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Board construction: Carbon vs Glass

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Created by crabs > 9 months ago, 30 Jan 2009
crabs
18 posts
30 Jan 2009 12:24PM
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Hi everyone, I'm new to posting but have been reading this forum on and off for a long time.

I was hoping to get some information and opinions about board construction.

I'm trying to decide whether to build a full carbon wave board.

For glass boards I use two layers of 4oz for the outer skin. The way I see it, if I use the same amount of carbon cloth I'll end up with a stronger board. Is this correct?

Are there any disadvantages of a full carbon wave board?

decrepit
WA, 12770 posts
30 Jan 2009 7:03PM
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The cost!!!!!

And carbon isn't more ding proof either, it's a heap stiffer, you could use 1 layer of 2oz and have the same stiffness as your 2 layers of 4oz glass. But touch it with something hard and half sharp and you have an instant hole.
That's the prob with carbon, it's so stiff there's no give, the load from a hard point contact, is taken at the point of contract only. Where as glass has a bit of give, allowing the load to be spread over a bigger area, you'll get a bit of a dent, but not a fracture.

I use carbon as reinforcement only, between mast and rear foot areas, I really don't think you gain much by covering the whole board with it.

I made a board for Hardie a while ago, and used 1 layer 8oz carbon on the outside, when he came to pick it up, he dropped a fin on it, from no more than 2 feet up, and put a hole in it.

WINDY MILLER
WA, 3183 posts
30 Jan 2009 7:25PM
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decrepit said...

The cost!!!!!


I made a board for Hardie a while ago, and used 1 layer 8oz carbon on the outside, when he came to pick it up, he dropped a fin on it, from no more than 2 feet up, and put a hole in it.



whilst frantically adjusting his tie; did he say "thats another fine mess, i've got myself into!"


good work oly





gazza
WA, 647 posts
30 Jan 2009 8:00PM
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WINDY MILLER said...

decrepit said...

The cost!!!!!


I made a board for Hardie a while ago, and used 1 layer 8oz carbon on the outside, when he came to pick it up, he dropped a fin on it, from no more than 2 feet up, and put a hole in it.



whilst fantically adjusting his tie; did he say "thats another fine mess, i've got myself into!"


good work oly








your a funny man windy or is that Stanley

nebbian
WA, 6277 posts
30 Jan 2009 9:20PM
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decrepit said...
I made a board for Hardie a while ago, and used 1 layer 8oz carbon on the outside, when he came to pick it up, he dropped a fin on it, from no more than 2 feet up, and put a hole in it.


That same board shredded Spot X last sunday, and had some very enjoyable drag races with Lao Shi today...

Nothing wrong with it from my perspective

Gestalt
QLD, 14669 posts
30 Jan 2009 10:43PM
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vacuum bagged timber veneer would be my choice.

impact proof and softer riding.

decrepit
WA, 12770 posts
30 Jan 2009 9:47PM
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nebbian said...

decrepit said...
I made a board for Hardie a while ago, and used 1 layer 8oz carbon on the outside, when he came to pick it up, he dropped a fin on it, from no more than 2 feet up, and put a hole in it.


That same board shredded Spot X last sunday, and had some very enjoyable drag races with Lao Shi today...

Nothing wrong with it from my perspective


Glad you're still enjoying it nebs, but you don't drop fins on it do you?
How did it go at spot X, have you added that extra wave riding strap?

nebbian
WA, 6277 posts
30 Jan 2009 9:57PM
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Hey Decrep,

I try to remember to put the fins in the box, not drop them on it

I didn't end up putting that extra strap on, didn't need it. Move the back foot just before you take the drop, really lean into the bottom turn, then wiggle along the wave yelling out YEEEEEEEEHHHHAAAAAAAA!!!!!!! as loud as you can.

Worked for me


Every time I ride it that board puts a big smile on my face

decrepit
WA, 12770 posts
30 Jan 2009 10:12PM
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Great to hear, puts a big smile on my face as well ('')

NotWal
QLD, 7430 posts
30 Jan 2009 11:31PM
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WINDY MILLER said...

decrepit said...

The cost!!!!!


I made a board for Hardie a while ago, and used 1 layer 8oz carbon on the outside, when he came to pick it up, he dropped a fin on it, from no more than 2 feet up, and put a hole in it.



whilst frantically adjusting his tie; did he say "thats another fine mess, i've got myself into!"







I certainly hope so Stanley

NotWal
QLD, 7430 posts
30 Jan 2009 11:54PM
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I wonder if there is any advantage to heaps of stiffness. The old poly boards were as soft as my old schlong but got along quite a bit faster.

There seems to be more use made of Technora these days. Unlike carbon it's quite flexible but still very stretch resistant and strong as buggery.

What happened to Dyneema/Spectra ? Starboard used to use it in their boards.

sick_em_rex
NSW, 1600 posts
31 Jan 2009 1:02AM
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what happened to the carbon/kevlar twill? Impact resisitant AND stiff!

decrepit
WA, 12770 posts
31 Jan 2009 6:31PM
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NotWal said...

I wonder if there is any advantage to heaps of stiffness. >>>>>>>


Well the stiffer the skin, the more it spreads the load on the core foam, so the more delamn resistant it is.
Also the more crease resistant the skin is, so the board's less likely to snap.
If you don't mind it being a bit egg-shelly the board can be lighter, (thinner sandwich, less dense foam core or lighter carbon), with the same delamn and crease resistance.

But not what I'd want in a wave board, nice to have some impact resistance there as well.

crabs
18 posts
1 Feb 2009 4:33PM
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What about protection from flat landings etc. Would full carbon hold up better to the normal on-water punishments of a wave board?

decrepit
WA, 12770 posts
1 Feb 2009 7:57PM
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crabs said...

