical
power and management systems are finding wider favour, particularly in application to ships engaged in services or trades necessitating frequent and rapid changes in power requirement and/or high levels of redundancy. Advances in diesel-electric engineering
are complemented by the development and uptake of hybrid powering solutions, combining electric propulsion with mechanical drives, offering improved vessel through-life efficiency and other benefits. Gas-electric plant is also making inroads into certain sectors, driven largely by environmental criteria. Fuel cell technology in relation to
marine applications is being taken to the product stage by some of the industry’s leading organisations, and is the subject of new collaborative research endeavours, while sail-assist power, albeit in today’s technically-sophisticated forms incorporating advanced control electronics, is generating new interest through various European initiatives.
Diesel-electric solutions Operational benefits and ship design advantages conferred by
Whale-watching vessel Elding (credit: Icelandic New Energy).
and more sophisticated types of offshore support vessel, Houston-based Rigdon Marine Corporation has played a signal role in advancing the concept in application to the smaller classes of ship and to the industry in the USA. The GPA 640-series, conceived by
electric
propulsion have seen an accelerated uptake in commercial marine applications over recent years, spreading across a broader front to encompass payload-carrying types such as small tankers, ferries and offshore support ships as well as special- purpose vessels. While diesel-electric systems have
become the powering mode of choice among operators of many of the larger
38
Rigdon and brought to the design realisation stage by Guido Perla Associates of Seattle, put down a new marker for the medium-sized vessel category with its diesel-electric drive and electrically-driven class 2 dynamic positioning (DP2) system. In an intensely competitive market, the 640 generation of 210ft supply vessels achieved a substantial gain in carrying capacity through the more
flexible
machinery layout permitted by an electric solution compared with a conventional
mechanical drive train. Although smaller than the preceding
GPA 640 type, the follow-on GPA 654 class applies the diesel-electric propulsion concept and design rationale that underpinned the earlier project. Rigdon and Guido Perla sought
to
ensure the competitiveness of the design in supporting drilling both on the continental shelf and in deep water far offshore. The initial 10 platform supply vessels (PSVs) of the GPA 654 series were ordered from Bollinger’s Lockport yard, with deliveries commencing in 2007, and provided the basis for the subsequent GPA 654M PSV and also the GPA 254L anchor-handler. Within main dimensions of 190ft x 46ft (57.9m x 14m), the 1850dwt GPA 654 is claimed
Ship & Boat International November/December 2008
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