Sailing and Steering Sailboats
Sailing a boat is about changing the direction of the sailboat using wind direction and using a tiller.
The Physics behind steering sailboats
The wind passing over the top of curved sail must travel further (slower speed). However the wind travelling under the sail is traveling faster because of shorter distance and that causes pressure. The consequence of this is that the air above the curved sail has a lower pressure than the wind below the sail and this pressure difference creates the lift.
In other words, the side of the sail exposed to slower moving air is subject to greater air pressure, creating lift. Lift is a force that acts perpendicular to the direction of the force created by the air, as lift causes the boat to move in the direction of the higher speed air, which results in lower air pressure on the sail.
This force can cause the boat to go side ways, however the boat has a keel below the water). So the lift effect is counterbalanced by the water forces acting upon the keel. Resources: https://www.youtube.com/watch?v=yqwb4HIrORM