hi i want to run, one length of carbon fibre unidirectional 30 mm wide from nose to tail, top and bottom of a 7 foot stringless blank, instead of oredering a blank with wood stringer “as far as board breaking in two in the surf is concerned” whch choice should i take , if i take the carbon alternative will one tape be enough top and bottom? i will be using polyester resin.
No a thin strip of carbon will do near nothing even more with poly résin.
It’s my under standing is 1 yard of carbon streaches 1/16" it will break, so this makes everything else null and void. Wider carbon maybe?
What you need to fight against breakage is skin buckling strengh. One way is to make skin flex stiffer, by using stiffer material and more effectively by increase thickness.
It is funny that empirically people seem to have “success” using carbon this way, that is, poorly, despite it theoretically being silly. I suspect it may be merely because they are creating the thicker skin they need in their bitchen black reinforcement strips and patches. And some may be flooding the carbon a bit, it’s different to wet out. This helps too, if the board is globally stiff enough to support the carbon, which is hilarious.
So I would say, sure, go wider, if you’re gonna do it. Or just add 2 layers of e glass strips instead of a carbon one. Result may be superior, or merely similar. And cheaper.
for strength, full deck patch (glass will do). carbon in small quanities is more about stiffness, and the results depend on the design, details etc…
A flat strip of carbon laid under fiberglass will add strength on the tension side, but only minor support on the buckling side of the sandwich.
A better idea might be to incorporate slotted rail channels on the deck side and fill those in with carbon… one or more strips in each channel. The ‘corrugation effect’ of the 3D carbon strips inside each channel will add more stiffness and structural support than flat strips only.
By strategically designing the length, depth and placement of the channels you will be able to control the flex pattern in the board as well.
johnmellor wrote
A flat strip of carbon laid under fiberglass will add strength on the tension side, but only minor support on the buckling side of the sandwich.
Agreed.
Stretch vs. compresson.
The bottom increases in length the deck compresses.
As you say, surface channels (channel beams) would likely be better.
thanks for all your input everyone, i did not know that it stretched? is that after its been wetted out and cured or as it comes straight of the roll? if it was properly wetted out with no air bubbles and used epoxy instead of polyester it may be ok , have not ever used epoxy so im not about to start now, i guess epoxy is a lot thinner therefore it soaks in better, im only guessing.
The bottom increases in length and stretches as the board is being ridden.
Fatter laps help with this and breakage.
A strip of any fiber will increase strength as well.
Just does not look as cool as Carbon strips.
Does no one remember the 90’s Kelly boards.
All fashion, no function.
Nothing beats a wooden stringer.