SkunkTracker for iOS displays live, updating maps of ships and boats. It uses AIS data streams received over WiFi, either from your own dedicated AIS receivers or from public network feeds such as and

AIS (Automatic Identification System) transponders are carried by all large ships, all passenger vessels, and many recreational boats.

Note: you need an AIS radio, or access to a public or private AIS feed, to use SkunkTracker. Your boat's AIS transponder may have a network interface already, and if you can connect to the same network you can use that radio. Your radio can be connected via WiFi or via cellular data.

If your radio doesn't have a network connection, you'll need a WiFi-RS232 converter, such as the Global Cache WF2SL or the Grid Connect RN370.