To repair a hole in a fiberglass boat, prepare the damaged area, and cut cardboard and two pieces of fiberglass cloth in an oval shape that is slightly larger than the hole. Place the fiberglass on the cardboard, and wet the fiberglass with epoxy resin. Run a copper wire through the center of the patches and cardboard, and place the cardboard and patches inside the hole. Wrap the wire around a stick, and tighten the wire until the patch dries.
To prepare the damaged area, cut the damaged fiberglass away, and feather the outside edge of the hole with a rotary sander. With the stick outside the hole, place two wood shims between the boat and the stick, and tighten the wire to ensure all parts of the patch touch the inside of the boat.
When cutting the patches of fiberglass cloth, cut across the weave diagonally. If desired, use Kevlar instead of fiberglass cloth to repair the damaged area.
To repair a hole on the exterior of the boat, use the same process, but place the stick inside the hole. Sand the area around the hole to ensure the patch sticks, and leave the stick inside the hole after the repair is complete.