Re: Question about wet sanding
The pinstriping keeps the fiberglass gelcoat from oxidizing, thats where your seeing the difference. Unless it is a very dark color, you can usually blend the area in to the surrounding gelcoat to match the un oxidized gel coating under the pinstripes. Your plan is to start with 800, I would start with 1000. The less grit you can use to acheive what your looking for the better. Yes 600 grit is fine if you don't mind going back and wet sanding more with 800, 1000, 1200, 1500, etc.. Every time you sand you are removing gel coat, so the less you can sand the better. Some projects will require 600 but not all. Try the lesser grit first. Basically you are scatching the surface, the more aggresive the grit. the deeper the scratches and the more you will have too sand to remove those scratches with less aggressive paper..
Power equipment should not be used to wet sand imo because you can remove to much gelcoating. Especially if you have not done it before and are inexperienced! If you are going to use a power sander, use a air compressed DA sander. It will give you more control and not shock you. Again, I would do it by hand. Lot of work but worth it in the end. It really does not take long to wet sand a boat. The rougher the paper, the harder it is, each sanding gets less hard because the hull becomes smoother. Make sure you keep the paper wet at all times. If the sand paper starts to stick a little while going across the surface, it is time for more water.
Once you have wet sanded up to 1200 to 1500 grit paper, use a restore compound to bring out the finish/shine and then coat wiith wax.
Dark gelcoating will sometimes require up to 200 to 2500 grit wet paper.
Don't sand corners as hard, you can sand through the gelcoating here because it usually isn't as thick on the edges. Good luck