Well, the concept calls for three coats of epoxy on EVERYTHING to render the wood basically inert, and prevent ANY moisture exchange (which creates expansion and contraction and stuff) and then spar varnish (read varnish with UV inhibitors) to protect the epoxy.

  That being said, it is all marine grade materials and varnish alone would likely perform just fine.  In fact they don't call for epoxying the mast and booms just because it's so much extra work... 

  I would epoxy it all.  But the sky isn't gonna fall if you don't.  

   The boat is now clean, dry, in the shop, etc., etc..  Put the epoxy on, says me.  A bit more work now, but a whole lot of future effort saved.  Varnish over bare wood, IF, and that is a gigantic if, regularly maintained can supposedly go forever without ever going back down to a bare wood refinishing project.  I've never seen that happen.  However, varnish over your epoxy will last much longer between the need for any varnish touch-up, and touch up really should consist of only light sanding and a few new coats of varnish for the life of the boat.  Depending upon usage and storage, here are my rough estimates of the time you'll need to be going back for about 2 maintenance coats of varnish. There will be a contiuous spectrum between these extremes, and these are only personal opinions, but based on experience.  And if over bare wood, you'll probably only get to repeat the refresh cycle a couple of times before a complete refinish.  Over epoxy you should be able to refresh basically forever.:

Varnish over wood:

heavy use, tropical sun, stored outdoors, usually covered: 1-2 years

light use, stored indoors: 3-5 years

Varnish over epoxy:

heavy use, tropical sun, stored outdoors, usually covered: 2-3 years

light use, stored indoors: 5-8 years

Also keep in mind that Okoume is rated as a non-durable wood because of its softness and poor rot resistance. Those problems are solved with an epoxy coating because epoxy seals the wood against water and provides a formica-hard abrasion resistance layer. For the smaller types of paddling/rowing boats sold here it's the ideal material - light, flexible and available in large high-quality plywood sheets - as long as it's encapsulated in epoxy.

For larger boats it still works but requires complete covering in glass, inside and out. A fiberglass layer provides much better sealing and abrasion resistance.

Even full-size blue-water cruising vessels can be built from Okoume. Those typically use the wood as a core for composite construction with the outer layers being heavy unidirectional glass and/or carbon fiber. That's way beyond what an NE Dory needs, but it shows that with the correct coatings even serious boats can be made from a soft, rot susceptible wood as long as the correct coatings are used.

If that was my boat I'd buy the extra epoxy in a heartbeat.

Laszlo

   I think Bubblehead and Laszlo have given just the right advice. My dory with light use and stored in the garage is holding up beautifully .  . . But I'm very pleased to have it fully encapsulated in fiberglass/ epoxy. 

   I'm on boat # 5 and I've always had to buy extra epoxy I always wind up wasting  alot