The GRP Fiberglass hull of my 6.4 m boat has hairline cracks in the surface.?

Question

Is there any polish / cleaner / coating that I can apply that will cover these unsightly marks. They are not structural but attract dirt. Thanks

Answer 1

those cracks are not structural as you said but are unsightly. to get rid of the dirt in them you can use a cleaner with oxalic acid in it but be careful not to get it in your eyes. If you get the acid crystals from a chemist mix one and a half cups to a normal household bucket of water and mix well.Wipe it on the area with the cracks and LET IT DRY,then wash off with a hose and sponge but don't get any of the overflow on anything galvanised, you may have to repeat a couple of times.Remember to use rubber gloves and goggles.Hope this helps.

Answer 2

The outer coating should be gel coat. So the first thing I'd try is to see if 500 grit sand paper on a DA sander will take care of the cracks. Then if it does, get the buffer out with some high-abrasive buffing compound and shine it back up to new.

If it doesn't, I'd grind out the cracks with a Dremel or die grinder and fill them back up with new gel coat, sand, sand again, then buff.

If you were looking for a 15 minute method, this isn't it. It is also not something someone with no experience in gel coats would probably want to try on their own boat, but I learned how to do fiberglass work at a boat repair shop and that is how we did it there.