yes automotive products can be used on boats. Well most of them. Gelcoat is nothing like paint however. It is 50x thicker, and stronger. You will need some strong compounds, and really good rotary skills to get a perfect polish on a boat. As for #16, it works very well, but is quite the pain in the a** to wax a boat with it by hand. What i recommend, and use about a bottle a day of is Collinite Fleet Wax. It is a real thin wax that can be applied using the PC, and it wipes clean very easy. The stuff also holds up very well, it is detergent proof, and seems to handle the harshness of being in the water and direct sun very well.