Wing Commander: Cyril Coste

 Cyril Coste's name is deeply woven into the story of foil innovation since its recent popular emergence. Now, as Duotone Division Manager and a key player in the development of their new and uniquely innovative Assist system, he opens a new chapter in both his own story, and that of foiling itself…

Photos BEN THOUARD & THOMAS BEVILACQUA

Cyril, let’s start right at the beginning – what first drew you into water sports, and how did that then evolve into a design career within the industry?

I grew up in the north of France, close to the sea, and was naturally drawn to wind and water from a very young age. My family was passionate about sailing, and I quickly discovered windsurfing, then kitesurfing when it first emerged – which immediately hooked me in.

By the time I was 15, I was competing professionally on the kite world tour, which gave me the opportunity to travel, meet people, and test gear in all kinds of conditions. I’ve always been curious and hands-on with gear, and even during my athlete years, I was constantly adjusting and modifying my equipment to make it more suitable for my riding style. That curiosity gradually grew into a true passion for design and innovation.

Eventually, this led me into R&D roles, starting with Naish in Maui, and later launching my own projects and brands. I never really planned to work in product development – it was simply a natural evolution from riding, testing, and wanting to improve gear for myself and others.

© Ben Thouard :

You’ve launched some pretty major innovations in previous roles – so was there an itch you were trying to scratch when you came up with the Duotone Foil Assist concept?!

Yes, definitely. We had been working on this project for quite some time already, as we really wanted the freedom to catch waves further out, ride smaller foils, and explore spots with 100% independence, whether it’s for wave riding or downwind runs, in the simplest and safest way possible.

So yes, it really came from a personal “itch,” as you say – a desire to spend more time on the water, with minimal logistics, and to make sure every session is fun, even in conditions where traditional foiling can be a bit frustrating or limited.

The battery-in-harness design is a big shift from most assist and eFoil systemson the market currently. What led you to this design, and how different is the riding experience?

Yes, it’s definitely a big shift – and honestly, a complete game changer when it comes to the foil riding feeling. We tested many configurations, but having the battery on the board or mast never felt quite right. It always took away from the pure foil feeling. Placing the battery in a waist harness changed everything – it keeps the setup extremely light underfoot, preserves perfect balance, and allows you to foil as naturally as possible while enjoying the benefits of assistance only when you need it.

100% of the riders who tested it agreed – it just feels right. Even if using a harness might seem unfamiliar for some prone foilers at first, you forget about it almost instantly. It’s all upside, with no compromises.

What were the biggest challenges in developing an assist system that still preserves that “pure” feel of foiling?

There were quite a few challenges in developing an assist system – but if we focus specifically on preserving the pure feeling of foiling, I’d say the three biggest were: managing weight, avoiding drag, and keeping full freedom of movement.

We addressed the weight issue by placing the battery in the harness – this removes most of the mass from the board and keeps the setup light and perfectly balanced under your feet.

To reduce drag, we fully integrated the motor and pod into the mast. On the D/LAB version, it’s completely molded into the carbon mast, and on the alloy version, fully built in. A clean leading edge was essential – during testing, we saw massive differences when the front of the mast was free. It drastically improved touchdown performance and overall glide. You actually forget there’s a motor on the mast.

Finally, keeping the rider’s hands free was critical. Instead of a bulky remote, we developed a minimalist control system that doesn’t interfere with your riding style – preserving that natural foil sensation.

© Ben Thouard :

It’s an impressively modular system. Was that a priority from the beginning?

I wouldn’t say it was a priority from day one, but we definitely knew we wanted a system that was easy to maintain – where every part could be replaced without technical skills, using just a few tools and screws.

As the project evolved and we started thinking more broadly about the product line, it became clear that modularity was key. We wanted users to be able to progress and adapt their setup – whether switching from an Assist to a Cruise configuration, or upgrading individual components – without having to buy an entirely new system. 

Talk us through the testing process – usually we get a little heads up on new tech as we have eyes and ears everywhere, but this one escaped us! So where did you and the team trial the system, and were there any big fist pump moments?!

We’ve been doing most of our R&D and testing in Taiwan and Japan. We’re lucky to have access to incredible spots with all kinds of conditions – waves, downwind, flatwater –but the best part is that they’re totally empty and far from the eyes of others.

