Crinkle cuts and the great Macaroni fin experiment
Did you visit Swellnet during Flexi Week? And did you read the article with Professor Marc in het Panhuis and his wonderful Flex Machine? Yes..? Great!
What wasn’t included in that story, however, was that when I shook Professor Marc’s hand his knuckles were covered in cuts and scabs, and when I looked at the surfboard fins arranged on his office desk they were unlike any I’d ever seen. As strange as it seems, those two disparate observations were intricately linked.
Allow me to explain....
Marc in het Panhuis is a professor of materials science working out of Wollongong University. His main research consists of two strands: the development of new materials, some of which were covered in the last Swellnet article, and his other scholarly passion is additive manufacturing - what the mug punter calls 3D printing.
Peering into the future: Professor Marc in het Panhuis from the University of Wollongong
“My main expertise,” explains Marc, “is developing or repurposing materials for uses that they haven’t been designed to do.” For instance, Marc recently turned Vegemite into electronic circuits that could be 3D printed. He also used a food additive - “something that can be found in all sauces” - and turned it into a material that can harbour living cells. Again, it could be 3D printed.
Though the occasional science article makes the mainstream media, it’s safe to say that Joe Public hasn’t fully grasped the promise of 3D printing. Additive manufacturing can create highly customised products - think high end engineering or even human body parts - and it can also create rapid prototypes as there’s no need for molds or machining. One-of-a-kind products can be designed in the morning, printed in the afternoon. Many industries are closely tracking the rise of 3D printing.
Separate to his lab work, Marc also has a thing for GPS devices. About three years ago, Marc was surfing with a sensor attached to his board. This was when a few similar products hit the market, including Rip Curl’s GPS watch, each of which tracked and quantified the wearer's movements: the number of waves caught, distance travelled, turns completed etc. And while he was out in the water, well away from the laboratory or classroom, the gel of thought crystallised into an idea of substance.
GPS sensors were the catalyst that provided Marc with the means to combine his two academic interests with an abiding love of surfing. When fins are 3D printed, various materials can be tested for strength and durability, while prototype fin shapes can be put through the performance wringer, tested both subjectively (by the rider) and objectively when GPS data is downloaded from attached GPS sensors. The idea is multidisciplinary. It’s neat and symmetrical.
But to make it work the waves also had to be...well, neat and symmetrical. There are so many variables in surfing that it’s difficult to remove the static and isolate just one feature for testing. Difficult, but not impossible.
The first experiment took place at Snapper Rocks two years ago, and the success of that trial emboldened Marc to broaden the scope. The test site had to be consistent, and the waves had to be predictable and repeatable. “I contacted the Kelly Slater Wave Company,” says Marc, “as it would be the perfect setting, however I got no reply.”
After Lemoore, the next-best wave is Macaronis and so the lab space was booked. There was, however, more to the operation than organising airline tickets and watching the swell forecast.
The laboratory
Funding for the experiment - actually, experiments - came via the Global Challenges program at Wollongong University, an initiative that links research with industry to tackle contemporary issues. When I visit Marc at Wollongong University he points out a building where research ideas are incubated and developed for commercial release. Already a number of businesses have been launched there.
The Global Challenge program insists on local business development, and it’s here that Dylan Perese from DP Surfboards at Thirroul stepped into the breach. To limit the variables each surfboard had to be identical, thus 14 DP surfboards were replicated for the experiment. They all had to be glassed on the same day.
Dylan also volunteered as one of the test pilots, though with a paid trip to Maccas it wasn’t much of a sacrifice. There were, however, requirements to be met: only skilled surfers with technical awareness were involved. “They didn’t have to be QS-level surfers,” explained Marc, “but they needed to be able to articulate what they’re feeling and they also had to be able to follow specific instructions.”
Dylan Perese from DP Surfboards
Thus Dylan was joined by Geoff Latimer who runs the surfing program at Illawarra Sports High, Chad Uphill who runs Board Thought, surf coach (and shark attack survivor!) Brett Connellan, Nick Clifford from Zink Surf, and James Forsythe who’s a PhD student at the university. Three goofy footers, three naturals. Three surfers in their twenties, three in their thirties.
