Wow, Ok, I have shaped some boards, I am now riding a fairly flat 7’ 10" sort of mini long board tri fin that I love. It has a little V in the tail and a little belly in the nose, fairly soft rails from the nose to about 3/4 to the tail, then I tucked 'em a little. I just wanted to know easy stuff like how does concave of a particular depth and shape REALLY affect a planing surfboard. And is concave more or less important than nose/tail kick. Telling me that there is no way to test simple stuff like this because there are too many ethereal variables so the only valid test is experience man…is just a cop out. And sounds a lot like my favorite line from the movie The Wizard of Oz…“Pay no attention to the man behind the curtain!” Yes there is test data, or no there is not is all I was looking for. I don’t discount years of experience and trial and error, I also don’t want to go along with the herd just because I read it on Swaylocks. And by the way, Swaylock’s Rocks, thanks for the forum! Thanks, Mike Freshwater California BTW what ever happened to the single fin Mcoy shapes Shane was riding in the 80’s?
Points well taken, forgive me if I am out of context, as my testing was exhaustive and continues to this day; I don’t see empirical testing to be avoiding the issue. More important is what is to come. A good analogy would be the development of the airplane for its’ first 30 or so years. Many, many great minds were striving to build the best aircraft; an epic braintrust. After WWI it was realized that streamlining and better propellors were the answer. Into the 1920’s and 30’s international air races came to the forefront as the motive for better technology. Many companies and individuals working out of their sheds contributed in huge ways. Shaping better propellors became an art. Go to a museum and have a look; you shapers can appreciate the functionality of their efforts and talent. The contributions plateaued conceptually and the increases slowed. Most of the highest performing aircraft started to converge design-wise. Their performances throughout the world were very similar even during the life-and-death push from WWII. Then, seemingly one day, this British guy comes up with the jet engine. Basically, all the artists are throwing their propellors in pile. Everyone starts pushing the jet technology, and though propellors still exist and continue to improve (get refined) the jet comes to the forefront. Which leads to my question, “Are we due for a change?” Worrying about how my concave can get me 7 percent more efficiency is just refining the propellor; whether I got this effect from a test tank, workbench, or local beachbreak is irrelevant. The time is really right for someone to come up with something that you and I will remember seeing or hearing about; making us go “holy s*#t!!!” We’ll all be running back to our shops to build our version and that’s the real rush in a shaper’s/boardbuilder’s life. Please don’t take offense, refinements are all I did for almost 30 years; I’m guilty of building inside the box. I make my living making mostly tri-fins; but I also try some crazy stuff. I mean, imagine how it was for longboards (since modern surfing’s inception) to suddenly (six months) mutate into the shortboard. I bet many visitors to this site can tell us very clearly where they were when they first saw/heard of a shortboard. Or the tri fin. Or… …is this Paradigm Shift inevitable, or am I just spewing words???
no your not spewing words …its construction technologie …its the next big break …ive been building longboards for the last ten years that are in the water and surfing …finished product …lighter than just the blank of a conventional board, ive been building 9’ plus boards that weigh 8 pounds… and to prove its no hoax have produced 4 open australian national titles since 99 …and on the the aussie west coast in 2003 had 7 west coast titles of 9 possible surfing divisions .now thats 1 manufacturer out about 140 in this state who took out over 70% of the possible titles we coulda taken more but didnt have guys riding our boards in those divisions… i would call that an advantage due to technologie …if we look at a lot of the champions of the last 30 years ,many came with new technology…weather it was M.R. with the twinny ,simon with the thruster,curran with reverse v , and so on ,but now where can you go shape wise??? construction is next , get involved or go like the dinosaur…
