2023-12-15 00:00:00 Transponder app for yacht race tracking at Sailtracker.net. Transponder uses your Android phone to communicate realtime position and performance data to the Sailtracker website where a race can be watched live or later via playback. This version of the app only works with Sailtracker. The Pro version allows connections to other tracking sites. Note: continued use of GPS running in the background can dramatically decrease battery life.