The Company Tom's SpeedSail has developed the “Aero-skimmer”, a combination  of catamaran and sailplane. In 1994 Tom Bakker, a technical engineer from Haren  in the Nether-lands, starts with preliminary sketches of this type of sailboat.  The concept: whereas a “normal” sailboat turns sideways by wind forces and  pushes the hull into the water, which increases the drag, Tom bakker’s idea was  to invent a sail construction, which makes the boat “lighter” as the wind  increases. Right from the start a team of engineers from Airborne International with its  expertise in light weight constructions and FlowMotion as an expert in aerodynamics has been formed. Soon the  concept of an inclined half-solid wing has been born. In particular wing challenges both the design team and the sailors  (European champion in catamaran classes) with is „strange“ sailing behaviour.  Design target for FlowMotion was to develop a wing, with maximum driving forces in  combination with minimum aero dynamical drag. Also the aero dynamical stability has to  be taken into account. In ideal circumstances the force vector generated by the wing  passes the centre of gravity. Thus no moment is generated to turn the boat sideways.  However the direction of the force vector of the wing depends on wind-speed and wind  direction, which are usually not constant in real sailing conditions. If the force vector  moves out of the centre of gravity, moments are generated and the boat starts to turn,  which moves the vector even further away from the centre of gravity and the boat turns  even faster. This effect is called aero dynamical instability. The sailors this faces this  instabilities during the first test of the preliminary Aeroskimmer prototype   In the final design of the wing this instabilities could nearly be eliminated. The wing  design has been performed with various flow simulation tools (CFD Computational Fluid  Dynamics). The calculation of the wind shear (wind-speed and direction varies with  height), which changes with boat speed and course has been essential to predict the  behaviour of the boat.  Next to the optimization of the wing FlowMotion has also assist the design of the rudders  with respect to drag reduction. In this part of the project   infrared thermography has  been applied. With the help of a team of experts from different engineering disciplines  rooted in aerospace engineering a high speed catamaran has finally been built, which  achieved the 1. place in the 1997 “Speedweek” in in Weymouth.  Offices: The Netherlands Leeghwaterstraat 21 2628 CA Delft Tel.: +31 15 278 2907 Germany Weenermoorer Str. 193 26826 Weener Tel.: +49 4953 922 969 Consultancy for Heat Transfer and Fluid Dynamics CFD makes fluid dynamics visible. ANSYS The Flying Dutchman Design of a Highspeed-Catamaran Tom’s Speedsail Speedsail pressure distribution on the wing hydrofoil at the sword We solve every Flow problem.