RaceQs is a free service and a free App that offers incredible 3D live tracking and replay, as well as a wealth of sailing analysis tools. It comes highly recommended by top sailors and is available in the iPhone App Store or for the Android at Google Play, search for RaceQs. Please see http://raceqs.com/started/ for instructions and to sign up for the free service there. (I found signing up using Facebook most convenient for me.)
In it’s most basic form it just provides GPS tracking, the phone does not need to be mounted for this. Be sure there is only one phone on and tracking on your boat, all phones running RaceQs in the same area with tracking enabled will appear. Live tracking increases the safety of the fleets and adds the ability for shore spectators to monitor the race in real time. To enable live tracking please download the RaceQs App from your respective App store. The phone should be plugged into the boat since the overnight race will task the battery. Cell phone data needs to be on for live tracking.
Now for the really exciting part! These smart phones have very sophisticated motion sensors. By mounting your phone to the boat, 3D Tracking and Replay may be enabled! After the race during Replay this gives you incredible analysis capability. If the signal gets out the live feed will show the boats moving as they actually are in the race including heel and wave action, using a 3D avatar. The data will ‘catch up later’ if the signal is too weak. The RaceQs suggested mounting is to purchase an inexpensive case that can be Velcro’d to the boat. If you have a belt clip it may be mounted then the phone clipped to it. The most inexpensive method I have employed on my small sailboat is to tape a Zip-lock snack bag down, then zipper the phone in that. These small bags are just the right size for a cell phone and will help keep it dry.