Inside X-Core Reactor blanks
It's been ten years since Gordon Clark upped and shut his foam blowing operation and the reverberations are still be being felt. Yeah, Grubby Clark was US-based but when his PU foam monopoly ceased the hounds of creative destruction were released and new ideas raced across the globe. Creativity was loosed, perhaps forever, and no longer were board makers bound to a single construction method.
Ten years ago Nick Miles was a mechanic on the Northern Beaches of Sydney, a vocation that suited his naturally analytical mind even if he didn't enjoy the company of colleagues. “I always look at things with that mechanical eye,” says Nick. “Yet I didn't like the people I was working with.” Once his trade certificate was secured he turned his back on the industry.
His search for satisfaction led him to surfboard manufacturing where trade certificates aren't required but inquiring minds are. Nick landed a role at the Hayden Shapes factory in Mona Vale around the same time Hayden Cox was selling Fibre Flex to the world. “I learned about it all,” says Nick. Within a year he was running the factory.
Hayden Cox had settled on his technology, yet Nick was sure he could improve upon it. “With Fibre Flex the materials – EPS foam and carbon - worked really well but the way they were being used could be improved. I knew that.”
Nick's conviction led him to start his own label, Sculpt Surfboards, but more importantly it was the impetus for the design and patent of a whole new surfboard blank. X-Core Reactor is an EPS foam blank with dual carbon stringers running longitudinally inside the blank. Nick says X-Core gives “strength where you need it, flex where you want it.” Which also makes a fine tagline for when he has to hit the marketing trail.
Greg Webber agrees with that analysis. Webber has made ten boards with X-Core blanks and likes “the balance between the strength and the flex.” It's not just the placement of the stringers but the fact they run at an angle inside the blank. Says Greg, “Nick has experimented enough to get the angle of the carbon within the blank dead right.”
The reason the stringers run at an angle is to effectively transfer the load from the biggest hits a shortboard will endure – landing big floaters and airs – toward the rails. However, the reinforcement, according to Nick, shouldn't be around the blank but through it. For added strength carbon can be recessed into the deck to stabilise twist and reduce deck compressions.
Watch the video for a demonstration how X-Core Reactor blanks work
As an aside, Greg believes X-Core blanks have “the only defendable patent where carbon is being used.” His reasoning, acquired through years of researching patent law, is that surfboard makers “have been using different types of clear fibreglass on the rails for years and it's more that the carbon is black that it's being perceived as novel, and not that it's revolutionary in itself.”
Another early adopter of X-Core blanks is Dane Hamilton of Hammo Surfboards. In July Hammo took an X-Core to Japan as a personal rider. While there he placed equal 9th in the Murasaki Shonan Open, a QS1500 (equivalent to a 3-star in the old parlance), and the orders piled in.
“There was no better way to show they worked,” says Hammo. Prior to Japan he'd made 10 boards with X-Core blanks, now he's currently got 45 of them on order. Like Greg Webber, Hammo says the blanks have just the right trade off between strength and flex.
“Sometimes EPS has too much flex but Nick has figured out how to get the stiffness in the right place,” says Hammo. “I also like that I can finish it however I want to finish it or however the customer wants it finished.”
And therein lies another deviation from past technologies: each blank is made to order but Nick's involvement ends there. The customer – that is, the shaper if it's a stock board or the buyer if it's a custom - can glass it how they like. “Consumers want choice,” says Nick. “It makes no sense to tell them how their board is going to be finished.”
“I'm just taking it slowly,” says Nick of his business model. “I speak to shapers, answer their questions and let them try the blanks.” And the approach is working, organic growth has been gradual, the sales charts steadily heading north. His conviction in the technology has so far been well-founded.
Further vindication arrived this week and it shouldn't be understated. Just after Nick spoke to Swellnet news came through that one of the 'shapers' he'd been talking to was Channel Islands and they were yet another X-Core convert. “Yeah,” said Nick doing his level best to play it cool, “Channel Islands Australia will be taking custom orders and shaping floor stock for shops.”
Postscript: Since the video was made Nick has decided to reduce the choice of densities from three to two. The middle category - UL, Ultra Light - was deemed unecessary.
Comments
Where can I buy one of these blanks ?
There's contact details on his website Udo:
http://xcorereactor.com.au/
Interesting technology, eh?
Yep already checked there....thought there may have been a blank size list and pricing .
Sculpt Stock boards using those blanks are around $1040 ..ouch...
Try contacting the Glasslab at Tweed, they "may" be able to point you in the right direction ;)
http://www.theglasslab.com.au/friends/
It looks like the X-Core option is $200 which is pretty reasonable I think, so you can get a custom board with x-core for $910.
IMO anything new out of the standard PU/Poly box is good.
But wouldn't this stringer design enhance the risk of snapping the board at the points where the stringers stop???
Wow the flex of the blanks in that vid is impressive.
Have you seen the flex in a standard PU blank before it's glassed?
How elastic is the finished product? That is, what percentage of the energy used to deform the board is returned as kinetic energy? This should be fairly easy to determine in lab tests. Now I don't have any problem with a low number since my best guess is that flex in a board is more about the board conforming to the desired curve out of the turn than it is about boosting its speed, but yeh I'll take the extra speed if it is on offer.
