I live near a busy harbour and wanted some dynamic data for my NMEA2000 testing. A DIY AIS receiver seemed like a ideal plan and I had most of the parts in my spare parts pile. Found a site that had a prebuilt Raspberry Pi image and I also found a quick and very cheap way to make your own antennas out of coax and PVC tubing. Mounted it all in a box outside and was soon seeing real-time marine traffic. See this page for all the details: AIS Receiver