This seems to be a good way to catch input on various things, so: Ok, somewhat silly question, but to my understanding, Kevlar is faster that fiberglass, correct? I’ve heard that Kevlar tends to “fizzle up” when trying to repair it. I’ve also heard that CD uses a hybrid that is light and strong like kevlar, but behaves better for repairs like fiberglass.
Do many companies make kayaks out of this hybrid material?
How much of a difference will the kevlar make in speed? And how are the chances of it needing a repair, with careful use? Obviously I will test them before I buy, but the place I’d probably buy it at is on a somewhat fast section of river and it might make things difficult. Thanks,
Nick
A Kevlar boat is “faster” than a glass
boat only if it is significantly lighter. A poorly planned Kevlar boat can be over-flexible, which costs speed.
If used as the outside layer of a hull, Kevlar will fuzz under wear. However, some of us think it is STUPID to use Kevlar as an outside layer, not because it fuzzes, but because it is not as stiff as carbon, S-glass, or even E-glass; and because Kevlar is not strong in compression.
S-glass excels as an outside layer. For a long-lasting whitewater slalom boat, the most-used layup is 2 layers of S-glass outside, and 2 to 3 layers of Kevlar inside. The S-glass exterior wears like iron, and the Kevlar interior resists splitting and tearing. You can use carbon outside, and it will be stiffer and lighter, but it does not resist wear as well, and is less able to take extreme distortion without breaking compared to S-glass.
If one gets stuck with a boat having a Kevlar outer layer, there is no special problem repairing it. I cut the fuzz off by sweeping it with a propane torch, and then scraping or sanding. This also works with boats having Nylon or polyester outer layers.
I don’t know what “composite” CD is using. Some builders are using a weave which is roughly half Kevlar and half carbon. It fuzzes less than pure Kevlar, and is stiffer. There are certain locations on WW boats, especially the lateral corners next to the stern, which come under tension rather than compression when the boat runs over a ledge and the stern gets violently thumped. For those locations, Kevlar is better than S-glass is better than carbon. For most of the outer hull, S-glass will outperform Kevlar and carbon. It approaches carbon in stiffness, and exceeds it in “modulus” or ability to be distorted without breaking. It exceeds Kevlar in contributing stiffness to the hull (which means speed).
I just ordered some Kevlar/carbon composite cloth from John Sweet to use for repairs… to the later stern of my WW boat. For other exterior repairs, I will use S-glass.
misc.
– Last Updated: Mar-19-06 4:06 PM EST –
1. Kevlar is faster that fiberglass, correct?
No, kevlar is a material that is strong in tension and not compression. You can make a light kayak with it but that doesn't necessarily make it faster. A heavier "fast" kayak made out of glass can be faster than a lighter kayak made out of kevlar. Let's say a glass kayak Model A weighs 55lbs and kevlar version weighs 50lbs. The kevlar one is easier to pickup. That's pretty much it. If you weigh 200lbs with all your gear on your body and carry 15lbs of stuff you and the fiberglass kayak weigh 270, you and the kevlar kayak weigh 265. Five pounds won't make much difference in speed or acceleration.
2.Nearly all composite (glass,kevlar,carbon,etc) use a COMBINATION of materials, often in conjuction with core materials that provide thickness for rigidity.
Not sure what this means:
" but the place I'd probably buy it at is on a somewhat fast section of river and it might make things difficult. "
sorry for lack of clarity
Well, i merely meant that it might make a good test ride a bit difficult sice the current is much faster at the kayak place than where I’d use it.
Recently
did some failure testing of a lay-up consisting of a carbon / polyester co-weave, glass, and Kevlar inner layer. Some areas were cored with soric. In all the samples the carbon / polyester co-weave was tougher than the Kevlar! I didn’t get the co-weave to tear at all, but did get the Kevlar to tear. I was shocked by the results. I’ll see if I can post some photos’s when i return home. The overall matrix was impressive and light. Soo much cool stuff out there.
carbon/polyester?
one cloth?
Salty, do you think the Carbon / poly
trials have begun since carbon is becoming so scarce ? The stuff does look cool if used with pigmented resin. Playing with it now.
PF Red Ball Flyers
I used to have a pair of PF Red Ball Flyers, and I swear I could run faster and jump higher in them.
I do
I think you are exactly right. I tell ya, this stuff so far is impressive. Vectran was NOT. I’m still a fledgling with a lot of this, but as a paddler am asked to destroy boats. Folks who think composites are delicate are not aware of the facts, or are stuck with old technology. I tried to drive a screwdriver through a recent test boat to no avail. Hammers bounce off…
Let me know what you think of the carbon / poly.
Like the ads said I would
The coolest part
was the decoder ring that came free with them. Secret compartment, sun dial. Cooler than even a deck mounted compass.
I now realize
– Last Updated: Mar-20-06 8:01 AM EST –
these posts have nothing to do with kayaking and apologize. Give me a minute and I'll (re)move them to B&B.
application
is this a vacuum bagged only material?
pictures, pictures
an interesting fellow came by a kayak shop asking whether people would be interested in 28lb kayaks that were nearly indestructible,duh,“for what price?”…and he described a titanium/aluminum foam/titanium composite,sounded bizarre.
Heard of that also
Ti, is an amazing material with outstanding properties applicable to the outdoor industry. I’ve heard of ballistic material combining Kevlar with Ti strands. I think Ti would be an excellent material, as it’s inert in salt water, strong as hell, light, and flexible.
Two Titanium surf kayaks have been built. I dropped a heavy piece of concrete on one and it bounced off!!! These were superplastic formed hulls and decks, which were joined by epoxy, which failed. They need to be tig welded together. It was an interresting experiment that had me dreaming about a Titanium touring boat that would equal the weight of composite, but last forever. Environmentally friendly, needs no coatings, ultra strong, doesn’t transmit heat or cold easily…etc. But who’d pay 8k or so for that when you have folk who think NDK lay-ups are state of the art? These were pure Ti, not a cloth. It’s very possible, but finacially and market-wise not viable. But, Ti interwoven in a matrix…COOL…I WANT ONE!
I think this "laminate"
was used for subs in fairly thick sections, he said it could be made thinner.