WINDYAK hybrid boat, already a good sailing trimaran

  • WINDYAK sailing tests show that obtained performances are close to the ones of an equivalent capacity sport catamaran. Windward angle when close hauled is the one of a cruising monohull, and accelerations down the wind are good, due to limited wetted area and displacement:
  • The level of performance reached results from a favourable power/drag ratio more than the design goal of maximizing power as for a catamaran. These ones are probably faster is some conditions, but require more physical and technical skills to the crew.
  • The best WINDYAK performance is got when she sails unheeled, only the main hull dragging in water : the float due to its limited length generates an important drag, although it has been shaped for the corresponding relative high speed reached : narrow bow and smooth run, V-shaped bottom to limit the drag when WINDYAK sails unheeled. This V-shape bottom is nevertheless quite open, and allows, thanks to a significant positive trim, to generate a dynamic lift to add to the limited Archimedean buoyancy of the float (60 litres).
  • To get more stability close to the wind and at reaching, it is possible to one crew to sit astride the beam, generating a righting moment close to the one of one person using a trapeze wire. We plan to equip the aft cockpit with rappel straps to allow the helmsman to generate additional righting moment. Moreover if we fit the tiller with a telescopic stick, it will be possible for the sailor when sailing singlehanded to sit herself or himself on the beam, then getting an excellent power/drag ratio.

A natural transition to pure sailing foiler trimaran

WINDYAK development boat attendance to La Rochelle boat show in September 2006 allowed us to notice that there is also a demand for an pure sailing trimaran. She will be potentially faster than WINDYAK , but will keep the true ‘pros’ brought by light weight and fast mounting induced from the ‘kayak like’ approach. In addition to the advantages got for transport and handling, folding capability onshore will allow easy storage in closed premises with very limited bulk. Foreseen evolutions of initial WINDYAK concept for this boat are:

  • Use of a more conventional round bilge shape for the main hull. Current WINDYAK hull as a compromise between sailing and paddling practices has indeed a large wetted area from stability and so waterline breadth necessary in kayak mode.
  • Use of a typical catamaran-like shroud-fitted rig with full battened mainsail, jib and gennaker to go downwind, and equipped with trapezes to increase stability. This much more powerful rig will allow in addition an excellent sail shape control.
  • The single beam will be fitted with triangular trampolines allowing the crew to move more upwind and possibly sit on the upwind float.
  • Optionally, the boat will be equipped with T-shape foils, equipped with control wands automatically adjusting foil angle of attack. They will be fastened to float’s bottom with crash-boxes to avoid problems in case of impact.
  • The float folding mechanism will be kept and adapted, for mechanical strength and easy handling brought: It is possible indeed when beaching to fold the float+foil assembly above the beam to avoid contact of foil with ground.

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