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.
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.
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.