2005 - COPYRIGHT JEAN MARIE LIOT
The fastest sailing boat of the world combines dream and high technology. This extraordinary sailing boat can fly over oceans at a very high speed combining the leading techniques of the aeronautical and marine industries.
Hydroptere is a unique and innovative project, which conveys extremely strong human and technological values.
Motivated by passion and daring, Hydroptere teams knew how to take advantage from the technological innovations to make a pioneer boat fly and become reliable, combining glide and perfection.
To understand Hydroptere, a little review session is necessary! First, an etymological review. In Greek, hydros means “water” and ptère means “wing”. And then a mathematical review, with Archimedes’ principle saying “A body immersed in a liquid is buoyed up by a force (buoyant force) equal to the weight of the displaced liquid.” Thanks to this theory elaborated twenty-five centuries ago by a Greek genius, traditional boats can float but with much resistance to achieve high speeds. It was then necessary to make the boat rise above the sea surface to eliminate this drag by replacing Archimedes’ buoyant thrust by the water’s dynamic lift. This physical phenomenon has been analyzed in detail for the air in the early twentieth century by aeronautical engineers and its application to water (800 times denser than air) is one of the prides of the Hydroptère team. To take off, Hydroptere has "marine wings", the foils, which are placed under each of the floats of the trimaran.
Once the boat reaches 10 knots, these immersed “wings”, deployed at 45 degrees in the water, generate an upward thrust. With the appropriate angle of attack of the foil, the sum of the pressure at the intrados and of the depression at the extrados generates an upward thrust with a reduced drag, which raises the boat like the wing of a plane. This is called the “lift” i.e. the same principle that allows the wings to make a plane take off. Then the hull and the floats of Hydroptere fly five meters above the sea surface. Only 2.5 m² of the boat are in contact with the water and she is able to sail from 20 to 45 knots (from 37 to 83 km/h) in 10 seconds. And same result in the sea and in the air, the higher the speed, the greater the lift.
In theory, everything seems to be very simple. But in practice, the achievement of this incredible project has encountered numerous obstacles. Between the initial model made in 1985 and the first record broken by Hydroptere in 2005, Alain Thébault worked hard during twenty years and fell many times before finding the ideal configuration which allows this technological jewel to fly above the water.
But in the end, they managed to combine opposites: Lightness and robustness. Because the foils must resist pressures twice as high as those exerted on the wings of a jet fighter. To do this, they used composite materials such as carbon fibers impregnated with epoxy and associated with titanium parts. To meet the laws of hydrodynamics, the shape of Hydroptere has been optimized to ensure a greater efficiency of the sails while minimizing as much as possible the air friction on the structure of the sailing boat. The “papés”, the brains of the high-tech industry who have been helping Alain from the genesis of the project also equipped the cross beams with huge strain absorbers, inspired by the landing gear of the airliners. They imagined a reversed centreboard, similar to that on the planes and designed absorbers derived from that of the Rafales, which allow the foil to be lifted during a strain peak and then to come back to its original position before the next wave. They also installed on board a hundred sensors which measure the pressures, the twisting or the speed. The data acquired are modelled in a flight simulator to analyze every reaction of the boat and to improve adjustments. They have realized thousands of calculations to reduce the problems of hydrodynamic flow: When Hydroptere reaches 50 knots, the water begins to boil around the foils, which reduces the lift and stability.
Today, thanks to the passion, energy and daring of these worthy successors of Ulysses and Icarus, thanks to the alchemy of science and resourcefulness, marine sensitiveness and cutting-edge technology, Hydroptere is the fastest sailing boat in the world. With the help of, Alain Thébault and his team wish to write a new chapter in this epic between the sky and the sea, with the conquest of the greatest oceanic records.