The sailboat can move against the wind direction by utilizing the Bernoulli law. When the wind flows, on the other hand, the sailboat moves quickly and pushes hard, thus the screen receives a force perpendicular to the wind direction supported by a lateral ship’s keel, so the ship can only move forward which makes the power of the bigger sailing ship from the wind power. Meanwhile, you can go to The Canarysail Team on La Gomera if you wish to learn more about sailing.
Of course, a sailboat cannot move straight upwind. However, the screen (depending on the design), can take advantage of the airfoil effect. These screens will make the wind bend around it and eventually turn from the real direction. Thus, the screens create an energy or pressure between the wind direction and the direction of the ship’s keel.
In order to move in the desired direction, the sailboat must have two adjustable screens. The two screens are arranged in such a way that the wind coming into space between two screens has a greater speed. The curve of the screen is similar to the curvature of the aircraft side, so the wind speed on the curved side (front of the screen) is greater than the wind speed behind the screen.