I remember seeing a video where taj was surfing a door and slater was surfing an upside down coffee table....
And Norchock was riding an upside down union Helmet.
Which had the most flex or Xfactor
Yep.
That is epic. Gotta try one of these. This makes so much more sense than some of the other core technologies out there. I think I found my board for this summer:
http://www.sculptsurfboards.com/store/?product=two-step
Thanks Stu. What I enjoy about the Swellnet Community is learning and growing as a result. A broad mind leads to a broad view. Cheers & Thanks.
Like the best designs it's simple when you think about it. Flex only works when the board is releasing out of a turn so it's only required through the tail. If the whole board flexes equally it'll absorb the force and can slow the board, or it can release it where you don't want it - say through the middle or front half of the board. Good on Nick for Figuring out how to focus the flex to where it's needed.
Apropos the last paragraph in the article, a couple of CI sticks with X-Core:
Looks good nothing new though flex has been important for eons . See ancient paipo & alaia , greenough , Mitchell rae & so forth . Im sure it works , lets see if it works for big wave surfboards too
Yeah ok it is pretty advanced good stuff
If a parabolic stringer reduces twist and loads a board up like a bow during a turn, providing speed and projection out of a turn would a reverse parabolic stinger not do the opposite? Increase twist?
Brutus, would like your thoughts on these blanks ?
What's not to like? that one on the right looks particularly nice stu.
Good luck to Nick Miles.
More BS is what this is, but the stringers won't do any harm so buy the hype if it feels good.
More BS is what this is, but the stringers won't do any harm so buy the hype if it feels good.
More BS is what this is, but the stringers won't do any harm so buy the hype if it feels good.
Why is this so Roy.....BS ?
The outer skins are what determine almost all of the stiffness in a board, for any given shape. That will be why they don't show the flex in finished boards.
I also noticed that their transverse kevlar deck inserts use the material to resist compression, yet kevlar is very weak under compression.
Roy doesn't like it? I'd be wearing that judgement like a badge of honor.
It's just a matter of physics, not like or dislike. Figure it out yourself.
For those wanting to learn more, or understand it a bit more, have a look here:
http://www.firewiresurfboards.com/technology.php?techid=tech
Yes, it too has some marketing hype, but... you'll soon understand what Roy has noted.
Thereafter, if you want to know more ... a visit to Swaylocks is probably in order. Just make sure you have plenty of time to read, oh and yeah, search using google rather than the search function on that site. A lot of "noise" on there among some absolute gems.
Good Luck on your journey :)
Wingnut just looking at the 'Springer tech' explanation on FW there's almost no explanation at all on the flex part of the construction, it's more or less just stated that it optimises flex... thereby taking potential customers either as idiots or possessing huge dollops of faith.
Denser foam as placed isn't going to alter flex significantly since the foam will still be more flexible than the outer skins which take almost all of the load.
This point is basically fatal to all the 'optimised flex pattern via changes to the core' products out there.
Smoke and mirrors.... the really sound science which these companies use is marketing science.
As opposed to Roy's "physics" for which he cannot provide experimental evidence nor theoretical back up.......which makes it just another opinion. Not to mention that anyone who denies evolution and climate change, amongst other things, can hardly be said to have any understanding of sound science.
It isn't 'my science' it's well established engineering science which is being conveniently ignored by the surf industry marketing wallahs, and it is backed up by countless studies and experiments.
If you are looking for surfboard flex specific peer reviewed scientific studies the big comanies don't have them either... but I've been making boards which are engineered to flex for the past 21 years and have the theory intact as well, so I do know what I'm talking about.
Funny how you give these industry-centric companies a free pass to spin BS which 'denies' scientific principles but adopt a nauseating and inconsistent 'man of science' demeanour when I point out what is actually going on.
This is what you are best at: highly inaccurate reports regarding my unrelated to the topic opinions, and defamatory personal attacks. You use this as a substitute for clear on topic, rational thinking.
Even a cursory review of the principles of logic which should underpin rational debate would deter you from this sort of behaviour, but it's so much easier to just play the man rather than the ball isn't it?
Shame on you!
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........still no data, no references, just more unsubstantiated opinion. Shame? You should talk!
I' m not giving anyone a free pass Roy, just noting that you continue to be unable to justify the position you assert. As for denying climate change and evolution I think it is highly relevant to anyone trying to evaluate the likelihood of unsubstantiated assertions of a scientific nature being correct to be aware that the person making those assertions disagrees with the overwhelming majority of working scientists on two fundamental and important theories. I am sure you would appreciate this as an entirely logical position which does not reflect on your character in anyway, only on the probability of your assertions being actually correct. Now do you want to talk science and engineering or just keep telling us that you are right, everyone else is wrong and the entire surfboard manufacturing industry is in some sort of conspiracy to prevent the "truth" being revealed.
You continue to completely misprepresent my position on multiple points, so really you are just attacking positions which you have set up for the purpose, these have nothing to do with me yet you incorrectly attribute them to me.
This is a logical error in argument known as the 'straw man' fallacy.
It's asad state of affairs that elementary logic is no longer taught at school, a consequence of this is that the sort of nonsense which you have posted above is rife in society. It really impedes rational discussion.
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So if you have an identical board shaped with a stringer and one without both with the same blank and same glass job the flex will be the same????
Im no shaper or expert but that is very hard to believe.