The last time surfboard fins were tested to such a degree was in 2005 when FCS, then flush with funds from Macquarie Bank, designed the H2 fin. FCS undertook extensive tank flow simulations, essentially just R&D. The University of Wollongong team took a different approach blind-testing all the fins, their range including 3D printed fins and those made by fin manufacturers. All the markings were removed and every fin was painted black.
To eliminate bias, the surfers couldn’t know what fin they were riding; Marc and his assistant fitted the fins and lowered the boards in the water. If a board rolled over, say after a wipeout, then another set of fins was randomly placed in the board.
Brett Connellan
Each board was fitted with a GPS sensor, the surfers each wore two sensors, and every wave was filmed. Marc was looking for particular information. “I wanted hard driving turns, I wanted the rails engaged as much as possible for as long as possible, and I wanted as much speed as possible before turns,” insists Marc.
But what he didn’t want was what every surfer sought. “No barrels! Barrels tell me nothing,” he says with a grin.
After a week of rigorous testing, Marc had terabytes of data to sift through, however he also had qualitative feedback from his test pilots who downloaded their own thoughts after each session. The findings, and these were blind-tested remember, surprised them.
We’re sitting in Marc’s office and he hands me the fin that garnered the best results. “It wasn’t unanimous,” clarifies Marc, “but a large majority thought this one performed the best.” He hands me a black fin that has a standard ‘tuna fin’ profile, yet viewed front on it has a series of crinkles running down it. “The surfers thought it was faster and had less drag.”
The crinkle cut design seems counter-intuitive, though I’m reminded of an article I recently read where the US Air Force were surprised to make a similar discovery. If a pilot had to eject from a stricken plane they went from the calm of the cockpit to being thrust into a 1,000km/h headwind. Few would survive, their spinal columns snapped clean. Yet the Soviets designed a dimpled helmet for MiG pilots, the rough surface having less resistance, so the pilots could survive the sudden turbulence.
“When we did computational modelling, this fin had a more efficient flow, which had to do with water movement around the crinkles,” say Marc. "And when it was tested, most of the surfers thought it was faster and had better hold.” There were a few variations of the crinkle cut fin, yet the design most surfers settled on had crinkles on just one side and used as front fins only.
For surfboard shaper Dylan Perese, the experiment struck a chord. “I know what it’s like to try new ideas on riders and how hard it is to get past that resistance,” says Dylan. “Surfers don’t like trying different things. Yet that’s what Marc got us to do: we had no idea what we were riding.”
Dylan has spent his life around surfboards, seeing the same shapes and forms over and over again, and he was fascinated by the results. “It’s really got me thinking about what’s possible,” mused Dylan. Surfing may never again see a design revolution such as the Thruster, however for a high performance technician such as Dylan Perese, the future has just revealed itself. Already Marc and Dylan have a series of projects lined up.
Marc has done computational modelling on other fins even more esoteric in shape, however his experiments have a commercial angle and there’s a point where shape and appearance would deviate too far from the norm to be commercially practical. No-one would buy them...yet.
In time, Marc will publish his finding on fin shape, materials, and the 3D printing process in a science journal. He’s not sure which one, however it will be publicly accessible. And what about the intellectual property gleaned by his experiments? “It will be out there,” Marc shrugs, “for people...companies, individuals, surfers, to use as they please.”
At that I bid Marc farewell and once more he reaches for a handshake, stretching his open-palmed hand towards me. The one with cuts and lacerations across his knuckles. I gesture down and raise an eyebrow.
“These?” He says, looking at the wounds. “Well, you can’t go all the way to Macaronis without testing it for yourself.” And he then explains in great detail the lab experiment that went horribly wrong, replete with late takeoff, waves on the head, and a solid dry-docking on the Macaronis reef. All in the name of science.
Comments
Another great article Stu...loving this design and research series.
Cheers Crg.
