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Old 05-12-2010
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svHyLyte svHyLyte is offline
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One can easily measure an entire route using the Ruler tool in Google Earth. One can also select the units of measure--either statute miles, nautical miles, meters and kilometers or what have you. There is no particular reason why one needs actual distance over the ground due to tacking as what counts on up-wind legs is VMG which detemines trip time. If needed for academic purposes, however, you can calculate the potential distance of the upwind legs to account for tacking although, for most yachts, one can safely add 25% for up-wind legs and be in the ball-park.

For example, the distance from the south Tampa Bay Sea Bouy to Smith Shoal Light off Key West is about 180 miles. In a 12 knot southeastly we'd be beating on a port tack at about 35º apparent making roughly 8-1/2 knots but with a VMG of about 7. Assuming no wind shifts (which is silly as the wind almost always goes east as one gets further south) it would take about 26 hours to cover the leg (the important number) during which we would have sailed roughly 220 miles over the ground or about 22% more than the actual distance.

FWIW...
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