----- Original Message ----- From: "Peter Chopelas" <pac_at_premier1.net> Sent: Thursday, October 09, 2003 3:20 PM Subject: Re: [Paddlewise] [PaddleWise] Kevlar vs. Full Carbon Fiber? > It sounds like this company does not know that much about the materials they > are dealing with (which is no surprise). The three most common composite > fibers are glass, kevlar and carbon fiber. <SNIP> Peter, you make some interesting points, and it sounds as if you know your stuff. I'd be interested in your opinions on a couple of things. How do you feel about homemade wooden kayaks, in which two layers of fiberglass are separated by a thin layer (1/4") of wood? Does the small separation between fiberglass layers add anything in terms of strength or stiffness, compared with two layers epoxied directly to each other? I have a stitch and glue boat made of 4mm okoume plywood. The plywood adds quite a bit of strength, so there isn't that much fiberglass - a layer on the outside of the hull, a layer inside the hull in the cockpit, and fiberglass tape on the inside of the hull seams. I'm presently building a strip boat. I didn't do such a perfect job of joining the strips together as I might, so I question the structural integrity of the wooden shell. However, I'm counting on a layer of 6 oz. glass inside and out to make it strong. On another topic - paddles - the kayak is for my wife, who has fibromyalgia, which affects her forearms, wrists, and hands more than anything else. Therefore, lightness and "ease of paddling" are paramount. I'm thinking a short (220cm?), small bladed (Little Dipper), small shafted paddle made of the lightest material possible - carbon fiber - is the way to go. How durable will such a paddle be? Hopefully, some of her paddling will be done on the open ocean here on the central coast of California, but I don't see her doing any rock-gardening, or surfing. > Peter Chopelas, PE, BSME > *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
Kevlar fibers have a very high tensile strength, but carbon fibers in an epoxy or thermoplastic matrix are much stiffer. This means you can make a much lighter boat for a given stiffness. Kevlar is also weakened by exposure to UV. As noted, the lightest and strongest race cars and military jets are made from carbon fiber. -- mike -------------------------- Michael Edelman http://foldingkayaks.org http://findascope.com *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
Paddlewise, Gosh, when you hear about all of these problems with fiberglass, Kevlar and carbon fiber, it makes plastic sound good! Duane Plastic, plastic, plastic... *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
On Fri, 10 Oct 2003 09:53:39 -0400, "Michael Edelman" <mje_at_spamcop.net> said: > As noted, the lightest and strongest race cars and military jets are > made from carbon fiber. High end racing kayaks/canoes/shells are going to nomex and carbon layups. The outrigger canoe team that I paddle with has a vacuum bagged carbon 6 man outrigger canoe it weighs 180 pounds - it's 45 feet long. Rumor has it they have a new hull on order, the manufacturer is going to build from nomex and expects the weight to be under 150 pounds. A traditional fiberglass layup is 400 pounds. -- Kirk Olsen kork4_at_cluemail.com *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
Someone correct me if I'm wrong, but I heard that the hot new material is boron. The rowing world is embracing it as is the fishing world, but it looks like kayaking is ignoring it for the time being. I mean, CF is old skool in the world of rowing. I've heard that boron it is incredibly stiff and strong and all the cool kids are using it. Anyone wish to comment? It seems like the sea kayak world comes fairly late to technological advances. As an example, seat ergonomics have been big in whitewater for awhile now but are only recently coming to sea kayaks. Of course, you don't really need those fancy seats when you've got some minicell and dragonskin. Only one example, but I'm sure there are many. So, titanium sporks, boron-enhanced flip-flops, cold-fusion GPS - technology good or bad? Pick a side. Wood greenland or carbon fiber bent-shaft wing blade. Always an interesting conversation to have while we aren't on the water. -Patrick On Fri, 10 Oct 2003 09:53:39 -0400, Michael Edelman wrote > Kevlar fibers have a very high tensile strength, but carbon fibers > in an epoxy or thermoplastic matrix are much stiffer. This means you > can make a much lighter boat for a given stiffness. Kevlar is also > weakened by exposure to UV. *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
On 10 Oct 2003 at 11:36, Patrick Maun wrote: > Someone correct me if I'm wrong, but I heard that the hot new material > is boron. Boron fibre has been around for quite a while. It's been used to some extent for at least 25 years in aerospace. I know golf clubs were made with boron starting in the, ummm... 80's(?) - well a while ago. Expensive and quite stiff, I'm not sure it would be useful in kayaks, however in paddle shafts I could see it being used. Given that paddle shafts that are sufficiently comfortable for us to use (i.e. not ultra stiff) contain a glass/carbon mix, I don't see boron saving much weight. For racers, where ultra stiff is useful, maybe. There are other exotics of sapphire-like materials ($$$) that were being researched way back when too. We need things that are stiff and strong on several scales. For example, paddle shafts have to have good flex characteristics over their lengths and also be stiff and strong enough to not crush if sat on. High strength fibres provide the former but not so much the latter. What we really need is relatively bulky, light materials that are strong. This would allow us to make kayak hulls with high local stiffness (no buckling or oil-canning) and high overall strength too. Mike *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
