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post #41 of Old 08-19-2006
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Originally Posted by jerryrlitton
I do not have much sailing experience but my time is in aviation. There is a lot of correlation here since it is all fluid dynamics and the keel depth type etc discussion is a lot like a weight and balance problem. Remember the simple mathematical formula… weight X arm = moment. Where the depth (Length?) of the keel is the arm. Also whenever vortices are formed you also find drag. Just like whenever lift is formed you make drag. Just my 2 cents worth.

Yes, but the weight of the arm must also be considered. The righting moment of a typical fin keel is the mass of the keel * X% of the length, which is determined by the center of mass of the keel. A bulb keel has a greater righting arm than a fin keel of the same draft and mass, as the mass of the keel is concentrated further out, in the bulb.

Captnero— I was speaking specifically, and only about stability and righting moment, and not the sailing performance of the boat. I'm not sure where you got the idea that I was speaking of sailing performance. Sailing performance of a boat is affected by much more than the shape of the keel, though the shape of the keel is an important factor to consider. I don't see any real advantages in a wing keel, when it comes to providing stability, over a bulb keel. However, the wing keels have serious disadvantages IMHO and experience, over bulb keels—so there is no reason to have one as far as I am concerned.


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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
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