Shop around, here is Z-spar Captains for less

http://store.hamiltonmarine.com/browse.cfm/varnish-captains-w-ultra-violet-shield-137763/4,402.html

Different epoxies and different finishes are combinations of chemicals which may or may not be compatible.

The first varnish I used on three day old epoxy never cured. Captains cures well on System Three and MAS epoxy.

I've tried many finishes and varnishes. I like the way Captains brushes out and gives me enough time to go back and fix a missed spot.

Captains is not the most durable, but it's easy to apply and looks great. All the boats on my web site are coated with Captains 1015

Rob