For many years I used the inflatable bottom paint from Pettit available at West marine. I think it only comes in black. I would put a fresh coat on the dinghy each spring and splash the dinghy for the season. I did this for ten+ years. We kept it in the water behind the boat in the slip and towed it wherever we went. Our sailing waters in Barnegat Bay, NJ are mostly salty but the river where our slip was located was on a river with brackish water. At the end of each season I would haul the dinghy and use a low level power washer to clean the scum off the bottom. There was some scum but not much and maybe a few small barnacles - much less than was on our sailboat itself when we hauled it at the end of the season. I would deflate the dinghy and roll it up but used a thin plastic tarp as I rolled as to not scuff the topsides with any of the black bottom paint. Although there was some paint layer build up, it did not seem to crack or flake off despite years of rolling and storage.