: I have some preliminary test results of various coatings for polyester skin.
: I did 4 samples, water-based urethane (Varathane Outdoor Diamond Wood
: Finish), oil-based urethane (Minwax Helmsman Spar Indoor/Outdoor), spar
: varnish (Z-Spar Captain's), and elastomeric roof paint (Snow-Roof, primed
: with Elast-o-Seal).

Hey Mike Don't you think you should also try epoxy as your coating since you are testing these other materials. It also might be worthwhile to try an abrasion type test to mimic what might happen if your moving kayak scraped across a rock or hard surface. This is where you might see the coating separated from the polyester if the initial bond is not strong enough and that seems like a priorty in this situation. Epoxy may form a stronger bond and it should exceed the other coatings in abrasion resistance but you would need to find one of the more flexible epoxies to optimize the skin coating combo.

What weight polyester are you using? Marty H