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When composites are mentioned, Norway does not instantly spring to mind – yet it is the home of the highly innovative Devold AMT company. Founded in 1853 and originally a producer of textiles, the company spun off Devold AMT as a manufacturer of composite reinforcements as early as 1992. Since then, the company has developed into wind energy and marine and aerospace reinforcements.
(Published on December 2005 – JEC Magazine #21)
In 1988, the Norwegian navy was seeking to replace its old minesweepers which had been built of wood as long ago as the Second World War. The concept was to build vessels that would be both light and strong, and would stand up to the rigours of an often severe maritime environment. This, in turn, led to the selection of multi-axial fibre reinforcements, which would have all the necessary strength and weight requirements.
From these early, tentative steps, Devolt AMT has now moved on to produce, with its close partner, Brødrene Aa, boats constructed entirely from carbon fibre and vinylester-sandwich composite.
Today, the owners and operators of ships are on the look-out for both reduced risk and a return on their investment.
These concerns were uppermost in Devolt AMT and Brødrene’s minds when their joint project began to take shape. In the final analysis, the owner/operator of such a carbon-fibre passenger boat would have a higher investment to make than in conventional craft, but he would profit from a longer service life and reduced operating costs – factors of vital importance to any commercial operator.
The project started in 2001 and the first prototype was produced just one year later, in June 2002. The two companies had worked together for a long time and so it was natural that Devold AMT support Brødrene with their experience of carbon fibre while Brødrene targeted their customers with an improved vessel that would be highly economical, while offering a longer life and greater corrosionresistance than a vessel in aluminium, for instance.
The considerable weight savings involved would in turn lead to fuel savings of around 40%, thanks to the boats’ greater manoeuvrability.
“As a matter of fact, we started using composites as far back as 1972, so we do have considerable experience in that field, having built nosecones for Norwegian trainfronts and protection structures for subsea oil installations, amongst others.
In the nautical field, alongside a considerable number of other craft, we have the distinctinction of having built the world’s fastest megayacht, “Moonraker”, delivered in 1990.
Our 30-odd years of experience in composites and our specialisation in the field of shipping were, I think, the main reasons why Devold AMT sought us out as their chosen partners for their project. For us, they in their turn represented an ideal partner in view of the great quality of their products and also their know-how. And from a purely practical point of view, they are located quite close to our premises – only three hours by car – which made matters so much easier for both parties.”
“Brødrene Aa and Devold AMT have worked together for a long time and it was natural for us to support them with our experience in carbon fibre when they came to a new improved vessel design that would economically replace earlier vessels which they had supplied.
The filament diameter of carbon fibre being significantly lower than that of fibreglass, the infusion process was more complex, but with the relevant permeability data, we were able to choose the right fabric for the process.
The joint project has been a great success and today four operators in Norway have carbon fibre vessels in their fleets. It is only a matter of time before the advantages of such vessels are recognised internationally.”
Three types of boat have so far been developed. The Rygerdoktoren is an ambulance boat capable of a speed of 44 knots, for the same fuel consumption as its predecessor at 28 knots. The Rygerkatt harbour shuttle ferry has a total capacity of 64 passengers and benefits from its reduced weight in terms of both acceleration and deceleration. The third member of the family, the Rygerfjord, is a conventional passenger catamaran, built to carry 97 passengers. With a crusing speed of 35 knots, it has the lowest fuel consumption of all Norwegian fast ferries. The boats are all between 18.5 and 20.5 metres in length.
The carbon fibre and vinylester sandwich has brought significant advantages to operators and customers alike.
On the ambulance boat, for instance, the stiffness of the hull makes for greater comfort and even with its higher speed, fuel consumption is lower than on a comparable, conventional craft.
The shuttle ferry docks and undocks over 200 times a day and here the composite contributes to easier handling, and thus to rapid turnarounds and consequently to fuel savings. The ferry also offers greater comfort with less noise and fewer vibrations.
The reasoning behind the approach adopted both by Devold AMT and Brødrene was as follows:
the carbon-fibre and vinylester sandwich would entail considerable weight savings, ensure reduced fuel consumption and guarantee environmental protection.
The lighter structure of all three boats (in other words a 40% reduction in mass compared with a fibreglass reinforcement, for instance) would require a smaller engine;
this would mean lighter shafts, propellors, … and smaller fuel tanks, which in turn would lead to savings in fuel.
For Brødrene, all this represents a major breakthrough in the use of carbon fabrics in commercial applications.
The company is highly experienced in the construction of high-speed boats, such as luxury yachts and much of their experience has been channelled into these new craft. The designing has been able to attain greater efficiency through the use of materials hitherto used exclusively on luxury sailing boats, racing craft and military vessels.
The joint project has turned out to be a great success for both partners. The market breakthrough came in the autumn of last year, with a first order for three shuttle boats to be delivered in 2005. Now, no fewer than eight boats have been delivered to different operators and several more are under construction, with a 300-passenger boat also under development at the moment.
For the time being, this new generation of carbon-fibre commercial vessels is operating only along the Norwegian coast and in the fjords, but, say the makers, it is only a matter of time until orders are placed from farther afield.
The boats’ versatility and notable performances were duly recognised at this year’s JEC Composites Show where the partnership ran out winners in the “Marine” category, against extremely stiff competition.