I think I see what you mean, but… the jet engine, lets say, had a long period of research and development before it really was more than a curiosity, before its actual performance caught up with what thermodynamic theory said it could do. Lots of failures, lots of really, really bad jet engines that failed before they got some that’d really be useful in an airplane. And even then, they were hung in airframes that were not all that different from what had been flying around with a propeller on the front. Now, is there a paradigm shift coming? Maybe. Will you see it? Yeah, but not as a paradigm shift. Huh? Yep, 'cos you are prolly gonna be one of the guys making it happen and you’ll see it as one more incremental improvement in a long series, which it will be to you. To the general population it’ll seem like some instant work of brilliant invention, but they are gonna be wrong. They didn’t see all the wee maddening refinements in the background that add up to the major increase in performance. But what Mike from Freshwater is looking for is something pretty useful. All those improvements in aircraft design, they didn’t come about because somebody was building airplanes and taking 'em up and flying ‘em with no instruments and then going on to something better. Nope, what they were working with was NACA airfoils and cowlings and propellors that were tested in wind tunnels with lots of instruments busily measuring everything. Those that didn’t do a lot of testing may have gotten real lucky now and then, but it was both unlikely and it could get kinda hairy. My favorite example of ‘kinda hairy’ is the Gee Bee racers. Designed and built by the Granville Brothers ( hence the Gee Bee) it was not a helluva lot more than a couple little wings and a great big honkin’ engine ( http://www.aerofiles.com/geebee-r2.jpg ). Damned dangerous airplane. The racers all crashed. And the guy who was most successful in one was Jimmy Doolittle, who wound up leading a bomber mission over Japan that took off from an aircraft carrier. He also had a Ph.D. in aeronautical engineering from MIT, which is probably a big part of why he managed to live through all of it. The Gee Bees went like hell, but lets say their envelope had some funny folds in it. Took a guy with systematic knowledge to figure those out and stay away from them. But that’s getting off to one side. Back on track, testing things is important. And it’s important to have it under controlled conditions, with something more than how good it feels like it’s working, even with a highly experienced feel for how surfboards work. That’s where model testing and some sort of test rig come in, not building a board and going out and surfing it. I’ll happily grant that it’s not as simple as towing a model surfboard along a tank, it’s more complex than that by quite a bit, but it can be done. Then take what’s been learned, build one full-sized and take it out and see.
i got more data than you can poke a stick at from actually quite cheap and inexpensive methods from towing boards behind a boat with a couple of bricks on them and using a set of fish weighing scales on the tow rope to find out how viscous drag affects different size boards and also relate that back to different rockers and bottom contours, crude i know . actually sacrificing boards to science …and keeping data from customers over a 3 year period to find out average snap ratios and other information…making a small flow tank (which actually got quite big due to turbulance problems )for the purpose of testing fins there foils and how much lift and drag ,and at what angle of attack they could handle before they failed or started to experience induced drag …made from a bore pump some guttering a plastic container and two sets of kitchen electronic scales and of coarse the usual pain that goes with r&d…cheap yes , also efective ,but dont forget all that information now has a commercial value …you think im gonna post my results here???for the time being i can use it to strengthen my position in the surfboard market place and as long as were still producing champion surfers …the rest of the industry will be driven in our direction…you go to a car race …the car that wins on sunday sells on monday… regards BERT
I’ll be damned…Good for you, Bert. While some might raise a great wailing about why Bert ought to release his data, I won’t. His time, money, effort and ingenuity went into it, so to my mind it’s his and not some sort of public resource. I may have mentioned NACA airfoils and such in a previous post - the thing about those is that they were developed by a publicly funded agency whose specific purpose was to do research and disseminate information. NACA became NASA and they are still doing and publishing basic research in aerodynamics for everybody to use. Not applicable to somebody doing their own research, though. They don’t have to publish and quite often they don’t. Probably mentioning something you know already, but… Bert, I’d be real picky about dating and documenting stuff. If you want to patent something, the better documented it is, the better. keep up the good work doc…
I truly believe in the science of all this, but the human element and the infinitely variable ocean wave element will always be there. I was lucky enough to live in an environment where the waves were very similar most of the time. It was my ocean tank testing station, if you will. Part of the reason my boards and fins developed the way they did was because of this constant. I must stress though that my goal was to make the best stuff for me, and me only. I achieved something close to that, and by chance some other people liked them too. I’m still scouring my brain to try and make my life better. Reading everyones ideas and opinions here is helping me do that. Thanks to all.
