Check out West Marine. I used to be into boating rather heavily and they have some great prices and good products. I love and trust just about any and everything from 3M; they have some great boat products too. I've used a PC on a boat, but like Pappy said, I have to agree that a rotary will be your best bet. Otherwise, you will literally give your self some tendonitis from using so much elbow grease!
Mike