Garmin Foretrex 201. It has worked great but is not state of the art. I hear that the Locosys GT 31 is the way to go, but I haven't got into Speedsurfing.com or have I downloaded any of the data off my GPS. Someday I will have to upgrade.
I keep it in an Aquapac small arm band case. The Garmin's are suppose to be water proof/resistant, but I decided that I would not take the chance. I read some reports of them leaking after hard crashes.
Formula 160; iSonic 111; HiFly Move 105; Tiga 263; '85 Mistral Superlight.
Maui Sails TR 11.0; 9.2; 8.4; 7.6; 6.6; Maui Sails Switch 6.0; 5.2; Maui Sails Global 4.5; 4.0.