Dunno if it's an age thing, but not so long ago I was feeling like there was nothing new under the sun, that all the great discoveries are behind us. But speaking to guys like Marc you realise that's simply not so.
Yeah definitely. I've personally tried quite a few old/new/different designs in my boards for probably 10 years now, after riding your stock thruster since forever. With everything I tried, the commonality was a degree of compromise - trade in for more of this but lose that. This looks to be pure improvement with no downside. I like the sound of that.
Yep, I see two elements here and I really like from a functional point of view. Breaking the concept into its two components, first is the jagged leading edge, that's significant and very logical when you think it through. I will be testing that for sure at some point. Second is the lateral wings or crinkles as you have called them Stu. I know the focus of the concept seems to be on the channels funneling away the turbulence created by the knob as it breaks the water on the leading edge, but there is another aspect to them (the high ridges) that would engage the power base in the wave. I saw something similar in an article you flipped from the ABC a while ago. Again its not revolutionary but certainly very interesting and for me, quite sensible. He has obviously done quite a bit of work to reach that point of refinement. Simplicity is anything but simple.
Great points Shaper, and another top Swellnet article, thank you.
Humpback whales have been testing those turbuncules on the leading edge of their fins for a few million years now.
Hats off to Dr Marc, this is ground breaking stuff.
This is a great example of the kind of work that needs to be done. It will be really interesting to look at the actual data. In particular how well the subjective data lines up with the GPS data and how reliably the surfers choose the same fin.
Id REALLY like to know what material he used in the fins too. Looks to be a pretty good finish for a 3D printer too. I recently had prototypes (not fins) made up at an industrial scale and the finishes were nothing like that.... very disappointing. We went to CNC milling.
shaper who did your CNC milling ?
Udo, it was a contact in China connected with a technical designer that I engaged for a tech project. Unusually easy to deal with for Chinese and very competent. Milled this two piece case case out of a solid block of ABS plastic as though it was an injected piece. Lovely work.
3D Fins have small channels on the inside tip of the outside fins on the JO'B model, with dimples on the outside. Wonder how that set up fits with Marc's findings and if it might be same same but different?
Great articles thanks Stu.
free IP too? what a guy. he deserves a trip to lemoore to test in the name of science! I dont know much about social medias, but someone start a campaign and hassle kelly #SendProfMarcToSurfRanch
Cool.
Roy Stuart has been doing leading edge tubercle (crinkle cut) fins made by 3D printing for a while.
I tested an upright single fin in a bonzer set up and it definitely felt lower drag to me.
Would love to get hold of another one but Roy stopped making them.
The article and experiment is great.
BUT.
It doesn't really tell us the results other than guys liked the crinkle fins.
Would have been great if we got what each person thought of each fin tested and what the fin was size, shape, material...was it in thruster set up or quad.
Indo all that data should be in the scientific paper when it is published. I'm sure Stu will put up the link when that happens, but acceptance for publication can be a slow process, peer review and all that, so it might be a while.
So BB who might those 'peers' be. If this 'scientific experiment' was so groundbreaking and unique, who has the scientific knowledge in such a field as to test the veracity of such claims?
If any 'peers' could review it, a good place to start would be right here on SN, but alas it would seem prof. Marc has gone to ground and not available to clarify some basic questions being asked.
As is mentioned in the article, the work will be published in a science journal.
Yeah, science is built on scepticism, but maybe wait till the full findings come out?
Whatever scepticism exists is only fuelled by some weird secrecy/avoidance to engage with the very audience that one would think the Prof. would embrace to put some meat on the bones of what just seems like junket surf trip funded by who knows who?
Happy to be shot down and discover that the new fins will revolutionise surfing performance, because that is what is being touted.
Surely you'd appreciate the asymmetry at play. The vulnerability of opening yourself to anonymous online snipers with undisclosed agendas.
You use to work for FCS, yeah? Presumedly did a lot of work around the H2? Got a bugbear no doubt.
