Re: glassing over removed thru hull. what glass to use?
Keeping in mind that a 2 inch hole in 1/2" glass needs ( to be done properly) a patch with a diameter of 14 inches. Its not a small repair! I've done 6 on my current boat this way and have 5 more to do. I use epoxy because its got better secondary bonding and allows me to build the whole 1/2" thick patch on the laminating table and apply it in one go ( sort of like applying wallpaper). I also back the patch on the inside with 3-4 additional layers of 1708. I use 1708 for all my patches because its easier to cut (without fraying) and makes a very strong repair. I put peel ply on top of the outermost layer and then smooth out the outer layer.
I've also had very good success covering my epoxy repair with gelcoat to blend into the rest of the hull. No issues with getting it to stick.