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Old 01-05-2003, 09:42   #1
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This may be a stupid question.

Last friday night we went for a sail in 21 knot winds on lake Michigan. It was the fastest sail I have ever had. My question is : is 8.9 knots per hour in 21 knot winds in a 64000lb boat fast?
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Old 01-05-2003, 19:21   #2
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Fast, I'd say so !

My understanding ( such as it is ) is that the theroetical( sp ?)top speed of a displacement type hull is the square root of the waterline length. In your case I'm estimating around 7.5 - 8 miles per hour. Your speed was close to 9 knots which translates into about 11 miles per hour. Good on you ,Sir. I would say you had that Lady planing. Whooe.....
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Old 01-05-2003, 20:36   #3
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Hull Speed

Hull Speed (Kts) = 1.34 x Square Root of Waterline Length (Ft).
If LWL = 55' Then Hull Speed = 9.9 Kts.
See:
http://sailingusa.info/cal__hull_speed.htm
And a great boat design informational at:
http://www.tedbrewer.com/yachtdesign.html
Ted Brewer Yacht Design

Regards,
Gord
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Old 02-05-2003, 22:42   #4
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So that old girl can move! I knew that hull speed was 9.9 knots for our boat, I just did not think I could come that close to it so soon.
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