How to Make Reinforced Polycarbonate Fins

Polycarbonates, a member of the thermoplastic polymer family, are better known as Lexan, Tuffak or Makrolon. This material is very strong and resilient, and it is often used in surfboard, kiteboard, wakeboard and water ski fins due to its rigidity and ability to be formed through the use of heat. Although polycarbonate material is strong, when fins made from it come into contact with rocks, cables or other hard surfaces, they can and will often break. You can strengthen the material further by coating it in Fiberglas. Don't worry; it isn't very difficult.

Things You'll Need

  • Polycarbonate sheet (6 mm thick)
  • Jigsaw
  • Isopropyl alcohol
  • Fiberglas cloth
  • Fiberglas epoxy resin and hardener
  • Paintbrush
  • Sandpaper
  • Eye protection
  • Respirator
Show More

Instructions

    • 1

      Trace the outline onto which you would like to build your fins on a sheet of polycarbonate plastic. Include the mounting block sections, if necessary.

    • 2

      Cut out your fins using a jigsaw. Follow along the line marked onto the surface of the polycarbonate.

    • 3

      Clean the polycarbonate fins using a cloth soaked in isopropyl alcohol to remove any grease, oil or other debris that will prevent the Fiberglas from adhering properly.

    • 4

      Mix your epoxy resin and hardener according to the manufacturer's directions, wrap the fins with a single layer of Fiberglas cloth and paint on the epoxy using a paintbrush. Completely saturate the Fiberglas cloth with the epoxy.

    • 5

      Add subsequent layers of Fiberglas cloth to the fin saturated with epoxy, based on the desired maximum thickness to which you would like to build the fins. Set the fins aside for 24 hours to allow the Fiberglas and resin to cure and harden.

    • 6

      Sand and shape the Fiberglas-coated fins using 80-grit sandpaper wrapped around a sanding block. Concentrate on thinning the fin's trailing edge, as well as rounding the leading edge. The thickest point of the fin should be about 1/4 the length of the fin from the leading edge. Once the contours of the fin have been attained, go over the fins with a sheet of 400-grit sandpaper wrapped around a sanding block to smooth them. Install as you would a regular fin, and enjoy a much stronger, glass-reinforced polycarbonate fin system.