So a balanced debate might start with your stating your name and previous work in the field. Anything else is just a waste of time. Wait till it comes out in a journal and read it then.
Huh? Who is sniping and what agenda? The story was interesting but made some pretty big calls prior to the data being released and it was others, not I who raised questions about funding. I simply agreed they had a good point.
Worked for FCS, Got a bug bear, stating my name? Sorry got it wrong and thought trying to 'out' people was for simply supporting another post and have a dialog with Prof. Marc would garner such an aggressive reaction Stu.
C'mon mate. Howsabout start with your post on Sunday 15th at 12:11PM in the flex article that took a pro-active swipe at Marc managing to condescend "the dear professor", cast aspersions about his funding, and dispute the findings - "commercially driven hoax" - before you knew anything about it.
Don't be obtuse about having an agenda. Of course you do.
Crinkles are a good variation on and existing theme. It would be great to collect more data on a range of variations. Josh Kerr uses golf ball dimples on his fins to improve laminar flow. They have test data to show the improvements. Millions of golf balls flying through the air over many years are also proof of the dimple effect. Small leader fins, slots, flutes and cutaways were used by windsurfers in the 90's and they reduced cavitation and seemed to improve speed. I messed around with cutting a slot in the rear fin of my thruster set and also used a wing keel rear fin. Variations seemed to work on specific boards. I have been using Josh Kerr fins for a few years now but I had to go back to a standard surface fins on my latest board when I used it as a quad ... just too fast in bigger waves. The rear fins have dimples on both sides making them very quick. There is plenty of room to develop surfaces to fit specific situations. Crikey ... add that to the current range of materials, sizes and profiles ...
Are you saying your fins are too fast in big waves ?
Or that your fins can’t handle the speed in big waves ?
The layout of fin positions on my most recent board created a bit more "squirm" than I was comfortable with. The speed was fantastic but more squirm than pivot. My previous board had the rear fin plugs closer together and the rear fins were more vertical. I surfed my previous board as a quad and as my main board on the North Shore a few years ago ... it gave me the speed and hold of a quad but with some pivot that was closer to a thruster. As you know, there are a myriad of variables when it comes to fin size, shape, and location, composition and board design but when I have tested the JK 3 d's on the same board, same waves and same session they have always felt faster than a similar standard fin. Hmmm ... to answer your question ... dimples on both sides of the rear fins in a quad set up on my most recent board were probably too fast for my style of surfing in bigger waves.
On a bit of a fin mission today...
Did they use the Quobba fins in the trial?
Nah, don't think so LP. I saw all the fins used and they were a mix of lab-printed 3D fins and commercially popular fins with their own plugs.
I don't really have much to add to the above except while reading the article, the dimples on a gold ball occurred to me and I'm glad it was brought up.
Been some fine reading on SN as of late.
I use the JK 3D dimples on my DS they are a small fin, find they have the Drive of a bigger fin but feeling like they have very low drag. I think they feel bigger as cavitation is reduced. Interestingly I don't like them in small waves on a wide tail board, they lack drive and feel too small. Quad set up.
Factory seconds thruster set FCS base Dimplefins are only $50
Yes SN you have been excelling yourselves lately and well done.
Interesting about the crinkles making a difference and a mate said why not other parts of a surfboard as in rails or along the bottom etc,so whales have nodules on their flukes and also grooves along their bellies similar to Phil Myers channels so maybe there's a lot to learn from looking at the worlds greatest ocean travellers.
I remember Bean shaping dimple bottom boards back in the 80'. Real pain to shape and glass not sure how they went.
Great article.
I have been experimenting with all sorts of different materials and surfing equipment since the 80's and fins are one of my favourite variables because of the diverse range of different forces that act upon and are acted upon by surfboard foils / fins. (Included though not limited to surfboard shapes, flex patterns) I have found that there is definitely a relationship between surfboard shapes, mass and the types of fins used and the types of waves surfed (even water temperature.) This is probably why there is such a diverse range of surfboard fins on the market now. I feel that with current technologies, fabrication, materials, data and knowledge, there has never been a more exciting time in surfing hardware development and the best is yet to come. Information sharing has enabled much of this. Of course, you can just grab a surfboard and go surfing because it's so much fun.
