How to Fix Boat Transoms

A boat transom has an inner and outer fiberglass skin, separated by the boat's framework and the hull's core. If the transom develops soft spots, it means that the water has caused the fiberglass to separate from the core. This problem is called delamination. As the delamination spreads across the transom -- as it will, if left unattended -- it compromises the structural integrity of the transom and may lead to a sunken boat. You can prevent this with a timely repair.

Things You'll Need

  • Reciprocating saw
  • Hammer
  • Chisel
  • Chain saw
  • Pry bar
  • Duct tape
  • Transom filler
  • Clean bucket
  • Orbital sander
  • Orbital sander
  • 220-grit sandpaper
  • 420-grit sandpaper
  • Paint
  • Automotive paste wax
  • Electric buffer
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Instructions

    • 1

      Cut the top of the transom off with a reciprocating saw. Chip the flotation material out the transom with a hammer and chisel.

    • 2

      Remove the wooden framing from between the inner and outer transom skins, using a chain saw, hammer, pry bar and chisel. Repair any damage to the fiberglass -- use duct tape to cover holes smaller than a dime -- according to the transom filler's directions.

    • 3

      Mix the transom filler according to the manufacturer's directions in a clean bucket, using a drill and mixing attachment. Pour the transom filler in as soon as you have finished mixing. Attach the spacers provided by the transom filler manufacturer to the inner and outer fiberglass transom skins, to space the skins properly.

    • 4

      Mix a second bucket of transom filler, if necessary. Pour the second bucket into the transom as soon as mixing is completed. Allow the second pouring of transom filler to cure completely before adding any more filler.

    • 5

      Add additional transom filler as necessary. Sand the top of the transom filler flat, using an orbital sander and 220-grit sandpaper.

    • 6

      Replace the fiberglass transom cap on top of the transom. Apply the repair material specified by the filler manufacturer to the seam. Sand the repair material flat with 420-grit sandpaper.

    • 7

      Paint the repaired seam, if desired. Apply automotive paste wax to the entire transom. Wait for the paste wax to dry. Buff with an electric buffer.