Unfortunately, my boards shapes and width are all over the map so my account is more subjective than I would like. Back when I saw Bert’s boards it was very obvious to me that his boards “felt” different to me than my did. If you pressed on the board it had a different response than mine. I have “borrowed” three of my boards shapes from Bert, but they were in no way similiar to his. With my current board I was cleaning some smeg off the bottom of the board and I was surprised how much it flexed (it felt like I remembered Bert’s boards). I’m not as tuned into my boards characteristics as many on this forum are. If its subtle then I’ll most likely miss it. This board surfs way differently than my other boards and there’s not that many differences from my other boards. I narrowed my search to a few different variables that I’m looking at in my future boards. I’m not a short boarder, so I’ve been toying around with building a board for my brother this Xmas to test some of these theories. He’s pretty harsh and will definately let me know what he thinks. Since he hasn’t has his mind shaped (tainted) by all this stuff and would be more likely to find fault with a board that I’ve built I think he could provide some useful input.
hi bert good to have you back
meecrafty
i think this board is a bit stiff
im gunna take it to kaikoura on the weekend to test in some juice.
unfortunately its got micro bog all over the rails from a dodgy sand down on the first lam…
oh well. im trying the international polyureathne for the final finish.
i noticed that pic, with the sikaflex down the rails on one of your boards.
hows the water seal holding up as im thinking of doing it to my second board to see what happens.?
hack carve modify test
bring it on frankenstein
now im really confused…first you claim this:
Its even more than inside out. Its the inner board and the outer board. On a traditional board you really have one board since the core doesn’t really add anything. With the componentized board you end up with multilple boards. The outer board which keeps everything dry, and the inner board which you actually surf. It really doesn’t take much glass to keep the board intact since the low resin ratios really improve the strength of the glass. If you overstrengthen the outer board it will prevent the inner board from working. Here’s why I don’t think you can get away without modifying the eps. If you were going to describe your perfect board would you use terms like trampoline or air matress. Eps left on its own is an air matress - sure it light but its meant to be sleep on. On a trampoline, everytime you jump it stores your energy and rebounds you. If you surf a trampoline the rebound will help to dig the rail in and project you out of turns. If you only worked the tail of the board you wouldn’t need to things like springers, but if you are trying to make speed down the face of a wave and are more centered on the board a springer will allow you to store the energy thats generated through pumping the board.
and now youre saying this:
I’m not as tuned into my boards characteristics as many on this forum are.
???
now regarding this comment:
This board surfs way differently than my other boards and there’s not that many differences from my other boards.
Is board thickness one of those differences? what about length vs thickness?
do you understand this basic engineering concept regarding shear force distribution of a composite panel:
if so, how does that affect your earlier comments regarding inner and outer boards?
which component of the composite sandwich is doing the bulk of the work wrt shear forces?
and how does the Surflight patent address this issue?
Considering shear force alone, between Surflight and Sunova, which approach deals with the issue more elegantly?
when comparing construction/design variables, how critical is the panel stiffness equation S=T^3 ?
if you agree its critical, have you plugged in some numbers just to see what you get?
and do the numbers jive with some hands on tests youve performed?
regarding bottom panel flex/elongation, how are you addressing it?
youre using 2020 on the bottom…great! how does the elongation of the resin compare to the glass fabric’s elongation?
and how does adding additional layers of said fabric affect total elongation characteristics?
Looking forward to your response.
Regards
Read the first confusion as - if I can feel it and I’m not that tuned in it must be a big change from what I’ve normally surfed. As far as explaining what I’ve felt and attributing it to what I know is in the board - its theory.
As far as quantifying the board - I don’t think anybody (with the exception of Airframe and that study that just started at somewhere in Europe (I know thats vague)) have made any real attempt to quantify mathmatically what should be in a board. Until somebody really understands and has tested the forces that are applied to a board explaining it in numbers is not going to happen - its is my analogy better that your analogy. I’m not saying that your design ideas are wrong, just that they do not fit into my theory’s. Could you honestly answer mathmatically why your board surfs the way it does? If so, you are way ahead of me.
so youre reluctant to deal with one itty bitty equation with only one variable T that you can easily measure with calipers? now thats not very scholarly of you dan
funny but i asked you so many other things that dont require any math and you refuse to answer any…why? is it easier for you to theorize than to deal with the most basic engineering facts?
