Flying on the water? A Leonardo Da Vinci’s dream that is becoming true today. Foiling. The credit goes to foils, the wings that, instead of supporting aircrafts’ flight in the air, support the boat and make it run above the water surface. Without taking off, of course. But what are they and how do they work? Here are the questions and answers to the current phenomenon called foiling.
Foiling refers to the use of wings attached to the hull of boats, which provides additional lift at planing speeds – often enough to lift the hull completely out of the water.
What’s the advantage?
When the boat sails over the water surface, navigation gets more comfortable and gentle. Mobile foils, moreover, can improve stability and maneuverability. When they are properly adjusted, they can improve boat efficiency even without lifting the hull.
How do foils work?
Wings work in a similar way to airplanes’ ones. As they move through the water they deflect the flow, which exerts a force on the wing. If this force is facing upwards, the faster they move, the higher is the lift.
Why are they smaller than airplanes’ wings?
Because the water is almost 800 times thicker than the air. Foils must “push” more than aircrafts’ wings and therefore not require the same surface.
Who invented foiling?
Italian inventor Enrico Forlanini began to work on hydrofoils in 1898 and used a “ladder” foil system on Lake Maggiore. During World War II, the Germans built a 17-ton prototype that reached 47 knots. In the ‘50s, the first commercial hydrofoil sailed between Italy and Switzerland and, ten years later, a foil-equipped yacht appeared in James Bond’s movie ThunderBall.
What was the evolution that changed things?
Today, instead of two fixed V-shaped foils, four independent L-shaped foils are used, coming out of the hull with an angle of incidence on the water that can be modified. They are much more efficient and can be integrated in the hull, solving docking and draft problems. In addition, the computer-controlled active systems allow you to adjust the foils according to speed and sea conditions. This not only improves efficiency but also makes driving and handling easier. An active system adjusts each foil to induce the right degree of inclination. Modern materials also reduce aerodynamic drag and cavitation.