The hull is being wet sanded with 220 grit paper. Gelcoat is pretty thick but one must be careful not to sand through to the fiberglass. The purpose of sanding is to remove the weathered top coat. The sanding also smooths the finish and minor scratches can be blended out. The color of this boat is actually a light grey, not white, and the true color is coming out. The lines of the boat look better without those '80s era pinstripes.