Marine antifouling paints do not require a primer to improve adhesion directly to gelcoat. Unanimously, antifouling paint manufacturers recommend applying an epoxy barrier coat primer directly to the gelcoat substrate prior to applying antifouling paint because gelcoat has a sense of porosity and is susceptible to osmotic blistering. An epoxy barrier coat provides an impervious film that prevents water from coming in contact with the gelcoat. Epoxy barrier coats also provide an excellent, inert surface for antifouling paints to bond to. TotalBoat TotalProtect Epoxy Barrier Coat and Interlux InterProtect are examples of suitable epoxy barrier coat primers.