I initiated this thread and would like to thank all who replied, especially Messrs. Kruger and Diaz. I do have one or two more questions. Assuming proper storage, it would seem that crystallization is the principal factor in loss of flexibility and resistance to shock of PE.. First, this means that the thickness of the material is not a factor, except that a brittle piece twice as thick is twice as strong anyway. I.e. it is always harder to break 1" thick glass than 1/16" thick glass. Nevertheless, you folks with Feathercrafts still have to worry that your PE cross members are suspect after 8 years. Second, it is astounding that kayak manufacturers do not warn of this latent defect. I know they don't because no such warning came with my 1997 roto Sealution XL. Your roto yak looks the same after 10 years, only it is so crystallized that the first big sea you fall off (or the first waterfall you boof off for the WW crowd) will reduce it to shards. Moreover, the conditions under which such a failure are likely to occur are also likely to result in serious injury or death. Needless to say, to the extent that this starts to happen, there will be opportunities for new kayak companies, because none of the old ones will survive. Ken Cooperstein (also a Greenland II owner, BTW) *************************************************************************** PaddleWise Paddling Mailing List Submissions: paddlewise_at_lists.intelenet.net Subscriptions: paddlewise-request_at_lists.intelenet.net Website: http://www.gasp-seakayak.net/paddlewise/ ***************************************************************************
In a message dated 12/5/1998 6:41:02 AM EST, romeug_at_erols.com writes: << > So I don't know about boats, but poly bottles and boxes of a > certain age, subjected to sudden shock, are not the best. > > RGM Would the cold add to the brittleness Richard? >> I can't vouch for teh cold, but I am sure it does make them more brittle. I can however vouch for teh age down here in teh south where it never gets cold. \\A new quart Nalgene bottle when dropped on concrete will bounce with little damage full or empty. One about 3-4 years old shatter about 1/2 the time if dropped. One 5-6 years old is sure to shatter every time. Like the previous post about airdropped poly bottles shattering like glass. I have found the same thing. All it takes is a little triggering mechanism John *************************************************************************** PaddleWise Paddling Mailing List Submissions: paddlewise_at_lists.intelenet.net Subscriptions: paddlewise-request_at_lists.intelenet.net Website: http://www.gasp-seakayak.net/paddlewise/ ***************************************************************************
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 *************************************************************************** PaddleWise Paddling Mailing List Submissions: paddlewise_at_lists.intelenet.net Subscriptions: paddlewise-request_at_lists.intelenet.net Website: http://www.gasp-seakayak.net/paddlewise/ ***************************************************************************
In a message dated 12/5/1998 12:59:16 PM EST, dkruger_at_pacifier.com writes: << Hank Hays, and others, however, can no doubt attest to the fragility of well-aged polyester layups, which use styrene as a copolymer adduct / plasticizing ingredient. Sorry for running on ... I'm an academic, folks, I can't help it! -- Dave Kruger Astoria, OR >> Dave, You are a "Gewel" Most academia won't even stoop to share with underlings such as we. You crawl on your belly like a reptile to share your froth with us. For this we are forever grateful. Sincerely John LeBlanc *************************************************************************** PaddleWise Paddling Mailing List Submissions: paddlewise_at_lists.intelenet.net Subscriptions: paddlewise-request_at_lists.intelenet.net Website: http://www.gasp-seakayak.net/paddlewise/ ***************************************************************************
In a message dated 12/5/98 5:23:06 AM Eastern Standard Time, mitchelr_at_ucs.orst.edu writes: << Everything was packed together in a multilayered semi-hard drop container, very tightly packed). We figured the tin would not make it but counted on the plastic. Wrong, wrong, wrong. *Every* poly container shattered upon impact. >> Just out of interest, do you know how high your drop plane was flying and how long he was up before the drop? In other words, how cold was the contents of the load? Temps can effect plastic a lot. My unused Sea Lion is probably ten years old, but is in good shape. I have made a point of never dropping it out of an airplane, however --- at least at altitude. Jack *************************************************************************** PaddleWise Paddling Mailing List Submissions: paddlewise_at_lists.intelenet.net Subscriptions: paddlewise-request_at_lists.intelenet.net Website: http://www.gasp-seakayak.net/paddlewise/ ***************************************************************************
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