Hi there, been lurking for a while and finally signed up to see if anyone could help me out.
I’m doing a dissertation in a Surf science and Technology degree on ‘The effect of Carbon fibre tail patches’.
The aim being to build and test them with impact and bend tests and come to a conclusion on what difference they make, the main reason being not one of the big surf companies has any mention of what they do and seem to sell them purely by the pro’s riding them.
The trouble is i’ve only just started shaping really and have no experience with carbon fibre in boards.
If anyone could give me some pointers on any aspect of them really it’d be massively helpful, whether it’s what they’re designed to do in a board, any studies have already been done or how to best go about glassing them in a PE blank.
Hey Ollie 10,000 words on carbon fiber toe patchs? The topic might be too narrow, do you think you’ll get that many words out of it?? Maybe you should write it about the different types of fiberglass and their properties in modern surfboard design? Would be easier to hit 10,000 words maybe? Look for posts by this guy BenjaminThompsonon swaylocks I believe he has done research into this stuff, maybe you could contact him and read his papers to get some ideas for a more broad topic??
When you’re finished post it on sways, we would love to have a read of what you find out!!
Thanks for the reply and ideas. Initially i’d planned to do what you’d suggested but when I met with my project supervisor was told it was too broad a topic for a dissertation, because it’s a scientific paper it’s a 4,500 word limit luckily, 2,500 words of that is literature review aswell so I haven’t got to write too much original material by the end of it.
Will definitely be getting in touch with BenjaminThompson, his previous work looks really interesting.
I’ll make sure i post it up here when finished, doubt it’ll reveal anything groundbreaking but could be useful to have some stats available.
I think it depends on where the patch it - it does add some rigidity to the tail, but the most functional once I have seen go over the finboxes on the deck side - this seems to keep the FCS plugs from busting out the deck of the board over time - aside from that I would think that it stiffens the overall flex of that area the way an additional stringer would - What I want to know is what is with the carbon fiber strip on the base of boards like the ones that Slater rides - seems to be a single strip of carbon fiber tape on the stringer line - maybe about 12 inches long at most right around the center mass of the board. Maybe it’s just to re-inforce the board against the reef when duck-diving??
I want to start playing with carbon in my designs. Seems cool and has some great properties without getting much heavier than glass. I often wonder how a carbon-fiber stringer would feel and how much life you would get out of it.
I managed to have a chat with Rob Vaughan (Billabong shaper) while in france and he’d said the deck patches were to stop the tail snapping downwards when landing airs onto the lip which makes sense. I’d also seen some guys on here talking about them stopping heel dents which then lead to breakage, a way of getting around using lighter glass on the deck as CI and others are doing. Hope to find out just how much difference they make with this experiment.
As for the carbon strip on the bottom i’d guess it’d prevent buckling, noticed Kelly’s buckling a lot of boards recently. Managed to get in touch with CI who said they’ve been doing it through trial and error hence why there’s so many different little things they’re using carbon for at the moment.
Still struggling with lay-up though, anyone know the best way to go about it? Is it just polyester resin or better to use epoxy on carbon then polyester on the glass?
Use epoxy resin for the lamination. It adheres much better than poly based resins, and you're not using an intermediary layer like windsurf boards use. You can hot coat it with poly, but be very careful to laminate smoothly and evenly.
“toe patches” - carbon or any additional glass patches in this area of the deckside rail near the back foot are meant to delay what is known as “tail cancer” - a common death knell for high perf lightweight shortboards. Light glassing + soft poly foam + thin rails + heavy heel & toe pressure = cracking at the rails aka tail cancer. Once it starts in this area the board is pretty much a goner
Beams were constructed to replicate the carbon patches in boards. These were 14" x 4" x 1.75", this size was taken from measuring boards with patches.
Glassing schedule was 4+4/4 (Top/bottom), 4+C+4/4. 6+4/4 and 6+C+4/4. All polyester resin.
Carbon used was 6oz 2/2 twill Bi-directional. While other types are being used this has shown to be the most popular.
3 beams of each glassing schedule were tested in 3 point bending.
The testing replicated the tail flexing and eventually snapping downwards. While some people have said that the tails more likely to crease on the deck, both Channel islands (through email) and Rob Vaughan (personal correspondence) have stated their reasoning for patches being to minimize downward snapping.
