How to Repair the Fiberglass Gel-Coat on a Fender

Repairing a fender, the bumper you hang between boat and pier, is a small project. Repairing the gel-coat finish on a fender is an even smaller project, but still one to be attacked as if it's your reason for living. The gel-coat finish will not cure while exposed to air, so it's imperative that you cover the fender in an air-tight cocoon while it dries.

Things You'll Need

  • 220-grit sandpaper
  • Gel-coat repair kit, color-matched to the fender
  • Clean plastic cup
  • Plastic wrap
  • Duct tape
  • 600-grit sandpaper
  • Automotive paste wax
  • Soft, clean cloth.
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Instructions

    • 1

      Sand the surface of the fender with 220-grit sandpaper, to give the gel-coat a surface to which it can adhere.

    • 2

      Dispense 1 ounce of gel-coat resin for each square inch of the gel-coat finish that requires repair into a clean plastic cup.

    • 3

      Add 4 drops of the gel-coat hardener to the cup for each ounce of gel-coat resin. Mix the resin with a clean plastic picnic knife. Stir up all of the resin from the bottom, sides and corners of the cup -- to confirm the hardener and resin are thoroughly mixed.

    • 4

      Spread the gel-coat resin onto the area requiring repair on the fiberglass fender by using a plastic spreader, like those found in paint shops. If it bulges, fine; it will shrink as it cures.

    • 5

      Wrap the fender in plastic wrap. Secure the plastic wrap with duct tape. Tape the edges of the plastic wrap down, to exclude air from the repaired area.

    • 6

      Allow the gel-coat to cure for 24 hours. Remove the plastic wrap and lightly sand the area with 600-grit sandpaper. Clean away the sanding dust. Wax the fender with automotive paste wax. Hand buff the fender with a soft, clean cloth until it displays a mirror finish.