I argued for flex. I actually said, out loud, that a little flex in the mast was a good thing. That it made the ride feel more forgiving. That it gave the foil a nice, lively response.
I was wrong. And the embarrassing part? I didn't even know it until I rode without it.
That's the insidious thing about mast flex. It doesn't hurt you in any obvious way. It doesn't throw you off the foil. It doesn't announce itself. It just quietly taxes every single input you make — and you adapt around it without realizing it. You call your compensations "style." You think you're learning. You might even be getting better. But there's a ceiling you keep bumping into that you can't explain.
The Delay You Can't Feel Until It's Gone
Here's the best way I can describe what mast flex actually does: imagine every input you make on the foil has a 200-300 millisecond lag attached to it. You load the front foot, the mast bends, stores that energy, then releases it back at you on its own schedule. You didn't ask for that. It just happens. And over time your nervous system starts to predict it, work around it, even lean into it.
It's like driving a car with a loose steering column your whole life. You'd adjust. You'd get good at it, even. But the second you got into a car with tight, direct steering, you'd realize you'd been fighting the whole time.
One rider I spoke with described the exact moment this clicked for him. He'd been on a standard aluminium mast for years. Switched to high-mod carbon. Went back to the aluminium — and felt like the thing was alive beneath him in a way he'd never noticed. "I thought I liked flex," he said. "Now I hate it. I go to such lengths to get it out of the system."
That's the journey. And most people never make the comparison, so they never have the realization.
Where It Hurts Most
Flex shows up differently depending on what you're doing. In surf, it muddies your lines. You think you're drawing a clean arc — but there's noise in the system, little micro-corrections firing between you and the foil, and when you watch the footage back you can see it. The turn is good but it's not as clean as it felt.
In downwind pumping, it's even more costly. Every pump cycle that goes into bending the mast is energy that didn't go into lift. It's like pumping a bicycle tyre with a slow leak. You're working. You're just not getting the return you should be.
And on bigger boards — foil drive setups, downwind boards, anything with real volume — the problem compounds. The leverage a thick board puts on the mast is significant. Wider foils feel it more. You'll notice it as a kind of lateral instability, a subtle swim, like the foil never quite settles. That feeling isn't the foil. It's the mast.
The Hard Part Is You Won't Know Until You Know
This is why I want to talk about it. Because I had good riders around me for a long time and nobody flagged this. You just kind of accept whatever baseline you started with.
If you can, borrow a stiffer mast. Ride it back to back with your current setup in the same session. Pay attention not just to how it feels, but to what your hands and feet are doing. Are you constantly making micro-adjustments? Is there a moment of delay between your input and the foil's response? Are you working harder than you think you should be for the speed you're at?
Stiffness doesn't make foiling boring. It makes it honest. You stop playing chess with the equipment and start actually surfing. And once you've felt that, trust me — there's no going back.
"I didn't know what flex was, so I was just compensating for it in my riding style. It's only once I got the high modulus that I went back and was like — oh, whoa. This thing's moving like it shouldn't be moving."