Heel dents. T stringers under the feet. Between Poly and PVC. Very effective and light.

Good to see that finally the general sailing public is at last bring into question the build quality of boards coming out of Asia. It is definitely helping Custom board builders gain more sales here in OZ .
While I will not disclose any of our building techniques gain over 26 years of building and selling boards, there is many ways to skin a cat, and to say you must use product X, Y, Z in a certain way to build the best board is BS. There is no reason why you cant use only 4 oz E glass for a wave board that would last for yourself. The problem arises when you start asking money for you labour of love from some one else. It then become paramount what you are building and selling ,will out perform,both with on water performace and construction, everything in the market place, with the numbers of satisfied customers to back up what you are saying.
This only comes with trail and error, so see what works and holds up for you, give it a go.
If you still cant get what you want, contact your local custom board builder for his expertise .

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OESaustralia said..
This only comes with trail and error,

Off course a lot of testing is needed but just trial and error would go very slow. Using some engineering skills and phyical laws can speed up the process considerably. We have calculated that the way I build up the heel area is about 20 to 30 times as strong as Cobra production boards. With about 10-20% extra weight in this area. Sometimes the solution is something different than just beefing up the part that has broken.

^^^ I can't see 20-30x stronger in the heel area. 20x stronger would mean a 500kg man could jump it daily for years.
Is this your "calculation" or the result of destructive stress testing on a jig with measurements taken?

Then of course plenty of Cobra made boards never get heel dents, so obviously double sandwich and decent pads / heel bumpers IS enough if it is made right.

NO insult intended but about 20-30x sounds like salesman not engineer.

Hubble, bubble, toil and trouble..

Yep leans back puts his feet up, has a sip from his glass......tick tock tick tock.

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R1DER said...
Yep leans back puts his feet up, has a sip from his glass......tick tock tick tock.

Should I grab the popcorn ;-)

Okay now a serious question. Could you substitute klegecell/divinylcell etc with sign makers pvc foam sheet called Ex cel manufactured by Jains I think.

www.jains.com/Plastic%20Products/Sheets/pvc%20free%20foam.htm

^^^ interesting. I saw it is 55 - 70kg/m3 if my maths is right? So a bit less dense than divinycell / Herex etc, but not much
So it may be useful.........
If it is cheaper and as strong......

The sign pvc I have seen has a smooth outer coating and to me looked to stiff to bend it also
looked to light and brittle..Why not buy a small bit and make up some test panels.

I got some from Damowest in Osborne Pk in a few densities...you can see a bit of it sticking out the tail of my board(edit) before it snapped off on its first run at Cervantes..its brittle and takes a lot of heat to bend. I used the last of it as a tool to form a repair on the bottom of a concave'd board..without release agent. Worked nicely.

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Mark _australia said..

^^^ I can't see 20-30x stronger in the heel area. 20x stronger would mean a 500kg man could jump it daily for years.
Is this your "calculation" or the result of destructive stress testing on a jig with measurements taken?

Then of course plenty of Cobra made boards never get heel dents, so obviously double sandwich and decent pads / heel bumpers IS enough if it is made right.

NO insult intended but about 20-30x sounds like salesman not engineer.

We?ve got a 4-5 months waiting list so not much need for salesman talk.

It is calculated by an engineer. They can do that nowadays. You can even simulate the force when you land flat which can add up to about 8 times your body weight. If you know through physical laws how it works it is easy to achieve a 20 to 30 x strength. It does cost a bit more in labour, weight and material cost, but only a bit so why not? For a part we allready have off cuts we?d throw away otherwise. Even if many Cobra made boards never get heels dents, there are others who?d break them within a month or even a day. I had a customer from Pozo, who sailed one board for 6 years, which is over 600 sessions, which is over 25,000 jumps of a high level. Off course it had heel cushions. To protect his ankles not the board. For conditions where you ride as well I prefer a more direct contact so do not use heel bumpers as a standard. The board started to go soft eventually and the shape older so he ordered a new one but it still works and the only thing repaired was a new non slip. Then there are also other heavy jumpers from Pozo who?d never be able to buy something else. And the brands they used are happy they?ve got rid of them.
Like this guy weighs 110kg:


And the board he is using is 5 years old.

Good morning, Mark,

Not sure if you know, but Witchcraft (Bourke) is a highly-respected board maker in a hard-hitting wave area of Spain. He contributes regularly here http://forums.boards.mpora.com/forumdisplay.php/5-Equipment and is one of the few designer/manufacturers who actually replies to comments about his products.

His thoughts on board materials, board making, fins and carbon mast extensions show years of experience.

He is definitely NOT a sales rep.

I find your own thoughts on board materials enlightening but hope I never have to use your info.

guys,
Thanks for the advice re: Ex-cel PVC foam board. Looks like I have to purchase a large sheet of klegecell for a small A5 repair piece unless someone has a small piece they can spare???


