Drag/Torque            So, the shape of the sail uses the concept of lift to move forwards, but why doesn’t the boat move laterally or just tip the boat right over? Drag is the answer. Drag is the force resisting motion caused by an object moving through a fluid such as air or water, which in this case is both. The narrow sleek shape of the boat’s hull is designed to minimize the drag force that the water exerts on the boat. However, the sailboat is outfitted with a keel which is designed to heavily resist lateral motion by creating high magnitudes of a drag force. The drag from the keel is what keeps the sailboat from moving laterally.(Maciel)                     (physicsbuzz.physicscentral.com) (real-world-physics-problems.com) Why does the wind cause the boat to tilt , but not tip completely over when it blows against the sail? The reason is that the torques are in balance around the center of mass on that particular axis. The stronger the wind blows against the sail, the higher the torque on that side of the point of rotation, which is somewhere in the hull depending on the dispersion of mass. The resistance that counteracts the increasing torque from the sail is also the keel. However, the reason the torque of the sail doesn’t completely overpower the resistance of the keel is because as the boat tilts over, the angle of the wind changes. As the boat tilts, the wind's angle of contact hitting the sail is no longer perpendicular to the radial line which, in this case, is along the mast. As the angle of contact gets furthers from 90 degrees from the mast, the magnitude of the torque decreases.(Wolfe)