How To: Fiberglass Boat Stringers

Preparing the fiberglass fabric

• 1

  Measure the thickness of the original skin on the stringer using your paper mic--a device that measures the thickness of paper, plastics and metals. Note that the top skin is likely to be thicker than the sides and underneath--known as the "tabbing". Determine the number of layers of fabric required to create the correct thickness.

• 2

  Measure the size, length and width of your stringer. Cut the appropriate number of strips from the fiberglass fabric. Cut the first strip extending as far as the original tabbing from one side of the stringer to the other. Cut the remaining strips 1/2-inch for each side.

• 3

  Lay out the fabric layers, stepping the fabric edges to make a tapered edge. Stepping the edges allows the load from the stringer to be distributed gradually to the hull. Wrap the stringer end with the same stepping effect at the bulkhead or transom.

Preparing the surface for fabric bonding

• 4

  Apply a degreaser or detergent to areas exposed to gasoline or oil build-up. Thoroughly clean the area with your solvent, wiping it dry with paper towel.

• 5

  Connect the grit disc to the hand drill.

• 6

  Grind the surface to a dull, no-gloss look. If necessary, clear heavily textured surfaces with a wire brush.

Applying the fiberglass skin to the stringer

• 7

  Wet the stringer and entire bonding surface with your mixture of fiberglass hardener resin. If the surface is heavily textured, apply a thin layer of 406 colloidal silica filler--at about the consistency of mayonnaise--to the surface, squeegeeing away the excess.

• 8

  Saturate the largest strip of fiberglass fabric with the hardener resin, squeegee away the excess. Center the strip over the stringer so that it covers the sides and top with approximately 1inch of fabric left on each side.

• 9

  Repeat Step 2 for applying each of the remaining strips. Step the fabric edges as you did when initially preparing the fabric. The last strip should extend 2- to 2 1/4-inch of each side of the stringer. Use a wooden craft stick to press the fabric into the inner corners.

• 10

  Allow the layers of fabric to reach its initial cure, per the instructions of your epoxy.

• 11

  Apply two additional coats of the hardening resin. The additional coats fills the weave of the cloth. Apply your coats while the previous coat is tack-free--before the resin becomes sticky.