A 7 meter speed boat consumes 15 times more fuel than a family car. Therefore, all current electrical boats have a very short range. The engineers at Candela Speed Boat AB have set out to change this. To achieve an electric boat with a range and speed on par with a traditional boat, the energy consumption must be cut back with 75%. This is achieved by reducing the weight with 50% and by lifting the entire boat hull clear of the water using hydrofoils -wings under the water surface. With hydrofoils, the weight reduction becomes harder than in a traditional boat. From a structural engineering perspective, Candela is more like a helicopter than a boat. “All the load is centred at the two struts holding the main wing”, says Olivier Philippot, Lead Mechanical Engineer at Candela.
With plenty of computer power alongside SAERTEX's deep knowledge of carbon fibre fabrics, the team designed what may be the lightest boat with a length of 7.5 meters ever built. Without batteries or a drive train, the boat weighs only 350kg and is able to manage 5 G-loads at more than 30 knots in 1 meter waves.
The engineers at the SAERTEX plant in Stade have been working on customized composite solutions for its customers since 2002. Finished components are manufactured in Stade–from development and prototyping right through to production.
SAERTEX was involved from the start of development of the Candela Speedboat. Candela engineers and SAERTEX materials experts worked together in selecting the most suitable materials. Besides mechanical qualities and weight, the total cost and suitability of the materials for subsequent production had to be considered. An individual solution was found for each single component. Finally, one uni-directional and three different multiaxial carbon fabrics were selected, along with SAERfoam® as core material - all at a weight of approx. 1000g/m² .
The component experts from Stade developed a vacuum infusion-capable prototyping process for the hull and deck. During numerous infusion tests, the flow qualities of the matrix in the planned laminate were tested and optimized. Numerous lay-up tests finally resulted in the definition of the ideal laminate structure.
Thanks to prototyping, the project staff managed to achieve a stable process and a very good stiffness to weight ratio.
"For us, the Candela project required the ideal combination of fabrics knowledge, process development and core material expertise to achieve the best weight/strength ratio for an electrical hydrofoil,” says Jan-Nommen Ebsen, SAERTEX Stade Plant Manager.
Candela Speed Boat AB
SAERTEX fabrics, also known as NCFs (non-crimp fabrics), are characterised by stretched fibres within the individual layers. In comparison with crimped fibres, as found in woven textiles for instance, straight lay-up (non-crimp) fibres have the greatest possible load-bearing capacity.