I'm in the market for a single touring kayak moving up from our family kayak station wagon (Perception Jocasse). In local classes at Southwest Kayaks in San Diego I''ve used the Necky Narpa. I like its handling. I recently saw the Prijon Kodiak. What do readers of the list know about the high performance thermoplastic used by Prijon vs. the standard plastic used by Necky and most of the other plastic boats? Thanks foe any help. *************************************************************************** PaddleWise Paddling Mailing List - All postings copyright the author and not to be reproduced outside PaddleWise without author's permission Submissions: paddlewise_at_lists.intelenet.net Subscriptions: paddlewise-request_at_lists.intelenet.net Website: http://www.paddlewise.net/ ***************************************************************************
> -----Original Message----- > From: PGevanthor_at_aol.com [mailto:PGevanthor_at_aol.com] > Sent: Tuesday, May 30, 2000 9:10 PM snip > What do readers of the list know about the high > performance thermoplastic used by Prijon vs. the standard > plastic used by > Necky and most of the other plastic boats? Thanks foe any help. In my layman's understanding - Prijon uses a blowmolding process that utilizes a cross-linked polyethylene. Most other poly boat makers use a roto-molding process - linear polyethylene. The long polyethylene molecules in a cross-linked plastic are "linked" to each other thus forming a stronger bond and the result is a stiffer plastic. Linear plastics have the same long poly molecules all laying side by side - but without the crosslinks between molecules. I think that Old Town uses a composite polyethylene consisting of a linear polyethylene "skin" sandwiching a polyethylene foam core - supposed to be pretty stiff. Their ads also claim it adds flotation but I'd take that pill with a grain of salt. Flotation perhaps - significant in the event of a capsize well...YMMV. There was a post by Debbie Reeves(?) a while back about rescuing a swamped OT Loon that wasn't floating too well.... Is there a long-term durability or performance difference between the two? I can't really say. I think that both types are equally susceptible to UV degradation. The Prijon WW kayaks that I've seen (paddling buddies' boats) "seemed" stronger than some of the roto-molded kayaks, but that was strictly a subjective observation. My roto-mold Skerray is in its fifth year of life and I haven't had any cracks or _noticeable_ brittleness yet. (it's the brittleness that I can't detect that worries me!) If you decide to go with a plastic boat of whichever construction you will best serve it by storing it indoors and regularly treating it with something like 303. Dave Seng Juneau, Alaska *************************************************************************** PaddleWise Paddling Mailing List - All postings copyright the author and not to be reproduced outside PaddleWise without author's permission Submissions: paddlewise_at_lists.intelenet.net Subscriptions: paddlewise-request_at_lists.intelenet.net Website: http://www.paddlewise.net/ ***************************************************************************
"Seng, Dave" wrote: > > > -----Original Message----- > > From: PGevanthor_at_aol.com [mailto:PGevanthor_at_aol.com] > > What do readers of the list know about the high > > performance thermoplastic used by Prijon vs. the standard plastic used by > > Necky and most of the other plastic boats? Thanks foe any help. > > In my layman's understanding - Prijon uses a blowmolding process that > utilizes a cross-linked polyethylene. Most other poly boat makers use a > roto-molding process - linear polyethylene. The long polyethylene molecules > in a cross-linked plastic are "linked" to each other thus forming a stronger > bond and the result is a stiffer plastic. Linear plastics have the same > long poly molecules all laying side by side - but without the crosslinks > between molecules. Good description, Dave. X-linked PE is stiffer, also, which may reduce the oil-canning problem some PE designs have. There are other differences between the two ways of making PE boats. Some may significantly affect boat lifetime. In rotomoulding, the PE is measured into the cold mold as a passel of small (pea-size) lumps. Then the mold is warmed, and rotated along at least two perpendicular axes, so as to distribute the PE "uniformly." Then the mold is cooled, and separated, releasing a yak body, ready for trimming and outfitting. Naturally, the skill of the operator/software who/which controls the rotation process affects the result. In blow-moulding, my understanding is that the "bubble" thins as it expands into the mold, and the main deficiency is that the PE layer can get too thin as it stretches over bumps in the mold surface. I have not seen many blow-moulded boats, but before I bought one, I'd look for this flaw at places where the shape changes rapidly. Not knocking PE boats -- I owned a roto-moulded "Blem" made by Perception for several years which performed well -- and it was strong. But, it pays to check over the specific boat you buy. -- Dave Kruger Astoria, OR chemist *************************************************************************** PaddleWise Paddling Mailing List - All postings copyright the author and not to be reproduced outside PaddleWise without author's permission Submissions: paddlewise_at_lists.intelenet.net Subscriptions: paddlewise-request_at_lists.intelenet.net Website: http://www.paddlewise.net/ ***************************************************************************
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