Fixing Glass-On Fins
I recently picked up a fun looking board that had been neglected for a while. The board was covered with dings, as you would expect from a board of this age, except for the glass-on sidebites. They were de-lamming and it looked like there was dirt shoved between the glass and the wood. It was clear that this was more than just a patch job, so I set to work.
(It’s kind of strange for a 9 foot board to even have side bites like this and I considered taking them off and leaving the board as a single fin. Ultimately I decided against this because there are two deep channels running down either side of the stringer almost like a Bonzer. Because of this, I opted to keep the board as was originally shaped.)
Removing the Fins
The first step of this repair was to take off the existing fins. There are lots of ways to go about this, but I ended up using my rotary tool (an off brand dremel) with a cutting wheel. An angle grinder would have been faster, but I still hadn’t added one to my tool box at this point. Once I cut through the fiberglass, the fin was fairly loose but I had to pull it out to break the roving.
Cleaning Up the Aftermath
The fins left a decent sized groove in the board that had to be cleaned up before anything could be reattached. I took my sander to the board with a 60 grit sheet. I made sure to sand down all around where the new fins would be so that I could see the weave of the fiberglass.
Cleaning Up The Fins
After the fins were off the board, I was able to take a good look at them. I determined that it would be too much work to get the fins back in good shape so I decided to make new ones. I grabbed some baltic birch plywood I had laying around, cut out the rough outline and used my belt sander to shape and foil them. A quick coat of wood stain helped them match the board and they were ready to go.
(If you are doing a similar repair and don’t want to make new fins, you would strip off all the glass used to attach the fins to the board. Once down to the original material, you would sand the fin so it will bond to the resin better when you glass it back onto the board.)
Glassing On the Fins
At this point, I just glassed on the fins like normal. I used a small amount of resin to glue them to the board at the correct angle and toe-in. Once dried, I used fin rope at the base and then laminated both sides of the fin with a layer of 6 oz fiberglass. My lamination was a little messier than I would have liked so once it cured I sanded all the bumps out. I then hot coated the fins and sanded them to a nice smooth finish. Once that was done, the fins were ready to go.
This kind of repair isn’t the easiest ever, but is totally doable for someone who has a moderate amount of experience with fiberglass and resin.