"Bill Tuthill" wrote in message
...
riverman wrote:

Hmm, I don't see an obvious easy solution to this, but what you're
envisioning doesn't look good. I once saw a royalex boat that was too
close
to a campfire reach the temperature where it lost its cohesive
stability.
The hull suddenly had the consistency of freshly cooked lasagna noodles,
and
it was was impossible to hold it in shape with our hands while it cooled
and
got rigid. We flopped it down rightside up on the ground, and to this
day it
still has a completely flat bottom because of that. If it had landed on
a
stick, that would have just gone right through the bottom.

Sounds like Royalex is a tradename for polypropylene. Is it?
Polypropylene has a very low melting temperature, but is otherwise
strong, lightweight and durable.


Royalex is a Uniroyal trade name for a laminate sheet of Crosslink Vinyl
sandwiching ABS sheeting and an ABS (or PVC) foam core.
http://www.easyriderkayaks.com/royalex_canoes.htm
The core itself has little strength, so the next layer of ABS sheeting gives
it backbone, while the vinyl coating provides UV and abrasion protection.
Its when the outer ABS sheet starts to melt that your troubles begin.

Lots of companies use different thinknesses of core, different coverings,
etc, but they are all 'Royalex', and all made by Uniroyal. Some of the
'other' names for Royalex are Royalite and Oltonar. Royalite uses a PVC core
and a thinner layup. Currently, the rights to manufacture Royalite is owned
by Spartech.
www.spartech.com

--riverman