I used acetone, then 600 grit wet and then wiped again with acetone. Do it in 2-3 ft at a time dont try to knock it out in one shot. Also gelcoat areas around where you are wet sandiung should be covered with tape to prevent hitting you gelcoat while wet sanding and wiping with acetone will turn blue or black and may stain your gelocat.
One other thing I learned is to make sure you cover your cleaned up rubrail with paitertape before you compound and wax the hull. I found myself constantly touching the rub rail and leaving white marks form my hands that stained it again.
Have to do it again this weekend , Wax aah On small circle , Wax aaah OFF... beeeeg circle ...
Oh and mop and glow will flake off and start looking like the rubrail has
psoriasis or something.
will post before and after pics.