There is a case to make for leaving narrow 3- or 4-sides-exposed wood parts above the waterline uncoated with epoxy --things like masts and rails. Epoxy is fairly brittle as far as waterproof glues go, and as a glue it needs the wood to be dimensionally stable. Wood movement is +/-99% driven by moisture changes, and epoxy is a fantastic moisture barrier. But narrow strips of wood don't have enough width to move much against their substrate, and when exposed on three or four sides they can quickly dry if/when wetted through scratches in the varnish.

Coating such parts with epoxy and then varnish makes scratch repairs more difficult, and thus perhaps less likely to be done. It's a trivial thing to keep a nail polish bottle of varnish around to touch up varnish as damage is found- it's a bigger process to sand away the varnish, cover the scratch with epoxy, smooth that, then repair the now much bigger gap in the varnish coverage.

For rails though, it's really important to coat and seal the upper exposed edge of the boat's plywood. Perhaps install your inner and outer rails 1/16" above the ply, then fill that trough with clear epoxy, and then sand the whole top surface flat. 

OK, I get it. Started the epoxy coating today to seal the rails and wales. Getting close to the finish line, so no need to back off now. Thanks for the   opinions.

Charlie D

Charles,

Glad to hear that you're sealing the rails and wales  with epoxy. I apparently didn't seal the exposed edge of the plywood well enough there and after 5 seasons, that's the only spot that I have to touch up before launching my Peeler this season.

Good choice,

Dick