How to Make Surf Fins

Choosing to make your own surfboard fins blows the lid off the possibilities for fin shape, materials, and production methods.

Depending on your resources and ingenuity, you can make surf fins that look like they belong on a secret government flying machine or like they used to part of a fence. The choice is yours.

You’ll just need a design, some tools, and materials to get going. And lucky for you, you’ve got plenty of options.

Materials Needed to Make Your Own Fins

For the average home-builder, the following list of materials and tools will get you going with DIY fin building:

Materials

  • Wood (if making wood fins)
  • Fiberglass
  • Epoxy resin & hardener
  • Tools
  • Jigsaw or bandsaw
  • Variable speed sander/polisher
  • Sanding pads
  • Sandpaper
  • Squeegee (or something to spread resin)
  • Scissors
  • Gloves, eye goggles, face mask
  • Measuring tools (e.g. ruler, micrometer, etc.)
  • Clamps

Designing Your Own Surf Fins

The first step to making your own surfboard fins is designing them. You can either mimic a fin you’ve got handy or you can design your own.

When designing your own fins, you’ll want to consider:

  • What surfboard you’ll be using the fin(s) with.
  • What kind of surfing you want to be doing.
  • What kind of waves you’ll be surfing.

With those things in mind, you can start to think about the different combinations of fin characteristics you can use to achieve what you’re looking for.

If you’re designing your fins by hand, a ruler, an angle guide, and some french curves can be useful. Or you can always wing it. Draw the outline of your fin either onto a template or on your material itself.

FinFoil for Designing Surf Fins

If you want to get a bit more advanced, you can choose to design and model your fin in a CAD program. If you’re not sure familiar with CAD, finFoil.io is a perfect option.

finFoil.io is open source, free software designed specifically for making surfboard fins. You have the option of using the online editor or the desktop version to design whatever fin you want.

The finFoil editor allows you to easily define units, fin depth, and maximum and minimum thickness. With a vector-like anchors and handles, you can edit the surfboard fin’s profile, sweep, and base.

You’re also able to import an image file of a fin or whatever so that you can trace a fin profile that you like to use as a starting point.

Making Wood Surfboard Fins

If you’re making your surfboard fins out of wood, you’ll simply need to transfer your template onto your sheet of wood and cut out the profile using a jigsaw or bandsaw.

After that, you’ll be ready to foil your fin.

Once your wood fins are foiled, you’ll then add a layer or two of fiberglass and resin – then you’ll be ready to surf.

Making Fiberglass Surfboard Fins

If you want to make your fins out of fiberglass (or carbon fiber, or G10), you’ll need to create a sheet panel.

To make a panel of fiberglass, you’ll need about 30-50 layers of 6oz glass (depending on the final thickness of your fin). A single layer translates to roughly .01”.

Lay down a flat piece of glass or wax paper and begin laying a few layers of fiberglass. Add a enough resin to saturate the layers until you’ve finished – working a few layers at a time.

Allow your panel to dry completely before removing it from the surface. You can take a razor blade and cut around to edges to make it release a bit easier.

Using a carbide blade, cut the profile of your fin out of the fiberglass panel and get ready to foil the fin.

Be sure to wear plenty of protective equipment when working with fiberglass and resin in any capacity (goggles, respirator, etc.).

How to Foil a Fin by Hand

Once you have your fin template cut out, you’ll be ready to begin foiling your fin.

You’ll want to work slowly and gradually so you don’t take too much material off at once.

Clamp your fin in place and take your variable speed sander with a sanding disc attached.

Generally, you’ll want your leading edge to be a bit rounded and more gradual, and you’ll want your trailing edge to be sharper. Varying the angle of the foil will alter the performance of the fin.

Move your sander from the base of the fin to the tip at the same angle throughout the entire motion and repeat until you have the desired foil on each side.

Finished up by sanding smooth. If you’ve made wood fins, you’ll be ready to glass them.

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