PS - I have to agree with Mark that without empirical evidence Witchcraft's empirical claim does have that "salesman" feel about it. I don't think Mark was being disrespectful but unless Witchcraft can back their statement "about 20 to 30 times stronger" with test results then it just another meaningless sales pitch.

If that guy in the pic is 110 kg and doing back loops like that on the same board. Then that pretty much backs up bourkes 20x claim. At some point I'm sure there would be a flat landing and from that height and his weight normally result in catastrophic failure and a rather awkward swim in.

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Troppo said..

If that guy in the pic is 110 kg and doing back loops like that on the same board. Then that pretty much backs up bourkes 20x claim. At some point I'm sure there would be a flat landing and from that height and his weight normally result in catastrophic failure and a rather awkward swim in.

but Troppo that's exactly what we're talking about - his claim as opposed to any test results. I don't think we're questioning the strength of Witchcraft's boards, just the claim that they're 20 to 30 times stronger. Maybe actual testing proves they're a gazzilion times stronger (but exactly what forces are being tested: compression &/or torsional twist &/or, tension, etc) but without any scientific process the statement has no factual basis.

Id like to see a fight between bourkes and Thor

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Troppo said..

Id like to see a fight between bourkes and Thor

I hope they don't tie knots in their carbon fiber if they use it.

I would be doing that hammer test with a helmet on for sure, but I am not 100% sure the hammer hits on the pieces of their board were as hard as the hits on the other boards.

Either way, their boards must be pretty strong to be able to comfortably hit it like that.

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sausage said..

but Troppo that's exactly what we're talking about - his claim as opposed to any test results. I don't think we're questioning the strength of Witchcraft's boards, just the claim that they're 20 to 30 times stronger. Maybe actual testing proves they're a gazzilion times stronger (but exactly what forces are being tested: compression &/or torsional twist &/or, tension, etc) but without any scientific process the statement has no factual basis.

No, i did not say that. I said that the heel area was calculated by a composite engineer to be somewhere between 20 and 30 times stronger. Depending on the exact construction with which it is compared. Maybe it is in practice something like 15 times, I dont know since it is impossible to do objective tests on the water.

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FormulaNova said..

I would be doing that hammer test with a helmet on for sure, but I am not 100% sure the hammer hits on the pieces of their board were as hard as the hits on the other boards.

Anyone visiting our workshop can do the hammer test or test the fibres strength for themselves. And many do.

I knew I should not have said it. Yes Windman I know who Bourke is and I know his boards are beyond great. I'd love one (or 3)

In my very humble opinion though, 20-30x stronger is a big claim. For example how much can you put on the footpad area of a normal waveboard before it crushes? About 200kg? So Witchcraft can show 4 tonnes on that small area.....? Sounds a bit rich.

If the engineer calculated it, all good I will shut up.

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Witchcraft said..

sausage said..

but Troppo that's exactly what we're talking about - his claim as opposed to any test results. I don't think we're questioning the strength of Witchcraft's boards, just the claim that they're 20 to 30 times stronger. Maybe actual testing proves they're a gazzilion times stronger (but exactly what forces are being tested: compression &/or torsional twist &/or, tension, etc) but without any scientific process the statement has no factual basis.

No, i did not say that. I said that the heel area was calculated by a composite engineer to be somewhere between 20 and 30 times stronger. Depending on the exact construction with which it is compared. Maybe it is in practice something like 15 times, I dont know since it is impossible to do objective tests on the water.

Apologies as I did take your comment of the heel area being X times stronger and extrapolated it to being the entire board. Anyway I think the hammer test shows just how strong your boards are and it's commendable that there's custom manufacturers out there making quality products.

The discerning public are just pessimistic / dubious whenever they hear a product is x times stronger, better, faster, tastier, thinner ...when there appears to be very little scientific proof to validate a manufacturer's claims. Anyway I didn't (nor do I think Mark) mean to make a mountain out of a molehill so apologies again.

No need to worry about hammer testing your board round here with our glorious golden sandy beaches. Makes for a lovely stroll when it's gusting 40kts and hundred+ foot of plushness to walk over on a low tide. For some reason we don't get many sunbathing beauties which is a bit disappointing

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McSmurfin said..

No need to worry about hammer testing your board round here with our glorious golden sandy beaches. Makes for a lovely stroll when it's gusting 40kts and hundred+ foot of plushness to walk over on a low tide. For some reason we don't get many sunbathing beauties which is a bit disappointing

Most of our spots on Fuertes north shore have lava rocks sharper than that. There is reason why I started using Dyneema 20 years ago since it was not easy to figure it out and not exactly cheap either.

Yesterday:


And a guy I dont know:

Seabreeze might have more input from industry sources if you guys behaved yourselves..

According to my calculations this site would be 35x more informative.. And my desk would suffer 15x less forehead dents..

Start a thread on board construction, one of the most established custom board manufactures personally signs up and offers an opinion and ya'll try and bite his head off..

