Just finished: Shinai Black Diamond (Vector Net, bamboo,FG)

[plummet]

Looking interesting and good man.

Some action shots next man!.

[downunder]

Down under,
great looking build!!
can you comment the use of vector diamond on the top sheet?
do you use the carbón to control the twisting of the board?
why carbón on the compression side and nothing on the bottom?
what characteristics did you get by using the vector diamond?
what are the diferences you get from the use of the epoxy rail vs the urathane?
your work and finish is awesome!!
Pedro

Thanks

You do NOT want Diamond on the bottom because it will make a wavy surface. Look at the top and you can slightly see that. Maybe if one uses it under the topsheet for the water line.
Torsion control as the idea. "Big boys" are doing it.
There is a FG on the bottom, as always.

The PU rails are pre made:

They make excellent finish and fast building with fast epoxy:

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[chrislandy]

You wouldn't need the carbon diamonds on the bottom if you used a light bi-ax glass over the entire board, it would be of equivalent stiffness and strength as the diamond glass.

The problem D is that a single layer on the top is not doing much as it's on the compression side in most load cases so you need the bi-ax or similar on the base to create the torsion box and also so its on the tension side

[downunder]

Yes,

a FG cloth must be on top of Vector Net. One board has 100g and the other has 200g. Both bottom glassed.

The need for it is two folds. As Chris said, torsial and there is no way to wet out the Vector Net. The light cloth is better for having a smoother surface after glassing. 200g cloth preformed worse.

D.

[BWD]

In theory diamonds or biax on the bottom (or top and bottom) would help much more with torsion and stiffness than top alone.
But as Yogi Berra said,
"In theory, there is no difference between theory and practice, but in practice, there is."

So if it works, it's good!

[chrislandy]

Ah but it does work, make a little test coupon say 50 wide x 150 long with 3-4 layers of fabric (about 1mm thick) where all the fibres run at +/- 45 deg (it doesn't matter whether its ud, bi-ax, woven as it's a demo). Once it's cured bend in on its length and it will be fairly flexible, then try and twist it...

[BWD]

I think no one is disputing that.
I was just pointing out that in practice, things other than the textbook example of laminate theory may also give good results....

[plummet]

I don't think anyone is disputing a duel layer top and bottom of fibres on the bias is more efficient. regarding torsional stiffness.

But what is practical?
Putting a layer of this diamond stuff on to bottom is going to end in resin rich zones so that is not practical. Putting a complete layer of double bias on top and bottom is going to be a lot heavier and provide way more torsional rigidity than is potentially needed.

This is an interesting practical solution.

The most efficient layup is not the primary concern in a kiteboard. If you can achieve your desired surface finish/shape on the bottom and flex characteristics with the most efficient layup then good. If not then its plan B.

.

[downunder]

And finally some sunny, windless days, good for building:

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Fins added:

Hope you like it!

D.

[plummet]

looks cool,

I want to know more about the bottom surface. Where to you get it and how to you apply it? how much weight does it add?