Great article Stu and more power to you Proffessor Marc in het Panhuis
Great article, great concept. For general interest they've been using a similar flow redirect like the 'crinkle cut' on fighter jets over the years to help with wing tip vortices. They go pretty fast so I'd say theory thoroughly tested... https://goo.gl/images/5Ff7sA
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What a waste of funding money. I am not sure how this falls in the scheme of Global Challenges Program. Seriously
It is an interesting question you raise nick3.
I am sure the good professor Marc is reading/watching this thread and would love to hear his response to that and several other questions that may emulate from such a response.
You out thereProf?
Need to take it easy here ljkarma. If he is publishing the results in a scientific journal, he can't publish them here or discuss them on the swellnet comments board. No journal worth its salt would publish if the detailed elements and findings of the study have already been released.
Last week, in fact the day before I posted this article, a press release was sent to my inbox trumpeting Surfing Australia’s National Shadow Squad enjoying a three day camp at Kelly Slater's wavepool. It was the second camp of its kind, the first happening last month. Each was in preparation for the Olympics which is still two years away - vis-a-vis there'll be many more such camps before Tokyo.
"This camp wouldn’t be possible without support received from the Australian Institute of Sport," stated the press release.
Should I leave that statement hanging there for the people who cry foul of funding waste?
Perhaps just a bit longer...?
Go ahead, read it again.
Yes, you people funded that trip, you funded the last one, you'll fund every trip to come, you'll fund the coach, you'll fund the physios, you'll fund the assistants, you'll fund the coming Oz wavepool (especially now that KSWC was knocked back free land), all of these moving parts, outrageously expensive moving parts, are so that Australia gets two - yes TWO - surfers in the Olympics to compete in four days of competition.
Against that, cry me a river that a researcher taps into some funding for themselves.
Fact is, what Marc is doing has the potential to benefit every single surfer and not just the lucky few who milk public funding with no accountability.
If it comes down to tax dollars being spent on building new hospitals or improving Sally Fitzgibbon’s air game it’s a pretty obvious answer though isn’t it ?
It’ll be Sally every time.
Not many terminally ill children can produce a fund raising smile like Miss Fitzgibbons.
Someone say tax dollars?
Come celebrate Surfing Australia's new $6.5 million Olympic Training Facility!
The gravy train starts here - Toot! Toot!
Im just lost for words :(
Would 6.5Mil build a wave pool? That I can see as a place where high performance can be observed, measured and improved.
Edit: there is a similar hi performance athlete venue proposed down this way, which was to include a wave pool. Residents have invoked NIMBY and it will be put up for approval without said pool.
Is that an open invite ?
Anyone keen to lend a hand in attempting to drink $6500000.00 worth of free piss at their opening do ?
Guaranteed it’ll be the only way any of us will ever see a return on that particular “investment “.
Looks like we missed the RSVP.
It's a "cordial" inviation but I'd be ordering something a hell of a lot stronger than that. Maybe a Moet shandy? Why not...
Also, the $6.5M is just the upgrade, the federal government has put in that much again to get it to this point.
That spending on the SA OTF is an outrageous waste of public money, and so are the visits to the wavepool. All they need is a shed on the north coast for their gear, food and lodging nearby and basic expenses. If the athletes don’t like it, they can give their spot up to someone else who will gladly go surfing any day it’s on rather than go to work.
That stuff on the UOW website is just the usual advertising tosh trying to attract funds or interest from the private sector for their projects. Their mistake was to ask a student or lecturer from the Business faculty Marketing stream to write it. However, their coining of the name of Crinkle Cut fins was probably a good move. Calling them Serrated fins might not have gone over so well.
Wasnt J Bay held immediately after the training session at the pool ?
I haven’t checked the results but I bet the athletes that attended the session dominated.....