BTW. still think even if these blanks perform great they have a weak point just asking to snap once it goes beyond that point of flex.
Almost the same, yes.
It's easy to understand, just check out beam theory.
.........and when you do you will find that beam theory only applies to perpendicular forces and specifically cannot be applied to twisting forces......such as those which produce flex in a surfboard. Further, if you want to quote beam theory this is a mathematical theory so you actually need to have some data .........or it's pure speculation.
That's incorrect since physical principles and their relationships can be explained without measured data... indeed you have attempted to do exactly that in your comment about beam theory above.
Now I suggest that you get on to those above who are making all sorts of claims about their new blanks and apply your supposedly rigorous standards to them.
Feel free to explain "physical principles and their relationships" Roy. All we have had so far is "beam theory" with no explanation as to how it applies to a surfboard. I mean, I think it is unlikely, but you could be right, I am always open minded. Personally I think you would probably need some experimental data to check the maths, but if you want to get into fourth derivatives and so on, I'm waiting with great interest. I mean if you are right I have no problem taking issue with the "industry". Consumer affairs are always interested in corporations making unsubstantiated claims which, I suppose, is one reason that their claims generally have more credibility than the unsubstantiated personal opinions that appear in comment threads.
Beam theory https://en.wikipedia.org/wiki/Euler–Bernoulli_beam_theory
Okay that shit just went right over my head.
I do remember a guy showing me the flex in his board a stringer less Epoxy EPS board he turned it up side down and stood in the middle and it just flexed almost flat, never seen anyone try with a similar construction board with a stringer but can't imagine it would do the same thing.
It will depend upon the specific structures being compared.
I have a board with wooden stringers which is capable of deflecting four or five inches under hand pressure, it would be slightly more flexible without the stringers, but only slightly.
"The outer skins are what determine almost all of the stiffness in a board, for any given shape."
I'm sorry Roy, but that was what you said and that is what I am asking you to justify so no straw men. I also note your constant appeals to authority, that is that you have been doing this for a long time so must know what you are doing......a logical fallacy of blatant and absurd proportions. So I anxiously await your engineering analysis to justify the very straight forward claim you made above......but sadly, not with any great hope of getting one.
...another massive logical error: you expect me to accept that because you now supply one direct quote, that the long list of incorrect statements about what i think on a variety of subjects (which were used as 'straw men') have now magically ceased to exist?
That's like saying after committing perjury in court many times, that one has not committed perjury because one has just made a statement in court which is not false.
The fact is, you have misrepresented my position in public with monotonous frequency, and have posted many defamatory personal attacks, many of which have been deleted by the moderators.
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It's funny really, first you ask for authoratitive support for what i'm saying about flex, then as soon as i enter the territory you accuse me of arguments from authority.
Have it one way or the other. but not both ways.
I'm not a great fan of appeals to authority, and don't use them unless someone aks me for an authoritative source... nevertheless the appeal to authority as an argumentative technique is not "a logical fallacy of blatant and absurd proportions" it is an 'informal fallacy' and there is plenty of debate about the number and type of exceptions to the rule. In other words appeals to authority are not always logically incorrect.
Far more blatant logical fallacies include three which you have used: one being the 'straw man' tactic... it is never acceptable to misrepresent your opponent's postion in order to attack that position... and by extension your opponent. another, which I'll simply describe as a contradiction, as to demand X and when the opponent attempts to supply X say that X it is unacceptable to supply X. The third, which you have used towards me far beyond the point where it became illegal, is the ad hominem attack.
Whenever the core is less stiff than the skins, the skins take most of the load. That much should be obvious.
In the case here, we have blanks which contain a very small amount of material which is stiffer than the skins, this will have a slight stiffening effect on the board. I could calculate approximately how much stiffer ( which is surely the job of the blank manufacturer, who could alternatively, since they have access to the blanks, conduct a few simple experiments to show deflection under load of finished boards with and without the stringers.) and might consider doing so.
Regarding twist, the vertical orientation of the stringers will resist twist far less than they resist vertical loads.
You seem to have things back to front, you should be asking the blank manufacturer to support their claims with evidence. I am merely a sceptical observer making myself heard... so apply your standard consistently and get on their tails... then report back with their evidence.
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Mere assertion, still no evidence or calculation or anything really except an opinion based on an appeal to your personal authority. Maybe not the weakest possible line of argument but pretty far down there. The absolute worst line of argument though is to base it on a scientific theory you don't understand or had totally misapplied, but you wouldn't do that, so I'm sure you will give us a mathematical analysis of how beam theory applies to surfboard construction any day now.
That's not what's happening.
Here's a novel idea for you: think about it, research it, test it, or do whatever it takes for you to figure it out yourself.
I must say that your username is apt.
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I seriously doubt that Firewire would waste the time and money to put in a "stringer" if it did nothing. Ditto, for all the "standard" PU surfboard blanks used by thousands ...
But, what would I know, I'm just a backyard hack. A design and construction kook if you will ... oh, but I can read :) ... swaylocks people, swaylocks ;)
It's just a foam insert, it's physically impossible for it to make a significant change to the flex of the board.
Nevertheless it isn't likely to be a waste of time and money putting it in, as with the right marketing mumbo jumbo it sells.. and the primary purpose of the company is to make money.
