I have decided on a new kayak I want and the choice is carbon-kevlar (lighter by 6lbs; beautiful look of clear gel coat) or fiberglass composite (in some color). My paddling is as much as 90% solo and I carry my current kayak (same weight as the kevlar one I am thinking about) on my right shoulder from water to car. Maybe 55lbs (fiberglass) doesn’t sound heavy…especially to you folks with British boats but the weight is on one spot on shoulder and I ain’t gonna be younger and the boat ain’t gonna be lighter next year. Not always in a spot where a roller will work. Any thoughts, comments ?
You pay the premium once…
…but you smile every time you pick up that boat …
The price of carbon is going crazy because of demand (see Boeing) and the difference between FG is going to keep increasing.
Carbon…reply to all and myself
…well it’s an academic question at this point since I have placed the order. I won’t get any stronger next year either…carbob-kevlar for me !
Congrats… Which Boat? nm
painful shoulder carry
roll up (or fold) a towel and put it on your shoulder under the kayak. The weight will be the same but it won’t bite into you as much.
I think that if the builders replaced
the carbon with S-glass, keeping the Kevlar inside, they could still get the boat weight under 50 pounds with only a tiny sacrifice in stiffness.
painful shoulder carry
For my heavy sea kayaks I fashion a carry yoke so I can roll the kayak onto my shoulders and carry it like a canoe, with one hand supporting the coaming rail and the other hand carrying my paddle and PFD. If its a long distance or windy or rough terrain I wedge the paddle and PFD into the cockpit and use both hands to steady the kayak.
And also if they
used better resins. Most commercial canoes and kayaks are made with either polyester or vinylester resin. Marine epoxy is more resilient, but quite a bit more expensive.
S-glass vs E-glass is the same issue: S is stronger, but E costs less.
I’d like to see someone use a layup that Necky used to use (Carbon fiber ribs and deckbeams, kevlar and glass laid up around it – I’d add a carbon keel and gunwhales and make a complete “frame” of carbon) with s-glass and marine epoxy. It’s a tough layup that can be easily beefed up for expedition boats or lightened for racing or people who want light boats.
We have an old Arluk 1.9 with that layup, and it’s strong AND light.
The only problem with carbon is if you rely on it too much, and don’t lay it up with enough other materials — carbon sacrifices resilience for strength, and can be very brittle. That’s why you see it paired with kevlar a lot, because they complement one another: Kevlar isn’t particularly stiff, but it can take a huge pounding and remain intact, and carbon is very stiff, but doesn’t have a lot of give to it before it fails. Mixing the two in the right way with glass makes a very good composite for boats.
That said, my two most used boats are fiberglass and wood/fiberglass. When I can’t lift the glass one anymore, I’ll consider going lighter as well.
Life and Weight
It’s a sad fact of life that only High School football players are getting stronger - the rest of us are headed in the other direction, so lighter is always better if fubction is retained.
Of course, when you build something light it gets fragile of expensive. Strangely, we pay more to get less[weight].
Properly engineered carbon/Kevlar hybrids seem to make the best paddlecraft. I have a Bell Black/Gold FlashFire that’s twelve years into its and my life and still looking good and going strong.
Sounds like you made the best decision.
Broad brush strokes
Sounds like you’re making a good quality decision in your kayak search. So, what specs are you looking for in a kayak?
See you on the water,
Marshall
www.the-river-connection.com
Hyde Park, NY
Careful what you say, Wayne. You’ll
bring Salty out of his rocky sea cave.
On resins, polyester resin is pretty much out of the picture. Having been all over the internet on this, I found that vinylester is close to epoxy in actual performance, and I prefer it, but many builders are getting excellent results on kayaks and canoes with vinylester. One example is millbrookboats.com, where Kaz builds and races S-glass/Kevlar canoes using vinylester and vacuum bagging. His boats are very light, durable, and very repairable.
picture?
Can you post a picture? I’d like to make something similar for portages in wilderness areas where carts aren’t allowed.
What’s the point G2?
We have a guy being nostalgic about old Neky lay-ups when the new infused non-kevlar Necky’s are far stronger both in the lab and on the water. Necky’s head designer is my long time friend, so I’m familiar with their stuff and have been a part of destructive testing. I owned several old Necky kevlar lay-ups. I broke the nose clean off one…hmmmm how could that be…it was Kevlar??? Good old boats for sure but the new ones are tougher!
Challenge: I will take a hammer to my infused Chatham repeatedly (glass / carbon) if you’ll let me do it to the old kevlar Necky or any of your boats.
I know you wont get Spike building anymore surf boats with Kevlar in them.
Kevlar makes for great lightweight boats, especially when combined with glass / carbon, and coring. It’s a wise material for applications where weight is critical.
People toss terms like strength around all the time without any understanding of what that means. Strength how? Agree that epoxy resin is probably best if Kevlar is chosen, but many many superb builders prefer Vinylester. Something else to argue about.
Strength
With kevlar, the “strength” is tensile strength: How hard is it to pull on the ends, and cause failure. Kevlar is very strong that way, which is why it is used to make bulletproof vests and car tires.
With carbon, the “strength” is stiffness: How much force to make it bend.
Then there’s the “strength” of modulus: how much will the material stretch given a certain load. All three are factors in determining the layup for a composite for a given use.
Glass is good all around, but doesn’t excel at any one thing, which is why it is so commonly used, well, that and price. IMO, the best bang for the buck for all around performance. If other factors are important, mix it with other materials.
I rarely see any new Neckys in my neck of the woods anymore. They used to be a dominant brand around here, but it seems not anymore. I have no doubt the infused layups are stronger, but I haven’t had the opportunity to try one out to see for myself. As I recall, weight was an issue in the original post…
New Necky’s
are lighter and stronger. I fully understand the difference between tensile and cmpressive values. Thanks though… BTW Ballistic kevlar is NOT type 49 used in kayaks.
Nothing I can find on the internet
supports what you claim your industry buddies have found, either about deficiencies of Kevlar or about indestructibility of any glass/carbon combination.
It does not surprise me that your boat can withstand hammer blows, but hammer blows actually do not model the longer, deeper displacements that occur in whitewater use.
If you have not already seen the old comparative data presented in the “Boat Builders Manual,” the SSKK layup significantly outperformed everything else. Unfortunately carbon was not part of the testing. But the results make the SSKK layup look so good that it is easy to see why it is still in use.
You say that Kevlar is most useful for light layups, but in competition slalom kayaks, Kevlar is passing out of use for the hull, because carbon and glass, with some spheretex, makes for the stiffness needed in competition. I suspect that carbon and glass will always provide a lighter craft for any degree of needed stiffness, compared to a layup including Kevlar. Kevlar is used to prevent propagation of catastrophic damage. When you go past the threshold for your carbon/glass layup, the cracking is going to go right through the hull and travel three ways. If your boat had a couple of interior Kevlar layers, the hull would not crack through. It is possible that the carbon/glass layup would last longer over a series of subthreshold blows than would the glass/Kevlar layup.
Anything you can cite that is published, on the internet or elsewhere, is fair evidence. I am not interested in private phone conversations with your favorite experts. If they are experts, they have published.
Stick with psychology!