How to Fix a Leaking Boat Deck

A leak in a boat deck comes from multiple failures in the boat's watertight integrity. The first failure is the caulking, the material that fills joints that aren't routinely sealed. If caulking is used, as it is on wooden decks, the water must penetrate the caulking first. The second failure is in the deck -- a crack in the fiberglass or, on wooden boats, damage to a plank. Short-term fixes and long-term cures are available for a leaky boat deck.

Things You'll Need

  • Two-part marine epoxy
  • Small container
  • Putty knife
  • 1 1/2-ounce fiberglass mat
  • 320-grit sandpaper
  • Orbital sander
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Instructions

    • 1

      Locate the source of the leak.

    • 2

      Mix two-part marine epoxy in a small container. Spread the marine epoxy on the crack from above, using a putty knife.

    • 3

      Cut a piece of 1 1/2-ounce fiberglass mat large enough to cover the crack, if the crack is substantial. Wipe the crack with acetone. Grind the edges of the crack to form a "canyon" the length of the crack, using an orbital sander and 40-grit sandpaper.

    • 4

      Press the mat into the epoxy. Apply epoxy and fiberglass, pushing the fiberglass mat into the epoxy each time. Repeat three more times.

    • 5

      Remove the ceiling panels, if any, from the overhead of the compartment directly below the leak. Spread the marine epoxy on the inside of the crack -- from below deck -- using a putty knife.

    • 6

      Replace the ceiling panels in the overhead. Move to the deck and sand the patch down to the level of the deck, using 320-grit sandpaper and an orbital sander. Paint the repair, if desired.