Torsion control on foils

I was wondering if torsion control has ever been used on foils, and if it could be an interesting idea. The goal is not really to talk about the feasibility, but just the concept.

What I mean is being able to control separately the angle of incidence (not sure if it’s the correct word) of the front wing and the stabilizer. Think of it as leaning on the front wing while the stab is kept still.

I have felt that in skateboards, a skateboard feels “surfier” when carving a big bowl if the board is not completely rigid and has some torsional flex. I really liked that feeling. In foiling it would require two separate masts, akin to skateboard trucks.

there is a thread for good ideas like this

I think likely at some stage. Snowboards, skis, skateboards, surfboards, bicycles all have highly engineered flex patterns in carbon.

I think at this stage it seems unlikely the mast will be the point of flex.

Loading and releasing through carves as the most obvious value of flex, like a surfboard or carve skateboard.

The other use is dampening of rough conditions, like a carbon bicycle front fork

Much more likely that the foil itself will incorporate some give to enable this. Somehow I don’t think the gear is mature enough to find much value in engineered flex

I think the pivot point have to be at the fuselage. I built a board with no carbon reinforcement at the foil box. It was super flexy at the box where it seems to have a delay input and I can only ride it less than a sec before it get super wobbly. I end up putting carbon to reinforce the box area.
I still think as stiff as possible is best for foiling and precise foil control. I don’t see the need for damping as the foil is inside the water unlike surfboard or other crafts that ride on the imperfect surface.
But it will be interesting to see adding flex to the foil tip or anywhere on the front foil might create similar flex. I think KT stab use g10 and he said most testers preferred over it than carbon.

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Development:
The journey started with the extreme flexy stab experiment. First expectations were for it to be unrideable, but instead it delivered surprisingly smooth surfing! That led to the exploration of purposeful flex as a contributor to carving with feels similar to snowboarding in powder. Countless hours were dedicated to exploring airfoil sections and planforms to deliver the best possible mix of performance across the speed range whilst maintaining stability and hard carving grip.
CRISP on Instagram: "Introducing the Crisp Flex 130 stabiliser Specs: Area = 130cm2 Span = 325mm Aspect Ratio = 8.13 Design Intent: Big smiles! The Jan 2025 survey gave some great insights into who, what, where and how you were all foiling. It was clear there was a need for a stabiliser which delivers glide/pump efficiency, speed and carving to intermediate/advanced foilers seeking maximum fun. Development: The journey started with the extreme flexy stab experiment. First expectations were for it to be unrideable, but instead it delivered surprisingly smooth surfing! That led to the exploration of purposeful flex as a contributor to carving with feels similar to snowboarding in powder. Countless hours were dedicated to exploring airfoil sections and planforms to deliver the best possible mix of performance across the speed range whilst maintaining stability and hard carving grip. Then came the prototypes and crash test dummies (thanks team!) Characteristics: Riding this stab always results in a big grin. Feedback from a variety of riders in various foiling disciplines has been overwhelmingly positive. It's most at home downwinding and prone foiling, but it's also proven to be a lot of fun for winging and flat water. It punches above its weight in low end, feels effortless at average speeds and holds its own when moving quickly. The magic happens when carving as the tip flex irons out any unsettling bumps and allows dynamic adjustment through the turn. The first batch will be a limited release. Register your interest via the Pre-Order Form from the link in my Bio and you will be contacted with more details. . . . . . . . . . #foilsurfing #foilsurf #winging #pronefoil #wingfoil #wingfoiling #loyaltothefoil #supfoil #hydrofoil #foilhub #foilfeed #foiltheworld #foiling #foilfroth #foilingmagazine #downwind #downwindfoil #downwindfoiling##"

The foil tip being slightly flexible will for sure be something worth looking into. There are surf fins specially designed with that in mind ( https://www.s-wings.surf/en/produit/twin-520-verte/ ), don’t know how they feel though.

But what I was talking about was being able to control the angle of turn of the front wing and the stab with some independence. Which would probably require them to be on separate masts. Think of it as something like a waveboard ( https://www.decathlon.co.uk/p/beginner-waveboard-100-stickers/_/R-p-354613 )

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I like the concept. I feel like you’d need some dampening and self-centring to reduce the pressure on each foot.

I imagine you’d get to roughly the same point as a surf skate in the end, a relatively unstable novelty toy, but the engineering challenge would be interesting.

That is the torsion part. Instead of having two pieces with a hinge, it would be a single board that could bend longitudinally, having an strong equilibrium point in the middle, with an increasing return force as you bend it more.

Really felt a different ride when I carved a bowl with a skateboard deck with “longitudinal stripes” that made it have more torsional flex than a usual popsicle.

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Lift had a fuse/tail where the fuse section was super thin solid carbon and I think was designed for a ton of flex. Never caught on

sounds cool, you’d need straps I guess