I have a 23' sailboat and the smooth topsides (especially aroung cockpit) have what appears to be pin size black speckling. I have been told that this is the gelcoat wearing thin and the fiberglass underneath showing through , however; if i put boat scrub soap to it, it noticably improves and washes away but is still there. It seems to be almost a mildew or mold look, but cannot get rid of it completely. Was I informed correctly or is there a product to solve this?