epoxy as varnish

[tnert]

So I have a wooden sloop, al natural. The centerboard trunk was rebuilt with Ply. I'm using West to seal the ply. I've noticed rot in the transom and have read a bit about CPES, an expensive thinned epoxy. I have used West on the centerboard trunk and have now saturated the transom with thinned West. I have also read of the dangers of "glassing" a wood hull. My question is: How does epoxy ALONE affect the wood. Should I consider it a superlative varnish, or am I encapsulating it in plastic. If I coated the hull in epoxy (with-out glass) what am I doing-- coating or encapsulating?

[Ed Harrow]

I'm not going to touch some of this, LOL, but epoxy alone will not stand up to UV. You need to put something over it to protect it.

[tnert]

Ya, I plan to coat the trunk with varnish. The question is: is the wood helped by absorbing expoxy and becoming stronger, or is it becomimg brittle and therefore weaker? An alternate thread could consider entymology of the word plastic which means flexible--have I got any of this right?

[Banjo]

G'day tnert? and ED.

I find the arguments against epoxy encapsulation quite amusing. Why?. What did people use to coat boats with _before_ epoxy came along? Paint... All sorts of weird and wonderfull concoctions were devised to keep water out, they even added rot inhibitors just in case the water got "past" the paint! smile.gif

The argument now seems to be that because epoxy is superior to paint as a water barrier that it works the other way and stops water getting out again thus creating the perfect environment for rot to develop.

This means that the construction of boats with encapsulation in mind using epoxy needs special care in areas of stress, abrasion, drainage, dockside bumps etc etc...
With the use of cloth and epoxy in varying layers in the areas noted above the problem of water ingress can be very minimal or eliminated totaly.

As for refurbishing an existing boat with epoxy great care must be taken to "NOT" encapsulate existing rot.

I have noted that many people advise the no epoxy aproach to boats that are moored, I have also noted that many people with trailerable boats or boats stored dry "still" get the same advice from these people!

In my opinion (based on logic and common sense) a boat that is continually plonked and pulled from the water is better off with the superior protection of epoxy and cloth where it matters.
Common sense also tells me that the same boat in storage should be protected from sun and rain just as you do your car, truck, caravan etc etc..

So what's my point? I dunno, I lost track...... Ohh that's it!

I advise everyone to look around, ask questions, listen to others then form your own opinion, use these points to guide your decision.

The size of your boat.
Your budget.
Will it be moored or trailered?
Is it a cheap throw away boat?
Will it be your last dream boat?

Geez I think I've opened a can of worms, seems to be more questions than answers! smile.gif

[Banjo]

Originally posted by tnert:
Ya, I plan to coat the trunk with varnish. The question is: is the wood helped by absorbing expoxy and becoming stronger, or is it becomimg brittle and therefore weaker? An alternate thread could consider entymology of the word plastic which means flexible--have I got any of this right?Ahhh just read this one..
Now you have opened another "can o worms" smile.gif

Some brands stay a little more flexible than others, but if the wood you are coating is going to do a lot of flexing, ie; tapered wooden free standing masts, and long spars then I have noted that a sealing coat or two of epoxy is ok with paint or varnish to protect from UV.

You have to keep in mind that not many parts of a boat bend or flex to the point of fracturing the timbers or even the epoxy on it's surface, so your concerns of epoxy elasticity are not needed in most applications.

[JimD]

The question is: is the wood helped by absorbing expoxy and becoming stronger, or is it becomimg brittle and therefore weaker?

The epoxy will be more water resistant than paint and stronger. Epoxy has to be quite thick before it becomes brittle, more than a coat or two or three.

[tnert]

I am not going to do this, but for the sake of argument: The boat is a 19' Lightning with a double planked cedar hull. If I coated one side (the outside) with unthickened epoxy -- no glass-- will the the planks still take on water and expand? If the coating is applied while the planks are swelled surely they would shrink. I think I'll limit epoxy to plywood. I'm just curious about CPES or other thinned epoxy that is absorbed into the wood and what it's effect is.

[Gary E]

As someone who was associated with Lightning #352, I am glad you are not going to glop it up with poxy... look up how old #352 is...

http://www.lightningclass.org/

and talk to other owners...
http://forum.lightningclass.org/

G

[Bob Smalser]

Originally posted by tnert:
-- will the the planks still take on water and expand? If the coating is applied while the planks are swelled surely they would shrink. I think I'll limit epoxy to plywood. I'm just curious about CPES or other thinned epoxy that is absorbed into the wood and what it's effect is.Epoxy allows water vapor to move in and out some...slowly. So the shrink-swell cycle is slowed, but not eliminated.

What concerns me is encapsulating old, punky wood and the attendant moisture-loving fungi that cause rot, then creating conditions so the wood can't dry quickly once it gets wet. You can also do that with paint...that's why many pre-epoxy old-timers kept interior coatings as light as possible.

And epoxy has both poor UV and heat resistance, so a protective coating is required.

[ 09-14-2003, 02:59 PM: Message edited by: Bob Smalser ]