Power Foils-added power to carry sail...

[Doug Lord]

Originally Posted by Munter

Doug at less than 20kts you might not use the power foil - how do you balance the boat during this time? Through sheeting and weight adjustment like a moth?

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Yes-probably using sliding bench seats...you may be able to see them on this model:

[Richard Atkin]

I like it

[Doug Lord]

Thanks,Richard.

[Doug Lord]

Power Foils on monohull foilers will work very similarly to the way the windward foil on the Hobie Trifoiler and the Rave work-but the main difference is that they will only be used in heavier wind- with the boat sailing on just two foils in light and moderate wind.This is what Greg Ketterman had to say about using a windward foil to develop negative lift:

"Hydrofoil boats can be categorized into two categories; 1) Incidence controlled hydrofoils and 2) surface piercing hydrofoils. The difference lies in the way the boat maintains the proper altitude above the water surface. A surface piercing hydrofoil boat maintains proper height by varying the amount of foil submerged. The boat raises up as the speed increases and reduces the amount of foil submerged and therefore the lift. The boat finds equilibrium at the proper altitude. An incidence controlled hydrofoil sailboat has a mechanism that controls the angle of attack of the foil to maintain the proper altitude. It is generally believed that surface piercing is simpler, but incidence control is more efficient. In reality, it is the method that works with fewer problems that is simpler.
From the beginning it was felt that incidence control was better suited for a sailboat even though most of the existing hydrofoil sailboats were of the surface piercing type. There are many advantages of the incidence controlled foils; however, the most important is what I call the DLA (dynamic leveling affect). This is the increase in righting moment or stability due to the ability of the windward foil to pull down. The DLA has little affect on the low wind performance, but it essentially makes the top speed of the boat limited to the strength of the boat. Conventional boats with a finite amount of righting moment can only extract so much power from the wind, but with the DLA, the righting moment is virtually unlimited."
http://www.hobiecat.com/sailing/TriF...lls%201990.htm