The AIS system is used to track the positions of ships. A location signal is broadcast in the 160 mhz band that provides information about the location, direction, speed and other characteristics of ships. The Skunkworks team built a tracking system using a Raspberry Pi and a RTL-SDR radio that will track ships on the Delaware River and other local bodies of water and will upload that data to the aprs.fi web page where it is displayed.

More information about this project is here.