wanting to upgrade and i was told that fiberglass breaks easily but kevlar is great. anything helpful? I’m looking at a hawk and i know these are said to be top of the line but I do not know. HELP!
Kevlar is good for the inner layers, but
for the outer layers the best materials may be S-glass (a better fiberglass) or carbon. When used on the outside of a boat, Kevlar fuzzes under wear. Also, while very strong in tension, Kevlar is inferior to fiberglass under compressive forces. So stiff fibers, glass or carbon, make better exterior fibers.
You can visit the following site for information on composite boat layup.
strength is relative
according to a particular measurement,
fiberglass is about two times stronger as steel,
while kevlar then is about 5 times stronger than steel,
so decide how much stronger than steel you need
I prefer Kevlar too, but mainly because canoes
made with kevlar are a bit lighter and a bit stronger.
does this cause water resistance problems really? I’m looking to keep this kayak for more than 10 yrs if I can.
a fuzzy kevlar laminate will absorb water, causing more problems. Gelcoat doesn’t stick too well to kev, either. I’ve seen stems that were kev turn into real headaches with wear and tear. I generally build up a rub strip of glass tape with epoxy over the kev.
s-glass is good in this application but more $$$ than fiberglass.
Steve,is s-glass not used simply because it doesn’t have the marketing impact as kevlar? I don’t know the layups in kevlar boats but they must have glass in them,seems to me that a 1/2 s-glass 1/2 kevlar would be a better mix than all kevlar, or the areas where e-glass is used replace it with s-glass,or at least in the areas like the center of the hull where rigidity is desirable then s-glass on the exterior/bottom would make sense so that s-glass gets hit before the kevlar.
I wish I knew
all the characteristics of E and S in hard-core layups.
I am going to be doing some work in the near future with John Jaycox, Wildy’s composite guru and ol’ school ww boat builder from Colorado, and figure out the best layup schedule for hard core use.
I’m playing with some graphite/ f/g layup right now. light, strong and stiff. not sure on longevity. that’s what I get to test!!!
I’ll keep the list posted.
have you read his book? It’s based on someones Masters thesis and whitewater composite kayaks. It’s a fun read. My gut feeling is that if you’re not looking for ultralight weight where carbon is worthwhile that s-glass/kevlar is the best layup for durability. If lightweight is desired then leaving the gel coat out and putting in s-glass as a protective ablative layer makes more sense pound for pound.
I do have a copy stuck back in my library and I need to study up on it!
S-glass/Kevlar is the basic whitewater
layup. Check that John Sweet site I put on my first post.
As for Kevlar soaking up water, this is true of most organic chain fibers used in layups: Nylon, Kevlar, polyester (Dacron). Polypropelene does not absorb water, but it floats on the resin in layup, so is not favored by builders unless they use vacuum bagging.
In fact, this water absorption is a minor matter. Else why would knowledgable builders like Gary Barton (Upstream Edge/Bluewater) be using Nylon and Kevlar? I have several boats made with organic chain cloths, and I have not detected any delaminating tendency, even though I have ripped well into the cloth layers while paddling whitewater.
The fuzzing of organic chain cloths, if used on the outside of a boat, is a real problem. Whether it slows a boat, I can’t say. A few years ago, I torched off the fuzz on two of my decked boats, and rolled a thin layer of epoxy onto them. Of course I sanded them smooth. It seemed to me that they felt faster, but I have no objective evidence.
From what I have heard,
from a seemingly very knowledgeable person,
the absorption of water in fibers like Kevlar is mainly a problem
in applications with very high temperature differences, like
in airplanes. Than it can really matter. In well_made canoe
or kayaks the problem is probably negligible, at least I have
never heard about problems like that with kevlar canoes.
look at the boat
something tells me that if you “do not know” and are looking at an Arctic Hawk you should consider other kayaks if you haven’t developed a strong preference for that exact kayak from paddling it. A glass kayak will last as long as a kevlar one. Your use and the particular model will matter more than whether it’s made of kevlar, carbon, glass, plastic or any mix.
laminate delam from frezzing temps and soaked fibers.
best to keep the fibers/ laminates dry, if possible.
This is where kev is a PITA, as gelcoat isn’t very well liked by the slippery kev fibers.
is there a layer of glass between gel coat and kevlar in a “kevlar” kayak? Seeing a 1/2" chunk of gel coat chip off the bow of a friends Sirius makes me wonder about gel coat attaching to gel coat.
I’d be curious to see a kayak made with vinyester and s-glass replacing gel coat pound for pound then painted and see the difference,it’s gotta be tougher than gel coat.
You were lied to
Fiberglass does not “break easily”. In fact, I’m continually amazed at how much abuse a 'glass kayak can handle. Just as important, fiberglass is very easy to repair, meaning your boat will likely last as long as you want to keep it.
On the other hand working with Kevlar can be a real pain. It requires special shears to cut it and it cannot be sanded without turning into a fuzzy mess. It’s a good fabric for the inside of a boat, provided that the surface is protected from abrasion.
but it’s bullet proof!
On a couple Wilderness Systems kayaks,when they made the kevlar version it was without taking into account the reduced rigidity with kevlar compared to glass,Cape Horn specifically,which resulted in easily cracked gel coat.