How do the boats of theAmerica’s Cup to “fly” on the water? It may seem incredible, but these boats long 21 meters, 5 meters wideheavy 6.9 tons (including the crew), can rise more than a metre from the sea and reach impressive speeds, up to 100 km/husing only the wind. The secret behind this “magic” are foils, advanced technological wings that allow the boat to rise and minimize resistance.
The foils are the “wings” of the AC75, which allow it to fly on the water
Foils are mobile appendages positioned on the sides of the boat, which enter and exit the water via a hydraulic system. They have a T-shapewith a structure that connects to the boat and a real wing that creates the lift, the same principle that allows the planes to fly. Immersed in water, the foil generates a pressure difference between the upper and lower part, pushing the boat upwards. The density of water, much greater than air, allows for the generation of great force even with small surfaces.
The lift created by the foil can be adjusted by changing itsangle of incidence through flap, similar to those found on airplane wings. However, to start “flying”, the boat must reach a minimum speed of 18 knotsa sort of take-off speed.
The double sail and the foils that replace the daggerboard
Moving on to the sails, they also work like the wings of an airplane, but vertically. When the boat has the wind in its favor, the sail uses the lift to push it. The AC75 boats, like Luna Rossa, in fact, have a sail which, if seen from above, is a wing Almost perfect: It is made up of two twin sails, which perfectly reproduce the drop of a wing profile and which are made of filaments of carbon, so as to delete almost completely any kind of resistence, so that the wind can act at its maximum potential.
A traditional sailing boat uses a drift to counteract the skidding, that is, the tendency to deviate from the course due to wind pressure. In the AC75, however, this role is played by the foil which, in addition to being fundamental for the balance of the boat, lift it, eliminate the resistance caused by the waves and allow the vessel to reach speeds of up to 53 knots (almost 100 km/h). This is made possible by the combination of lift and stability offered by the foils and the T-rudder. The play of lift created by the foils and the double carbon sail allows this type of boat to reach speed impressive, even three times higher than that of the real wind.
The Role of the Crew in AC75s Like Luna Rossa
The crew of the AC75 is reduced and hidden in cockpits to minimize aerodynamic drag. Each boat has two helmsmen And two trimmers, responsible for adjusting the foils and sails, as well as four “cyclors”. The latter are like cyclists who pedal for generate energy through a hydraulic pump, powering the systems needed for raise And lower the foil, as well as for regular the sails. The use of mechanical energy, combined with a complex system of cables and control units, makes these boats masterpieces of mechatronics.
Everything on board is designed down to the smallest detail, from theaerodynamics to the stowage of the electronic components to protect them from contact with the water. This approach, along with the continuous adjustment of the sails and foils by the crew, is essential to maintain the balance and efficiency of these extraordinary boats.
In short, the America’s Cup boats are real technological marvels, capable of harnessing complex forces to reach extraordinary speeds, making their “flight” seem almost magical.