Hey Bret, The kind of R & D your doing makes a hell of a lot more sense to me than any other approach I’ve heard of. Surf-craft development has always be a pull you own bootstraps up kind of thing. Industry starts at home and by jove it’s clear to me that you’re in your own kitchen cookin’ up some grand recipes for surf-craft performance. Too bad you’re on the other side of the world. I sure would like to see your boards and fin set-ups. I know I could learn a lot just looking at them first hand. I’m thinking the best way to enter your hydrodynamic picture is to send you a set of glass-ons for whatever board we might decide on. I hope you’ll email me at so we can go from here. I think I’m on to something that’s really good but I need more feed back, so far it’s excellent, but no one that I get it from has a background like you. There aren’t many who are willing to invest the time to gain the knowledge and experience to make both their own fins and boards around any more. It would seem that when it comes to both hydrodynamics and surfboards that less is more. It’s called efficiency. Sometimes how you arrive at it comes from the time you’ve invested in your own back yard and then taken your concepts to sea. At least that’s how it is for me. Gone Surfin’, Rich
This is like a breath of fresh air. Good to know there are people out there testing in once sense or another. In engineering school there are design courses where the emphasis is rapid prototyping. Imagine building a 747, rolling it out, attempting take off, crashing. Build another 747, and so forth until you have one that works; like Doc says, a lot of development goes behind legitimate ideas that ‘suddenly’ appear in the mainstream. But, in the case of surfboards, there is very little penalty, to have a vision, make it, “fly” it, and succeed or crash it. They don’t cost that much, are rarely lethal, and are fun to test. I know that G Lopez tests by towing behind a boat in a lake. I am fully aware of theoretical bases used for fin design, NACA/NASA, and simple beam theory for composite construction (very intriguing Bert) techniques (I’ve relied on this stuff for years). Even with all the test data, devices, etc WE STILL HAVE TO COME UP WITH THE PROTOTYPE THAT IS GOING INTO THE TANK. The Wright Bros imitated birds then went off on their own using wind tunnels and tons of foils. But where did the foils come from?? They saw how they performed (too difficult to build a Wright Flyer for each idea) and used their intuitive genius crossed with what resources were available. They did this systematically for every critical aspect of their complex craft. It saved lots of time. With surfboards, we can do this as well but remember we are super-simplified; with the advent of UV resin, we can make (relying on our previous schema (and others’ ideas as well)) a prototype surfboard in the morning and try it by that same afternoon. I’ve tested in Indo at places where there are extremely repeatable waves; and it works, you learn. But like Feral Dave says, “the more you learn, the less you realize you know…” Maybe tank testing will anchor this knowledge. The common method of evolving the modern surfboard is like a room full of typewriters with monkeys (please, no offense) seated at each one; eventually one will type out Shakespeare. That’s brutal, we’re better than that, but it’s done us right. Most of you out there are building what, single, twins, tris, etc. You imitate what you see because you know it works; you saved yourself a lot of headache. As boardbuilders, a collective idea generation (ie. Design Forum) is HUGE; and fairly recent. With that said, almost everything works; how would we know that we were reading Shakespeare if one of us hammered it out? (win a world championship on one; it that where we’re headed?) The direction R&D goes is multiple, just remember the most substantial developement will come from a drastic design mutation, rather than refinement of present stuff.