Of course, we went through so many different phases – plenty of frustrations along the way! But also a few really big fist-pump moments. One that really stands out was when we finally found the right setup to foil with a 700cm² front wing and keep consistent power throughout the session on a regular prone board. At that point, we already had the battery-in-harness setup, but finally reaching the torque we were aiming for – and scoring a solid wave day without the need for a jet ski – was just incredible. That session is still one of my favorites!

How did your collaboration with Duotone’s wider R&D team shape the final product?

Our main R&D for the Assist takes place in Japan and Taiwan, with Homare Imai playing a key role in its development. The Duotone R&D team in Munich brought an additional layer of expertise to the project.

We work as one unified team – not separated – and collaborated closely with the foil department to design the best alloy mast profile specifically for the Assist. We also ensured that our D/LAB Assist mast meets the same high standards as the existing D/LAB masts. The Munich team provided valuable input on the complete setup, helping us refine every detail of the product.

Being part of the Duotone team is incredibly exciting. I can confidently say Duotone have one of the most dedicated and forward-thinking R&D teams in the industry – always pushing hard in terms of innovation and performance. Thanks to this truly collaborative effort, we were able to bring the Assist to the highest level.

The Watch Ring Remote is a cool touch. Why was “hands-free control” so important to the design?

Hands-free control was a key part of the design from the very beginning. After years of riding with eFoils – and even more so with eTow – we always found it frustrating to have a big remote in hand. It really limits your movement. Not being able to fully open your hand blocks your turns and just doesn’t feel natural or comfortable.

The ring-style remote changes everything. It frees up your hands so you can paddle, carry a wing, duck dive, or simply grab your board without compromise. It also makes take-offs easier, as you can use both hands to push up. 

All of these elements combined make our remote a real step forward compared to standard remotes. It's a small change that makes a huge difference in riding experience.

We saw Matahi on this system in Japan in our last issue, and there are more shots of him riding here. What’s been the early feedback from riders like Matahi? 

Yes, we actually have a lot more footage of Matahi using the Assist – not only in Japan, but also in Tahiti, where he’s been catching some serious waves.

Getting his feedback was super valuable. Matahi rides at such a high level with such a pure, committed style, so honestly, I wasn’t sure what his reaction would be. But from the very first session, he got hooked. He immediately saw the potential of using the Assist – not just for ease, but for extending his range and making the most out of every session. He’s been using it a lot lately in Tahiti to chase all kinds of swells, and we’ve got some really exciting footage coming soon. Watching him go full send with it, especially on big days, was not only impressive, but also a great validation of the system’s performance in real conditions.

What aspect of the design would you say you’re personally most proud of?

I'm not personally proud of any one feature in particular, but I’m honestly just super stoked about how the whole system came together. It’s by far the best product I’ve ever been involved with in R&D – and the one I use the most myself! It’s been a true team effort from start to finish, and that collaboration is what really brought the Duotone Assist to this level.

It’s clear from your career history that you've always chased innovation. Foiling has moved pretty fast in that respect… is it tough staying one step ahead of the curve?! And where do you see the biggest growth area for foiling currently?

Foil design has evolved a lot – and fast. In the early days, it wasn’t really about innovation, but more about responding to a growing sport and the need to make it more accessible and fun. Today, things have shifted. There are full teams focused on every aspect of design, and that pushes both performance and usability to another level. I’ve seen that firsthand at Duotone recently, and there are some really exciting things coming.

As for innovation in foil disciplines, I’ve never chased “innovation” for the sake of it. For me, it’s always been about creating product that fits the way I want to ride – things that let us have more fun, ride longer, or push our performance. Right now, I think parawing and assist are the biggest drivers of change. Assist especially opens and will open new doors for so many riders, and I truly believe it will help shape the future of foiling.

Seems like you're always a pretty busy guy in the years we’ve known you. Do you get much time in the water yourself? 

Yes, I’ve definitely been busy over the past few years… but I always find time to get on the water, no matter where I am. It’s just part of my rhythm – being out there keeps me grounded and inspired.

When it comes to R&D, even if you’re working with the best engineers and designers, the only real way to push a product to completion is by riding it in all kinds of conditions. Being on the water has driven my life since I was a kid, and I think that’s what’s allowed me to keep working in a field I’m truly passionate about.

And finally Cyril, what’s coming up next from you? Any spin-offs from the Foil Assist system already in the works?!

At the moment, we're fully focused on finalizing the production of the complete Assist range – including both the boards and the Assist sets – ahead of the official launch this fall. But with R&D, the work never really stops. We're constantly testing, refining, and exploring new ideas with the team. That’s the most exciting part of product development – there’s always something new around the corner!