>Properly built carbon boats are remarkably strong especially when matched >to the proper core material and with the fibers properly oriented. Usually >they are made from epoxy pre-pregs vacuum and heat cured under pressure. I >had a canoe that was built that way and it was truly remarkable. One of the >great sins is to use the mixed materials (carbon/Kevlar) cloth. It looks >sexy but the result is poor. > >As Hank Hays says, "Carbon is not all it's cracked up to be" > >Cheers, >John Winters A manufacturer told me that he puts 3 layers in a sea kayak hull: A 3/4 layer of fiberglass next to the gelcoat, then 2 other layers of fiberglass. A kevlar hull will have one of the full layers of kevlar, but the 3/4 and other layer still fiberglass. He also uses a carbon/kevlar hybrid, and sometimes a carbon layer. Do you still consider that a carbon/kevlar hybrid is a "great sin"? So you have 4 possible materials: fiberglass, kevlar, carbon, or hybrid. Assuming that you need fiberglass next to the gelcoat, that leaves 2 layers, each of which can be chosen in 4 ways. Therefore there are 16 possible constuctions of the hull. (Not to mention various choices for the resin.) WITHOUT CONSIDERING COST AT ALL, what is the best construction if you want the lightest and strongest boat? Jerry *************************************************************************** PaddleWise Paddling Mailing List Submissions: paddlewise_at_lists.intelenet.net Subscriptions: paddlewise-request_at_lists.intelenet.net Website: http://www.gasp-seakayak.net/paddlewise/ ***************************************************************************
On Sat, 27 Jun 1998, Gerald Foodman wrote: > WITHOUT CONSIDERING COST AT ALL, what is the best construction if you want > the lightest and strongest boat? Based on a property sheet I saw a few years ago I would like a 3 layer vacuum bagged spectra hull. Spectra is another synthetic fabric. According to the article it's brutal to work with as it is lighter than water and it floats on the resin instead of being easily wetted out. It's been a couple of years, I've seen a couple of canoe manufacturers (Novacraft?) making spectra boats. The original article had a picture of an olympic athlete's 7 pound whitewater race boat being held by the athletes young daughter. kirk *************************************************************************** PaddleWise Paddling Mailing List Submissions: paddlewise_at_lists.intelenet.net Subscriptions: paddlewise-request_at_lists.intelenet.net Website: http://www.gasp-seakayak.net/paddlewise/ ***************************************************************************
Jerry wrote; >A manufacturer told me that he puts 3 layers in a sea kayak hull: A 3/4 >layer of fiberglass next to the gelcoat, then 2 other layers of fiberglass. >A kevlar hull will have one of the full layers of kevlar, but the 3/4 and >other layer still fiberglass. He also uses a carbon/kevlar hybrid, and >sometimes a carbon layer. > >Do you still consider that a carbon/kevlar hybrid is a "great sin"? Yes. Rather extensive testing by myself and others indicates that the best use of carbon and Kevlar is when the materials are used in their own discrete layers to take best advanatge of their characteristics i.e. layer of Kevlar/ layer of carbon/layer of Kevlar rather than mixing the two in the same layer. > >So you have 4 possible materials: fiberglass, kevlar, carbon, or hybrid. >Assuming that you need fiberglass next to the gelcoat, that leaves 2 layers, >each of which can be chosen in 4 ways. Therefore there are 16 possible >constuctions of the hull. (Not to mention various choices for the resin.) > >WITHOUT CONSIDERING COST AT ALL, what is the best construction if you want >the lightest and strongest boat? The layer of fiberglass on the outside is nice (it does not fuzz when abraded) but not essential. An ideal layup might have a 2 oz. S glass cloth on the outside, a Kevlar/carbon knit (Kevlar facing out) - a syntactic foam core and another Kevlar/ carbon knit with the kevlar facing in on the inside of the boat. The weights of the cloth would epend upon how much durability I wanted. If I were vaucuum baging I would replace the syntatcic core with honeycomb and heavier skins. I might also use Spectra Instead of Kevlar. Of course, you said money was no object so one might look into Boron fibers or maybe even ceramic whiskers. Have't been keeping up with such things but they are reported to be as strong as they are expensive. Cheers, John Winters Redwing Designs Specialists in Human Powered Watercraft http://home.ican.net/~735769/ *************************************************************************** PaddleWise Paddling Mailing List Submissions: paddlewise_at_lists.intelenet.net Subscriptions: paddlewise-request_at_lists.intelenet.net Website: http://www.gasp-seakayak.net/paddlewise/ ***************************************************************************
Jerry wrote; >A manufacturer told me that he puts 3 layers in a sea kayak hull: A 3/4 >layer of fiberglass next to the gelcoat, then 2 other layers of fiberglass. >A kevlar hull will have one of the full layers of Kevlar, but the 3/4 and >other layer still fiberglass. He also uses a carbon/Kevlar hybrid, and >sometimes a carbon layer. > >Do you still consider that a carbon/Kevlar hybrid is a "great sin"? Yes. Rather extensive testing by myself and others indicates that the best use of carbon and Kevlar is when the materials are used in their own discrete layers to take best advantage of their characteristics I.e. layer of Kevlar/ layer of carbon/layer of Kevlar rather than mixing the two in the same layer. > >So you have 4 possible materials: fiberglass, Kevlar, carbon, or hybrid. >Assuming that you need fiberglass next to the gelcoat, that leaves 2 layers, >each of which can be chosen in 4 ways. Therefore there are 16 possible >constructions of the hull. (Not to mention various choices for the resin.) > >WITHOUT CONSIDERING COST AT ALL, what is the best construction if you want >the lightest and strongest boat? The layer of fiberglass on the outside is nice (it does not fuzz when abraded) but not essential. An ideal lay-up might have a 2 oz. S glass cloth on the outside, a Kevlar/carbon knit (Kevlar facing out) - a syntactic foam core and another Kevlar/ carbon knit with the Kevlar facing in on the inside of the boat. The weights of the cloth would depend upon how much durability I wanted. The best finish (also lightest) would be one of the two part polyurethanes such as AWLGRIP or Dupont Imron. If I were vacuum bagging I would replace the syntactic core with honeycomb and heavier skins. I might also use Spectra Instead of Kevlar. Of course, you said money was no object so one might look into Boron fibers or maybe even ceramic whiskers. Haven't been keeping up with such things but they are reported to be as strong as they are expensive. Cheers, John Winters Redwing Designs Specialists in Human Powered Watercraft http://home.ican.net/~735769/ *************************************************************************** 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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