The stringer is an important part of a surfboard. Not all surfboards need to have stringers. Obviously having no stringer means that the board will be a quite a bit lighter. But I figured that the existing foam was low density polystyrene anyway, and some extra weight from a stringer wouldn’t affect the performance too much.
I had three main reasons for having a stringer:
- I wanted to give my board a little more support and durability, since the original foam was already damaged.
- Having a stringer makes shaping the board a little easier by giving you a frame of reference.
- You can set the rocker. The existing foam from the soft-top surfboard had a very high rocker, and I wanted to have a flatter rocker without sacrificing too much foam. I could bend the foam and glue it to the stringer to hold it in place to reduce the rocker.
I looked into using different materials for the stringer. Ideally, I would have used balsa wood. But I then I would have had to buy a bunch of pieces (as they only come in small pieces) and glue them together. To me, this didn’t sound too strong structurally, and I imagined a bunch of stress shielding and crack propagation. Now that I look back I still wonder if I should have gone with balsa wood. I also looked into getting a piece of Paulownia, but the only places that would supply the wood were far away, and weren’t too good on the communication side. I was impatient, raring to get started, and went to the local hardware store and bought a sheet of 3-ply plywood.
Below is an image of the design of the stringer that I had come up with. As you can see in the image below, I will be reducing the rocker from 6″ to 5″ at the front. Since I am cutting the tail shorter and introducing a swallow tail, the rocker of the stringer will be 2 1/4″ at the tail end (dotted line).
Below you can see the marked up the shape of the rocker on the sheet of plywood and some of the tools I used to do it. A ruler was used to mark the first few feet from the head and the tail. The distance of the top and bottom surfaces of the stringer was marked onto sheet of plywood (Note: the thickness noted in the image above was the original thickness of the blank). Using a long thin piece of wood (left of the foam), I joined up all the dots to create a smooth outline. I made sure to avoid any knots so that all the fibers in the on the outer plies were pointing towards one direction.
Cutting out the stringer
Once I was satisfied with the outline of the stringer, I used a jig saw to cut out the stringer. If you’re wondering why I had clamps, at this stage the stringer was a bit rough, so I used some low grit sandpaper to make the edges smooth.
The next step is making the blank. More in the next post!