It'll depend on how long you'll leave the boat in the water. If its just for a weekend, you don't need paint at all. If it's a week, I'd suggest something like a hard paint. If it'll be left in the water for a month or more, then look into ablative paint. If the boat will be hauled out after every use (like a week long cruise) then you shouldn't have to worry about a barrier coat, although it does add a little extra protection.
Merit 25 # 764 "Audrey"