Our design to break the World Sailing Speed Record

January 10, 2022

Breaking the world sailing speed record: easier said than done. Since 2012, no one got faster than the Australian Paul Larsen onboard Vestas Sailrocket 2, that is 65.45 knots (i.e. 121 km/h).
Breaking his record is already a fabulous challenge, and we have set the even more ambitious goal of being the first to sail at 80 knots (about 150 km/h)! To achieve this, our team had to innovate and rethink the codes of naval architecture. This new year is an opportunity to recall the main concepts behind our extraordinary boat.

Why do we use a kite to tow the boat? 

To reach 80 knots and pulverize the current record, we need huge power. If we followed the traditional codes of sailing, we would require gigantic sails and therefore a boat of enormous size and mass to support such a rig.

With this in mind, our three co-founders quickly turned to the great potential of kites. Indeed, kitesurfers can reach incredible speeds (more than 57 knots / 105 km/h)! To go even faster, the limiting factor is not the kite itself  but the human being who has to support the kite’s power! Our pilot Benoît, kitesurfer since his childhood, knows this well as he often sped at over 45 knots (83 km/h).

This is how the idea of replacing the kiteboard with a boat that would act as the middleman between the kite and the water took shape. The boat would support all the forces induced by the kite and could thus reach phenomenal speeds without putting the pilot at risk. Compared with a traditional sailboat, pulling our little rocket with a kite also gives us a great benefit: it allows us to modulate the surface and the shape of the kite according to the wind conditions encountered on the record day!

What about the take-off and landing? On record day, our pilot will be helped by boats and external systems. This is essential to handle a huge kite in windy conditions! 

 

SP80 EXPLAINED IN VIDEO

How do we keep our boat stable?

At 150 km/h, stability is key so that our pilot can accelerate safely until 80 knots. Our team therefore focused on this essential criteria when designing the global architecture of the boat: its three floats ensure a constant balance, whether it is at standstill, during the record attempts, but also and above all during the transition phases of acceleration and deceleration. 

However, the floats by themselves are not enough to prevent the boat from flipping over at high speeds.

That’s why our boat is also designed to ensure a constant force alignment, a concept that Paul Larsen already used in 2012.

Thanks to a complex mechanical system developed by the team, the opposing forces of the kite & foil are aligned at all times. This balance between the kite pulling up and the foil pulling down keeps the boat flat on water. 

 

SP80 EXPLAINED IN VIDEO

SP80 EXPLAINED IN VIDEO

But why are we keeping our little rocket close to the water when today we often see flying boats? Classical foils actually allow boats to raise above water and thus accelerate by reducing their drag as much as possible.

However, at very high speeds, these foils tend to dramatically reduce the boat’s stability, mostly when the pilot has no electronic assistance to control them. In our case, and according to the record rules, our pilot doesn’t have the right to use electronic assistance !

Thus we rapidly decided to use a different foil that pulls the boat down, preventing him from flying every time it gets windy. The additional drag caused by our three floats touching water is compensated by the kite’s power.

But why are we keeping our little rocket close to the water when today we often see flying boats? Classical foils actually allow boats to raise above water and thus accelerate by reducing their drag as much as possible.

However, at very high speeds, these foils tend to dramatically reduce the boat’s stability, mostly when the pilot has no electronic assistance to control them. In our case, and according to the record rules, our pilot doesn’t have the right to use electronic assistance !

Thus we rapidly decided to use a different foil that pulls the boat down, preventing him from flying every time it gets windy. The additional drag caused by our three floats touching water is compensated by the kite’s power.

SP80 EXPLAINED IN VIDEO

What happens underwater?

Another essential component to stability is located underwater and is also related to our foil. When a boat sails at approximately 54 knots (100 km/h), unstable steam bubbles form around the foils, the water starts boiling around it, which slows the boat down:  this is called cavitation. 

To avoid this physical phenomenon which both increases drag & makes the boat unstable, our concept is equipped with super-ventilating profiles. The geometry of these profiles allows the formation of a stable air bubble that replaces cavitation: this is called ventilation. These profiles have a huge potential at very high speed and will therefore be used to reach 80 knots.

SP80 EXPLAINED IN VIDEO

Keeping in mind those key criteria, we tested our scaled prototype on Lake Geneva and we adapted our concept for the building of the real boat that we will present to you real soon !
In the meantime, if you have more questions, go check out our FAQ! 

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