About 20 years ago, my stepfather built a 14' wooden skiff based on a design by Arch Davis. The boat is okume plywood over mahogany and poplar frame. I inherited the boat a few years ago and have used it sparingly. It is still in decent shape but it is due for a little maintenance. A perennial problem was a slow leak from around the seams of the centerboard. I am not sure that I will be able to get any finish in the "slot" on the underside of the boat so my only option may be to seal it from the inside.

The boat could also a coat or three of finish on the bottom of the boat and on some of the interior wood. I don't have much experience finishing and am wondering whether I should use spar varnish or something more robust. My only experience with epoxy is as an adhesive, not as a finish. Any help is appreciated and thank you in advance.