Which GPS I want to buy a hand held GPS, but not sure which model. I'm looking at a few Garmin models. Does anyone use a GPS, and what is your opinion. I'd really like to see what sail adjustments do to my speed. Are the GPS units out there accurate enough for this? I'm not a racer, just trying to improve my technique. P.S. Had a great day sailing in Santa Barbara yesterday! About 75 degrees, no clouds and 10 knots. What a beautiful day!