I was interested in any advantages-disadvantages to using carbon fibre on boards. On kayaks, carbon fiber is significently better than any kind of glass, but on boards, are there any advantages of note or disadvantages of note that people have experienced?
(I’m looking for increased strength without increased weight for rock impact on rivers).
Corran
So your intention is to hit rocks on a river with your surfboard? tell me what i missed please…
I tried a surfboard made with epoxy and carbon fiber, it was really hard, it was light, and it surfed horrible… but i think the problem was in the shape.
Good luck with your research. I think there’s some information on the archives.
Ha ha… yeah… we’re on a seek and destroy mission. See how fast we can destroy $1000 boards 
Na, the simple fact of the matter is that there are rocks on the rivers where we surf, and you don;t get to see them before you tear the edge off your board. I’ve made up to 12oz deck and hull boards (HEAVY!) to resist this and that works, but OUCH its heavy. So, I want to keep weight down (6 over 6) by going carbon for strength.
Corran
Carbon seem to work best resisting soft, heavy objects, rather than sharp, tearing objects, because the carbon is really held together with resin, which cracks on impacts. The carbon sheets would tend to tear off in big layers, which would be a messy repair.
Might I suggest you look at the composition of river kayaks…all polyethelene plastic tubs.
Then consider all the scratches you would get, and now look at the bottom of surfboards and come up with what… BICS!
ha ha… yeah, I make and design whitewater kayaks, and also a plastic surfboard (not unlike the bic) for river surfing, but they are realitively heavy (sad face)…
Corran
Heavy yes, but they will resist impacting the bottom and keep on riding!
Here in the American River, NO one rides on the custom fiberglass/carbon river kayaks anymore, not even for rodeo tricking. EVERYONE is riding the supeshort 7’ long plastic tubs.
Also, rivers tend to be very choppy and uneven, so a heavier board is smoother and easier to ride, holding in better, and giving your body time to react.
Just make a short 6’ x 24" double bottom board, and you will be able to snap it around.
Lighter is always better.
http://xackers.net/pages/?ID=547
narrower is faster ;-). My little red board here is a 5’11" x 18" x 2 1/4" squashtail and it MOVES! The blue and white one is a 6’3" x 18.3/4" x 2 3/8" squashtail too.
But for most people, performance Fish boards seem to do the trick.
Corran
Hey Corran,
You wouldn’t happen to live in Quebec, Canada wouldn’t you?
Yup - Montreal
Me too,
I’ve heard about you during the Chambly river fest,
The plastic river fish,
I thought I was the only one thinking about building a board like that here
I’m from Montreal as well, and getting into shaping.
How’s it going business wise?
Any plans on commercializing the riverfish?
Don’t worry,
I’m not a competitor here.
Just a backyard shaper interested in the Montreal shaping scene.
Riverfish!
Strange, you know the riverboogieboard, the black one used for river rescues and such. The inventor came to see me for more than two years before deciding on actual size, as he had bought some big boogieboards from me, but mostly liked to come in and BullS, looking for free info.
I was a manager at a big windsurfing/surfing store at the time, and knew enough to know he was one of those “inventor” types.
Also, the guy who kept winning the custom division of the SantaCruz Cold Water Yak division, RashadChung, used to hang around to discuss steering apparatus for his modified windsurfboard/surfriding sit downs! Now he’s the inventor of one of those self propelled scooter things.
Do you stand up on your boards?
I used to ride ChiliBar, a sorta local famous river hole, on my 9’ Blue Hawaii log, to the consternation of the rodeo yakkers. I soon switched to a Perception Whippit and as soon afterward accepted.
Actually I call it the Swallowtail.
http://www.dragorossi.com/product.asp?ID=5
Not much of a shaping scene here… I do some boards now and then for mates looking for river specific boards.
Corran
I have used carbon fiber in my kiteboards and based on my experience and research I think carbon fiber is not all it is cracked up to be.
True, the tensile strength is very high but this does not always mean higher strength overall. The shear strength of carbon fiber is very low. Carbon is stiff, but actually pretty brittle. Fatigue strength is also low, look at all the America’s cup hulls that have failed.
What I seem to get in my kiteboards when I use carbon is a board that is stiffer, but also quite a bit more fragile when it comes to things like dings and scratches.
If you really want a rock-resistant board take a look at kevlar. It can be pain to laminate and is very difficult to sand because it fuzzes up, but in my experience it is super resistant to abuse. I have seen a kiteboard with a glass over kevlar lamination get ridden over and then bashed into large rocks with only minor dings (rider was not so lucky) while a board with a similar layup using carbon instead of glass had the rail shatter just from riding it up onto a gravel beach.
Carbon is way overrated- I think mostly it gets used as a marketing point.
trent
Totally agree there!
But of mine, LMG, has made about 150 kiteboards now, and gave up on carbon, except for heel patches, since about #50.
Currently, no kiteboard makers are using carbon, except a small 6" patch at the heels.
Each has their pluses and minuses. The carbon is very stiff in it’s strength to weight ration in tension. But, it’s not great in compression. Aramids or Kevlar are super strong in compression and not real great in flexular modulus. The trick is to use the right material in the correct part of each structure. I’ve raced carbon fiber/Nomex hulls to Hawaii that are pushing 20 years old and it’s still a super rigid structure. While I’ve hauled out all aramid laminate hulls that sagged worse than our GRP laid up Mac Gregor 65. Previously, the Whitbread around the world race would not allow carbon fiber hulls. Now they can have carbon fiber hulls with Kevlar bulkheads and crash boxes.
The two, in the same laminate, can be a nightmare.
The two, when used separately to enforce a solid bond, can be quite effective, and costly.
I guess that’s why they are used as composites, rather than mixtures.
i think the main difference with carbon fibre is in the layup, if you laminate carbon as you would on a board with a sqeegee it really is not much better than glassfibre, its only when you use pre preg and a pressurized auto clave that you have a far better composite, pete
Thanks guys. I am very aware of the benifits of kevlar, having laminated my Olympic kayaks out of this (with carbon). Also vacume bagging and other systems of composite laminate. What I’m interested in is resistance to rock DING (or DONG - so pressure poc, not catastrophic smash)… to resist this I needed 10 or 10oz glass. A serious impact will break either for sure - but I want to eliminate the hull of my board from looking like the deck - heel imprints everywhere.
Kevlar CAN be awesome, but to really work it MUST be vacume bagged with Epoxy - otherwise the resign fails before the kevlar has even startd to take the load. Making a 2oz kevlar under a 4oz glass might work too… but thats a pain in the ass, so Carbon seemed like a simple but effective solution to the issue (especially since I pay the same price for it).
Corran
I thought that kevlar had good tensile strength but was poor under compression. According to Don Stackhouse of Aerotech, the following is the case:
“The situation for Kevlar in compression is a bit different. The Kevlar molecule actually buckles under compressive load, so although its compressive stiffness is high, its compressive strength is low (only about 40% of the strength of ordinary “E” type fiberglass). Initially the Kevlar fibers carry the load, but when the molecules buckle, that load is shifted to the epoxy, which then crumbles. The Kevlar molecules retain almost all of their tensile strength after failing in compression, so once again the structure turns into a rope, at a load somewhat higher than pure epoxy”.
Kevlar also breaks down in sunlight