Hi,
I'm pretty new to the board. I was just looking around and found this thread. Last year I built a small plywood boat and coated it with epoxy and then spar varnish. I've also done a lot of research on the web about epoxy and boat building lately. I've learned a lot, mostly stuff not to repeat. Based on my limited experience, I can offer some observations and suggestions. Some of these have already been touched on in previous posts.
1) Epoxy resin is excellent for stabilizing wood that will be exposed to water, both because of its superior bond to the wood and the fact that unlike polyester resin it's impervious to water.
2) But it hates light. It will turn dark and weaken over time if it's not protected with paint or a clear coat with UV inhibitors.
3) It doesn't have much surface tension when in liquid form, so it's difficult to achieve a smooth finish on an application thick enough to protect the wood.
4) It's a bitch to sand. Hard as a rock. Substantially harder than polyester resin.
5) Its much stronger in compression than in tension. In other words, it doesn't hold up to bending loads unless it's reinforced with glass cloth.
Based on all that, I would use the finest glass cloth I could find, 3/4oz to 1.5 oz, on the wood when you coat it with resin. The cloth will ensure a uniform thickness of resin, it will wet out clear, and it will strengthen the epoxy. It will also be fairly easy to sand to a smooth finish. Then I would coat it with a clear two-part polyurethane like Interthane Plus or spar varnish. The varnish will scratch easier and need more maintenance. Here are some links you might find informative:
http://www.oneoceankayaks.com/Epoxresl.htm
http://www.oneoceankayaks.com/Wshophtm/Shop28.htm
This guy did an exposure test on several brands of epoxy resin and the results may help you to decide on who's epoxy you want to use. I think Raka performed best overall.
Good luck with the project.
Dave