A friend of mine in the office is an avid yachtie - although he insists on sailing a Beneteau on time share for the same per year as it would cost to own a Top Hat.... but that's another story.
If you have an iPad or iPhone and don't want to shell out the hard earned for a complete AIS system, there is an iPad application that will show you where all the traffic is.
http://itunes.apple.com/au/app/ship-fin ... 60636?mt=8
He uses it whilst travelling up and down the coast, and said it was great in low visibility to see what was around. At $7.50 if you have the tools already it's a good thing. I'll report further once I've tried it out.
It's not a transmitter, so if you want to be seen you still need the AIS transmitter, it's only for seeing other ships.
Michael