The science of flex with Professor Marc in het Panhuis
How much do you know about surfboard design? Like, really understand why your surfboard does what it does?
If you’re like me, board design can be a fog of emotion and spin. On the one hand, there are people whose design explanations are a songline of feelings and impressions, artistic yet imprecise, and then there are those prepossessed to marketing, who tell the customer only what they want to hear. Close the sale and caveat emptor, OK?
Which isn’t to say there aren’t some people who know why certain features work, but it’s a recognition that design progression has been an inexact science. Most of us stumble along in the dark, perhaps making the occasional discovery but we’re largely ignorant of the physics.
This state of affairs provides fertile ground for Professor Marc in het Panhuis of the University of Wollongong. “Just call me Marc,” says the good professor when I meet him, though with 170 published papers, 4 patents, and a doctorate in Physics his academic title has been well-earned.
Originally from the Netherlands, Marc started surfing twelve years ago. “My wife got me into it. She bought a board and I thought, well, since we have a board I’ll try surfing.” A dozen years later he’s still fizzing with beginner’s zeal, he surfs everyday, presides over the local boardriders club, and he’s focussing his intense curiosity on the mysteries of surfboard design.
I meet Marc at the University of Wollongong’s Innovation Campus. It’s a modern building, all glass and polished metal. Quiet too. Studious people walk the hallways. Yet his office more closely resembles a teenage rumpus room with surfboards and fins strewn about the place. Marc explains that some of the boards are his, yet most of them, there were fourteen in the cubicle, were part of a recent experiment concerning fin design. That story will appear on Swellnet next week.
Given a choice he’d completely deconstruct a surfboard and test every aspect of it. “There’s just so much I don’t understand,” says Marc. But for now he’s finding the overlaps with his academic skill set, namely materials science, and this has brought him to question flex in surfboards.
Marc recalls speaking to a shaper about a new board and being asked if he wanted carbon strips in the tail. “What do they do?” asked Marc. “Oh well, they….help,” the shaper replied meekly. No doubt the shaper was discovering, as I now was, that Professor Marc asks a lot of questions.
“When shapers talk about flex, what do they mean? Where is the board flexing? Through what plane? What is good flex and what is bad flex? It is all shrouded in mystery,” concludes Marc. However, it's a mystery he intends to solve.
We walk out of his office and upstairs to the second level of the building where he hands me a set of safety glasses, and then we open a swing door and enter a white-walled lab. Inside it’s busy, the bench tops are crammed with machines and equipment of indeterminate nature - I can’t name then, couldn’t even say what they’re used for. Yet in the corner is a form I recognise, a shaped foam blank, but it’s sitting inside another machine I can’t identify. “It has no name,” says Marc of the apparatus, “I had to get it custom built especially for this purpose.”
Pensive expression fixed, Professor Marc peers deep into the mysteries of flex (Paul Jones)
The Flex Machine - I think I just named it - is effectively two sets of pads that can grip a board at various positions along its length. The rear set can also twist the board. All of it is built upon a solid metal base, its heft belies how precise the construction is. After all, it’s required to measure in microscopic increments.
To demonstrate, Marc simply presses the nose down and lets go. The blank shudders like a bow then falls still again. “When I’m testing, I place sensors on the board at regular intervals and I apply standard engineering equations to work out what the spring constant is. The higher the number, the faster, or less flex there is in the board.”
The machine is only new and without a body of work to draw upon Marc’s experiments are beginning on the ground floor. He’s testing anything he can to begin filling in the blank spots: good boards, bad boards, boards with a standard stringer, even boards with those carbon strips that help.
But none of it means a thing unless he also includes some field research - otherwise known as surfing. “I’m going to test a brand new board,” says Marc outlining one planned experiment, “then give it to a surfer and tell them to surf it ten times, bring it back and then I’ll test it again.”
“Who knows,” says Marc with a shrug, “Maybe there’s a use by date on boards: good for 300 surfs.” It’ll be just one of many experiments he conducts on the Flex Machine.
The accepted wisdom is that old boards 'die' because water seeps in through microscopic cracks in the laminate and adversely effect the foam. Is this the premise he's working on? "Nothing is assumed," says Marc, "The answers will come from the testing."
And it’s not just standard materials like PU foam and polyester resin that interest him. Marc gets particularly animated when he mentions a new family of materials recently developed by NASA. “Auxetic materials are new, their structure is such that they get stiffer as you flex them,” explains Marc.
When you stretch auxetic foam it gets thicker, not thinner. The more force you put on the material the stiffer it becomes. It also, at least theoretically, can never break. Auxetic polyurethane foam has already been manufactured and it has the potential to shake up surfboard construction.
Auxetic polyester foam gets thicker when strain is applied
There are many shapers currently working to harness flex and if they thought auxetic foam was impressive, Marc has something to top even that.
Most flex tail surfboards are built by joining two materials of differing properties, usually carbon fibre affixed to fibreglass. However, with his background in materials science Marc sees a better way of achieving the same result. Gradient materials are substances that start as one material and then continuously transition to become another.
“For example,” says Marc, “we’ve made materials that go from soft and squishy, like a gel you put in your hair, up to hard plastic.” There are myriad applications for such materials from industrial uses to prosthetics, great advances for humanity, but it’s surfboards we're talking about now. A stringer built from gradient material could be rigid at the nose and gradually become more flexible towards the tail leaving no stress points along its length.
While gradient materials and auxetic foams currently exist, it may be a while before they can be applied to surfboards. For now, Professor Marc is working with what we have, foam boards laminated with polyester or epoxy resins, and there's enough mystery and enough confusion to keep an eager scientist like Marc occupied for a long while yet.
I bid Marc farewell, but not before pulling a flex tail board from the back of my car for him to test. He eagerly puts it under his arm, rubs his hand over the smooth carbon tail, smiles broadly, then heads back inside to the laboratory.