Re: [Paddlewise] Life of plastic boats

Ken Cooperstein wrote:
> 
> One of the folding boat enthusiasts (who shall remain nameless, except
> to say that he is Ralph Diaz) wrote in his book that plastic boats have
> a life of about eight years and then become brittle.
> 
> Is this because of UV damage?  Or other chemical breakdown?  Does it
> afflict both straght chain and cross-linked polyethylene?

Ken, 

I don't believe that I said quite what you indicate above.  But that is
okay as the question is a good discussion to bring up and I hope we get
some knowledgeable feedback.

Re plastic boats as discussed in my book:

p. 7 "Their hulls become suspect after around 8 to 10 years of service,
and at that point they can't be easily patched."

And in a discussion of repairing boats in general p. 10 "Plastic hulls
grow brittle and inflexible with time, so the pliable patch material has
difficulty adhering properly. How well a plastic kayak has been stored
and treated determines the age at which it becomes too old to patch. 
Some experts advise that beyond about five or six years, a plastic hull
cannot take a reliable patch.  If you have to repair a five or six year
old plastic hull, they advise for safety sake that you relegate the boat
to light use from there on."

I based that on some things I have read and observed.  The most telling
was a discussion of repairing plastic boats in an old Sea Kayaker that
indicated that after 6 years or so, the original material is to brittle
to take a patch reliably.  Also I have seen discussions on this over at
r.b.p. that pretty much backs up the idea.

I suggest that you, in addition to any feedback you might get here, do a
web check to see what the word is in various places regarding this.

One problem is that there are plastics and there are plastics.  Some
obviously will last longer than others. And plastics as used in boats
has improved in the 15 years or so since plastic started to be used for
sea kayaks.  Also I suspect that size and style of boat may vary any
prediction.  A short whitewater boat would have less flex in it than a
longer sea kayak and therefore less stresses in that regard.  But it
would get banged up more.

The longevity was just one of the issues I raised about plastic. 
Another was that it is not quite indestructable as people might think. 
It oil cans easily and takes indents from car racks that may become
permanent.  Moreover, while you may think it is neat to drag a plastic
boat over beach sand and parking lots, you will pay a price in terms of
slivers that will slow the boat down on the water.

Also it is quite heavy, length for length, with other materials used in
kayaks.  One of the raps against folding kayaks was that they weighed
more than other boats.  But if you look at the realistic weights in Sea
Kayaker reviews (ignoring the advertised weight) you will see that the
average single plastic sea kayak weighs in the 65 pound range where as
the average single folding kayak is quite a bit less.  Of course most
fiberglass boats (except the British boats) weigh less.  The same is
true of double plastic boats vs. double folding kayaks.

> 
> I have my doubts about this assertion because I own a number of
> polyethylene objects that are over 20 years old and they are still
> flexible and like new.  OTOH, polyethylene left in the sun does indeed
> fall apart pretty quick -- a problem that can be solved for kayaks by
> proper storage.

Yes, proper storage will prolong the life of a plastic boat as it would
for any boat.  However, since a plastic boat's advertised selling point
is its toughness, owners tend to buy the hype and store them pourly,
drag em on parking lots, bang em around rocks etc.

Oh yeah, folding kayaks's life spans are pretty impressive.  A good 25
years on the skins and well beyond that for frames.

best regards,

Nameless

p.s. Despite being a folding kayaker I do rely on polyethylene in my
paddling...my pee bottle.  I have been monitoring its life cycle and, in
any update of my book, I intend to recommend that any one using a
plastic pee bottle plan to retire it after about six years for safety
sake.  :-)


 


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PO Box 0754, New York, NY 10024
Tel: 212-724-5069; E-mail: rdiaz_at_ix.netcom.com
"Where's your sea kayak?"----"It's in the bag."
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