DIY Surfboard Fin
About a year ago I made a wooden longboard fin and it was a fun challenge. I decided to take it a step further and make one out of fiberglass. It also was a fun project and I am really stoked with the results. Below is how I did it, but keep in mind that I am not a professional and learned a lot during the process. There are probably better ways to make your own fin, but this way does work.
The Layup
The first step in the process is to layup a bunch of layers of fiberglass into what I believe is called a resin panel. I used 36 layers of 6oz fiberglass which should have been just enough to fit in a single fin box, but ended up being slightly too thick. This is probably because I didn’t squeegee enough resin out during the layup because multiple sources I've found online say that my panel should have ended up being too thin. Anyways, 36-38 layers seem to be the accepted number.
I opted to use Total Boat Epoxy for my fin. Epoxy is great because it's really strong and still has a good amount of flex. Total Boat also supplied the resin for this build so huge shout out to them.
As to the actual process, I started with a silicone mat I got on Amazon (epoxy doesn't stick to silicone) and working with 2 layers of glass at a time, poured out the resin in my design and spread it out to wet the entire sheet of glass. I did my best to soak everything but did end up with a few air pockets and dry spots in the final product. It's not a huge issue but something to improve on for my next panel.
This process took longer than I thought and I had to stop halfway through because the resin started to kick. I let it cure for a couple of hours and came back to finish it off.
Cut Out Fin Blank
After letting my resin panel cure overnight, I got on Blending Curves and printed out a few templates. I want these to be removable fins but the templates are designed for glass-ons, so I took one of my regular fins and traced the base onto my print out. I then cut these out and transferred them onto my panel. Then, using a jigsaw, I cut my blanks out of the panel. I wasn't sure what type of blade to use for this and went with a wood blade. It got the job done but the epoxy dulled it pretty quick.
Foiling
The next process is to shape the fin into the final product. Using a combination of my bench top belt sander and my variable speed sander/polisher, I shaped the fin down to size. I didn't have too much of a plan going into this step, and just went with what felt right. I probably ended up making it a little too thin, but I am satisfied with the results.
This was the most difficult part. Trying to find the right balance of foil on both sides while still having a nice flow to the fin was not easy. It helped me understand why fins cost as much as they do. Experienced professionals are great at their job and deserve every penny.
Installing Hardware
At this point, I measured out and drilled a couple of holes, the first for the pin to hold the fin in the box and the second for the screw to tighten it down. For these, I started with a really small drill bit and slowly sized up to the final size. I secured the pin into fin with a little epoxy.
Finish
Because I had a couple of dry spots in my fin, I wanted to do a ‘polish’ coat of epoxy. To do this, I hung it from a shelf and brushed on a layer of epoxy. Once cured I gave the fin a final sanding and it was good to go!
The Final Product
Overall, I am super happy with this fin. It is really responsive in the water and it looks great. It is quite stiff which works well for the boards I've used it in, but I would want to experiment with getting more flex. This was a fun project that I will 100% be trying more in the future.
Stay Stoked!