What about protection from flat landings etc. Would full carbon hold up better to the normal on-water punishments of a wave board?


For flat landings, the stress is between footstraps and mast, that area should definitely be fully carbon reinforced, top and bottom.

I don't think I've seen a board snapped in front of the mast, however, if you're in a habit of doing this, by all means go carbon the full length.

I use 8oz carbon under the bottom and top skins between tail and mast, with the weave at 45 deg. then 2 x 4oz plus carbon feet patches on the outside.
5mm sandwich on the bottom and 3mm sandwich on top.
Built my current high wind wave board in 2000, it's had lots of high flat landings, with out a problem.
But I only weigh 70kg, if you're over 100kg, then maybe an extra carbon layer on the outside skins, is justified.
Have you had trouble breaking/delaminating your boards?

keef
NSW, 2016 posts
1 Feb 2009 10:56PM
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decrepit said...


Have you had trouble breaking/delaminating your boards?
remember that whatever pvc foam your useing(divinicell ect) its resin thirsty,so before you layup, fill the divinicell ect with a dry mix microballoons or Qcells then you will know there aren't any dry spots in the laminate(aswell as incress the density) you must remember carbon isnt like Sglass where you can see if all of the glass is wet through, and allso when buying carbon make sure its for a normal layup and not for fusion layup
the fusion stuff has a coating called fiberseal and is very hard to wet out even with a wheel
and remember that carbon will absorb moisture, so make sure that you store it so it's airtight otherwise it will go britle, same as microballoons, keep them dry or you will be adding weight

crabs
18 posts
2 Feb 2009 3:40PM
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Thanks for the replies. All food for thought.

To answer your question, Decrepit, my last board had a carbon bottom and it broke when jumping (cracked across the bottom). I had put previous glass/epoxy boards through a lot more punishment and was surprised that it broke so easily.

I thought maybe full carbon would take more punishment than just carbon bottom.

Seems like most folks agree that carbon is superior in strength.

decrepit
WA, 12770 posts
2 Feb 2009 7:53PM
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crabs said...

Thanks for the replies. All food for thought.

To answer your question, Decrepit, my last board had a carbon bottom and it broke when jumping (cracked across the bottom). I had put previous glass/epoxy boards through a lot more punishment and was surprised that it broke so easily.

I thought maybe full carbon would take more punishment than just carbon bottom.

Seems like most folks agree that carbon is superior in strength.


May be your broken board is a case of reducing weight too much, because of carbons greater strength?

How thick was the sandwich? What was on the inside of it?

Did it break in tension or compression?

Normally the bottom "creases" when your feet at one end and the mast at the other try to bend the board over the water you've just flat-landed on. The stiffer the sandwich the more it resists this creasing effect. I've never seen a carbon bottomed board creased, but I suspect because carbon's so stiff, once the creasing action started, the carbon would just snap, instead of bending the way glass does.
I've also repaired some boards where the carbon has been sanded into during manufacture.
That's one of the reasons I put my carbon on the inside of the sandwich, the creasing action puts it more under tension than when it's on the outside of the sandwich, where it's more in compression. Also the carbon is protected from impacts by the outer layers.
Running the carbon at weave at 45 deg also means that all the strands have to fail, not just the ones running along the board.

keef
NSW, 2016 posts
2 Feb 2009 11:21PM
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CHOSEN said...

http://www.jp-australia.com/2008/index.php?id=175&L=0
here's your answer to delamination crabs, do your math's www.jp-australia.com/2008/index.php?id=35
why is it soooohere we have 110lt with all that lay up( pads ,wood, 2 layers of sandwitch,finbox ,mast track, ect,and it weigh's 6.3 kg's, if you do you math's theres no room for resin,
so the way i see it JP use the lightest core, with the minimal amount of resin so therefore delamination
how many times have you seen a small dent on the nose(top) and a huge crack on the bottom about 6" long, has anyone got the answer, why is it soooo


crabs
18 posts
3 Feb 2009 10:50AM
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decrepit said...

May be your broken board is a case of reducing weight too much, because of carbons greater strength?

How thick was the sandwich? What was on the inside of it?

Did it break in tension or compression?

Normally the bottom "creases" when your feet at one end and the mast at the other try to bend the board over the water you've just flat-landed on. The stiffer the sandwich the more it resists this creasing effect. I've never seen a carbon bottomed board creased, but I suspect because carbon's so stiff, once the creasing action started, the carbon would just snap, instead of bending the way glass does.
I've also repaired some boards where the carbon has been sanded into during manufacture.
That's one of the reasons I put my carbon on the inside of the sandwich, the creasing action puts it more under tension than when it's on the outside of the sandwich, where it's more in compression. Also the carbon is protected from impacts by the outer layers.
Running the carbon at weave at 45 deg also means that all the strands have to fail, not just the ones running along the board.


Hi Decrepit, that was a production board. Sounds like either faulty construction, poor materials or I was just unlucky. It broke in compression.

keef said...
here's your answer to delamination crabs, do your math's http://www.jp-australia.com/2008/index.php?id=35
why is it soooohere we have 110lt with all that lay up( pads ,wood, 2 layers of sandwitch,finbox ,mast track, ect,and it weigh's 6.3 kg's, if you do you math's theres no room for resin,
so the way i see it JP use the lightest core, with the minimal amount of resin so therefore delamination
how many times have you seen a small dent on the nose(top) and a huge crack on the bottom about 6" long, has anyone got the answer, why is it soooo


Hi keef, interestingly it was the lightest board I've had.

That's why I asked in my initial question whether if I used the usual amounts of cloth and resin if I could expect to get a stronger board if made out of carbon. Seems you guys agree that it would be stronger, if built properly.



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"Board construction: Carbon vs Glass" started by crabs