I know very little about this except what I have read in the UDXF group. It does sound interesting, thought.
The technology in use here is called "AIS":
http://en.wikipedia.org/wiki/Automatic_Identification_SystemA few more replies in the thread mention
http://www.vesselfinder.com/#http://www.fleetmon.com/en/vessels[UDXF] Re: Marine traffic map
chs580328
To: UDXF@yahoogroups.com
Picture of chs580328
Hi Tom,
I monitor the GW network. A download of frequencies can be found here
http://www.udxf.nl/Globe_Shore_Ship_Freqs.pdf You will need to download Rivet and use the Ship frequencies. There are quite a few posts about the GW logs on here to have a browse through as well.
Also, the GMDSS DSC frequencies can be monitored but you will need software for these as well. I use MultiPSK but there are others.
It can take a bit of practice to get thinmgs to decode but once you get the hang of, conditions allowing, you should find some stuff to plug into the website.
Here is a name that I got earlier today on DSC calling Olympia JRCC Piraeus. Pop this into vessel finder to see where she is now.......
SEABOURN SPIRIT
HTH,
Chris S