Hydrofoil device

A sail powered watercraft comprising:

• (a) a sailboard hull, a sail assembly, and sail attachment means for joining said sail assembly to said sailboard hull
• (b) a main hydrofoil assembly comprising a main hydrofoil and main support means for mounting said main hydrofoil to said sailboard hull at a location rearward from the location of said sail attachment means
• (c) a canard hydrofoil assembly comprising a canard hydrofoil and canard support means for mounting said canard hydrofoil to said sailboard hull at a location forward from the location of said sail attachment means
• (d) fairing means for smoothing water flow past said canard support means
• (e) said fairing means being conformable so as to be able to substantially align with water flow past said fairing means during operation, whereby steerability and yaw stability of said watercraft are enhanced and whereby ventilation of said canard hydrofoil by air flow along the outside of said fairing means is inhibited.

A hydrofoil assembly for a watercraft comprising:

• (a) a hydrofoil
• (b) support means for connecting said hydrofoil to said watercraft
• (c) fairing means for smoothing water flow past said support means
• (d) said fairing means being conformable so as to be able to substantially align with the water flow past said fairing means during operation, whereby steerability and yaw stability of said watercraft are enhanced and whereby ventilation of said hydrofoil by air flow along the outside of said fairing means is inhibited
• (e) said support means comprising a support rod
• (f) said fairing means comprising a foil shaped fairing surrounding said support rod, said foil shaped fairing mounted so as to swivel freely on said support rod
• (g) sealing means for inhibiting undesired flow of air between said foil shaped fairing and said support rod during operation.

A hydrofoil assembly for a watercraft comprising:

• (a) a hydrofoil
• (b) support means for connecting said hydrofoil to said watercraft
• (c) fairing means for smoothing water flow past said support means
• (d) said fairing means comprising a foil shaped fairing made of flexible material, said foil shaped fairing fitted to said support means in such a manner that during operation said foil shaped fairing deforms so as to substantially align with water flow past said foil shaped fairing, whereby steerability and yaw stability of said watercraft are enhanced and whereby ventilation of said hydrofoil by air flow along the outside of said fairing means is inhibited.