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 Boat Design Forums Sail horsepower vs wind force?

#1
02-12-2004, 10:17 PM
 tommc Junior Member Join Date: Feb 2004 Rep: 10 Posts: 6 Location: Denver, CO
Sail horsepower vs wind force?

I am interested in calculating some sort of approximation of horsepower knowing force exerted on a sail. I am calculating force using:
F (lbs / sf) = C x V(knots)^2
Where: V = wind velocity
C = constant = 0.004.
Does anyone know a reasonable simple formula that would approximate the horsepower from this?
Thanks
#2
02-14-2004, 03:50 AM
 tspeer Senior Member Join Date: Feb 2002 Rep: 1533 Posts: 1,666 Location: Des Moines, Washington, USA
Power = Force * Velocity
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Tom Speer
#3
02-15-2004, 12:15 PM
 tommc Junior Member Join Date: Feb 2004 Rep: 10 Posts: 6 Location: Denver, CO
Thanks for the advice. I actually was thinking of that calculation but it ends up with HP going up as the cube of the wind velocity which I didn't quite want to believe was the case. So one more dumb question here. Does the available horsepower actually rise as the cube of wind velocity?
#4
02-15-2004, 02:49 PM
 tspeer Senior Member Join Date: Feb 2002 Rep: 1533 Posts: 1,666 Location: Des Moines, Washington, USA
Sure, until you reach the stability limits of the craft. Then the force must stay constant (to maintain constant moment), so the power only goes up linearly after that.
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Tom Speer