[Paddlewise] THINK

Jeez, Doug don't start T-H-I-N-K-ing on us. I for one love your
shoot-from-the-hip,  tell-it-like it-is style. I find it refreshingly
honest. Sure some are going to be offended by your truths but if they don't
like it they can write back (like I am going to do later in this post) and
give their own take on the truth. Message: Deal with it! Please, lets not
stifle Doug's freedom to say whatever crosses his mind uncensored.

Doug, I really enjoyed your description of the kayak you own and love while
also describing all its warts. If all paddlers were as forthcoming as you, I
'd say Sea Kayaker should get their kayak reviews from owner/experts (as
well as expert paddlers using the kayak for the first time as they often do
now. No paddler using a kayak for a few times can know about all the warts
but an owner who paddles a lot and in all conditions often does.

Doug, I think you are wrong about the veil between layers of Kevlar or
Graphite but would like to hear the arguments (and if possible test results)
for laminating that way before making up my mind. Why not do it that way
between glass fabrics too if it really is advantageous? I certainly don't
think it is a good idea to mix materials as different as Kevlar and Graphite
cloth in layers because of differences in their modulus of elasticity (which
will make them prone to sheer between the layers). Maybe a glass veil
between different materials might help prevent this sheer failure (and this
may be what your source was actually talking about--this often surrounds
graphite reinforcements to Kevlar kayaks). I always thought it was just to
hold the unidirectional fine strands of graphite (that are easily spread
apart) in place during the laminating. I suspect that the veil between
layers of the same material may actually make a weaker layer and encourage
delaminating.
I like Kevlar and Graphite mixed in the weave of the same hybrid fabric.
That way the differing materials can't delaminate and allows you to gain the
best qualities of both materials (they work together rather than fighting
each other and shearing apart at the boundary).

Maybe this is the time to talk about Graphite as a kayak building material.
For sea kayaks I like it better than Kevlar because the most likely damage
to a sea kayak is going to come from folding it rather than from a blow.
Graphite is very stiff for a given thickness. Its downside is that it will
fail catastrophically if it gets bent enough (it doesn't have as much
tensile strength as Kevlar but is much stiffer and harder to bend--so more
brittle). Like Kevlar if you make it the same weight as fiberglass it will
be tougher than glass but normally it is used to hold the kayak into shape
with a thin lightweight laminate. Then it will be more vulnerable than glass
to blows but a lot less likely to fold up than a Kevlar kayak of the same
weight. By mixing them together in the weave of a fabric you can use that
hybrid to make a laminate that doesn't fold easily (due to the graphite) but
will take a tremendous blow without serious damage (due to the Kevlar). I
believe that Kevlar and Graphite that are sold for laminating with resin
have surface treatments that make them bond well with the resin (not
necessarily slippery on each other once in a laminate). I for one would
rather not add a veil layer between them that would both add weight and a
potential sheering layer between the woven fabrics (although it would build
thickness more cheaply). I am open to more feedback on this issue from an
expert on these fabrics though. I haven't done any scientific destruction
testing myself with veil in various laminates. The experimentation I have
done aren't very scientific either, they consists mostly of hitting it
(usually the cut-outs for rear hatches) as hard as I can with a hammer and
folding them as far as I can to see how easy they are to bend pound for
pound and how they fail (when you can get them to fail at all).

Duane, glad to hear they were really 8 to 12 footers. I thought they must
have been bigger (or there are some really mean 5 to 7 footers down there in
California) from your description of what happened to you when you bailed.
Matt Broze
http://www.marinerkayaks.com

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