I’ve noticed that a number of kayak manufacturers offer their higher end boats in either fiberglass or kevlar. QCC offers theirs in fiberglass, kevlar, kevlar/carbon and carbon. What’s the main differences between these different materials (other than weight)? Is there an advantage over choosing one over another?
Someone will be here soon with a more detailed answer but here are the basics. Carbon is the stiffest and most brittle, Kevlar is the most flexible but the strongest and good glass is somewhere in the middle. So really a combination of all 3 materials used in the proper places is best.
I’m pretty sure carbon is the most expensive with Kevlar next and glass much less expensive than the more exotic materials. There is also a shortage on carbon thanks to the aircraft industry.
I fly competition hand launch gliders that are made of Vacuum bagged carbon and Kevlar. cool stuff.
My kayak is a Hurricane. It’s made of Trylon. It weighs 33 pounds. It cleans up easily and it seems very durable.
In the “old” days, the classic layup for
whitewater was two layers of S-glass outside, and two layers of Kevlar inside. Those still using this approach get stiff, durable boats. But ocean kayaks usually don’t take the long, hard hits that whitewater boats do.
There are many more layup options now, but if Kevlar is used, it is best to use it for inside layers where its resistance to splitting or tearing is important. Glass, especially S-glass, is hard, stiff, and resistant to compression forces, so it works well for outside layers. Carbon has wonderful stiffness and compressive strength, but as an outside layer it wears too easily.
Not Keen On Kevlar
If money is no issue and you are competent enough to miss rocks while moving at speed, then the carbon will be lighter, stiffer, faster and easier to put on the roof of your car. Plus carbon is proving to be much stronger in solid construction than many have given it credit for. Some recent studies with surf boats have shown the carbon boats are significantly outlasting Kevlar boats in a harsh environment. A northwest sea kayak builder recently posted some similar information about the longevity of carbon kayaks over Kevlar.
If you paddle in white water, plan on hitting rocks hard, or are a sucker for Kevlar hype, then you will appreciate the impact strength, yet soft and whippiness that Kevlar provides. Kevlar has very poor abrasion resistance so you may want to put a glass layer where your feet sit. My feet wore right through my Kevlar boat after about 5 seasons. That can be addressed, but once the hull goes soft and whippy there is no bringing it back. I’m not a fan of Kevlar in sea kayaks unless you plan on hitting stuff hard. I totally expect to be attacked for this stance because there are hundreds of paddlers on this site who have spent a premium for a Kevlar boat assuming it is the best material. I think Kevlar is over-rated for sea kayaks.
Glass is the most economical choice. QCC only uses good quality unidirectional and bi-directional glass combined with the best Vinylester resins so you can expect their glass boat to be among the best. They will last the longest, take a beating, and be easy to repair. The only problem is they are heavy.
I like the idea of a carbon/glass hybrid better than a Carbon/Kevlar hybrid. Why? QCC and most sea kayak manaufacturers use a solid (non-cored) construction method. With Carbon/Kevlar you are asking each material to make up for the weakness of the other. With solid construction you are asking each layer to move under impact nearly as much as the layer next to it. I don’t think you get the best of both, but rather the worse of both materials with solid construction method. Kevlar’s impact strength comes as the fibers are put in tension as it dramatically yields under impact force. During this extreme yielding, the carbon fibers will fail before the Kevlar becomes effective.
I suppose the Kevlar could prevent the hull from being holed during a slightly harder impact, but you will have a challenging repair on your hands as the gelcoat and carbon will still be damaged in the area. It is also a narrow window between the carbon failing and the one layer of Kevlar also failing.
In all but the hardest impacts two layers of Carbon or a layer of carbon and glass will resist yielding better than a Kevlar hybrid, therefore they will be more likley to resist a trip to the repair shop through a higher range of impacts.
