Although I learned a lot about fiberglassing by using it on these fins I’m not sure I’d do it again. Although the added strength is wonderful the work that I went through finishing the outsides doesn’t seem worth it. Too many air bubbles or waves to fill. Not sure how to reduce that and still get a perfectly flat surface. I think next time I would increase the number of fiberglass/epoxy layers within the fin’s layers, then stick with sanding sealer on the outside of the plywood. Here’s a few more shots of spot filling the surface of the fins and primer, gradually getting the smooth surface I wanted.
After one last coat of primer I’ll hit them with some wet sanding at 600 grit to prep them for final paint.