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Old 07-03-2007
sailingdog
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Quote:
Originally Posted by timangiel
Can a boat sail faster than hull speed and how good is the formula for calculation? If hull speed is calculated by the sqaure root of the lenght at the water line times 1.34 it does not seem right to me. My boat is 26 ft LOA but is 23 ft at the water line. The sqaure root of 23 is approximately 4.8 and if I multiply this by 1.34 I get a hull speed of 6.4. According to my knot meter I sail quicker than that on a regular basis. Is my formula wrong, is my math wrong, or is my knot meter wrong?
A knot meter isn't the thing to use to check boat speed. It may not be calibrated accurately, it may be affected by tidal currents... Have you checked the speed via a GPS.

Also, what kind of boat do you have. There are many smaller boats that can plane or surf. A Foiler Moth can sail well above its hull speed, since it lifts up on a set of hydrofoils. The basic SQRT (LWL) * 1.34 rule really only applies to displacement hulls. It fails on multihulls, small dinghies, foil-equipped boats, and a few others.

Sailingdog

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Telstar 28
New England

You know what the first rule of sailing is? ...Love. You can learn all the math in the 'verse, but you take
a boat to the sea you don't love, she'll shake you off just as sure as the turning of the worlds. Love keeps
her going when she oughta fall down, tells you she's hurting 'fore she keens. Makes her a home.

—Cpt. Mal Reynolds, Serenity (edited)

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