Now as I keep on saying you need to know the weight of the cloth and maybe the weave as well to get a full understanding of what your kayak is made of as there is more than just plain old Fibreglass in there (I hope!!)
When I build a Kevlar boat it is a 300gm per sq mtr cloth in a satin weave...bloody hard to cut with scissors let me tell you...what was that" I HATE KEVLAR"!!
Kevlar has been around for some time and has proven it self in many applications.
If I was to have just one choice and one kayak it would be a Kevlar hulled kayak as its super strong when used in a good weight/weave and for kayaking its general all round purposefulness makes it top of the choices.
Its puncture resistant,its abrasive resistant,its flexible and we need all of those attributes in sea kayaks especially if you are rough on your gear
Drag your boat up the beach...get Kevlar...
Like playing around rocks......get Kevlar..... stronger than plastic
Did I mention as a manufacturer I hate Kevlar !!
Now dont get me wrong all of the cloths have their down side ....Kevlar's is that it breaks down with UV something we have plenty of here in Australia but with a good Gel Coat and proper care keeping the sun off the internal bits of Kevlar makes this a fairly low risk of happening.
It also makes a great external keel strip being so abrasive resistant
Now why don't we see its usage so much in our kayaks.
1. Its so hard to work with it takes me 3 times longer to cut patterns for a Kevlar boat than any of the other fabrics
2. Its easy to get air bubbles when doing a handlayup with Kevlar resulting in extra time and resources to ensure this doesnt happen.
3. Won't sit down over bumps and ridges easily with out extra care ..hence decks are a night mare with Kevlar
4. Its so god damm hard to work with !!
As a manufacturer I hate Kevlar for the above reasons but as a paddler knowing the material used in our kayaks I LOVE KEVLAR for all of the good reasons I have mentioned.
It will result in a longer lasting tougher kayak
Did I mention I hate Kevlar!!!
9 comments:
Interesting post, an insider's view which many of us paddlers don't get to see very often. Thanks!
Excellent write-up!
Curious about UV breaking down Kevlar even after it's gel coated. What would the effects be on the boat that gets left on a car all the time for example? Great write up, Thanks!
Laurie,
I too hate kevlar. My forays into making kevlar paddles proved to me it really is a dog to work with.
You forgot to mention that when sanding repairs kevlar just wont sand and makes furry frayed edges, so repairs (when you do damage your boat - which you will - cause you paid lots for it and its kevlar so 'it must be tough..I'll be right in that rock garden..') really do suck!
Tom
Thanks Guys
James....Its only the visible Kevlar exposed that is effected but imagine the cockpit open to the sun with exposed Fabric...my boats have flow coat over the exposed area to protect fabric from this sort of effect,if yours hasnt, maybe a cockpit cover to stop the suns effect
Tom those frayed damaged Kevlar fibers make for an excellent binding to your new repairs and once you know how to deal with the fuzzy bits its not too bad..but I still hate it
I agree, kevlar (kevlar is a brand name - correct generic name is aramid fibre) can be a bugger to work with. The key to working with it is sharp tools and new sandpaper! For sanding kevlar, start with coarse paper and work down to finer and finer grades. Fresh paper will cut the fibres cleanly instead of dragging them out!
The UV degradation of kevlar is interesting. When exposed to UV light it will change over time from a light golden colour to a dirty brown. 'Haven't done any tests yet on what this degradation means for its qualities. Owners of kayaks with inner layers of kevlar would be wise to keep the kevlar from UV exposure!
In my current Nadgee, I solved the UV deg. issue by sandwiching 300gsm satin weave kevlar between the tie layer and a layer of carbon twill in the hull. No light can get to the kevlar and I think it performs better by being in the middle of the stack. The boat is full layer kevlar and full layer carbon, not a Ke/Ca hybrid.
I have some 450 gsm double bias kevlar fabric which promises to be the ultimate strength vs weight in hull lay-up for a true sea kayak. My test panels with the stuff could not be cut with a diamond blade! It was necessary to use a metal cut-off blade to trim the panels!
It presents a few problems in laying up and trimming but for someone wanting the best this could be it!
Very nice blog. I love your ideas - simple and back to basics . Great ideas
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To lay up Kevlar, infuse it or at the least, bag it, much easier and better resin ratio as no floating as with wet lay up.
Regarding fluffing when you sandpit/grind it for repair. Easy solution is to wet sand it with 120 wet and dry. Just make sure you give it a dry off with a heat gun before you lay up the repair. all good
RR WA
To lay up Kevlar, infuse it or at the least, bag it, much easier and better resin ratio as no floating as with wet lay up.
Regarding fluffing when you sandpit/grind it for repair. Easy solution is to wet sand it with 120 wet and dry. Just make sure you give it a dry off with a heat gun before you lay up the repair. all good
RR WA
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