[Paddlewise] Swamped rear compartment-Plastic

Duane wrote:
<SNIP>

<<The bulkheads in the plastic VCP Skerray I recently sold didn't leak, and
they where the welded in plastic type. >>

As someone later pointed out some of these welded in bulkheads have failed
catastrophically. I think they were the earliest ones,  I hope VCP has the
problem solved. If  I was looking at a used one I'd want to know the details
of what the problem was and if, when and how it was solved.  I have seen a
glued in foam bulkhead blown out of the bow of a double fiberglass kayak
that was in the surf.
The early ABS glued in place bulkheads (in glass kayaks) degraded rapidly in
the sun and became very brittle and easily punched through by accident.
Later ones have a vinyl (I believe) layer bonded on the surface of the ABS
core to protect it from the sun.

<SNIP>
<<The only reason plastic kayaks may have leaking bulkheads more often is
because of the abuse these kayaks take. Many of them are very old and have
been stacked, sat on, stored improperly, and left out side to weather and
bake in the sun, while fiberglass kayaks are treated like precious china.
All kinds of kayaks have leaking problems. There were recent posts on this
list about an all mighty fiberglass Romany having a leaking skeg box, and
there have been some posts about leaking seams in a variety fiberglass
kayaks.>>

While many kayaks leak for various reasons it isn't only abuse that makes
plastic kayaks with glued in bulkheads so prone to leak. Polyethylene is a
very difficult material to bond to. That combined with the often soft
flexibility of the material (testing the limits of the bonds) means that the
statement of one retailer (when asked the security of the bulkheads in the
plastic kayaks he sold)"guaranteed to leak in a week" was not a joke but a
statement of fact.

<Plastic kayaks, and the bulkheads in them, don't deserve the bad rap they
keep getting.>

I don't think the bad rappers are making up the stories I hear (or the dead
feeling I get paddling one--or the difficulty I have keeping a spraydeck on
some in the surf).
As to how plastic kayaks and glass kayaks are treated, people tend to treat
things in a way that reflects there worth to them. A well made glass kayak
is pound for pound as tough as an equal sized plastic kayak and after ten
years of aging and a little sun will be far stronger. Most glass kayak
buyers want to use the extra stiffness of glass to save on weight (rather
than be tougher) and the manufacturers try to comply so they will sell them
what they want as best they can. The market is driven by the customers
wishes often in the face of the manufacturers better judgment. Plastic
kayaks could be made lighter but they would then either be too soft and
flexible or if made stiffer likely be too brittle (with no fiber structure
holding them together).  I have considered making a plastic surf/play kayak
and think there are some advantages to plastic other than price for certain
functions especially for short lifespan kayaks such as for whitewater or big
surf and ocean rock garden bashing. Making the kayak more affordable
increases the market size and plastic kayaks can be popped out of a mold
with less than an hour between them so they can truly be mass produced.
Don't know if this will ever happen though, as things stand now just not
enough hours in the day to put much effort into it. I do want to make it
clear that I am not anti-plastic but just want to use the best materials for
the job at hand whatever that may be.

Matt Broze
http://www.marinerkayaks.com



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