How to Fix a Scull Boat Crack

Whether you're repairing a hole or a crack in a scull boat, it's a repair that's best made from inside. Making the repair from inside the boat means that you can repair the fiberglass hull the same way it was originally built -- from the outer surface inward. This means a small amount of the patch will be visible. It also means that the gelcoat surface over the patch will be virtually indistinguishable from the rest of the boat's gelcoat surface.

Things You'll Need

  • Hacksaw
  • Acetone
  • Commercial Dewaxer
  • Clean, dry cloths
  • Disk sander
  • 36-grit sandpaper
  • Clear plastic wrap
  • Duct tape
  • Mold release spray
  • Gelcoat spray
  • 1 1/2 oz. fiberglass mat
  • Scissors
  • 6 oz. fiberglass mat
  • Marine epoxy kiy
  • Plastic putty knife
  • Automotive paste wax
  • Electric buffer
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Instructions

    • 1

      Cut out the damaged fiberglass around the crack with a hacksaw. Wipe the area with acetone or a commercial dewaxer -- using clean, dry cloths -- to remove the wax from the area.

    • 2

      Grind a bevel into the fiberglass around the inside of the hole with a disk grinder and 30-grit sandpaper. The beveled area needs to extend outward from the hole a distance of 12 times the thickness of the fiberglass. For example, if the fiberglass is 1/2 inch thick, the bevel must extend 6 inches from the hole you made when you cut out the damage.

    • 3

      Tape a piece of clear plastic wrap over the outside of the hole, with duct tape. Spray mold-release spray onto the plastic wrap from inside the scull. Apply gelcoat spray to the inside of the clear plastic wrap.

    • 4

      Cut a piece of 1 1/2 oz. fiberglass matting, with scissors, so that it is about 1/2 inch larger than the hole. Cut a piece of 6 oz. fiberglass mat the size of the damaged area. Cut each successive layer of fiberglass mat 1/2 inch longer and wider than the previous layer. Alternate fiberglass weight: one layer of 1 1/2 oz., followed by a layer of 6 oz.

    • 5

      Mix the resin and catalyst of the marine epoxy, according to the directions on the epoxy kit. When the epoxy begins to thicken, place the first layer of 1 1/2 oz. mat against the plastic wrap and apply the epoxy to it with a plastic putty knife.

    • 6

      Press the mat that's the size of the hole against the first. Using the blade of the plastic putty knife, work the second layer of fiberglass into the first.

    • 7

      Apply a layer of epoxy to the second layer and apply third layer of mat, working it into the second with the putty knife. Apply epoxy once more, followed by the fourth layer of mat.

    • 8

      Apply additional layers of mat and epoxy, four layers at a time, until the hole is filled in. Permit the epoxy of each four thicknesses of fiberglass to harden before you add additional layers.

    • 9

      Remove the plastic film after 24 hours. Wax, with an automotive paste wax, and buff the finished repair with an electric buffer.