So, FW make more money, buyers think that they have something special, the board goes as well as it would without the foam insert which by all accounts is very well indeed, and everyone is happy except those who see that the pixie dust isn't real and wish that it was. There may be no such people, but one can't rule out the possibility that there's at least one.
Hi Roy,
I have read your comments with interest and whilst I partly agree with the theory of what you are saying the biggest challenge is having the technology to measure the flex and twist of a surfboard in use. There have been some attempts made but nothing ongoing. I have spoken to people who worked with engineers who calculated what they thought the boundaries of the flex on a surfboard were... These were blown out of the water on the first bottom turn. It is my understanding the the flex on the inner core is affected by the strength of the outer skin but definitely not controlled or limited by it. I am enjoying the exchange of ideas because it is the only way we more forward with our thinking such as what X Core Reactor has created.
Agreed. It's why I can waste hours reading stuff on Swaylocks.
And, on that note, "if" the foam stringer "doesn't do much" (note: for completeness, that's my abbreviation of what Roy said, not his exact words) , then I guess a variety of different core sections will do very little too?
See here: http://www.geoblank.com/#!cores/cee5
I could be wrong here, but as I understand, the geoblank crew had the same board made (i.e. same shape, thickness , etc.) and then glassed in the same construction technique with ONLY the geo foam changes in the layout of the blank. And, guess what, they found some differences in flex and performance of the boards. Wonder why?
NOTE: I am not affiliated with, in any way, either FireWire or Geoblanks. I'm sharing and adding links for the purpose of this "debate". With cory joining the fray, is this no classified as a "mass debate"? Hehehehee...
Interesting ( from the Geoblank site):
"When hexagonal honeycomb is bent, it exhibits a phenomenon where
the honeycomb is forcibly curved around one axis and the core reacts
by bending in a reversed curvature along an axis oriented 90°.
This phenomenon is called anticlastic curvature."
How much measurable difference, and why is the difference not shown or quoted?
There will always be a difference, but is it significant?
Cory's a blank developer?
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Have a look down the page, here is the link again: http://www.geoblank.com/#!cores/cee5 there is a "flex overview" table at the bottom of the page.
You can also select each "core" type from the menu headings, and then on each page, hover your mouse pointer over the picture of the blank and it shows up where the different cores are placed for each blank type.
See here for example: http://www.geoblank.com/#!abola/cdph
NOTE: I can not comment regarding Cory or his involvement with surfboards or surfboard blanks. I'm sure he / she (new age wingnut being politically correct and gender neutral :) ) will enlighten us in due course.
Yes I saw the table but it is obviously not showing a measurable difference.
Hi Cory
Yes the in the water situation is different from the three point land test usually used. The pressure disrtibution under the hull is quite different from the land test.
When you say that the calculated boundaries were blown out of the water, aren't you comparing apples and pears i.e. a number vs a feeling?
Hi Roy,
As I understand it (the study was not done by myself) the engineers involved calculated the flex properties of the stringer, polyurethane foam, fibreglass and resin to establish the boundaries. On the first bottom turn the flex in the board exceeded all calculations without reaching breaking point.
The most interesting thing to come out of the study in my opinion was they found surfboards 'twist' more than they 'flex' from nose to tail. Unfortunately the results of the study may never be released to the public which is disappointing. If we are going to move forward and improve materials then the way we test them is very important and needs to be standardized.
Cheers
The twisting aspect makes sense.
Are you saying that the flex in the first bottom turn was measured?
Yeah... Unfortunately I don't know the specifics of how... That is the most important aspect of the study! I can tell you it was done in the states.
But why is it physically impossible Roy? Simple question.
Because the foam material which is added as a 'stringer' is more flexible than the skins. The skins then take almost all of the load. That's the short answer.
As an extreme example for the purpose of visualisation, imagine a roof truss, if the voids are filled with foam do you think that the truss would be significantly stiffer? Of course there are differences between trusses and surfboards, but the example might help with understanding of the basic principle.
Even if the surfboard is made entirely of one material, the material on the outside of the structure takes more load than the internal material. The material on the neutral axis ( on a board that's a horizontal plane running through the middle of the board all else being equal) takes none of the load.
I hope that helps.
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But you don't have any evidence that the foam stringer actually IS more flexible than the skins. You are simply asserting this. It may well be true, but each skin on its own is highly flexible so what you are actually claiming is that the laminated 3D structure is more rigid than foam. My basic point is that it is counter productive to make these kind of broad brush assumptions about a complex situation and really quite offensive to the designers and engineers to dismiss their work, as you have done, as marketing bullshit when you have not the slightest theoretical or practical basis for your assertions.
If you can find a foam which has an elastic modulus greater than that of a glass and resin laminate then I'll be suprised.
I think that you are misunderstanding the situation. the fact that the skin laminate on its own is easy to bend does not give an indication of its flexibility as a material unless compared with a slice of foam of the same thickness.
For comparison look up the elastic modulus of the materials.
Obviously it is. It's not my claim though, it's common knowledge.
That's how composite sandwich construction works.
As you know a glassed board is less flexible than the unglassed blank.
Obviously one can safely make the 'broad brush' statement that adding a small 'stringer' made of foam will not significantly increase the stiffness of any glassed board.
