When you go to buy that brand new sea kayak first impressions are everything and what are you really looking at?
Are you just looking at that shiny new gel coat or are you looking at the materials that go into making your kayak?
As the materials that make your kayak make a big difference to the life of your new purchase and the strength as well.
It's easy to be sucked into the whirlpool when your looking at a new sea kayak and the marketing strategies are just amazing with name dropping all over the place.
Kevlar,Carbon,Carbon/Kevlar are just some of the names used to describe some of the materials used.
Now what do they all mean ?
Carbon/Kevlar(CK) is one of those materials that is used by manufacturers to upmarket their product and in some ways it does this but only in the weight saving as other than that its probably no stronger than a average Fibreglass layup ,if you think I'm the only manufacturer who thinks this have a look here
But the sea kayaking market has been totally sucked in by this material,WHY?
Every one wants light weight and you sacrifice strength for the low weight
It looks so damm sexy!!
Most manufacturers who vacuum infuse or vacuum bag love to use this product as it lends itself to this form of manufacturer as CK is a light weigh fabric easily bagged and infused.
This creates a stiff light weight boat BUT that is were the advantages finish for us sea kayakers.
Their is also a general rule in composite manufacturer and that is the strength of your material is equal to the thickness IE a thin laminate will be weak compared to a thick laminate ...its a general rule remember!!
Being a woven fabric of two different materials causes a whole different scenario as you get the strength of both ( but remembering its only a light weight cloth approx 180/190 grams per square meter ) but also the weaknesses of both and in such a light weight fabric your asking for trouble.
I regularly make test panels out of the different layups in my kayaks and CK is by far the weakest even compared to a Fiberglass layup .
Surprisingly when cracked with impact the cracking is irregular and tends to crack along the Kevlar in the weave set and unlike all straight fabric options the cracking is usually a long line where the others tend to spread out in a circled crack.
Now after all that it does have its place in Sea kayaking but not in the hull of our boats.Its best used for what it was originally designed for and that is weight saving.Its great in decks for this reason as it just wont cop the punishment that the hull of your boat gets.
If your careful with your kayak and don't plan on playing around rock gardens etc then this might be the fabric of choice for you but be warned it wont stand the punishment other fabrics can stand up too
Now if I was to use CK in the hull of my sea kayaks it would be a layer of straight Kevlar and then another layer of Carbon on top of the Kevlar....a true Carbon/Kevlar layup and doubly strong without the weaknesses of weaving them both together.
Oh by the way I can make you a carbon/kevlar sea kayak if you think your going to be light and easy with it as it can save you lots of weight and with good care will provide you with a suitable kayak
from a manufacturers perspective..... that is
7 comments:
Hi
Whilst I do agree with some of your comments the bit you miss is that for a given weight of reinforcement k/c is stronger than glass. This allows more choices regarding layup i.e. lighter with same strength, stronger for the same weight etc. and each manufacturer makes their own decision on this
Also in most Kevlar/carbon kayaks there are also layers of glass, diolen or both and the performance of the laminate is a combination of their properties.
Facts:
Vac bagging or vacuum infusing will reduce excessive resin in the laminate and give a lighter more consistent laminate. The down side is that the laminate will be thinner and more flexible but this is easily mitigated by either adding additional layer/s of reinforcement, giving equal rigidity but greater strength for the same or less weight than a hand laid laminate. Alternatively a core could be added giving even greater rigidity with no weight penalty
Kevlar and or carbon alone doesn’t a better or worse laminate, as the name suggests a ‘composite’ is the result of various layers of reinforcement, the resin system and the process of manufacture so no one element can be looked at in isolation but and it’s a big but all other things being equal i.e. laminate thickness, total weight of reinforcement per sq/m etc a Kevlar or carbon or Kevlar/carbon laminate will be better, stronger and more resilient than a regular glass one
Cheers
Peter (Valley Sea Kayaks)
Thanks for your comments Peter and taking the time to give me your take on materials.its all very interesting and good reading
I agree with your statement re vacuum infusion/bagging giving a more consistent laminate and also the down side of its use "thinner and more flexible" and using more material either core or more material to make it stiffer/stronger
BUT
My argument is based around equal layups with equal weight reinforcement and material etc I see no real advantage in using Carbon/Kevlar over the regular glass layup especially in the hull of a boat.
