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post #32 of Old 04-08-2012 Thread Starter
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Re: Garmin GPS 72H and VMG?

SinbadOz. Setting the distant waypoint is easy if you know the lat/long of both marks. Before the race, you should make at least one lap of the course. While making the lap, get the lat/long of both marks.

Now find the difference in longitude between the two marks, and the difference in latitude. Multiply the difference by 1000 and apply that number to the upwind mark's location. This will give you a lat/long pair that is 1000 times further away than the length of the course. (An example might be in order, just let me know.)

Yes, just set the device to goto the waypoint.

This system will also work for round the buoys races. For example if you are sailing an olympic triangle, then you will have three waypoints. One is far up the line between the downwind mark and the upwind mark. One is far down the line between the upwind mark and the reaching mark, and one is far down the line between the reaching mark and the downwind mark. After each rounding, you will have to set the GPS to goto the next target (because you will never actually reach it,) but otherwise you still try to maximize VMG in each case, except when going from the upwind mark to the downwind mark, you set your goto point to the upwind waypoint and try to minimize VMG. Yes, this gives you (or your crew,) something extra to do on each rounding.

The nice thing about this system is that when the wind shifts, you don't need to change any of your waypoints, unless the RC moves the marks.
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