Unless the rules changed, you cannot broadcast on AIS. However for $200 or so you can see an amazing amount of good info on the receive mode. It would be the best money I could spend in the electronics dept. Recieve only models are available for very little $$
In the Sound, if you get in a foggy or low vis. situation. Just call vessel traffic on VHF14 (I believe) and let them know who you are. They will keep you informed of any vessels. We did this clear out at Destruction Island before coming in the Straits. Combined with AIS you will be styling