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post #4 of Old 11-22-2002
Jeff_H
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Twin bilge keels?

A couple quick points here- Twin keels are a specific type of bilge keel in which both foils are identical. Bilge keels can be either twin or asymetrical. Assymetrical foils offer less drag for the amount of lift.

I don''t know why you beleive that twin keels (or any other kind of bilge keel) offers less rolling than a single keel of equal or even slightly less wetted surface. That simply has not been born out in tank testing. The conjectured reasoning is that the full area of the single keel acts in water that has not been disturbed by the rotation of the boat while the bilge keels act in thier own disturbed water. For an equal area or a smaller deeper area on a single keel, the single keel also have a lower roll moment of interia due to dampening than the bilge keels.

Jeff
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