How to Mount Boat Cleats to Fiberglass

Written by c.l. rease | 13/05/2017
How to Mount Boat Cleats to Fiberglass
Cleats provide a mooring point for a docked boat. (ballinamore county leitrim image by Keith Nolan from

Cleats allow you to moor your boat safely to docks or anchor your boat when out on the water. Installing cleats on a fibreglass boat requires planning and patience. Rushing the process will cause cracks in the gel coat covering the fibreglass and reduce the strength of the fibreglass underneath the cleat body. Using the proper to tools and techniques when installing a cleat on a fibreglass boat will ensure the cleat remains strong even under tough conditions.

Set the ends of the threaded rod on the bottom of the cleat on the area of the fibreglass boat requiring the mooring point. Run a pencil around the outside of each threaded rod. Remove the cleat from the surface of the fibreglass.

Measure the width of the gunwale and the distance between the threaded cleat rods with a tape measure. Add 2 inches to the distance between the threaded rods.

Insert a drill bit measuring 1/8-inch larger than the diameter of the threaded cleat rods into the chuck of a drill motor. Set the drilling direction of the drill to "Reverse." Drill a 1/16-inch-deep hole at each pencil-marked location to cut through the fibreglass gel coat. Switch the drilling direction to "Forward" and finish drilling the holes through the fibreglass.

Cut a piece of 3/4-inch marine-grade plywood to the earlier measured length and width with a jigsaw. Drill two holes -- matching the fibreglass hole locations -- with a drill bit 1/4-inch larger than the fibreglass holes. Remove burrs from the cut and drilled edges by sanding them with 100-grit sandpaper.

Mix 2-part epoxy per the manufacturer instructions. Apply the mixed epoxy on all faces and edges of the cut plywood with a small paintbrush. Allow the epoxy to cure for 30 to 45 minutes. Apply marine-grade sealant to one face of the plywood and around the connecting point of the threaded rods and the cleat body. Align the plywood holes with the fibreglass holes. Press the plywood tight to the fibreglass.

Slide the threaded cleat rods into the fibreglass holes and through the epoxy-coated plywood. Thread the cleat-mounting hardware on the threaded rods.

Tighten the cleat hardware with a matching socket, slid onto the end of a 14-inch extension rod, attached to the end of a 3/8-inch drive ratchet handle. Remove excess sealant from around the cleat body with a clean rag. Allow the sealant to cure for 24 to 48 hours before using the cleat.

Things you need

  • Pencil
  • Tape measure
  • Drill bit set
  • Drill motor
  • 3/4-inch marine-grade plywood
  • Jigsaw
  • 100-grit sandpaper
  • Two-part epoxy
  • Small paintbrush
  • Marine-grade sealant
  • Socket set
  • 14-inch extension rod
  • 3/8-inch drive ratchet handle
  • Clean rag

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