Never seen 2mm sandwich in any board, ever.
But a waveboard





Wasn't hard to ninja star a sliver of it into one of my cross-sections for a nice visual reference..... not hard at all, when that thin....

Wasnt one of those kiddies boards we saw break in 2 at Pozo Saturday was it?
Was it a production board?

Its a production board
Not a proto, pre-production etc etc by the serial.
Not a sand -thru in a small patch its just as bad in the low points as it is on the high point of the vee.
Its astounding.

Duotone SLS?

all new Hawk Tuah sandwich construction

somewhat of an oldskool classic on sectioned wave offerings, unfortunately
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Using thinner foam means it's an eco board. That foam sheet uses 2 % recycled pizza boxes . Saving our playground . Striving to make a cleaner planet.

Yeah maybe thats it.... they must think its the 'right stuff'
Maybe writing the 'right stuff' on the bottom is in the hope the logo strengthens it

If it's load bearing paint

I see same 2mm pvc, in a low density around 50 or 60 kg/m3 in local deck sandwich of wing foil board over ultralight big cell eps 10kg/m3. Board was ultra light, flexy at pressure on sandwich, don't try to push where there is not sandwich, too scary to go trough the single skin. Board last 10 sessions and crack at top rails under pumping. I repair it with a skin of 0,6mm hard wood on deck, 6oz biax carbon on rails all warped with a 4oz glass. Board is no more ultralight but usable for more than 10 ride. May be this 2mm foam is a good support for a good wood+fiber skin...

Ok Questions - I've been out of windsurfing for 25 years - but now with kids older and a little more time - I've decided its time to build a board and get back into it ..

First question - I know its important for lightness in boards - but why not increase the strength in the blank/core, instead of a 10kg/m3 blank why wouldn't you use a 32-38kg /m3 blank and reduce the layers of skins? - I'm building a basalt innegra creation with a special foam sandwich on the deck weight will be similar or just slighlty heavier (maybe 1kg max) with a 38kg molded blank - I might be wrong and it snaps first go.. but for waves wouldnt it be better to have a stronger core?

genuine questions as i'm way out of what happens in windsurf construction - compared to surf construction.. but 10kg/m3 just sounds wrong even though you are using tough skins - to me it comes down to the core?

valid question which this been debated on here at length. - fwiw I'm with you.

I have used both methods and either works fine up until where you want to do big jumps. at that point sandwich offers some strength advantages.

for denser foam, 24kg-28kg/m3 (M grade) will work without sandwich so 32+ is probably overkill and definitely excessive in weight

The foam core is not structural really, denser only helps stopping heel dents on jumping. .. but more carbon patching or wood does that.
Heavier core and lighter skins is the opposite of what an I-beam structure should be.
It works with heavier core, it can be easier build .... but for top performance in all aspects balanced against one another we have nailed it with 12-14kg core and 3mm 80kg PVC (corecell even better). 5mm bottom on abused stuff.

I just object to innovation thats clearly a more fragile product for no reason and with no disclosure by the company

And John i will tell you every secret i know in confidence... for a 100m roll of 4oz 30" SGlass

Seaclone, french eco board builder make monolitic windsurf speed and wave board using stringered 30kg/m3 eps foam and mostly linen fiber with success. From what i know those boards work and last for near half price and a bit more weight than his full sandwich carbon. For sure without specific skin 10kg/m3 is not good. For me 25kg/m3 work for monolitic surfboards with stiffners and not paper thin lam. I build sup/wing/surf/kite foil boards i use mostly 20kg/m3 foam with stringer and deck sandwich (2mm corecork with glass under and biax carbon over or 0,9mm wood with biax carbon under and glass over) and beefy monolitic bottom. From my experiment with big hybrid raceboard flat water, this build could work nicely at least for me. Cheaper and easier to make than a real full sandwich but with a bit more weight.
I

So yes like I said all things considered..... most people don't want heavier for same strength in a factory board. Half price is nice though....

