bene this works for any hole. but if you go too big you need something to back it up to hold the cloth. a trick that works well is to lay some cloth on the hull right next to the hole on top of some saran wrap. when it gets like leather peel it off, mix a little more epoxy and spread it on the inside of hull around the hole, then put the leathery FG over the hole. work out the bulbs, and let it cure. this will give you a good back up for the repair. if the hole is say over 6 inches, just let the leathery piece cure till real stiff but still bendable. it should be flexible enough to match hull shape but be solid enough to hold its shape.
if the hole was over 6 inches i would feather out both sides first and use the leathery piece as the first layer on the inside.