YO QUARTRO/Keith, I know you're reading, can you PM me your reasons why all the pros are apparently using S-glass boards? I won't argue with you..

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Witchcraft said..

FormulaNova said..

I would be doing that hammer test with a helmet on for sure, but I am not 100% sure the hammer hits on the pieces of their board were as hard as the hits on the other boards.

Anyone visiting our workshop can do the hammer test or test the fibres strength for themselves. And many do.

Look, come on, that's not realistic!

..but to help you out, I am happy to accept return tickets to wherever you just happen to be. Spain or even the UK, I'm okay with

I can bring the hammer too if that helps, but you may as well provide that as well.

(Its a worry that the boards you hit with a hammer are better than most of the ones I sail!)


edit: Sorry, I just realised how far away you are, so instead you can send me a few of your complete boards, and a hammer. I can supply the junker boards myself

Hammer test? I get nervous just carrying a board through my house, let alone hitting one with a hammer.

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barn said..

YO QUARTRO/Keith, I know you're reading, can you PM me your reasons why all the pros are apparently using S-glass boards? I won't argue with you..

S-glass is quite good stuff. Id prefer it over Innegra or carbon kevlar. Compared to normal E-glass it has about a higher breaking strength, 15% stiffer and 30% higher elongation at break. (from the top of my head).

Carbon Kevlar is actually a pretty stupid material. The modulus (elasticity) is very far apart so these materials do not cooperate. Who would lift a weight using a cable half of steel and half of elastic? What material would take the most force? Indeed but there is only half.

Hi Bourke, why do make the comparison between S-Glass, Innegra and Carbon/Kevlar? They are all used, if used properly, for very different reasons/solutions. I agree about carbon/Kevlar though I'm not sure why you would not make more relevant comparisons for example comparisons between Innegra and Dyneema or E-glass and S-glass. Or the benifits of minimising the use of Carbon wherever possible and to maximise high modulus fibres and resins in impact and repetitive load areas.
The two materials I would like to be eliminated from a(short/wave)board construction are carbon and eps.

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Man0verBoard said..

Hi Bourke, why do make the comparison between S-Glass, Innegra and Carbon/Kevlar? They are all used, if used properly, for very different reasons/solutions. I agree about carbon/Kevlar though I'm not sure why you would not make more relevant comparisons for example comparisons between Innegra and Dyneema or E-glass and S-glass. Or the benifits of minimising the use of Carbon wherever possible and to maximise high modulus fibres and resins in impact and repetitive load areas.
The two materials I would like to be eliminated from a(short/wave)board construction are carbon and eps.

Indeed some materials have complete different properties and should be used according to their properties in the various areas in the board. I do not remember the exact properties of Innegra but when I looked at them a couple of years back when it came on the market as a new material, I remember thinking it is far inferior as Dyneema in every aspect and lower modulus. it is more similar to Kevlar if I remember correctly.
S and E glass and Dyneema are more or less middle of the road for modulus. Carbon is available as high modulus and high strength but even the high strength carbon is still high modulus compared to the rest. What carbon is good for is compressive strength. Which is why it is by far the best material in masts. I use carbon in the areas with compressive loads. But since the elongation at break is 0.5-1%, it is the first to break if overloaded. So mixing it through a woven material means it cant be repaired without removing the other stuff as well. So where I use carbon it is on the outside where in case of breakage, what ever the cause, it can be replaced easily. Carbon is not impact resistant. So putting it on the nose and rails is silly. A full carbon board is also very stiff so loads, when landing flat, are much higher, both on board and sailor. A carbon kevlar board flexes more but then the carbon is strained to the max. Or over the max.

Thanks Bourke, I disagree about carbon performing well under compression. E-glass has about the same compressive strength.
From what I understand about carbon in relation to masts, the work the carbon is doing is more about controlling the flex characteristics and optimising the strength to weight ratio - the saving in weight albeit marginal, and more dynamic reflex is at the sacrifice of some strength and durability.
No?

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Man0verBoard said..

Thanks Bourke, I disagree about carbon performing well under compression. E-glass has about the same compressive strength.
From what I understand about carbon in relation to masts, the work the carbon is doing is more about controlling the flex characteristics and optimising the strength to weight ratio - the saving in weight albeit marginal, and more dynamic reflex is at the sacrifice of some strength and durability.
No?

I do not know the exact compressive strength of carbon or glass but I am sure that carbon is quite a bit stronger. Maybe creasing/buckling strength is the better word instead of compression.

Allready in the late 80s, the engineers of No Limitz figured out that carbon is a better material for masts than glass. Only that the proportions of the mast needed to be adapted to the properties of carbon. Hence a RDM.
When I moved to Fuerte 20 years ago, the first 2 years I snapped about 15 SDM masts of any make or type. Becoming desperate I then ordered some Powerex RDM masts from the US and they lasted 2 years.