Re: [Paddlewise] Boat Construction

Doug Lloyd wrote:

> A perfect
> example is the Gulfstream. The fellow had seen one too many with cracked
> back decks, etc. He ordered a heavy duty lay-up. It came in just under what
> the tougher hand-laid British version from P&H weighs. I rather think the
> vacuum bagging did save some weight in this case, and from what I saw,
> stiffness was addressed with judicious use of carbon fiber.
>

IMNSHO, CD uses too light a layup in the deck on all their kayaks.  I own a
Solstice GTH and enjoy it.  The fore deck, being arched near the cockpit and
peaked forward seems ok.  The rear deck, being flatish, seems just too soft.
I trust it, but...

It's interesting that CD's standard "expedition  grade" options (last I looked)
include heavier hulls and outside seams, but no beefed-up decks.


> Advertising in North America often
> suggests to customers that modern light weight kayaks are quality products
> with the implication that strength for rough water is concomitant with
> that. Conversely, I also disagree with advertising aimed at getting people
> into the sport, suggesting light is best and that heavier duty is only
> needed for the few. To me, that's herding the masses into a lightweight
> category of boat, thereby restricting participants from expanding to harder
> use. I get this all the time at the club: "Oh, I don't want to do that, my
> boat is too flimsy", or "Sorry, rule me out of the surf workshop, my kayak
> isn't built for that".
>

That point is well taken, but it's true in other sports.  It also works the other
way.  A certain Canadian Coop based in Vancouver insists on selling xc
ski equipment in Ontario that is well suited to BC's interior but not to the
much-more-common resorts of the East.  Hence I've seen folks in skis that
are too wide to fit into the ski tracks.  Caveat emptor.  It's up to us to
spread the word by mouth that the ads should be taken with a grain of salt.

>
> >> 9. All the above guides/instructors I know, also usually order the extra
> >> outside seams, [...]
> >But reinforcing may result in local stress concentration that increases the
> >likelyhood of failure.  The key is a balanced design;[...]
>
> Yes, agreed for the most part. This is part of the reason the Brits stay
> with straightforward lay-ups.

You know, the more I think about it, the simplest seam is probably the best.
Cosmetically, it would be a harder sell.  You've convinced me.  We can
probably do without the H sections and just toss the idea of trying to get a
strong seam with the geometric gyrations of wrapping around the H.
It's a subtle difference from an engineering point of view, but heck - simple
works.

>
> Too much flexing in a long sea kayak, to my way
> of thinking, must have a deleterious effect eventually.

One big problem is fatigue, but that is a tricky one.  Fatique failure
isn't necessarily coupled to stiffness or lack of it.  Hearing those reports
of failure that I have seems to suggest that fatigue and/or prior hidden
damage is a major contributing factor.  Like that big chunk you saw fall off
a kayak in rough conditions.


> Stiff is good. Stiff is fun. Stiff is wonderful. Stiff lasts, stiff survives. If its not stiffy, its
> iffy! [...]

You realize you're being emotional about this, don't you?

Think about this - an infinitely stiff kayak, being slammed by a wave will transmit _all_
the force to the paddler.  Sorta like a car without crumple/impact zones.

A kayak only needs to be stiff enough to avoid oil-canning and similar, hydrodynamic
messing-up effects.  Any stiffer is just cost and weight.


> . And...my next boat will be wood-strip, built by
> myself, to my specifications and covered in epoxy so that the whole kayak
> is a homogeneous unit. Unless you can point me toward a one piece
> fiberglass kayak, that's the direction I'm taking.

The rambling at the end of my last post led me to think that this is a really good solution.
The wood strip lets you fool with curves that a S&G won't allow.  Wood is an excellent
core material (rot aside).  It's relatively affordable and doesn't need exotic tools or autoclaves.
You can glass it any way you like and the results may end up georgeous.

I've got some crazy ideas for one-piece, fiber-reinforced kayaks, but that can wait.

Mike

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