Very good summary and very good points brought up. Let me toss a little into the mix, if I may. Prototype model-sized hulls for testing could, I suspect, be as quick and dirty as sanded foam and quick drying paint or plain shaped wax, given cool enough water. The wax hull could have quite a few advantages; castable, easily shaped, reshaped and adapted, what scaled weight you want for a surfboard-rider unit might be all in the wax hull. I’m harping on tank testing, or analogs of it, just so that we can indeed get some numbers out. In the last week, there have been at least a couple of ‘what’s fastest’ threads, for instance, and there’s actually no answers to that yet. The room full of monkeys analogy is pretty much to what I’m seeing at work in the biz now and as long as I have been watching it, with a few pretty bright monkeys doing some interesting things and most just cranking out the same old bananas and a few who seem to be plainly messing with coconuts. Though it may be that the coconut is what’s gonna work best, eventually. And as you say, you have to know what Shakespeare is to recognise it when one of the monkeys comes up with something. I’ll make a really awful analogy - if we equip the monkeys with word processors and spell check ( some efficient, relatively easy standardised testing methods and a few results to gauge them against ) then maybe the chances of Bonzo coming up with Macbeth or As You Like It are suddenly a whole lot better. Given quick, easy, easily changed and adapted models that can be tested, varied a little and tested again, well, the seemingly screwball idea can be checked out and fiddled with quick and easy and maybe that major jump forward can be accomplished much sooner, or maybe not given up on before that last little detail that makes it work right is found or tried. Dunno, that’s what I’m thinkin’, anyhow doc…
Ha!!! a “smartified” Bonzo. That’s great! Makes good sense in a twisted way. Data can be valuable, data can be tragically misleading. I would really like to measure the “gooosh” feel that a board has as it loads up through a serious bottom turn. Perhaps a Field test bottom turn board set up with strain gauges and Plasti gage to interpret loads. We could find out how much the board is bending and twisting, then reproduce it in the lab. Then as we find a super good bottom turning Field board, we could measure it in the lab under load and perhaps measure WHY it is so good. As a board is loading up through a bottom turn (acting like a spring) the water rushing beneath it is also acting like a spring as well; a spring that varies in energy retention with speed. You know, when you are really moving fast and you eat it and skip on the water before penetrating. Higher speed=less spring. Water is hard to model. I had access to an incredible computational dynamics program that would model such a thing fairly accurately, giving a visual data output, but that was years ago when I was involved with some serious Defense projects; no more access. Any one out there have something like that? Anyways, the last important thing is physical modelling. Scale factors must always consider that the medium (water) does not change as we down-scale, ie. density of the water stays constant. Reynolds numbers must be utilized to change the physical shape of the model to compensate for the change in flow. It could be very possible that the model will not look anything like the actual surfboard anymore. I was quite surprised when I saw this in other modelling studies. Lastly, it has been my experience that testing is expensive, and always much more expensive than I anticipated. To get an accurate depiction of what is happening will validate the data and this will take consistency and tenacity. I’m feeling burned out just typing this, I think I’ll keep being a lackey chimp / factory robot and just test my stuff out in the water… …who needs Shakespeare anyway.
Uhmmmm…let me see if I’m following you correctly: Mebbe analyse/model some successful boards, then go from there, as a start, anyhow. Indeed, it’s the only way to get any ideas if the numbers you’re coming up with are really useful. I like the idea of measuring strains via a strip of something that’d permanently and easily elongate. Could see, for instance, how close a given lamination was coming to failure, though it’d mebbe assume that the deck ( or the other side, anyhow) wasn’t compressing to any real extent. Though something could be worked out, mebbe another strip that’d compress. I think the desktop PCs are coming along to such an extent that the kind of electronic horsepower was used for defense projects and Cup hull modelling will be available pretty quick over the counter, though I have seen some used recently…you just have to be kinda patient. A reasonably quick Linux box, running what’s probably Unix/C software that’s out there someplace ready to download… Though…if I’m remembering right, those were all for displacement hulls, dunno if there’s anything for planing hulls. Which leads to an ‘oh damn’ moment, a whole set of software I’d just a soon not think about developing. Apropos of nothing at all, you may have run across the Barnes Wallis experiments, trying to get bombs to bounce off water. Probably not applicable, but you never know. Same sort of thing, there’s stuff out there for hydrofoil design, and the differences between that and software for airfoil design might be useful. Damn…this means I’m gonna have to crack the books some… oh well, it was getting a little dull, up here in the trees, scratchin’ and waitin’ for the bananas to get ripe…
