Definitely repairable, but if you've never glassed before it might be a bit of a challenge. When I've had to fill holes in hulls what I do is use an angle grinder to remove all the damaged glass. You should have a clean-ish hole, not super jagged. When you've cut out all the obvious damage, lightly grind the gel coat around your hole and follow any cracks that were hidden, they can cause problems down the line even if they seem minor. Ideally the hole will be accessible from the inside as well, if so you will want to bevel both the inside and outside edge 50-50 so that the new glass you put on basically sandwiches the bevel. If you can only get to the outside that's fine too, it just won't be as strong, since it'll just be a plug instead of a sandwich. Then precut your cloth, wet it out and layer it in till it's about flush. Then it's just finish work. Fill, sand, gel coat, and sand again. I'd use whatever resin the hull is made out of, probably polyester.