You’ll Be Thinking A Lot More About Fins After This
How did one type of rudder lead to 77% of CT event wins?
In 2024, one fin model was beneath the feet of a winning surfer throughout 7 out of 9 regular-season CT events.
Those events were Sunset Beach, Portugal, Bells, Margaret River, El Salvador, Brazil, and Fiji. That fin was the JJF Signature Techflex from Futures. The JJF fin also helped the man whose initials it bears win the 2024 World Title.
Another impressive stat? Nine out of the ten surfers who competed in this year’s WSL Finals ride Futures. Something is going on here.
In 1998, an aerospace engineer named Vince Longo made the curious decision to leave his field and start a surfboard fin company. Twenty-six years later, considering the stats above, it seems like Vince chose an appropriate name for his biz.
Fins are unique in board design in that they’re a variable you can isolate. Want to see how the same board would go with just a bit less exit rocker? Not happening, for the myriad reasons Jon Pyzel explained in the latest Stab In The Dark. Including: Foam is hand-poured and therefore vulnerable to inconsistencies, every stringer is different b/c wood, the temperature and humidity during the lamination process, etc etc.
You can, however, swap a set of fins and immediately feel it. You can unlock different personalities in a board, and even turn a plug into a electric foam missile.
Intro: fin (sorry). Now here are the highlights of my conversation with Vince.
Trends amongst team riders
Working with the surfers is key. They’re all in different phases of understanding fins, so it’s about supporting them in every continent and making sure they feel confident they have the right fin wherever they go.
Five or so years ago, it seemed like most tour surfers were choosing one fin they loved, and then they’d ride that fin in everything because they knew how it would feel. But it’s not about just having one magic fin anymore. These days, most of our surfers are switching fins for different conditions. They’ll go from a Techflex, which is a little stiffer for more powerful waves, to a softer fin like a Blackstix in conditions where they need to generate speed.
When they go to waves like Pipe or Teahupoo, they want to go smaller and stiffer. But when you move to somewhere like Bells, where it’s big but you still have to generate speed, they’ll go for a softer fin.
Jack Robinson and Jordy Smith both have two different versions of their fins — one stiffer and one softer. And John meticulously tries a bunch of different fins. He’s using different flexes for different conditions for sure.
The success of the JJF fin
That template is neutral, so it’s right in the middle as far as rake and pivot. It really works well with a lot of different rockers. Our Techflex construction resonates with a lot of the CT surfers because they have great technique and a lot of power. That fin is on the stiffer end of the spectrum, but it has a unique flex to it. When you put pressure on the tip, it actually folds over a bit because of the carbon and the way the layup is made.
We did a lot of back and forth with John on it. We done ’em a lot softer and stiffer, but we ended up at that flex. We can measure flex numbers by pushing the fin at a certain point and seeing how much it moves the tip. We started seeing the flex numbers we wanted, but they still weren’t feeling right, so we had to start taking pictures to see how exactly it was flexing and modify that until it felt right. Once we got there and released the fin, a lot of our team gravitated to it.
Variables and experimentation
When you think about a fin, there are seven different variables to consider: Placement, cant, toe, surface area, flex, foil, and outline. As a consumer, you really only have control over three of those variables: flex, outline, and foil. For the most part, placement, cant, and toe are already set by the board manufacturer.
Surface area is easy to understand. More surface area creates more drive, but if it’s too much, the board feels clunky and less responsive. Flex gives you that springy, lively feeling, but only when it’s in the right range.
You want to get more lift and drive out of less drag. If you can get more efficiency, you’re going to go faster.
Futures can produce fins that let our team explore different cant and placement by changing how and where the fins sits on the base. Three out of the top five guys have been doing that. We made fins that were set at a different position on the fin base so that they could take the same board and mess around with the cluster for the different wave sizes.