With a carbon/glass hybrid you gain some stiffness and weight-savings benefits of the carbon, but also add the abrasion resistance and water barrier resistance of glass. Its a gain/gain situation with carbon/glass hybrids. For instance you will see some carbon paddles offered with a glass layer at the end of the blades to resist abrasion and chipping damage from rocks. This is an excellent use of two materials to gain the benefits of each.
I also think there may be some bonding advantages of carbon to glass versus carbon to Kevlar. Not sure if this matter since I have not seen delamination as a serious problem in sea kayaks.
Obviously, I am a fan of carbon and glass and not so keen on Kevlar. This is always an unpopular position here on P.net and one that will not be supported down at your local shop where the salesman would prefer to increase his commission with the sale with a Kevlar boat.
Thanks for the additional data and experience.
if money is an object
I’d prefer a kayak made with biaxial/unidirectional e-glass, s-glass and core material, Screw the expensive stuff.
I think S-glass over carbon would be
a very good choice for a sea kayak, or possibly for a surf kayak, as long as the boat is not going to have to take the “over-the-top” shots that are common in whitewater.
Properly designed Kevlar boats are not “whippy” or flexy becaue they have S-glass layers on the outside. The only composite boat I have that is flexy was built by Noah without any glass (or carbon) at all. The laminate is damn tough, but the whole boat could crumple around you without splitting.
Nothing can be said meaningfully about Kevlar, carbon, S-glass, or any cloth unless it is in the context of a properly planned layup. Without a properly planned combination, any cloth can be made to look bad.
Lee, I haven’t yet seen biaxial and
unidirectional fabric used for large areas of a boat. Examples? Just curious.
Perhaps your best post ever regarding composites.
Carbon, glass boats, properly designed and constructed can have phenominal impact resitance. Materials are just that. Good design is the application of materials against an objective. Marketing is often designed to sell, not inform.
LeeG is correct in implying that plain old glass is great stuff…s-glass even better.
The most “tear proof” impact tough material I’ve seen to date in a kayak is Carbon Polyester co-weave. Kevlar in that matrix sheared in three tests…the co-weave did not. Food for thought.
The inside of the QCC I’ve got looks like it’s a knit biaxial cloth, not over/under weave, maybe I should look at it again. Wouldn’t unidirectional glass be a good thing to lay transversly in the cockpit from sheer to sheer? I’m thinking of the accumulation of lenthgwise gel coat cracks around the chines on a well used hull. I guess core material can solve that issue but it seems like a good direction to lay some straight fibers. I’m totally guessing on this stuff.
Tide Race kayaks
i may be wrong, but i think Tide Race may be using a similar coweave in a layup option. i was looking at their site earlier and as they are having Plastex making the boats; they will be decidedly, and enormously, un-British in their construction. they give specifics here. i look forward to seeing, and perhaps demoing one of these nice looking boats.
i gotta think these will be be expensive to make and priced accordingly.
I bet it’ll be pricey
TideLINE did this + had uni
under the seat, across the rear deck,and longitudinally in several areas. Around 50 different plys in hull and deck. Not counting seat, coaming and hatches.
Just had a look …
but they lost me as soon as I saw mat in there.
How about the Phoenix FG/nylon lay up?
I have an Isere, Poke Boat and Vagabond and they seem to hold up pretty well. Mine are all unpainted natural color.
The Poke Boat was severly abused on shallow rocky streams befoe I bought it and it does show some signs of possible delam in the stern, but still seems stiff. Much of the finish on the bottom has been worn down so that you can feel the texture of the outer cloth. The cloth has not been abraided into, though.
Their not pretty boats, but do seem to be pretty durable. I still hate the sound of them grinding over rocks and gravel in the shallow and sometimes swift streams around here.
If a deck is comprised of tight curves around hatch curves or recessed fittings wouldn’t mat be an appropriate material as opposed to cutting multiple pieces of cloth?
No and …
They still get the regular stuff on top of it soo…
Mat will always be a substitute for skill @ the customer’s expense
No kevlar, which I think is a good call on a sea touring boat. Vectran has similar properties, but seems to be less prone to interlaminar breakdown.
All in all, looks good.