: Lexan has incredible impact resistance. However it has one major flaw that
: may cause you to rethink using it. It is very prone to stress-cracking. I
: worked for a company manufacturing an underwater flashlight. The original
: spec called for a Lexan body and lens. It was incredibly strong. The lens
: could deflect a 38 slug fired at point blank range. But the pressure the
: o-ring between the body and the lens caused cracking in both sections. We
: check with the manufacture, GE, they verified the stress crack problem.
: The specification was changed to ABS and Plexyglass.

: I am not sure what kind of a design you are thinking of. However I would be
: very wary of the curved surfaced being subject to stress cracking. It
: takes very little pressure exerted over time to cause the cracking.
: Ignoring the bending stresses on the hull, I can also guarantee you will
: stress-cracks anywhere you have a through the hull fitting, like rigging
: hardware.

I wonder if the way Eddyline makes their carbonlite kayaks relieves those curved-hull stresses. If they're vacuum-forming, the heat would soften the plastic enough that deformation from the curved-hull state would cause stresses, rather than the deformation into the curved hull. Yeah, on a stressed, curved panel, you would definitely see stress cracks at through-hulls.

I wonder if the hull could be heat-treated. Similar to heat-treating or annealing of steel. Make a large oven and put the finished hull in it. Raise the temperature high enough to relieve the stresses, but no so high the boat gets soft and deforms.

Heck, a lexan or plexiglas kayak model would look pretty cool. I'm not saying Johnnie shouldn't build his--I'm thinking that building that sort of model for my own wall would be neat!

Shawn