Re: [Paddlewise] Sound of one hull cracking...

The fabric used in this boat is a Carbon - Kevlar weave. The boat was 
built in 1995 (but purchased new a few weeks ago) and I was informed 
that Valley has changed the way they cure the boat..it's now "baked".

The gelcote is almost glass like in brittleness and sort of 
shatters... a small impact produces a star like crack.

Great River stated that they will probably replace the boat once they 
have a chance to verify the details with Valley.

John, thanks for your detailed response. I'll pass on any specific 
information about the layup that I receive.



> This sounds like a defective gelcote? When I press on the hull, I
> hear the sound of one hull cracking!
> 
> (SNIPS)
> 
> I am not fond of carbon fiber where there will be impact or large localised
> loads. When it breaks it really breaks unlike Kevlar that has greater
> tolerance to impact. The problem with many of these hi-tech materials is
> that they require careful engineering. I remember when Kevlar first came
> along and people tried to build boats using regular polyester resins. What
> a disaster! It is important to match all the materials. These days builders
> are more savvy and use flexible vinylesters and flexible gel coats. Even
> so, things go wrong.
> 
> The problem with Bob's boat sounds (but may not be) like a rigid polyester
> gel coat or maybe even an incompatible gel coat (incompatible with the
> laminating resin). One really has to see the thing to form a reliable
> assessment though. I would like to know  what resin was used to build the
> boat and what gel coat. Of course, for the lay person this isn't much help.
> But at least one should know if the resin was epoxy, vinyl ester or iso or
> orthopthalic polyester. If it is one of the latter two then I would be
> upset.
> 
> Properly built carbon boats are remarkably strong especially when matched
> to the proper core material and with the fibers properly oriented. Usually
> they are made from epoxy pre-pregs vacuum and heat cured under pressure. I
> had a canoe that was built that way and it was truly remarkable. One of the
> great sins is to use the mixed materials (carbon/Kevlar) cloth. It looks
> sexy but the result is poor.
> 
> As Hank Hays says, "Carbon is not all it's cracked up to be"
> 
> Cheers,
> John Winters
> Redwing Designs
> Specialists in Human Powered Watercraft
> http://home.ican.net/~735769/
> 
> 
> 
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> 
Bob Denton
Gulf Stream International
Boynton Beach, Florida
Internet Web Site Development
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