wood,epoxy and heat

[fedor]

Hi all,

I stumbled upon this in a couple of books recently. Some authors claim that tropical heat can affect epoxy-treated wood, softening the bond. As I have epoxy-treated plywood decks and plan to start traveling southbound very soon - can somebody please advice me if there is any truth in it? (Actually, those authors advocate traditional boat-building methods against more modern cold molded/strip plank +epoxy construction. The idea of epoxy bonded strip plank boat slowly falling apart under tropical sun does not seem real to me, but you never know...)

Fedor.

 

[ccscott49]

Epoxy is not "boil proof" as the proper marine ply is, because it uses a different glue, but unless your boat gets so hot it would melt a fibreglass one, I don't think you need to worry unduly! Theres another thread hereabouts/recently, which explains all this. But I am not worrying but my wooden boat is pre-epoxy. My brothers mast is epoxied together, and he's been round the world with his boat, twice and has never seen any problem with it.

 

[Peterduck]

The softening point of epoxy resin is supposed to be 50 deg. C. This temperature is achievable in surfaces exposed to the direct sun, even here in Melbourne at lat. 38deg. S. However, I tried once to rectify a student's mistake where he had glued two pieces of plywood together when misaligned. I used a heat gun to heat the pieces of plywood up to the point where I could separate them. By the time they were coming apart, the wood was also charring! I don't think that this was anything like 50 deg. C. In short, go ahead!
Peter.

 

[fedor]

Thanks a lot for your reply, David

I think in the case with charred plywood you have to take in mind poor heat conductivity of wood.
In other words, to achieve 50 degrees between two sheets of laminated ply, you will probably need to raise the temperature on the outside to something much bigger.

I will try to do some experiments of my own...

By the way, are you running some kind of boatbuilding school?

Ted.

 

[ccscott49]

Don't bother doing the experiments, your boat won't fall apart in the tropics, have anybody elses?

 

[fedor]

Sure it will not!

I'm just curious how much truth is there in certain "gurus" writings...

 

[PBrooks]

...however, to be on the safe side, it's probably a good idea not to paint things matt black - stick to light(er) colours if you can.
Best regards
Paul

 

[Peterduck]

I once had a plywood trailer-sailer which I painted darkish mid-green, and in summer, when I used it most, it became quite hot inside. Dark - coloured boats are very rare here in Melbourne.
To answer Fedor, I wasn't so much running boatbuilding school, but helping some "Kids at risk" at a local school by helping them to build a number of small dinghies from kits. This was to give them a sense of self - worth, that there was something that they could do, and that there is some value in learning.
Peter.