the key variables your looking for are not obscure theory…the shear force graphic i posted is based on basic Newtonian mechanics, invented over 300 years ago…if you sat down and just tried to understand it you wouldnt be theorizing so much
youre theories are truly puzzling to me…instead of making so many odd claims why dont you just ask questions? why not study some basic physics? Bert doesnt have a formal engineering degree but i have seen him quote principles of Bernoulli, Boyle and Newton like a veteran engineer…to his credit he is also a very creative free thinker (a great combination that i admire)
sorry man but i just cant let your “theories” clutter these pages without a clarification to others who might want a second opinion…maybe im not winning any friends here but maybe i’ll help them save some money…god knows i’ve spent way too much chasing sunova when the answer was right under my nose
youre trying to re-invent the wheel by looking very very closely at the spokes…trouble is, your wheel isnt round
Again
look at this picture very closely…
blow it up to 400%
- Look at the seam where the foam’s been cut away and the under lying area next to the foam and the wood…
I don’t see any hit of glass fragments between the wood and the foam although the foam’s been ripped out pretty jaggedly. I also see signs of gaps or dark areas between the foam and the wood panel.
It looks way different than anything else I’ve seen posted here or by Ben’s testing regrading the glass layer binding the wood lam skin to the foam. I just don’t see any evidence of a binding layer.
- look at the thickness and depth of the rail layer…
Way thicker in perspective to the broken in half 9’0 which only looks 1/2"-3/4" thick at the most…The seam between the skin and the rail looks way tighter that the skin and the core…
Don’t know what this all means… kind of like archeology digging up old pottery and trying to interpret their meaning could be nothing could be everything who knows and I guess who cares.
The more you lock in the skins to the core,the rails to the core and the skin to the rails you end up with just another version of a surftech in balsa… That’s what all mine have felt like (cause we rail wrap the deck) unless I make them heavy.
I think a springy board will require a change in surfing technique… more light footedness versus the power carve. I’m learning the weirdness of it all from my 6’9" high performance surflight. You can’t feel anything anymore cause it gives first rather than pushing back immediately like a stiff board does so you have to anticipate the recoil in the timing of the next move otherwise it’ll throw you off. I think you have to be a faster reactive surfer to take advantage of these recoils to make any use of them. Way different than linking the slow s-line power carves us 70’s generation single finners learned. You need to be alot more confortable with the two and three fin shuffle to milk performance from these kind of boards. Just my experience so far with my surflight.
Hi Dan
A while back i did some pre glassed deck and bottoms,I tried using a pane of glass preweting the f/g on to the pane of glass then laying the balsa on top of that
The idea was that you got a perfect finish
It worked well but i did have problems with trapped air bubbles which are very hard to get out
I also tried infusion,with this 3oz glass by itself it will not infuse very far to increase the infusion distance i needed a flow medium this increased the amount of resin used and then i had to sand the surface to get a good finish so no great gains there
I have tried doing the glass as per the first way but with the balsa on the bottom and the glass on top,it worked ok
However you then need to have a good feather edge to lap the rail glass to so it fairs out into the deck or bottom ok
Untill you get your system right this can be more work than exterior glassing was!
which way performs better? i would say they are all much the same the amount of glass (layers )on the rail affects the flex allong with the rail shape and size
Sandwich not connected to the foam, i tried some contact for a floating system
Try it put it out in a warm room and very soon you will see why it needs a vent!!
I would suggest that if you try this you would have to beef up the sandwich so that it is a little more self supporting.
Otherwise you run the risk of making a board for some one and them leaving the vent done up and the board in the sun where it will very soon resemble a zeplin blimp!!
Final point if you are trying to make them light (I am averaging 1.8kgs now) you are very limited to what you can do as every little bit extra weighs that extra bit and before you know it you are back over 2 kgs
The top hats on the sandwich were the one way i found that you could get flex or stiffness just where you want it with minimum extra weight gain.
Mike
Could you honestly answer mathmatically why your board surfs the way it does?
nah…that one’s real easy…if i can shred on it, its a keeper
To start off with, I did not answer those questions in detail because I read them as “Hey look everybody, Dan knows nothing and I know all”. If this was not your intent then I’m sorry. I don’t honestly see how they were relavent to what I was saying. I’ve built 4 boards (which you know) and asking questions about how this and that relates to some patent has nothing to do with what I know.
