Sébastien Guého : “All the parts we design are in motion”

Based in Lorient, in the heart of Brittany’s Sailing Valley, GSea Design is a leader in composite structure engineering. Led by Sébastien Guého, the company puts its expertise to work in ocean racing and various industrial projects. Between academic research, in-house software and iconic projects such as Neoline and the Ultims, GSea Design perfectly illustrates Breton innovation in competitive sailing, focused on performance and the future.

Can you introduce yourself ?

I am Sébastien Guého, director of GSea Design since 2022. Before that, I was a partner with Denis Gléhen, founder and director of the company from 2010 to 2022. I trained as an engineer and started out at HDS, a company based in Brest, where Denis also worked. In 2015, we merged our structures and since then I have been leading the transformation of GSea Design. The company has grown from 8 racing boat enthusiasts to 25 employees and our activities now extend beyond ocean racing to include industrial projects.

What are Gsea Design’s main activities?

We are an engineering firm specialising in structural analysis. This means that we do design and dimensioning, but also software development, because we need powerful tools to carry out our calculations. We also do research: we are now on our fourth thesis in fifteen years, which is quite a high frequency. The subjects initially focused on materials and their mechanical behaviour, then vibrations, and now the analysis of embedded data in the nautical and maritime sectors. What is becoming increasingly important is the use of this data to understand the actual behaviour of parts in service, correlate our digital models and be able to better predict their performance and lifespan.

What materials do you work with?

Our core business is carbon structures, known as performance composites. In recent years, we have also explored the issue of eco-design. But to design effectively, you first need to understand the actual loads that the parts are subjected to. This is fairly simple in the automotive industry, but much more complex for certain nautical parts. That is why we have launched a thesis on the analysis of embedded data, in order to better understand what structures experience in real-world use. All the parts we design are in motion; this accounts for 99% of our business. We do not make street furniture, but parts that are subject to dynamic stresses. Weight reduction is always expected, structures are increasingly stressed, and expectations in terms of lightness, durability and safety are growing. This means working on high-performance composite structures, with large volumes of calculations, detailed knowledge of materials and a precise understanding of the environment in which these parts operate.

Can you name a few iconic projects you have worked on?

For example, we designed the rigid sails for the Neoliner Origine sailing cargo ship, developed in collaboration with Chantiers de l’Atlantique. This project began in 2013 and involved several rounds of research with universities to refine our hypotheses. Another example in maritime transport by sail: Gsea Design was asked to cross-check the structural calculations for two 52-metre-high masts for the Vela cargo sailing ships, a project led by François Gabart, among others. In ocean racing, we are working on Ultim boats such as Banque Populaire XI, Sodebo Ultim 3 and SVR-Lazartigue, for which we designed all the parts (foils, masts, arms, platforms, etc.). We also equip the Imoca class with standardised parts (masts, keels, booms), used on all Vendée Globe boats. All these parts are the result of our work on materials, behaviour analysis and data to improve each part from one generation to the next. We have also participated in projects such as IMOCA Paprec Arkea and TR Racing.

What avenues for diversification are you exploring beyond ocean racing?

We have a strong maritime culture, as 95% of our projects involve seawater. Offshore racing and recreational boating account for around 65% of our business, with the rest relating to what we call the maritime industry, including maritime transport and collaborations with major groups such as Naval Group and Thales. For us, diversification means anything that goes beyond sailing in the strict sense of the word. There are some very interesting avenues being explored in the field of drones. The issues are exactly the same as in sailing: the weight on board, the fact that the lighter it is, the less fuel it consumes and the further it can go. These drones can be used for scientific purposes, but also for space applications, with projects aimed at reducing the cost of satellite launches, and of course for defence applications, on which we are already working with certain players. And then in sailing, beyond racing, there are also production shipyards, such as Lagoon and Fountaine Pajot, with whom we collaborate on cruising boats. We also work on unique projects, or ‘one-offs’, such as large catamarans. Finally, there are masts: this is an area we know particularly well and where we are involved in cruising, racing and also sailing cargo ships. It is a specific component, but one that remains at the heart of our expertise.