Naquethey has the right idea. I repaired about a 4 inch long, 2 inch wide hole in mine with a FiberGlass Repair Kit too. It's been 5 yrs now, and it's still not even leaking around the edges. Trick was to clean the area real good first, measure the patch a inch wider all the way around, coat it on both sides, spread the patch tight, and let set over night. ( cheap Finger Nail Polisher Remover works good to clean around the hole with. It's just acetone.)

"Save a Stamp, lick a Mailman!"