Saying that there is no theoretical basis for this is ludicrous... please educate yourself on composite structures and beam theory in order to acquire the basic tools for the discussion.
The elephant in the room is that the blank companies which we are looking at offer absolutely no support for their claims regarding flex. As mentioned previously they should at least be able to demonstrate some differences in deflection under load between various blanks. It's alos noticeable that their theories apply only to unglassed blanks... they conveniently ignore the fact that once glassed, the skins dominate the sandwich in terms of flex.
It's unlikely that they don't know that they are making false claims.
Seriously it might do you a lot of good to get some education on the topic.
And since when was "common knowledge" anything but an excuse for ignorance and intellectual laziness? There is also the slight logical problem in your answer that you state that the elastic modulus of the skin is greater than the foam but, even after mentioning it, fail to account for the fact that the foam is probably two orders of magnitude thicker! As for what I know about blanks, I know enough not to make assumptions about recently designed products without supporting evidence, an approach you have repeatedly demonstrated is your preferred analytical tool.
Come on man, I'm trying to help you out here. what I mean by common knowledge is that the principle is well tested and established.
I've spent countless hours researching this stuff including about ten hours of head busting this week, so I'm not lazy.
I don't know everything by any means and am learning as I go, but one has to start with the first principles and that's what you haven't done.
Does that include the claims made by the manufacturer or is it assumed that these are correct unless proven otherwise?
There's plenty of evidence out there on composite sandwich construction and beams, all you have to do is look for it.
It's a rule of thumb in the composite structures industry that where foam cored fibreglass and resin skinned products are concerned, any foam with a core density of less than 5pounds per cubic foot ( 80kg per cubic metre approx) is deemed to have no influence on the stiffness of the structure (in terms of shear stress). The reason why this is the case is that the influence of lower density foam is practically insignificant. The introduction of the carbon fibre stringers which are the subject of this thread will increase the stifness but only slightly for a couple of reasons, one being the very small amount of material involved. I would be most interested to see a test done on a couple of finished boards, one stringerless and one withthe carbon stringers. The manufacturer is in the best position to do this and arguably has an obligation to do so, but if I can get a couple of suitable blanks I'll do the tests myself.
If the manufacturers are correct and are confident in their product then it would probably be beneficial for them to do some flex tests and publish the results, simple 3 point load tests would be a good start.
If this were a boatbuilding or aeromodelling forum the discussion would be educated, informative and to the point, and I'd just be in the middle of the group understanding wise. Unfortunately the sort of emotive angst filled personal attack filled uneducated nonsense which you are posting is generally par for the course on surfing forums. I am having to shoulder the burden of being better informed than the rest of you, which is a time consuming and rather tiresome occupation given your dysfunctional mindset. I'd be delighted if you'd get over yourself and do some research before spouting off... either that or read with an attitude of trying to learn.
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Never having surfed a Tuflite/Surftech , they are epoxy glassed over eps and have little or no flex at all , is that correct ?
Looks like a mix of construction: http://www.surftech.com/technology
Just FWIW, in my mind, "flex" is a relative and somewhat subjective term. All boards flex, just some don't feel to flex as much as others (i.e. they feel stiff, or to be more accurate, stiffer).
..Maybe some of you guys should go and try one of his range of demos if you want to feel how they work.
In my opinion they feel amazingly lively and fast and springy. if that's a word.
Stu
Hey Stu, don't tell me that the development process hasn't included simple deflection under load 3 point flex tests at some point... if they have been done let's see the results, if they haven't been done, why not and when will they be done?
The consumer has a right to know if the vague adjective filled hype is the marketing front for something real, or if it's all empty noise, smoke, mirrors, and placebo effect.
If I had demo models here I'd do flex tests on them, which would take about half an hour... just to get a feel for the magnitude of any difference present.
Surely they can do that?
Hey Roy.
I get your point. Really. There's is so much shit around that I don't personally believe can possibly work so I know what you are saying.
Thing is with surfing there's a lot of feeling involved.
As a example picked up an X-core 5'7 demo upon recommendation and wasn't rushing to ride it as I was super-happy with my boards (PU Chilli Cherry Peppa, and CI Flyer 3).
Long story short, after a few surfs on the X-core I kept it, sold the CI then later Replaced the Chilli with another X-core 5'5 as they have an amazingly lively, slingshotty feel. I didn't really expect this. My surfing has really improved on all levels.
I do see your point... As far as flex tests go Ask Nick I guess?
Yes I suppose so, perhaps Nick is following this thread... I would if it were my product.
Humans are in some respects pretty sensitive instruments so ride tests can't be discounted, but since flex tests are easy to do and are quantifiable it really ought to be done to eliminate the placebo effect and variables.
This is the nearest thing to supporting data that we get on the site... it's laughable.
Show us your test results or calcs, Roy. Until you actually provide proof it's only your opinion against theirs.
Calcs are not necessary in order to understand the principles involved.
In order to get test results, tests have to be done... and the onus is really on the manufacturer to provide them, they are the ones making big claims and asking people to pay for their product, yet they are treating their potential customers like idiots. There may be some justification for that ( lol ) but we are not all idiots and they need to front up.
Funny how no one else suggests that the manufacturers could respond with more info... is that not a PC thing to do?
Just look at the chart above which I was directed to as some kind of flex data... it's ridiculous.