Hard to know if it is Surfing Australia misleading the government by misrepresenting itself as being an inclusive body or just the usual mindless funding of elite sport. If the government wants to spend money on sport they should be doing it at the grass roots level because that's where the problems are. Surfing would be pretty low down on any reasonable list of priorities but if funds were available this would be about the worst possible use of them. One because it is unlikely to make any difference to the overall long term performance of our athletes and two because it is for the benefit of a tiny minority most of whom are doing very well thank you without any government support.
I thought I saw two brand new Mercedes Benz Utes drive by the other week emblazoned with Surfing Australia logos but figured I must have been mistaken...maybe not...
well the funding of SA is another different subject altogether and maybe worthy of an investigative story eh Stu?
Back to the good professor Marc, are you out there? Enjoying some crinkle cut chips and a glass of red in anticipation.
A few months back Sheepdog posted a comment about why competitive surfing in Australia is in decline. Something along the lines of the gentrification of the coast combined with the lack of hunger and this generation of spoonfed groms. I think he also mentioned that the decline of professional sport in general is inversely proportionate to the amount of funds invested in it or something like that. Look at the Oz swimmers in the last few olympics. Blaming everyone except themselves for their dismal performances despite practically swimming in cash.
Anyway, it was well writted and imo pretty spot on.
Back to the original issue of Crinkle Cut Surfboard Fins.
Question.... What sorts of speeds are required to bring the crinkle cuts into play providing significant effect on drive, lift, release, control etc.? I have spoken with an engineer who deals with fluid dynamics as it relates to the hulls and keels of racing yachts. She has considered dimples such as on golf balls and it seems that speeds of upwards from 28 kts are required before noticeable desired effect is achieved. The data is acquired from hydro-flow, tow and integral tank testing. One of the findings from these tests was that using ultra fine wet and dry sandpaper was the fastest surface over 28 kts. The method was to use long strokes with the sandpaper that are parallel to the majority of relative water flow that the surface will encounter. This was just a study limited to laminar water flows and did not quantify any deviation dynamics. I fully understand and will accept any reluctance to share for obvious reasons, though if anybody has anything to share the floor is yours.
Its interesting this push for measure and metrics. It was well accepted in the late 70s that wet sanded finish was the fastest surface. You can also see this supported by basic fluid dispersion theory. My point is that experiential research that the industry has relied on for decades is most certainly valid, just not documented and certified by academic process. I suspect that as this push for metrics advances it will confirm much of what good designers already know. Should also debunk a few myths of course too.
Isnt #320 wet rub the fasted finish..and 1200 is used only for cosmetic look ?
I think this fits in with some of the new approaches to aerodynamic shapes that Zipp are using for their bicycle racing wheels, they have been using dimple technology for a while, and now they are using sawtooth shapes. They are apparently modelled on the humpback whale's fins which are shaped with uneven surfaces and found to be very drag efficient.
Thanks for all the comments and questions. I am out there and reading them all. Enjoying them all, the supporting ones and the ones that criticise what we did. I will do my best to respond to each of them individually over the coming days or week. In the meantime, please feel free to come visit our labs in Wollongong and see what we do and how we do it. The labs are close to the surf in Wollongong. Drop me line on [email protected] or shoot me a text 0418294173 if you would like to visit us.
Marc
--
Professor Marc in het Panhuis FRSC
Soft Materials Group, School of Chemistry and Molecular Bioscience
ARC Centre of Excellence for Electromaterials Science
Australian Institute for Innovative Materials
University of Wollongong,
Wollongong, NSW 2522, Australia
E-mail: [email protected]
T: +61242213155 | M: +61418294173 | S: kiamasurfer
These look and sound really interesting. Are they available for purchase somewhere?
Hi N!ck,
Thanks for your interest. For the last 13 months I have been working on making the fins available for purchase. Hopefully they will be available later this year - subject to approval from my University.
Failing that, I will make the fin designs available for download in a format compatible with 3D printers.
Hi Marc,
Beauty, thanks. Will keep an eye out.
Hopefully the Uni gives it two thumbs up.
Good luck.