Should you be painting a boat or other frp object that is going to be subjected to temperature extremes and/or water immersion, i highly recommend epoxy-based paints regardless of the resin used in the frp. epoxy is simply a much more robust paint, particularly when that coating is subjected to salt or fresh water and near constant bumps and dings.. Marine gloss fibreglass boat paint / grp paint. this high quality marine gloss fibreglass boat paint formulation has been tried and tested for over twenty years. suitable for use above and below waterline, when anti-foul is not recommended. ideal for use on exterior and interior surfaces.. Supplyshed marine boat gloss black paint for fibreglass and grp 750ml. white spirit based for easy application.