As I said if I can get a couple of test blanks I'll do it, but I'm not paying for them.
Ok, so it remains your opinion against theirs.
Not exactly.
I'm not posting my own theories they are industry standards.
Flex modulus figures:
Flex modulus of glass/epoxy laminate: typically 22 GPa
Flex modulus of 2pcf eps: typically 0.0031 GPa
The flex modulus of the skins is thus around 7000 times greater than the eps.
This doesn't help directly when looking at the influence of the carbon stringers, but is helpful if wanting to understand the role of core materials in a sandwich with stiffer skins.
http://www.boatdesign.net/articles/foam-core/
If the skins are relatively thin and the core is considerably weaker the formula can be reduced to :
Ef = Elastic Modulus of the Facings (Skins)
Ec = Elastic Modulus of the Core
b = Width of the Beam
d = Distance Between Facing Centroids
t = Thickness of a Facing
c = Core Thickness
"it is apparent that the core material does not directly contribute to the stiffness of the panel or beam, (at least in lower density cores) but it's the distance between the skins that is the overwhelming factor. Increasing the "d" variable will have a much greater effect on the flexural rigidity than any other component in the equation.When dealing with higher density cores (usually > 5 lb/ft 3 ) and thicker skin laminates, the full equation must be used in order to properly predict the stiffness properties. "
Hi Roy,
I am just a shaper and don't have anything to do with manufacturing surfboard blanks. I do think that the current construction of PU/poly, centre stringers and carbon rails are obsolete.
I don't want to come off as a dickhead but can you explain what the 'facing centroids' would be on a surfboard?
If a part of the calculation is the 'elastic modulus of the core' and can effect the outcome... Isn't that the variable in GEOblanks and X Core Reactors?
Cheers
It's the midpoint of the glass/resin laminate or 'facing'.
Yes that's right but the difference is only significant if the core is denser than 5pcf or 80kg/cubic metre.
Of course the X cores have carbon fibre in there which is stiffer than glass, only part of it will have any influence (the middle third won't, being too close to the neutral axis) and there's very little material used so it remains to be seen what the difference is. Who knows maybe I'll become a convert for long flexible gliders, the stringers would certainly keep the rocker stabilised during glassing, and the marketing hype could be handy lol.
Jeez you're a wanker Roy. Carry on like you're Bertie Einstein but you shape boards for Freddie Flintstone.
Wrong on all three counts but it's nice to meet you.
Congratulations Roy that's actually relevant. But it refers to "lower density cores" without including density per se anywhere in the calculation which seems a bit careless.
More significantly, I would be reasonably sure that this equation is only valid for longitudinal stiffness with a perpendicular force such as you would have in a 3 point test on a standard beam of constant width and thickness. Now I agree that might be a reasonable proxy for the board's stiffness under other forces but that it is far from certain. We need some Mythbuster type testing here! Let me see what I can do.
Hi Blindboy,
I posted this in response to one of your posts earlier today and the info is also in the post which you are replying to here, it's also published on the boatdesign.net link which i provided.
"It's a rule of thumb in the composite structures industry that where foam cored fibreglass and resin skinned products are concerned, any foam with a core density of less than 5pounds per cubic foot ( 80kg per cubic metre approx) is deemed to have no influence on the stiffness of the structure"
(The simplified formula removes the shear stress calculation as it has such a small influence on the result. )
If you can drum up some tests then that would be great. I'm keen to learn more and I'm sure that it would be of interest to many.
Why don't you guys just try one then?
All the data on the planet goes out the window when you are riding.
Still. It's all interesting. big discussion points all round.
It doesn't look like they are available in NZ yet.
If they were and I could get the same blank with and without the stringers in a mid length then I'd grab a couple and have a go.
So the above formula may be used to assess a simple composite construction of skin/core/skin but in reality we're trying to determine flex characteristics of complex composite structures which have central cores of a much greater density (plywood >500kg/m^3, carbon fibre >1000kg/m3).
The rule of thumb posted above would suggest a plywood stringer would have a definite influence on stiffness.
Ding. Ding. Ding ... that's the sound of the bell ringing. You know, from that surf comp where the winner, a professional surfer who will take any competitive advantage over his fellow competitor, and who, all seem to ride surfboards with, wait, what's that, oh yeah ... a plywood stringer! :)
Don't get me wrong here folks, new tech is great, but until the elite professional surfers are winning events on them ...
That's not say, us weekend warriors / average joe's, or in my case, gumby kook, can't enjoy surfing on different construction.
I'm keen for the flex test Roy, how is it done?
The boards look great, thats what consumers want.
I think however that the reverse parrabolic stringers will increase twist and the boards feel good because EPS is a very light and springy core on its own. A good EPS blank with a light wood stringer will probably feel just as good.
Good luck to him though, tough game the surfboard industry.
Are you in the industry?
What I would propose as an initial test would be a double blind comparison using identical boards except for the blank. The boards would need to have exactly the same appearance except for being labeled A and B. Neither the experimenters nor the surfers would know which was which.
Ideally I would use a panel of professional surfers since, in my experience, they are much better than average at picking up subtle differences in performance. After each session the surfers fill in a short survey basically choosing which board they preferred, which board had the most flex, which was fastest, which paddled best and probably a few more. The idea is that by asking questions about many facets of performance both surfers and experimenters are unaware of the focus of the experiment. Tricky to set this up but you never know your luck.
