Stab Magazine | Leaked Internal Documents Reveal FCS H-Series' Top-Down Performance Influence

Leaked Internal Documents Reveal FCS H-Series’ Top-Down Performance Influence

“…we can tap into the minutiae of fin performance and how the elements can be adjusted to a level that will benefit all.”

Words by stab

There’s been much speculation following FCS’ release of their newest H-Series fin. 

With surf shops shuttering, it’s been hard for surfers to put their paws, personally, on the handsomely blacked-out, curiously-tipped, injection-molded, unidirectional carbon fibre thrusters. We’ve been doing some digging, trying to get the story behind what are at first glance the most hi-tech rudders on the market. Impossibly light, with a slick matte finish that’s almost cold to the touch, first impressions here at the Stab offices have been aligned with the design’s intent: a thruster set focused on top-end speed with total control and freedom. (Of course, this has come from our stubbornly progressive, ripping Japanese-Australian designer with a penchant for precision equipment across all disciplines.)

FCS and Futures remain the most universally ridden fin systems on the planet, by tremendous margins, and we’re always thoroughly curious when they roll out radically divergent offerings. While trying to get their fin engineers on the horn to answer some questions, a leaked document landed in Stab’s inbox, with FCS’ detailed internal memo around all the specifics behind the fins. 

Here’s what we found most profound:

The H4’s brilliance rests in the delicate and balance between the thoroughly engineered ménage à trois of template, foil, and Swiss construction with the precision in each fin modern robotics offers. 

“Made in Switzerland, a country known for high-precision manufacturing, the H4 combines premium materials and robotics for a fully-automated production process. This allows for the creation of identical fins—perfect geometry, precise flex, every time. This is very different from other premium fins on the market which are all hand finished.”

The secret is in the “traditional side fin templates and elliptical centre shapes.”

“In the early stages of development with Fanning, we were testing thruster sets with the same template on all fins, then we started swapping out centre fins that had small template deviations but as the day went on, we got more experimental with matching vastly different template shapes together.”


“We recognised at one point there was a combination of traditional side fin templates and elliptical centre shapes that brought out the best aspects in each template. We found maximum drive and controlled release with this unusual combination.

The H4 centre fin acts as the primary stabiliser of the set and it’s designed with a heap of rake which increases the set stability. 

Usually the stability comes at a cost of reduced manoeuvrability, we’ve taken some area out of the centre fin and massaged the geometry forwards at the base of the template finding the sweet spot between stability and manoeuvrability.”

On The Value Of “Turbulent Waterflow” And The H-Series’ Cute Little Beaked Tip

Aside from the center fins polarizing template, the most unique part of the new H-Series’ anatomy is its curiously beaked tips, and the subtle little channel that runs along the inside foil int the tab. 

The beak is designed to create turbulent water flow, which aids in releasing the fins in a slide. This offsets the large tip area by enabling the fins to be ‘broken free’ from laminar flow, into turbulent flow.

“The foil under the fin’s tip is a function of keeping the foil true through the entirety of the fin, to keep the fin working as efficiently as possible at all times. This has come about because we haven’t applied the smoothing we would normally use in CAD modeling our fins, this is a raw and pure foil.

Our resident aerodynamicist has shown us that the geometry near the tip is creating a double vortex or turbulent water at high angles of attack which wrap over the rail of the surfboard and help to create some looseness that wouldn’t be there otherwise.

“First of all these foils are the lowest drag foils we have made – compared to our most commonly used foil, used in the Accelerator, they are slightly sharper on the leading 20% of the foil and the thickest point of the foil is pushed back toward the centre of the chord.” 

“These foils were designed to break laminar flow earlier than the Accelerator foils but do so more gradually giving the surfer more reaction time. This early warning means the rider has more freedom to adjust the pressure on the board if necessary, the idea is that the surfer feels more in control.)”

On The Myriad Performance And Sustainable Production Benefits Of Mold-Injected Carbon

The precision feel of the H-Series lends much of its genius to Swiss Engineering, and the quality control modern robotics and digital imaging offers. 

“H4 is made with a proprietary process that intersects the world of injection moulding and carbon composite manufacturing. The production process is fully automated. It starts out with laser cutting UD carbon tape. This is then picked up by a robotic arm and with high precision. It’s placed inside the injection moulding machine. As the mould closes the glass-filled resin is injected and the materials are fused under high pressure.” 

“When the mould opens, the robot carries the fin to the finishing stations where a number of robots trim, polish and prepare the fin for printing. Throughout each stage of the production, the fins are quality controlled by several digital cameras, ensuring an extremely high level of accuracy and quality.”

“The weight is similar to PC construction, the Large set weighs about 230 grams.”

Of our performance fins these have the lowest wastage in manufacture and are made from the most ecofriendly composite materials we use. The production energy is generated from solar power. And they have a very low manufacturing reject rate of under 1%.”


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