Rick - "The 800N is for a 4 tonne proa with 18m lw hull at 4m/s; in calm sea conditions, no windage, perfectly smooth glossy hull, no in-water appendages like pods or rudders. Basically it is what you would get in a tow test with a 4m/s tail wind."
I see it as 3200N now : )
4m/s is close to the square root of the 18m hull length, the most efficient point for a displacement hull.
A single 2 tonne hull would need 1600W or a little over 2.1 hp to go 8 knots or .11 gallons per hour or 72 knots per gallon. At 60% efficiency that would be 43 knots per gallon.
Therefore a single 8 hp engine should easily be able to propel the proa at 8 knots in calm conditions? And get better than 18 knots to the gallon?
If that is accurate I think I could make a very strong case for scrapping the sails and just using an engine. A 200 gallon fuel tank would have a 3600 knot range.
Talador
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Posted by: taladorwood@yahoo.com.au
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