Why can boats sail against the wind?

health : Why can you sail faster than the wind?

Before venturing out to sea in a sailing boat, you should have your umbrella under control. You know that: It is raining horizontally because the wind is blowing quite hard again, you open the umbrella innocently and with the next gust you drift across the sidewalk as if unleashed. The expert says: You are sailing “before the wind”.

Sailing ships used the downwind course several thousand years ago. He is not ideal. You can never go faster than the wind in this direction. Even if the target is exactly in the direction of the wind, high-speed sailors will drive a zigzag course. The way is then longer, but the boat is so much faster that it arrives earlier. As the?

"The wind that drives the boat is made up of the true wind and the headwind," says Wolfgang Heisen from the Institute for Ship and Marine Technology at the Technical University of Berlin. “You can say that the boat makes some of its own wind.” More wind leads to more power in the sail and thus to higher speed, says the engineer. And if the wind comes exactly from behind, the wind speed decreases with increasing boat speed until the real wind and head wind finally cancel each other out.

If, on the other hand, you do not drive exactly “in front of the wind”, a second force comes into play. The sail is arched. Therefore, the air that flows along the outside of the sail travels a further distance than the air that passes inside. The lower pressure on the outside and the higher pressure on the inside result in a force pointing diagonally forward. It is the same force that acts on the upwardly curved wing of an airplane and can pull a whole jumbo upwards. They are then called buoyancy. In the case of a boat, however, it works forwards because the sail is vertical and not horizontal like the wing.

The gain in speed can be very large - greater than the propulsion from the tail wind. Modern sailors can therefore be faster than the wind.

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