This I/O talk may have some pointers:

All the Ships in the World: Visualizing Data with Google Cloud and Maps (https://developers.google.com/live/shows/505972914)

Not quite the same, but you can view the position/heading of some ships here: https://www.marinetraffic.com/en/

Yep. Use that a lot as a reference. (AIS transponders send quite a lot information and also a lot of people upload photos of vessels that can be viewed at marinetraffic.com)

There are also a few other projects that have overlapping data. (aprs sites, e.g. aprs.fi - more of an amateur radio thing but will still pick up lots of interesting signals)

(Edit: perhaps more interesting to people around here an usb/serial ais receiver can be had for a few hundred dollars and there is a site called http://www.aishub.net/ where you can get access to the firehose provided you cover your area. Disclaimer: I never tried aishub.)