Pete
I think I would go with a Marine VHF radio. If you need help, the coast guard monitors CH16. I have a hand held unit I like to keep in my pocket, should I fall out of the boat it comes with me

GPS in other pocket so I can call them in on me, while treading water.

I have an ICOM M3A which I also use hunting (less than legal off the water) 6 AA batteries, last days, not guaranteed waterproof, but awful close. About $170 +/-, lots of good models out there. West marine at Delta Park had the most models when I was shopping.
A CB radio might get you the "rubber duck" if you are close to a highway.
Warning to Boaters: Look out for a 21 ft White, 1966 Starcraft Inboard with windshield and Bentleys top.
[This message has been edited by Bait O' Eggs (edited 09-08-2000).]