If the surfers consistently pick the X-core as having more flexibility then it might be worth looking at lab tests, which are probably going to be difficult and expensive if they are going to be valid and reliable. If the surfers can't consistently pick a difference the lab data would be irrelevant to anything but purely theoretical issues.
That would be interesting.
Simple 3 point bending tests can be done by anyone and they give a a fair comprison as far as overall flex goes, although the numbers themselves don't tell us how much flex is happening in the water.
Twist could be land tested fairly easily too.
Hey BB, Roy,
I'm heading OS at the end of the week but if I manage to find time I'll put together a VERY quick FEA of the differing composites we're concerned with. These will be very simplistic and only focus on the stringer section. ie glass/eps/glass (no stringer), glass/ply stringer/glass, glass/carbon stringer/glass etc.
Hi Carpetman, that would be super cool.
If you can do it (I hope this makes sense) so that the skins meet at the ends rather than just as open ended composite sections that would be more realstic.
Thanks for your reply.
By the way Blindboy, I reckon that neither of us are as bad as the other might have been thinking over recent weeks. :)
Roy answer the question I asked before in the affirmative and it is all cool. Until then.......sorry but no respect.
There's a question of yours addressed to me which I hadn't answered further up the page, but it wasn't one which asked for a yes or no answer.
As for respect, I don't think that you are telling the truth since I'm willing to bet that you respect my right to life. I certainly hope so for your sake, since it's not healthy to wish people dead.
Gents, after reading this thread for a while can I suggest that BB's statement - 'If the surfers can't consistently pick a difference the lab data would be irrelevant to anything but purely theoretical issues' is the key point here ? I agree with you Roy that lab tests are the technically correct and objective method to get flex metrics but in this case apply this to surfers of different styles, ability, surf conditions just brings in a bucket load of variables. In this case, the marketing hype seems to be a powerful influence.
The flip side is that if lab tests can't find a significant difference in flex then the surfers won't either, but that wouldn't prevent them from thinking that they have.
It cuts both ways I guess.
Yes, that may be true but we need to start somewhere and quantifying the flex characteristics of each construction type will at least give us a better understanding of what we're riding and why we like it. Maybe one day it will be written on the board along with dims & volume.
I agree carpetman that down the line we will need some method of assessing the properties of construction objectively but at the moment I think double blind tests should at least tell us if we are dealing with a real difference in performance or the power of suggestion. Don't get me wrong, this is not a put down. I think the X core design is a great technical and imaginative achievement but how much impact it has on performance is an open question until it is tested properly.
A difference in feel vs the power of suggestion perhaps?
It's not at all clear that any particular flex 'pattern' delivers a better result across the board than another in any given conditions, perhaps it's just that some riders prefer the feel of one over the other. If a rider prefers the feel then they'll probably perform better, but I'm just suggesting that it might vary widely from one rider to the next... it's not necessarily a measurable or consistent performance gain like say horsepower in a car might be.
Hi Roy,
Surfers are a fickle bunch and conditions are always changing... But the feedback I receive and information shared with me by other shapers would suggest differently. Carbon rail/parabolic reinforcement boards are only positive in small to medium surf as the responding flex is in sync with the wave size and surfers response time. In larger waves the responding flex can 'buck' you of or throw out your rhythm as the responding flex is too rapid.
Stretch introduce cork and bamboo to his guns to dampen and slow down the flex to provide the surfer with a board that is more compatible with the surfer. It would appear that he is changing inch the elasticity of the core to change the boards flex properties with similar glassing combination used. It suggests to me that although the boat building formula is obviously accurate surfboards seem to have another element that needs to be considered?
Land based 3 point flex tests ( which I didn't suggest need to be done in a lab) are a quick, useful way of getting a feel for how much flex under load various boards have... of their stiffness basically. I'd like to see it done on these blanks vs stringerless eps just to see if there is a significant difference.
I've been making boards specifically to flex since 1994 and haven't measured it for years... I change the dims knowing which way it's going to take me from experience and the only land based flex test I do is a three point bounce test with my hand... a bit like wiggling a golf club to see how the flex feels. I can do a measured land test any time though if anyone is interested.
When altering flex I do it primarily via the thickness to length ratio of the board, thus the flex requirement influences the shape. Just the way it works out for me, not the only way by any means.
Assuming that a skin of glass and resin or material of similar stiffness and density is needed for structural reasons, the main influencer of flexibility is the thickness to length ratio. that's inconvenient when wanting ( as the industry does) to make identical boards with different flex. Because I make long boards with a big range of lengths, and because it's easy to get enough volume in them without going too thick to flex well, I can get a low thicknes to length ratio quite easily, and adding length or reducing thickness is no problem.
Please excuse me mentioning my own design activities.
Hi Roy,
Have you seen the Incide blanks using a combination of core densities and carbon fibre?
http://usblanks.com/catalog/incide/
The internal laminated carbon construction would have a big effect on the boards flex properties.
In addition to the necessary lab tests... I would like to see the same board made in the various constructions to compare 'the ride'.
......which is where I want to start cory. But to be a valid test you can't just ask the surfers, you have to do it so they, and the experimenter collecting the data, don't know which construction they are riding. This is a standard procedure in many areas of science known as a double blind test. Idea.ly you would do it in a wave pool to control the waves being surfed as well....it's the only legitimate reason to build one!
