Transponder

Transponder is for yacht race tracking at Sailtracker.net. Transponder uses your iPhone to communicate realtime position and performance data to the Sailtracker website where a race can be watched live or later via playback. If your phone loses signal temporarily while outside of mobile phone tower range GPS and performance information is cached and uploaded when signal returns.
Note: continued use of GPS running in the background can dramatically decrease battery life. It is recommended to connect to an external power source for extended use.