What ever you do dont trip over a Penguin… The only way we could see to measuring speed accurately was to have a predictable wave generated that would reliably have a consistant height, thickness, speed and density…Upon creating a reliable wave a rider with reflective surfaces could be laser clocked…using different boards built for the particular wave one could be raced against the next untill critical speeds are logged from each flow form. Then go to the graph and there will be a representation of each of the boards performances top speed, accelleration, stall speeds everything… Another way is this…Jet ski toein boards have lead in them so as to be able to achive speeds of 80km to 120km for runniing into a big wave. So useing a Jet ski and a tow rope you could cheaply and effectively find a straight line top speed…Although waves are not flat you still would get a feel for the boards stability and speed limits. In Pauls opinion conventional speed boards will reach a max of 60-70km before the shape delams, FP we predict will exceed 70km… http://www.geocities.com/wunderboyi/ninetysixpercent.html
One last bit of energy… That’s right, two visually identical boards but one is “okay” and the other “magic”. Set the boards up with adhesive strain gauges and clay-rod Plastigage. Take the boards out and have a consistent surfer bottom turn in a consistent manner at a consistent spot. Acquire data numerous times for each board. Go in right after each bottom turn; discipline. Establish load profiles for each board (an average of many sessions). Important: In the lab, place static loads on a board so that it is bent the same way as during the “snapshot” of the bottom turn. Note that we are translating the loads of a dynamic situation and representing them by static (constant) loads in the workshop. Stare at the boards. My rudimentary tests from 20 years ago showed bending in excess of 2"!!! This is over 2G. (“G” is a dynamic load, so a 170lb rider is imparting a 340lb load (static)). Moment of truth: one board looks a little different that the other while sitting there in “bent” profile in your shop. In order to make the “kinda good” board bend like the “magic” put in some carefully metered kerfs until the static profiles match. Test. Voila, control of the bottom turn “feel” has been mastered. During all this a smart monkey makes the comment that the rocker is straight through a certain line in the bottom of the board. Shaping to this, MORE control of the “feel” is realized. With bottom turns tested move on to cutbacks. Off-the-lips. Pumping for speed. Each aspect is cleverly recorded and mastered. Now implant a microprocessor and gyro/accelerometer sensor set that is tied to a T-alloy (the metal that changes shape w/voltage(heat) wire harness. The harness is just a bunch of fine metal rods anchored along certain crucial load lines; these rods contract when a voltage is run through them. Glass the board with a less rigid, low modulus composite shell. Entire ride profiles could be downloaded to the board right on the beach (Laptop). Profiles could be made for specific breaks and during specific conditions. Telemetry updates for changing tide, water texture, wave period etc could be made during the session through the subscriber service. With millions of dollars at stake, the top corporations program their factory riders’ boards with more zeal than Toyota does at Pike’s Peak. Complete control. Everything optimized in real time. Retro parallel processor surfboards come back into fashion as a “soul resurgence” makes the latest hyperkinetic alloy jobs passe. Telemetry espionage; controversy. Keeping the bored masses awake until the next subliminal commercial media loop tells them what they want. I don’t know; I might start doing crochet or something…
yah, I’m kinda running low on zip myself, so the ol’ brain may not be firing n all cylinders… Given a deformation of X from a single point load on the deck and two supports underneath, what would the required force be to bend that de facto beam to X given what seems to be support under the whole thing, given that the water is exerting some force along the entire immersed section of the turning board. Might be an interesting, and easier, move to wire in pressure sensors rather than strain gauges. And there’s cute little gizmos like the Basic Stamp line of microcontrollers/single board computers - quite small, build a black box for the board to do data recording. You can configure 'em to measure and record all kinds of stuff at what intervals you want - synch the clock with, say, the clock built into the video camera you have set up on the beach. Make that harness a little stronger, maybe use some of the muscle wires they use in model robotics and the like, or simply rig the board with some gizmos like they use to tune guitars: voila, tunable and variable flex. The guy wire/stiffener matrix doesn’t have to be just paralell to the centerline… parabolic or hyperbolic patterns… hmmm… adaptive… jeez, you’re as nuts as I am. this could get dangerous. http://www.parallax.com/
Its a real hoot reading all this stuff about tank testing. Why don’t you search the internet for starters … Go to the report suggested below and follow the references around. Some of this data goes back to the 1950’s, and its all free. If you look hard enough, you will find that a planing board is mathematically equivalent to the lower half of a wing. You will also find somewhere that rounded chines (rails) reduce lift. You will also find that concave increases lift. So go find out for yourself. Just please note that this information is not served up on a plate for you. Get going. http://naca.larc.nasa.gov/reports/1958/naca-report-1355/naca-report-1355.pdf
