We want to jump ahead for a second to let you get a peek at the veneer we are using for this current wakesurf board build. It’s called Zebrawood and it has a great look! Here is a picture
This is a wood veneer and quite frankly the wood veneers are crazy difficult to work with. They tend to want to split on the grain and require very careful handling. The Bamboo veneer is much easier to work with, but doesn’t quite offer the same performance as wood. However, you can cut bamboo with a scissors and there is no splitting to have to manage. The paperbacked veneers are one way to eliminate the splitting, but as we’ve mentioned then you’re gluing to paper and not the veneer itself, so those are a poor choice with this sort of veneer work.
We are really good at cutting the veneer to the proper size, so we’ll need to do a pin line to cover the transition from the veneer to the rails. This will offer a more eye catching transition, plus it will hide our sloppiness! What we are wanting to do, is paint the pinline and rails in a Zebra pattern motif, to sort of tie the Zebrawood theme into the carbon fiber rails as well as covering up the transition from the veneers to the rails. So here is the idea, but we haven’t finalized that concept just yet. We swiped the image from a stencil retailer, mostly we liked the pattern although we aren’t sure that will work out too well with the curved areas of the rail, but hopefully we’ll get something that will tie the Zebra motif in there.
That’ll be fun! Just thinking about all the taping and painting!
Moving on, remember this photo? It’s the unidirectional carbon fiber. What that simply means is the carbon tow only runs one direction and in this instance there is no tow running widthwise across the fabric. Basically it’s not woven. Unidirectional fabrics have a few real specific uses. One is where the loads imposed on a structure come from a single direction. If that were the case there would be no reason to incure the cost and weight increases to resist loads that would NEVER be presented to the structure. Another is where the structure will be built up with the unidirectional fabrics being laid down on various bisases. So say the first layer is at 0 degrees, the next layer might be at 45 degrees, etc until the structure had reached a specific thickness. For this build we wanted to address the twist off issue that seemed to be generated by the single linear tape on the bottom of a wakesurf board.
Example time! Do you remember as a kid playing with the small balsawood gliders you got at the five and dime store? Those were the best weren’t they and sometimes they lasted longer than the one afternoon you played with them! Remember back, the wings were die cut sheets of super thin balsa wood and the “fuselage”, if you will, was die cut from a thicker piece of balsa and there was a small red plastic piece that attached the wings to the fuselage. That red plastic part was the stiffest and strongest part wasn’t it? You know you’re smiling at the memories of running around the yard tossing those thing until you arm got too tired to throw one more time!
Ok so you have the visual and you probably wrecked your fair share of those as a kid. When they broke was it the red plastic that snapped? No, that was the sturdiest part, it was always the wings that went first. They were flimsy and floppy compared to the red plastic. If you applied eagual amounts of stress or load to the wing tips and the center red part where the wings attached to the body, the wing tips bent and then finally snapped long before the centrally located red part.
Ohhhhhhhhh, that’s like the centrally located carbon fiber strip isn’t it. Well only black and not red. This is the “weakest link” theory. If the structure is composed of some form of discontinuity, the forces will focus on the weaker areas and that’s where it will break, but also the loads will transfer out to the less stiff areas, causing more of the forces to be focused in those areas. Viola, twist off on the rails while the center section of the carbon fiber strip remains mostly unaffected, well at least it’s stronger and stiffer than the unreinforced areas and so it actually TRANSFERS loads from the stiffed sections to the unstiffeed section, causing the twist off SOONER than if there were no reinforcement at all.
What we wanted was to eliminate that discontinuity and so decided to cover the entire bottom, under the veneer, with a single layer of unidirectional carbon fiber. We love the idea of the carbon fiber on the bottom, being subjected to the tension forces so that when it’s loaded up, it TWANGS out of that situation, but not by twanging the rail in mid load! So, we are going to be applying this unidirectional carbon fiber to the entire bottom. The only issue we had was that we couldn’ find the uni carbon in widths close to the 20 or so inches we needed for the bottom, so we got enough to lay up two pieces side-by-side to cover the bottom.
Ok so that’s a bunch of info! We want to cover just one more area before closing this topic. The unidirectional carbon is basically just loose strands running in one direction. You can imagine if you cut, say 5,000 pieces of thread and laid them down side-by-side, that they would be like herding cats when trying to keep them in order. So, the manufacturers use a very small piece of binder thread to keep the loose carbon fiber threads in place. If you look at the following picture you can see the diamond pattern of the binder holding everything in place.
Also, you’ll note the pink’ish colored release film. Being that the unidirectional carbon is basically just loose carbon fiber threads, if it was rolled up on the mailing tube they would get all tangled up creating a huge mess, so that layer of plastic film, separates the carbon from itself as it’s rolled up. That’ll save us a huge hassle as we unroll it into the wakesurfer.
Ok so now you are undirectional carbon fiber fabric experts! We’ll get into laying this stuff up on the bottom of the wakesurf board in the next post.
Thanks so much for following along!