Are you sure its the fiberglass that is stained? If you've ever buffed and waxed your boat the wax should be absorbing the stain. Then you could just use a buffing compound to clean it up and shine the boat at the same time. Kills two birds with one stone that way.
boat was new last year and waxed it twice last year, i have not waxed the deck though just figured it would make it to slipery when wet. used the hot water pressure washer on it thursday and it did not take the stains off, but after saturdays rain the stains are all but gone. used the shaving cream trick only for a small spot before it rained. maybe there was enough truck wash residue left on to break it down and rinse off with saturdays rain. i don't, but it looks good again!
Oh, sorry, I was thinking it was on the gunwales... missed the "deck" part.
Maybe it was the sun bleaching the color out? Anytime we get tupperware that has that awful stain of spaghetti sauce even after a couple washes... we put it out in the sun and it "bleaches" the stain out. Amazing what a bit of sunshine will do.
So that's how you get the goshdarn spaghetti stains out ??????????? And you call me a backwards frenchman? Now that sounds like a frenchman technique, Guess all i gotta do now is put all my tupperware bowls on the front lawn LOL Take CAre God Bless and Tight Lines LOL Donkey Dave From up North The Backwards Frenchman