I’m teaching all the things that you mentioned to my eigth grades science class. I am familiar with all the things that you are talking about, but you are applying them out of context and without testing. What we’re doing is not engineering, but if could be if we knew what we were aiming. So what if the span between the layers of glass increases the panel strength. Do we know for sure its a good thing? A bad thing? Good some places and not good others? Its very possibe that I don’t understand what your trying to find out? Do I know my physics? Yes Does surfing apply to physics? Yes
What questions should I be asking? Who should answer them?
All I’ve put forward it that wood can store energy, without flex you can’t store the energy, and to many materials hinder flex. As far as new ideas, I’ve already said that on my next board I’m incorporting Sabs grid (but with my own twist).
I know you don’t like my theories, but what are you saying is better? How are my theories wrong? Its easy to attack, but what are you offering in its place. Once again, if I misread the intent of your post I’m sorry.
I’m not sure why mine turned out so well. There was not a bubble to be found. I did pull 24" of mg. Could that be the difference? After seeing infussion I gave up on the idea of using it on my boards.
I like your top hat idea. I was not extremely happy with the diagonal balsa on the deck (it was very hard to blend into the rails. I was thinking of using your tophat idea to re-enforce under the feet, and add some spring to the tail.
I think a springy board will require a change in surfing technique.
I think that this is probably extremely true. I’m not always the best at getting my weight over the fins so my turns lack the punch I would like. Being able to generate power from the middle of the board is a huge plus for me.
VERY interesting thread.
To pipe in from the sidelines… If you are using balsa from you springer/stringer you can very the resistance it provides by adjusting width/thickness.
Half the width, half the strength/resistance. Half the thickness, ONE EIGHTH of the strength/resistance.
A significantly stiffer section will act as a fulcrum point. But I really think you’ll need to reinforce the area under the fulcrum, to disperse the force without crushing the EPS.
Just my $1/50! Treat em rough - that’s how they like it.
-doug
This is what I’m thinking! I’ve done zero reinforcing at the ends of the springer. This is one of the reasons I’m holding off building my next board. I want to see how this one holds up. If there’s really as much movement as I think there is I could see problems developing - and only time will tell.
How are my theories wrong?
ok here’s a perfect example:
the basic shear force distribution graphic i posted, a fundamental engineering principle of composite panels, is showing exactly the opposite of this comment you made:
Its even more than inside out. Its the inner board and the outer board. On a traditional board you really have one board since the core doesn’t really add anything. With the componentized board you end up with multilple boards. The outer board which keeps everything dry, and the inner board which you actually surf.
believe me Dan, this is just ONE example of many…i’ve kept a very tight lip until today…
What questions should I be asking?
Who should answer them?
Reliable BOOKS or other reliable sources. A composite handbook is a good start…the one i bought cost me $225 right out of my own pocket…i could make two boards with that
I dont think i would have such a problem with your theories if you used words like “maybe” or “perhaps” or “what if”.
You speak in very absolute terms like youre the last word on the subject…go back and read your comments…you make very little effort to humble your lofty statements…
Pardon me if you feel like im attacking you…didnt intend to attack…just pointing out the obvious from an engineer’s perspective. What others reading here decide to rely on is up to them…
im out…
Hey Dan,
I think if the ends are resting on foam they should probably be reinforced - but that wil depend on the thickness of the end and its taper.
If you have a springer very well tapered at the ends with a chunky fulcrum the fulcrum area will need reinforcing much more than the ends.
It’s about ensuring areas with more load diffuse the load. Inlaying with some other, more crush resistant, material under the load area should prolong life significantly.
-doug
meecrafty and any Swaylurkers,
I’d really like to hear your opinions on varying springer width/thickness to tune spring. And thoughts on reinforcing load areas.
These seem common sense to me based on experiences working other materials. But I am a neophyte in this particular area and would value the opinions of those more experienced than me very much.
Thanks in advance,
-doug
well, what can i say …
give away hard earned information???
