Are fibre reinforced polymers the holy grail of fast vessel construction?
“If the game is high speed, then the smaller the boat, the more difficult it is to keep it light,” states Jaap Gelling, Damen’s Product Director of High Speed Craft. “As the design gets smaller and smaller – 15 metres for example – steel is unsuitable because for practical reasons it is not possible to keep the ship light. The shell plating simply needs a minimum thickness, to weld for example, making the ship heavier than would be necessary for strength only.”
One option is to build with aluminium. “You can build fine vessels with aluminium. It has the strength and the stiffness,” he explains. “But for really high speed there is only one enemy and that is weight. So the construction material should be light. However if you want to build even lighter, then aluminium is just not the right material any more. For example, building a vessel as fast as the Damen Interceptor 1102 is simply not possible with aluminium.”
Furthermore, it is a very sensitive material: corrosion of all kinds are a hazard for an aluminium boat in sea water.
“If you leave your steel tools in the bottom of an aluminium boat, and if there is sea water around, then the steel will start eating away at the hull of your boat.”
Lighter = Faster
he solution to the weight issue is to build with composite materials. “Composites are fibre reinforced polymers – combinations of glass fibres, resins and foams. With this material you can build a boat that is stronger and lighter than its aluminium counterpart. And composite materials do not corrode.”
The critical point, however, is the lightness. In the realm of the high speed craft, where weight-to-strength ratios are sacred, composite vessels are simply faster. “It’s all about the speed. Look at the Interceptor 1102. It can do more than 55 knots.”
One idea, three vessels
For other vessel designs other factors play a role: “Then it’s more about making the vessel stronger and less sensitive for maintenance. We also build lifeboats, small Fast Crew Suppliers, Pilot and Patrol vessels from composites.” The last three designs show the adaptability of composite materials. “These vessels have the same hull, same engine and same water-jet, but they differ significantly in terms of superstructure and engine ratings,” continues Mr Gelling.
“A Fast Crew Supplier needs 100% engine capacity for most of the time, while a Patrol Vessel sails at less than of half engine capacity more than 80% of the time.”
Not your typical shipyard
When building for speed, different shipbuilding materials are suited for different vessel dimensions. “With composites, the bigger you build, the less weight advantage you have. If you go above 25 metres then aluminium is the logical choice. And above 40 metres, steel is the best.”
A world away from the more traditional steel-centric shipyards, composite vessel production procedures are more similar to a laboratory than a shipyard, concludes Mr Gelling. “The chemical process determines the quality of construction so with our own yard and our people we have control over quality and procedures.”
A word from the workshop
Talking from Damen’s specialist composite vessel construction yard in Antalya, Turkey, Business Development Manager Composites Marko Pas tells more about operations there. “We build an average of 35 vessels per year. These include Interceptors, the smaller Stan Pilots, Stan Patrols, Fast Crew Suppliers and the 24-metre Water Bus. Starting with conceptual designs and engineering, Damen’s serial production mentality is present throughout.”
The Antalya yard also works towards optimising composite structures and developing production techniques with its own engineering team.
“To emphasise the benefits of composite materials, we have implemented a resin infusion process for the majority of our composite production,” says Mr Pas. “This results in less weight and consistent soundness of the finished product.” And, when the name of the game is speed, it is this consistent high quality that wins time and time again.
A KEY ADVANTAGE OF COMPOSITE MATERIALS IS THAT THEY DO NOT CORRODE