Re: [Paddlewise] Life of plastic boats

At 02:23 AM 12/5/98 -0800, Richard Mitchell wrote:

[..snip..]
>chemistry but one dramatic demo of the fragility of poly
>containers came years ago on a mountaineering expedition I'd
>organized on the Monarch Icecap in BC. 
[..snip..]
>counted on the plastic.  Wrong, wrong,
>wrong.  *Every* poly container shattered upon impact. 
[..snip..]
>So I don't know about boats, but poly bottles and boxes of a
>certain age, subjected to sudden shock, are not the best.  
[..snip..]

Might the cold have anything to do with that?  Twas an "Icecap" they landed
on, from still higher where it was even colder?  Containers had time to get
cold?  Many soft plastics turn quite brittle when below certain temps.
Happens to metal, too, but *you* wouldn't be operating in *those*
temperatures <grin>!  Few paddlers operate in such cold, and certainly
don't shock their equipment like that.  

I've not had any "plastic" boats, meaning polyethylene, but have some ABS
ones and I've had no problems with them.  I don't drop them out of
airplanes onto glaciers though.  Rapid mechanical shock seems to play a
part in plastic cracking (even the plastics used in composite boats).  

Friends who paddle whitewater claim there is a life to plastic.  There is
with fiberglass, too, but it seems to be longer, depending on specific use.
 The resin used to hold the fibers together is a plastic, albeit not
polyethylene.  UV degradation does play a large part, more in poly than in
composite.  Repeated flex plays a big part in degradation of both, from
what I've seen.  The glass boats are more expensive but seem to last longer
(not in a whitewater situation, though).  

Good luck on your next expedition, Richard. 

Hank Hays
Lightning Paddles


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