A Rotatable Keel Appendage comprising a conical hollow support fixed to a sailboat hull into which is juxtapositioned a rotatable cone member which supports a fin keel carrying a heavy ballast bulb. The rotatable cone member has a threaded shaft at its peak which has a diameter greater than the thickness of the fin and is lockable to the fixed appendage conical hollow support by a nut on the threaded shaft. In another embodiment, the rotatable cone member carries two fins, in either spaced parallel relationship or in spaced aligned relationship. Mathematical Formulas for Energy Balance are developed to establish that a tacking sailboat with the appendages in the Specification will hydrodynamically generate forces to both decrease the leeward drift and increase the forward velocity of the hull. Methods for sailing more quickly to reach a windward destination are set forth using the appendages in the specification.
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