Recoat inside of Foam Core Canoe?

I have a MNII Foam Core UL Kevlar. It has some scratches, and blotchiness on the the inside bottom. What can I use to to recoat it? I saw a post where someone used polyurethane.

If it
has never been recoated the factory told me I could use polyester resin. In my case there had been epoxy used at some time so I got a poor job using Poly.

Marine Varnish
Seems like a common technique mentioned for this is to wash/scrub with denatured alcohol and then put down a couple coats of marine varnish for uv protection. I bought some epiphanes varnish and plan to try it.