In order to complete his solo round-the-world voyage, François Gabart's team wanted to ensure energy self-sufficiency. It was therefore quite naturally that they turned to the engineers at Watt and Sea, whose good reputation is well known for their hydrogen generators, which equip all the current racing boats.
But how do you install a hydrogenerator on a trimaran whose hulls spend most of their time out of the water? Indeed, apart from foils, these boats don't drag much in the water! That's why the in-house engineer Matthieu Michou - to whom we owe the design of the hydrogenerator - got back to his drawing board to try and find a solution. Thus was born this new type of wind turbine.
A downwind wind turbine
To do this, he transposed the proven technology of hydrogen generators by designing a wind turbine. Contrary to the wind turbines on the market, the turbine is not held up to the wind by a tail, but fits naturally in the wind bed (the propeller is behind the mast). Thus the turbine is self-stable and does not require a tail. Mounted on a pivot, it follows the movements of the air flows and those of the boat exactly like a hydrogenerator in the water. This assembly ensures a very stable electrical production.
For François Gabart's trimaran, which is currently making its solo round the world record attempt, only 2 small blades (20% smaller than on a conventional wind turbine) were enough for the wind turbine to produce its maximum capacity (600 W). In fact, the apparent wind on this yacht is very often above 30 knots, which offers good recharging ranges. On a slower sailboat, longer blades with more surface area would probably be needed.
Compared to conventional wind turbines, this new design offers important advantages for offshore racing:
- wave stability and very stable power generation.
- high efficiency: thanks to this stability, power production in real conditions is in line with laboratory data.
- waterproof: the generator is that of a hydro and can withstand immersion!
- more manoeuvrable: the whole mast swivels and can easily be deflected if necessary to stop the propeller.
- the blades have been specially designed to minimize drag and operate quietly, with ergos at the tips of the blades to prevent whistling.
- light: the mass is less and the center of gravity is lower, less weight in the tops (very appreciated by the riders!)
For the moment this wind turbine is at the prototype stage in the test phase on the trimaran Macif . Marketing it would not be reasonable given the price of vacuum prepreg carbon blades. But this development, which seems to satisfy our solo sailor and his team, could open up new developments
