How to Make Fiberglass Fins

The fins of a surfboard allow for better control of the board. Having the right fiberglass fins might help you go from hodaddy to hotdogger, might even help you make it to kahuna. To make a fin out of fiberglass for a surfboard, the proper steps and materials are essential. It is easy to create a fiberglass daggerboard to keep the surfer from tipping. The hard part is hanging ten on the end of your board.

Things You'll Need

  • 4-inch-by-7-inch fiberglass sheet
  • Handsaw
  • Pencil
  • Vise
  • Handheld sander
  • Resin
  • Surfboard-specific hardener
  • Paintbrush
  • Sandpaper
  • Acrylic glue
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Instructions

    • 1

      Draw a fin design on a piece of cardboard with a pencil. Fins usually resemble those of shark fins. This is a rounded triangular shape that is long and thin. Six inches long and 2 inches wide is a good-sized fin.

    • 2

      Trace the fin template onto the fiberglass with a pencil.

    • 3

      Cut out the fin design from the fiberglass with a handsaw. Cut out the shape with about 1/4 inch extra space around the template, making the fiberglass cutout larger than the fin template.

    • 4

      Put the fiberglass fin in a vise and shape the fin's edges with a handheld sander. The back side of the fin needs to be thinner than the front side. The entire fin, except the end that will attach to the board, needs to be rounded. Rounded edges will cut through the water with less resistance than a flat edge.

    • 5

      Mix 1 ounce of resin with 1 ounce of hardener. Coat the entire fin with the mixture and let dry for about an hour. Recoat the fin with the resin and hardener mixture and let dry and set overnight.

    • 6

      Sand the fin with sandpaper until it is smooth. Attach it to the surfboard using acrylic glue.