In both cases it showed beams with carbon patches took Less force to buckle than their counterparts without carbon aswell as the flex patterns being pretty much identical.
If anyone could help me out with how to upload pictures there’s some graphs direct from the 3-point bend machine which show this really well.
Hope people find this interesting and shoot any questions in my direction
Very interesting! One issue may be the resin. It’s usually the limiting factor in strength especially with carbon.
Epoxies with carbon work best due to their higher strength/toughness than polyesters. But that rigidity can affect “feel”.
If there is a source for the paper I have some student friends that might be interested in expanding on it for their Senior Projects.
Some pics of the damage would be appreciated! Also of the 3-point bending fixture. Did you use an Instron to measure yeild and failure? We have some at the Cal Poly San Luis Obispo where I work.
Thanks for your curiosity, it will help to advance wave riding.
Super
interesting stuff! I just did a board for one of our shop guys who surfs
everyday and is definitely in the advanced category who requested the carbon
strip across the bottom of the board from tip to just past mid point, as well
as the strips on the deck (strictly intended to prolong the life of the board).
The ride report was that the board has a "pop" to it when doing airs
that made it more comfortable and consistent leading to more completed maneuvers.
The second observation was that the board had more drive coming out of bottom turns;
in his opinion he felt the carbon on the bottom springs the board back to its
natural position faster after being loaded from a hard turn allowing him to
generate more speed.
Does that theory and observation sound
reasonable to you guys?
Kinda scary that the reinforced pieces buckle
easier with less force, is it do the strength of the carbon ending and creating
a specific buckle point?
not sure if the question was to me but just in case…
the carbon on the bottom was under the single 4oz E and the carbon on the deck was between 2 layers of 4oz E. I used the colored carbon strips on the deck “RIBZ” and the standard carbon strip on the bottom. Off hand I am not sure the Oz. of the carbon in them.
I was curious about the OP’s project and patch lams. But I am interested in any input regarding lam sequence of the carbon tail patches. I appreciate the response.
Would be interested in location/placement of patches on the bottom. Have you noted similar failure patterns to the OP’s.
Hi EZ that’s interesting to hear how the bottom strips work, when talking with Channel Islands they’d mentioned it stiffens the board so that the flex is concentrated in the tail which would translate to ‘pop’.
I reckon with the top patches it’s partly to do with weakness at the ends of the carbon but also to do with the bottom glassing. Benjamin Thompson made some great points in one of his papers that within high impact surfing the bottom should have equal strength to the deck.
When my 3 point bend tests failed it was always from the bottom creasing from compression, i expect it would take way higher force before the top failed in tension. It may make sense when a surfers really hitting the lip hard to have a patch of fg or carbon on the bottom at the tail to stop creasing.
Stoneburner, on mine the carbon was between the two layers of the glass and was a standard weave (i think 6oz, i’ll have a look at the packaging when i’m back in the workshop), if i can get the facilities again i’d be interested in looking at the uni-directional EZ here is using
George, sorry almost missed your post and didn’t reply.
I’m still waiting for marks to be released then i’ll post it up online, bit worried i might get done for plagairism of myself otherwise, that’d be an awkward one to explain.
Yep, an Instron at Plymouth University, UK. Support 12" apart and a 60mm diameter driver.
I also carried out impact tests but they consisted of a weighted bar dropped from a set height. Since the bar was free-falling i wasn’t sure how accurate the results really were but they do show the carbon samples have slight less dent depths and a lot less cracking.
Still trying to work out how to post pictures, is it best to set up something like flickr or photobucket then use the url’s from there?
After all the flex-memory psudo science this is the best explanation I’ve heard. Given the same boundary conditions and same geometry stiffer materials with higher Youngs Modulus (E) generally have a higher vibration frequency, they will also flex less than less stiff materials. Stiff materials flex less and return to shape faster than less stiff materials but bear in mind that geometry also plays a very significant factor.
Bang on again. In structures it’s called a stress concentration. If you can imagine that carbon fibre has a greater ability to carry load than glass fibre, in a hybrid composite the carbon will carry a higher proportion of load. Abruptly stopping a carbon reinforcement will result in all the load from the carbon being dumped very suddenly into the glass causing a stress concentration. Try tapering out the carbon (often called a ramp).