make a comment on how one springer performs in relation to another for a given rider , then have a lurker pick it up , publish it and make out like hes breaking new ground …
doug , this has been my main area of refinement over the last few years tuning flex and return loads for varying weights in riders , i could seriously give you all the information you wanted , but why would i comprimise my posistion and the effort ive put in to date …
yes its a worthy pursuit , and if your in this business then youll have a better understanding of the boards you make for customers …
im all for exposing concepts that allow others to think …
but i do have problems answering direct questions , where crew ask for specific details in quantities , measurements , etc …
those things have commercial value …
i would much rather present a few scenarios and let peoples logic point them in the right direction …
meecrafty , your engineering diagram above was interesting , but could be re drawn with a whole range of different variables …
about the time i first appeared on sways , i tried to start a converstaion about the neutral axis …
the bottom line is , no one had a clue what i was talking about , so couldnt even converse on the subject in regards to surfboard performance …
your diagram shows a neutral axis and now we have all you guys familiarising yourselves with the construction techniques , so your experiencing performance differences in relation to whats happening around the neutral axis , so maybe now its a subject that can come up and we will actually be able to discuss it , (or at least my theories can be unlocked to an educated audience for some constructive critique)…
in your diagram the neutral axis is fixed at a given distance from both sides , that can all change with shape , skin/panel flex and posistioning of internal boosters …
your neutral axis exists in a 3 dimensional space and can move around inside the structure depending on how you have set it up …
designing your board so the neutral axis always exists under the rider , where ever his weight is on the board , will give ultimate control and a magic feeling anywhere on the face , (allowing for the right design to suit the waves) …
any centrally placed conventional stringer will interfere with the neutral axis and its ability to move inside your board , thus giving the board way less range and the need to keep the feet posistioned more accuratly in the sweet spot …
whereas a design based around a mobile neutral axis gives the rider way more control over a greater area of the board in a bigger range over the face of a wave , because flex in the board can be used where ever the rider is standing at the time …
this runs deep so i wont keep going , curious if it gets picked up …
i really hope someone is up to it , or we may have to shelve the subject for another few years …
dan may have inadvertantly opened up this subject , sometimes we can feel stuff we cant explain , but we know its there …
no answers from me , only crumbs on the path …
regarding surflight v sunova on the issues of shear forces and how they are dealt with ???
neutral axis over the largest possible area of your board is the key …
creating a focal point for the neutral axis , means our weight must be in the exact posistion for the board to work , then we must also be tuned to how the board was designed …
there is some really good comments being made here , and some of the performance observations being made are spot on in relation to the boards your riding …
ok thats me , ive got real work to do …
cyas
regards
BERT
Hey guys:
I’ve been following the sandwich stuff for a little less than a year. I’ve done some boards with balsa and eps, but not really any sandwich skins type construction just yet–still trying to work out the vac bag thing. However, I’ve been mulling over all the posts on this topic, to the detriment of my business, and have been mind shaping these things for months. As far as I can tell, Bert’s post seem to suggest that none of the components of the board should be locked together. I’ve been envisioning preformed skins with no bond to the eps and only abutting the rails. It also seems that the rails aren’t bound to the eps either. This seems to be the direction people are going with this, right?
A lack of concrete experience with this certainly impairs my though on the subject, but I’m working on that.
I’m confused about the analogy Bert often makes to a paper back novel when describing shear forces in a board. When I bend such a book, the pages slide against one another and the book flexes. At the sime time, to accomodate this motion, either the spine or side opposite the spine is elongated. If I actively prevent the this elongation, say by clamping really hard, the flex is inhibited as the pages have no where to go (like in Bert’s playing card example). Does this observation have any relevance in board building? Do the boards need to allow for lengthwise elongation? Ignore this post if it is patently idiodic. Thanks.
Hunter
dont forget to allow for morph action …
once you lock up in certain areas you force the shape to change shape under certain loads …
your basically planning what the curve should be in the board ,in a certain part of the wave , under a certain load to get the most out of it …
i get the feeling maybe i should stay out of some conversations till some of the basic construction techniques are understood first …
at least i know greg understands me …
someone overheard us talking recently and they said it sounded like a foreign language and they had no idea what we were even talking about …
ok bed time
regards
BERT
Don’t know much about biology
Don’t know much trigonometry
Don’t know much about science books
Don’t know much about the french I took…
But I do know that the one piece missing from this particular thread has been present in the past. Bert (& CMP, I believe) have both mentioned foaming epoxy.
I would guess that’s how the skins are connected to the foam.
Just $.02 from a non-engineer.
But, ironically, my degree is in archaeology! Didn’t someone say this reverse-engineering is like a dig…?
I love the hunt. Who cares if its all rhetorical theory or actually put into practice. It still enhances the knowledge & perspective of everyone participating. Agree or disagree with any particular statement, you’ve still learned something from forming your own opinion pro- or con- to that statement.
I know one thing for sure. My job has certainly never challenged me intellectually the way this crap does. Neither did college, for that matter. I’m feeling, well, very stimulated. 