Wetsand and buff x2. I've brought back some severely oxidized hulls this way. We've tried all the "magic solution" solvents and polishes at our yard and none of them deliver like sanding
. Heres the trick to doing it fast and easy. If you use a DA (random orbit sander) you will find you can get very fine disks for it. I usually go straight to 800 grit disks, but if the oxidization is really bad start with 600 and finish with 800. If I'm doing a hull
I usually guide coat first, it helps you acheive a really uniform finish with no holidays. Make sure you use a proper guide coat or you'll have problems with gumming. After you've acheived an 800 grit profile go to 3m perfect it and buff the whole hull several times. It'll look better than new! This job should take two people about two days to complete on an average sized sailboat. One day for sanding
and one for polishing. I mean in the yard with some decent scaffolding of course, in the water
would take much longer. Here's a source for 800 grit DA disks. Fisheries Supply
You can go up to 1500 disks but I find 800 buffs out great on gelcoat
. Many people buff at 600 but you'll still see scratches if you do. If you go to 600 re-guide coat between grits. Good luck and have fun!!