Hey Blindboy,
Maybe we could team up and get a huge gran from somewhere to pursue this... ;p
Yes I've seen them, the difference in flex will be slight, though it's a moot point where the difference between small and bi lies in terms of measurement.
A 3 point test may give some general idea of the flexibility of the board but is inadequate as a measure related to the board's performance. The load on a board, as it is surfed, is not supported by two points. It is supported wherever the board is in contact with the water. The load in a 3 point test is usually placed on the centre of the longitudinal axis which in no way simulates the load on a board in a turn. To accurately assess the degree of flexibility and how effectively the energy of deformation is returned as kinetic energy would require much more than measuring how much deformation a load caused when the board was mounted on a couple of saw horses.
Another point, about beam theory is that it assumes a symmetrical rectilinear shape so that the result of a three point test would be the same no matter which side was placed up. Try that with a surfboard!
Yes that's quite correct and I've written the same sort of thing many times.
The simple 3 point load test is still useful however, and if it shows no difference, then there is no difference.
If one plays around with the core and there is no measurable difference in flex then nothing has changed except perhaps the resonance or the weight.
Not relevant.
we are not comparing rectlinear beams with surfboards we are comparing surfboards with surfboards, and as long as the shape of both test subjects is the same then the test is a valid comaprison.
I disagree. The three point test could be the same while the performance characteristics were different. You explained this yourself when discussing thickness. If the foil to the rails around the tail is different the flex, where it really matters, would be different.
Yes but I'm talikng about comparing boards of the same shape, not boards of different shape but the same flex test characteristics.
Yes it will be different.
Where flex 'really matters' or whether it matters at all is a matter of opinion, or rather of preference.
Riders vary.
By the way you mentioned earlier that " The load on a board, as it is surfed, is not supported by two points. It is supported wherever the board is in contact with the water. " We are defintely on the same wavelength there and I've been saying exactly that for years, plus this: The support given by the water is not even, there's a high pressure band (much higher pressure) just behind the leading edge of the wetted surface area... that's the case with all planing hulls... and behind that the pressure diminishes continuously all the way to the trailing edge of the wetted surface area. So not only are there not two support points ( except when we add another factor which you might have figured out already) there's effectively just one fulcrum, at the front of the wetted surface area, and that fulcrum moves constantly. It's also usually ahead of the rider's front foot. You might think that it's odd that I still use a three point load test given that it doesn't represent what happens in the water at all, but it still gives a useful scale I think.
.......well if they're the same shape one might have a parabolic carbon stringer.
Don't think I'll have enough time to do an FEA analysis but will have a look when I get back in a months time.
Hey Roy and Blindboy,
It's clear that you are both very educated and I have enjoyed reading all the information you have posted. In my effort to better understand things i like to do my research. I understand what Roy is saying but I think it is too simplistic. I have been checking out the Resin Research technical data page...
http://www.resinresearch.net/id8.html
And the varying degrees of tensile strength, flexural modulus, barcol hardness and elongation of varying degrees. I cannot see how once size fits all when a company like this does testing and gets different results? Shouldn't they all be the same according to your theory? Add to that the variety of cloth materials such as fibreglass, carbon, etc.
I have manufactured a variety of constructions and all of the ride differently, flex differently and perform differently. I cannot provide the science to substantiate this only first hand experience. That's what makes this topic so interesting!
Hi Cory,
I haven't suggested that all skins have the same stiffness, or that changing the skin stiffness doesn't change the flex in fact quite the opposite.
Since the skins have the greatest effect on board stiffness ( for any given shape) then changing the cloth, resin etc will certainly have an effect. thanks for the link.
.
Geez,
I only got up to page 2 reading all this, will finish tomorrow night. Working late;)
One comment I noticed from 'Cory', which really stands out IMO is the,
"The most interesting thing to come out of the study in my opinion was they found surfboards 'twist' more than they 'flex' from nose to tail. "
This IMO is surprisingly something that people would not expect, which is why I have designed a new blank which will grab all of you by the balls.
Yep. have a look at the comment from mantown too. He / She (one can never tell, hey?) suggested the layout of the stringers should be looked at re: the twist impact.
No-one can tell Wingnut,
Apparently I'm an aphrodite ;)
There is many parameters able to input flexibility as Roy contextually explains. Many thanks to him to do this work all along those typed lines, :-)
IMO, one more mechanical principle would have to be apply is the compression of the deck skin . Like bodyboard does with soft deck made of XPE skin.
Out of this last point, I wonder how is the hand rail screened finishing, fine sanding the EPS foam over the carbon stringer section...?
As well that kind of blank must be machine shaped rather than hand shaped..?
IMO the core construction (IE foam/blank/the way it is laid) is an ever developing process and will be for a long time with the surfboard design and manufacture!
Mr Shane Peel said in another thread that snowsurfing was way behind surfing! Uuuummmm?
IMO blanks made with the inner core which will, with flex torsionally /back/front/side to side etc just like a snowboard will start to come close with what surfers and designers are looking for?
Just my opinion.
We will see probably 5-10 years down the line.
I was talking to Brutus about this awhile ago??????
This is just my thoughts;)