Clocking some video with data collection; GENIUS!!! (we just quadrupled the test budget). Seriously, one test I did years ago was to find the most crucial load line. By the seat of my pants I found it NOT to be parallel nor parabolic. It was torsional: An “X” pattern starting at the front foot and extending just behind the front fins (Tri). Twist is the enemy but longitudinal flex is our allie. If you know what Luder’s Bands are then you know how to overcome this torsion. Guess what the WORST load pattern is? It’s the one that promotes torsion and stifles straight bending. That’s right, Bi-directional cloth, it lets things twist (BAD) and reduces straight bending (also BAD). Answer?(other than 45 degree orientation): Tri-axial weave, I have a line on some that is low enough in weight (the stuff used on the B-2, F-18 and F-23 and others is too heavy at 18+oz.) but it is still being set up somewhere in the Carolinas. I used carbon graphite uni tape from ACP and was noticibly successful. There are also shape-associated behaviors to consider (anti-clastic behavior). Not enough time right now to elaborate. I’ll try to fill the gaps in the next day or so…
interesting dono where your gonna find the budget for some of that testing …but at the end of the day nothing is impossible… impressed as well with the multi faceted thought processes of some of you guys … as good as data is ,dont forget the wealth of knowledge that exists in the brains of shapers world wide which came through traditional trial and error see what works approach… but mixed in with that is the probability that some got it wrong …as a board designer your basic fundamental understanding of what is actually happening is crucial ,if what you think is happening for a particular reason is wrong and the basic concepts you base your designs on are flawed ,it can leave you frustrated and keep surfboards spinning in your brain all night and leave you with out sleep …and thats where testing and collecting data can help . isolate your variables … when learning about different aspects of design you need to keep everything identical except for 1 thing …simple example is changing fins on the same board nothing changes but the fins … or every thing stays the same but slightly differing outlines .other wise what you think might be making the difference is actually something else…ok thats pretty obvious stuff .eventually you find combinations will or definatly will not work together.it all takes time ,i think thats why most of the worlds best shapers are old guys… always test your theorys by trying to disprove them .you can do a thousand experiments to prove something is right .it only takes 1 experiment to prove it wrong . so after trial and error testing ,other types of testing can help you build a basic picture of whats happening … once you have conquored basic design principles and laws of physics, it becomes as easy as learning to spell coz youve learnt the alpabet,or doing maths coz youve learnt to count… but if you dont learn your alphabet or learn to count properly, then grasping higher concepts will be impossible and confusing and will lead to poor results… also one more point … stay on earth, you can go along way in your mind . but the reality is we all need to make a living and pay the bills ,and try and make some sort of progress that is within our reach with the resources we have … regards BERT sorry if that sounded a little know it all ,but after spending the time to write it i have to post it…
This has been a fascinating thread and I feel like a minnow contributing. But it seems to me that Tank testing assumes that everybody wants the same thing. (1) Its ok for aircraft where the object is to get from a to b as quickly as possible. How many shapers shape only 1 type of board, for a single rider. (2) As previously stated by others the wave parameters are too varied, height, Direction shape Seabed wind tide rips. rider These all change not for a beach but for different positions on each individual wave. So empirical evidence gathering is the only feasible way. (3) All you can ever hope to achieve is: In a perfect wave, how effective is each feature, and how does it affect other features, for a particular board size. Useful, but the knowledge is there its just that the numbers are not. (4) a component based approach may help, snap on rails, rockers, bottom designs, and it seems to me to be quite doable, using mini cell foam or something, particularly with CNC tools (5) There has been so much R&D into boards over the last 30 years, I believe that there are only going to be incremental changes, like the aircraft or automotive industry. There may be better surf craft developed but I don’t think they will be what we know as general use stand up surfboards. eg waveskis with hydrofoils, or 16ft boards towed into open unbroken ocean waves to get the longest rides. It all comes back to the rider,the human body is so incredibly accommodating. No matter what you build somebody somewhere will make it work for them. Like me noseriding yesterday on my nose and tail kicked 50/50 railer with belly right through. Just look at the range of devices for noseriding at the moment some swear by them and others hate them. Bert seems to identified the key features in his boards and they suit competitors, fair dues, but I’ll bet he got there by stripping out what was not needed and blending what was left. So, know the people and the waves you shape for and be critical when adding features, the information is probably there on swaylocks. As Einstein said ablot relativity: “To these fundamental laws there yields no logical path, simply intuition combined with being sympathatetically in touch with experience”