I see its advantage in its weight saving in areas that dont need to be as strong as the hull of a boat, like the deck.
If I needed to add more material to the layup to make it stronger well I have lost the point of using it.
but I agree with your comments each manufacturer has to come to their own decision on this
I would rather use a more appropriate weight/weave cloth with my regular reinforcements to give a superior layup up and with Carbon/Kevlar only available in a light weight's ..it just doesn't do it for me
I do make Carbon/Kevlar boats and a lot of them but I ensure the customer knows my understanding of the material and my take on it , http://nadgeekayaks.com.au/our-kayaks/fabric-options.html
Thanks for taking the time to reading my blog
Thanks
Lawrence ( Nadgee Kayaks Australia)
Hi Again,
Sorry, I hope I haven’t offended you and certainly not wanting to get into an argument over ‘which way is best’ because there is no right way. However your blog kind of gave the impression that for sea kayaks Kevlar/carbon was an inferior construction was too thin, making the resulting hull more prone to damage. My argument was that the laminate is the thickness you choose to make it irrespective of the material used and that all things being equal Kevlar carbon is factually stronger than glass.
However like all materials you have to work to the strengths that they have. We mitigate the low fibre weight of the material by adding more layers, it’s still lighter than a regular glass boat but way stronger, people like tide-race and Necky use a core, this gives a slightly greater weight benefit and makes for a very rigid kayak but, we believe, they are a little more susceptible to damage from point loadings because the hull can’t deflect as it passes over the corner of something like a sharp rock.
We all have our own thoughts on constructions, me I don’t like the current vogue for all carbon outer layers but there are plenty who are happy to do this. I’m sure you, like me, could debate the subject for eternity, certainly I think articles like your blog allow people to make more informed decisions and hopefully you appreciate my comments are only meant to provide another perspective and perhaps a little balance to this fascinating topic.
Thanks again Peter for your informed take on Carbon/Kevlar
I hardly make a general Fiberglass layup these days and the most asked question is "What Fabric do you recommend" as I offer Kevlar,Carbon and Carbon/Kevlar as options in different weights and weaves for what customers want out of their boats and I try best to fit these to their needs and uses
I'm just putting out there what I personally think of the fabric,rather than just offer Carbon,Kevlar or Carbon/Kevlar and Fiberglass and as a manufacturer, without any opinion would be pretty ignorant of me,
and personally I'll stand by my comments that its no stronger than a glass layup with all things being equal and I'm not the only manufacturer to offer that statement as per my posting in my blog but I respect( and very deservedly)your opinion and thoughts
Thanks Peter and I hope you continue to read my other postings on other fabrics and maybe contribute to them as well
Some good reading here!
My experience (not as a manufacturer but as a consumer that had his share of hulls crack and hole) is that all things equal, as Peter pointed out (same weight of hull), a properly laminated (possibly infused) C/K fabric is stronger than a glass one. My experience has shown me that.
What maybe has not been addressed is that glass ain't glass. There are some glass-only hulls that are way stronger than others, at the same weight.
Some manufacturers are using a chopper gun to make a thick and strong hull (but boy, are they heavy) while others are laminating thinner woven cloth. I know which one I would chose.
In my fleet accidentally one of Peter's kayak is the strongest (standard layup Nordkapp LV) but also the heaviest (no chopper gun there :-). My lightest kayak is a cored one and repairing it is rather tricky. If that kayak would be glass-only (same weight) it probably would have cracked long time ago.
and if you had to add "core" into your CK hull you would also have a tricky boat to repair Gnarly and generally as Peter mentioned you need to add some kind of "core" or other layers with CK as its too lightweight by its self
just because you have a heavy kayak doesn't make it strong (not saying Peter's boats are weak at all ,on the contary actually)a correctly well layed up kayak either by hand or infusion doesn't have to be heavy to be strong making it heavy does increase the general rule of increasing thickness to gain strength but the penalty is weight.
You will have to wait for the glass write up Gnarly ..its coming as
your right Glass just aint Glass
Once you go on outdoor trips then it becomes necessary that you must know how repair your boat and how to use Stretch Poly-Cords, Hold-Down Straps, and Boat Cover Support Pole etc.
Boat repair
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