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Mark _australia said..
And John i will tell you every secret i know in confidence... for a 100m roll of 4oz 30" SGlass

At 1 m wide

I have a roll of 3 mm cork. Can I use this for good or for evil? It's concrete and great, but sucks so much resin.

Wet out glass on table first then use in laminate with cork to avoid it sucking resin.
Not a fan of cork though...

Select to expand quote

Mark _australia said..
The foam core is not structural really, denser only helps stopping heel dents on jumping. .. but more carbon patching or wood does that.
Heavier core and lighter skins is the opposite of what an I-beam structure should be.
It works with heavier core, it can be easier build .... but for top performance in all aspects balanced against one another we have nailed it with 12-14kg core and 3mm 80kg PVC (corecell even better). 5mm bottom on abused stuff.

I just object to innovation thats clearly a more fragile product for no reason and with no disclosure by the company

All that is correct. It is about the I beam concept. . For most board breakings it means that the bottom gets compressed. And compression strength is difficult to increase very much without increasing weight or making a more complex I beam structure in the bottom. But this a topic on its own. There is something that is not talked much about and that is you can reduce the stress in the bottom if you increase the flexibility i.e. lower the tensile modulus in the deck of the board. This is why carbon should be avoided between the straps and the mast track. the modulus is to high and therefor all the stress goes into the bottom.

Select to expand quote

Gestalt said..
valid question which this been debated on here at length. - fwiw I'm with you.

I have used both methods and either works fine up until where you want to do big jumps. at that point sandwich offers some strength advantages.

for denser foam, 24kg-28kg/m3 (M grade) will work without sandwich so 32+ is probably overkill and definitely excessive in weight

Thanks mate
Good to know
Deck will be still foam sandwich but a different type of foam - more bullet proof with a 1.5oz Sglass underneath the foam sandwich
Bottom and deck has a basalt innegra hybrid with a layer of cloth we designed for JS when they made the first models of Hyfi range.

For cork you need right product, density size if granul?, binder. I use ony 2mm and i feel it with a micro slurry. Ended with high impact strentgh and great overall stiffness. Those roll of cork are make 20km from home cost me 8x less than basic pvc foam. Last experiments with wood over seems realy good.

For cork you need right product, density size if granul?, binder. I use ony 2mm and i feel it with a micro slurry. Ended with high impact strentgh and great overall stiffness. Those roll of cork are make 20km from home cost me 8x less than basic pvc foam. Last experiments with wood over seems realy good.

For cork you need right product, density size if granul?, binder. I use ony 2mm and i feel it with a micro slurry. Ended with high impact strentgh and great overall stiffness. Those roll of cork are make 20km from home cost me 8x less than basic pvc foam. Last experiments with wood over seems realy good.

For cork you need right product, density, granulate size, binder. I use ony 2mm and i feel it with epoxy foam. Ended with high impact strentgh and great overall stiffness. Those roll of cork are make 20km from home cost me 8x less than basic pvc foam. Last experiments with wood over seems realy good.

Select to expand quote

sanded said..

Gestalt said..
valid question which this been debated on here at length. - fwiw I'm with you.

I have used both methods and either works fine up until where you want to do big jumps. at that point sandwich offers some strength advantages.

for denser foam, 24kg-28kg/m3 (M grade) will work without sandwich so 32+ is probably overkill and definitely excessive in weight

Thanks mate
Good to know
Deck will be still foam sandwich but a different type of foam - more bullet proof with a 1.5oz Sglass underneath the foam sandwich
Bottom and deck has a basalt innegra hybrid with a layer of cloth we designed for JS when they made the first models of Hyfi range.

Oh you can't tease like that, what's the different foam?

Select to expand quote

Mark _australia said..

sanded said..

Gestalt said..
valid question which this been debated on here at length. - fwiw I'm with you.

I have used both methods and either works fine up until where you want to do big jumps. at that point sandwich offers some strength advantages.

for denser foam, 24kg-28kg/m3 (M grade) will work without sandwich so 32+ is probably overkill and definitely excessive in weight

Thanks mate
Good to know
Deck will be still foam sandwich but a different type of foam - more bullet proof with a 1.5oz Sglass underneath the foam sandwich
Bottom and deck has a basalt innegra hybrid with a layer of cloth we designed for JS when they made the first models of Hyfi range.

