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post #38 of Old 04-10-2012
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Re: Garmin GPS 72H and VMG?

GPS VMG to a waypoint is almost useless in normal short course racing. GPS VMG has a little bit of use when reaching and there is a current, but for a typical windward-leeward race course, VMG relative to the wind is much more useful information.

On upwind and downwind legs there is always a trade off between a little more speed through the water, vs a higher or lower angle. It is the wind derived VMG that is the critical analytic that helps make a determination of the most advantageous target speed/angle in any particular wind and sea state. To obtain a wind related VMG requires a wind instrument and a knot meter. Speed over the bottom does not come into play.

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Curmudgeon at Large- and rhinestone in the rough, sailing my Farr 11.6 on the Chesapeake Bay
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