[Public-List] Epoxy failure [was Steam bending Teak]

[Rachel]

On Feb 3, 2010, at 3:33 PM, Robert Kirk wrote:

>
>> Have you heard of any instances of failure due to creep of epoxy in
>> sailboat construction or repair?
>
> Haven't heard of anything, but I doubt if there's much use of epoxy  
> adhesive in loaded structural  things during boat construction, in  
> today's fiberglass boats.

That's what made me think of cold-molded boats.  As I understand them,  
they are made by layering thin wood plies with adhesive, and shaping  
them into a hull.  I don't know if epoxy is always used, but I do know  
it is used at least sometimes.  It seems like there would be a fair  
amount of creep stress there, wouldn't there?
> But, it's certain that it does creep under load, so I just wouldn't  
> use it to glue highly stressed laminated beams together and expect  
> them to retain their shape over many years... Bob

I know of several people who have made either mast beams in fiberglass  
boats (similar to the ones in an A-30) or structural beams (such as  
overhead beams and hanging knees) in wooden boats with epoxy between  
the lamina, and I have not heard of problems.  These beams are  
probably mostly not over 20 years old though.  Still, that's a pretty  
good track record.

I'm skeptical by nature, so I'm very willing to decide a product is no  
good; but then I also worry that perhaps epoxy is being discounted  
unfairly.  I like resorcinol, and think it's a good glue; but I also  
use epoxy and feel comfortable with it.  OTOH, if there is a good  
reason not to use it, then I want to know about it, absolutely :)


Rachel
ex-#221


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