Oh you can't tease like that, what's the different foam?

Ha Ha
We make it in house its a 2 part foam we call it SPS - comes out at about 60kg/m3 - you can hit it with a hammer and its solid but you can shape it in

We were going to do it commercially but the pressure in the cans made it too hard to transport and store (We had one go off one day and the lid hit our 5m ceiling sounded like a shot gun blast)- so we make it to order for the local ding repairers to fix up broken finboxes - did my brothers tuttle box after ripping it out of the board while wind foiling, that was 4 years ago the board is still going strong.

speaking of things in cans and cork...

decork have a cork render i thought might be fun to try as a core material. no vac bag needed, just trowel it on to the shape.

possibly heavy so might need some filler.

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SchobiHH said..

Mark _australia said..
The foam core is not structural really, denser only helps stopping heel dents on jumping. .. but more carbon patching or wood does that.
Heavier core and lighter skins is the opposite of what an I-beam structure should be.
It works with heavier core, it can be easier build .... but for top performance in all aspects balanced against one another we have nailed it with 12-14kg core and 3mm 80kg PVC (corecell even better). 5mm bottom on abused stuff.

I just object to innovation thats clearly a more fragile product for no reason and with no disclosure by the company

All that is correct. It is about the I beam concept. . For most board breakings it means that the bottom gets compressed. And compression strength is difficult to increase very much without increasing weight or making a more complex I beam structure in the bottom. But this a topic on its own. There is something that is not talked much about and that is you can reduce the stress in the bottom if you increase the flexibility i.e. lower the tensile modulus in the deck of the board. This is why carbon should be avoided between the straps and the mast track. the modulus is to high and therefor all the stress goes into the bottom.

If you cut a board in half does it look like an I beam or a tube ?

Select to expand quote

Gestalt said..
speaking of things in cans and cork...

decork have a cork render i thought might be fun to try as a core material. no vac bag needed, just trowel it on to the shape.

possibly heavy so might need some filler.

I look what is cork render. I think you are on right way. Look at hardcork from bufo (deutsch inovator shaper...). Because i can have cork so easily and with an engineer background (i am engineering teacher) I work on my own way to use it.
Find best results come from use cork as kind of bulker mat than a foamcore. At same weight a way to make beefy skin, flexible but tougher than foam sandwich, un effective ASA skin alternative.

Select to expand quote

Gestalt said..

SchobiHH said..

Mark _australia said..
The foam core is not structural really, denser only helps stopping heel dents on jumping. .. but more carbon patching or wood does that.
Heavier core and lighter skins is the opposite of what an I-beam structure should be.
It works with heavier core, it can be easier build .... but for top performance in all aspects balanced against one another we have nailed it with 12-14kg core and 3mm 80kg PVC (corecell even better). 5mm bottom on abused stuff.

I just object to innovation thats clearly a more fragile product for no reason and with no disclosure by the company

All that is correct. It is about the I beam concept. . For most board breakings it means that the bottom gets compressed. And compression strength is difficult to increase very much without increasing weight or making a more complex I beam structure in the bottom. But this a topic on its own. There is something that is not talked much about and that is you can reduce the stress in the bottom if you increase the flexibility i.e. lower the tensile modulus in the deck of the board. This is why carbon should be avoided between the straps and the mast track. the modulus is to high and therefor all the stress goes into the bottom.

If you cut a board in half does it look like an I beam or a tube ?

The question is not not if it more a tube than an I beam. The question is, does it make a difference in the argumentation? And I don't know of any physical reasons why it should make a difference... It is about tensile and compression stresses no matter of the concrete shape. The shape itself is only a constant, but the dimensions of that shape are what constitute the relation between stress and deformation.

Standard sandwich build is a tube. A center stringer with ud fiber cap can make an i beam realy effective, like air plane wings, that often made as a tube with an i beam.