Good points. I know nothing about boron (or any materials other than kevlar and fg) so couldn't say. I store one of my boats at a local rowing club so have talked with the various rowers about materials and boron has come up as one the things that rowing oar shafts are getting made out of. I read an article about the technological advances being made in artificial diamonds. Maybe we can get a boat or paddle in some sort of diamond/epoxy layup! That'd be one helluva exotic material. -Patrick (owner of several non-exotic fiberglass boats) On Fri, 10 Oct 2003 13:34:43 -0400, Michael Daly wrote [SNIP] > > We need things that are stiff and strong on several scales. For > example, paddle shafts have to have good flex characteristics over > their lengths and also be stiff and strong enough to not crush if > sat on. High strength fibres provide the former but not so much the > latter. What we really need is relatively bulky, light materials > that are strong. This would allow us to make kayak hulls with high > local stiffness (no buckling or oil-canning) and high overall > strength too. *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
Boron would be a good material for paddle shafts, but I'd have reservations about using it as a hull material. Boron fiber is roughly 3 times stiffer than steel, has a tensile strength of about 400,000 lbs per square inch, and weighs about as much as a comparable amount of carbon fiber. It also shatters like glass when it encounters a right angle impact. You can shatter a square inch bundle with your hands that is capable of lifting a railroad car. The solution is to mix it in a matrix of resin and other fibers like kevlar that are more resilient, but you will still encounter failure of individual fibers if the hull flexes much, or if you smack a rock. Carbon is more forgiving, IMO. Wayne (Who used to work with boron in the early '80's) Patrick Maun <patrick_at_patrickmaun.com> wrote: Good points. I know nothing about boron (or any materials other than kevlar and fg) so couldn't say. I store one of my boats at a local rowing club so have talked with the various rowers about materials and boron has come up as one the things that rowing oar shafts are getting made out of. ------------------------------------------------------------------------------------------------ Wayne Smith wsmith16_at_snet.net Check out my website! http://pages.cthome.net/wsmith16/home.html *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
That would explain it's use in oars. Those guys and gals try to never hit anything. Sea kayakers are a bit harder on gear than the average rower. Take a look at one of those fancy shells next time you get a chance. The deck is nothing more than glorified plastic wrap and the hull isn't much better. Of course, they weigh about four ounces and are faster than all get out. Just don't try a surf landing. I heard tell somewhere that Werner is bringing out some new materials next year? Maybe I heard wrong, anyone know anything about that? -Patrick At 1:03 PM -0700 10/10/03, Wayne Smith wrote: >[SNIP] > >You can shatter a square inch bundle with your hands that is capable >of lifting a railroad car. The solution is to mix it in a matrix of >resin and other fibers like kevlar that are more resilient, but you >will still encounter failure of individual fibers if the hull flexes >much, or if you smack a rock. Carbon is more forgiving, IMO. > *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
----- Original Message ----- From: "Michael Edelman" <mje_at_spamcop.net> > As noted, the lightest and strongest race cars and military jets are > made from carbon fiber. I believe that the reason that the military jets are made of COMPOSITES of many different and exotic fibers - not just carbon is because they don't reflect radar waves very well. . Steve Holtzman *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
> From: "Steve Holtzman" <sh_at_actglobal.net> >>> As noted, the lightest and strongest race cars and military jets are >>> made from carbon fiber. > > I believe that the reason that the military jets are made of COMPOSITES of > many different and exotic fibers - not just carbon is because they don't > reflect radar waves very well. . The newest aircraft have skins made of carbon fiber in a thermoplastic or epoxy resin. Radar reflectivity of contemporary aircraft has much more to do with geometry than with materials. -- mike ------------------------- Michael Edelman medelman_at_ameritech.net http://www.foldingkayaks.org http://www.findascope.com *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
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