jayp, I have used one of those "Fire and Ice" grill cooler combos with some success for grilling on the boat. Just don't cook things that are very greasy and splatter and you won't have any problems.
1. if you're on the boat, you gotta get in the water 2. don't bring whinny girly girls 3. don't complain, you're out on a boat for christ sake ...and last but not least: 4. the captain of the boat is god as far as the passengers are concerned.