How to Make a Wood Base for Boat Seats

Written by randal thomas
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Boat seats get wet and the water can rot the underlying wooden support base. Incorrectly fixing this base can lead to a seat that can't support a passenger. Additionally, the seat might absorb more water and weaken prematurely. Correctly replacing the wood base of a boat seat ensures you have the structural support you need in a boat seat and helps prevent future rotting. Boats might seem like money or time pits, but after fixing your boat seat, you will not need to throw any more time or money into that part of your boat.

Skill level:

Things you need

  • Ratchet
  • 3/8-inch socket
  • Measuring tape
  • 36-inch-by-36-inch square sheet of 1/2-inch plywood
  • Jigsaw
  • Pencil
  • Power drill
  • 3/8-inch drill bit
  • Waterproof enamel primer
  • Paintbrush
  • Three 3/8-inch washers, each with a minimum 1/2-inch lip
  • 3-inch-by-36-inc foam block
  • Scissors

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  1. 1

    Unzip the seat cushion.

  2. 2

    Remove the foam with as much care as possible, so you don't shred or tear it.

  3. 3

    Remove the original boat seat base using the ratchet and the 3/8-inch socket. You can usually find the bolts in a recessed groove, so you need to position the open seat cushion around until you can access each bolt. Depending on the seat, you might find three or four bolts.

  4. 4

    Measure the original seat base using the measuring tape.

  5. 5

    Cut the 1/2-inch thick plywood to match the dimensions of the original seat base.

  6. 6

    Lay the original seat base over the replacement base.

  7. 7

    Trace drill-hole circles through the original seat base's bolt holes using your pencil.

  8. 8

    Drill holes in the replacement seat using the power drill fitted with a 3/8-inch drill bit.

  9. 9

    Apply three coats of waterproof primer to the replacement seat base, allowing the primer to dry for 24 hours between each coat. Most factory seat bases do not have much if any treatment for the wooden seat base, so they can rot after two or three seasons. The waterproof primer will ensure the seat base can adequately resist future moisture damage.

  10. 10

    Insert the replacement boat seat into the seat cushion.

  11. 11

    Attach the replacement boat seat base to the boat seat using the ratchet, making sure to fit the bolts with the 3/8-inch washers. Do not use the old washers as factory washers come in small sizes that can't displace the pressure of the bolt on the wood, so the bolts can crack the wood and allow water damage to soften the area around the bolt. A wide washer displaces the pressure and keeps the area around the bolt head solid.

Tips and warnings

  • Make sure when finishing the wood base to cut replacement foam to match the shape of your seat using the scissors. Pack the cushion into the vinyl seat, making sure to allow a 1/2-inch space, so you don't stress the seams or stretch the vinyl too hard around the corners of the base.

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