Dane was also super into exploring cant. Six and a half degrees is the typical standard for all thrusters, but we would go all the way up to eight degrees. Once you start moving that cant out, it rolls over to rail to rail a lot easier. You could actually do proper bottom turns when you’re not at the bottom of the wave. But like anything else in design, if you make one change for a positive in one direction, you’ll lose something somewhere else. When you push the cant out, you lose a bit of that forward projection in that bottom turn. For a specific style of surfing or a specific wave where you’re going top to bottom, it works out really good. But if you’re going to want to project down the line and make it around sections, the six and a half degree is probably better.
The physics of fins
The purpose of a fin is to separate the water and create a pressure difference — a high pressure on one side and a low pressure on the other. When you’re driving through a turn, the high pressure pushes your rail into the water and helps you hold the board steady.
Flex is probably the most important aspect of a fin. The more a fin flexes, the more it loads that high pressure up. A flexible fin is going to give you more spring, and it’s going to feel really lively — flippy and whippy are pretty good words to use for it, too. And that’s when you’re pushing on it and loading up that pressure, you’re generating speed.
You want there to be resonance, too. You don’t want it to be soft and dead. You want it to be soft and lively. And if it’s too soft, it doesn’t work — you try to push on it, and it just folds under you. Conversely, if the fin is too stiff, you push on it and it doesn’t have any give.
When you’re dropping into a bigger wave — let’s say double overhead — you’re already flying. When you get to that bottom and load up the turn, you want to feel real secure, like you’re held in the water really well. So that’s when you’d want stiffer fins.
When you’re pumping down the line on a less powerful wave, you’re loading the board up, and you want it to come back quick. We engineer the flex to spring back quickly, but with just the right amount of give. You want the board to come back underneath your feet super quick. We engineer the flex so it springs back really quick.
Efficiency between lift and drag
The real driver on the lift is the fin’s foil shape. You want to get more lift out of less drag. If you can get more efficiency, you’re going to go faster. The foil has to be right to do that. When we started working with computational fluid dynamics, we saw somewhere between a 10-15% difference in efficiency between templates. When we started looking at foils, we saw as much as 30% difference.
It’s about getting more bang for your buck, more lift out of less drag. When you get it right, good surfers can feel it.
The enduring popularity of the thruster, and why quads feel fast
The thruster has been hanging in there for a long time. It works because it gives you control, drive, and responsiveness, especially when you’re in the pocket. Right now, I don’t see anything outperforming the thruster. The best designs are often the most simple, and they’re the hardest to improve upon. We’re experimenting with different configurations, but they’ve got to work better to replace the thruster, and I haven’t seen that yet.
When you ride a quad, it looks like there’s going to be more surface area but it’s not that much. Usually it’s only about five square inches, so it doesn’t create much more drag.
There’s something about the drag of the center fin. Once you take it away and move the fins away from the center, you change how the board is moving through the water. When you’re on rail, you have less fin in the water.
Riding a quad, especially with smaller side fins, makes it feel faster because there’s less resistance through the water.
How to experiment
Our thruster line is divided into three categories: pivot, neutral, and rake. This is part of the legacy series, built with RTM construction, offering a medium flex suitable for most conditions. You start with the legacy series and then choose between pivot, neutral, or rake, depending on what works for you.
If you’re riding one board, you can fine-tune the fin by considering your size — let’s say you’re 160 pounds, so you’d pick a medium fin. You’d try templates like R6, F6, or P6 to see which suits you best. Once you’ve found what works — let’s say the neutral template — my advice is to buy both a neutral blackstick and a neutral techflex. That’ll really give you a sense for how much flex matters.
And that’s just a starting point. There’s a lot of variation based on someone’s weight and skill. Someone might weigh 165 pounds with strong legs and like the feeling of larger fins. If the waves are big, I sometimes use flexible fins. For example, in Hawaii or Indonesia, if there’s a strong current, I’ll use a bigger board but still want performance. I’ll use black sticks, typically meant for smaller waves, to make a gun more responsive in less-than-ideal conditions.
