Now, if we straignten our hand, the lift stops. If we tilt out hand up only a tiny bit, there is still almost no lift. Sailboats also will not travel pointing very close to the wind. That is aerodynamics. Now it's time for the part of the boat under the water, called hydrodynamics.
Sailboats have another wing under the water called a keel .
The keel provides three main purposes. As we increase our speed, water is rushing over both sides of the keel providing not only some lift, but also helping us hold our course, or diretion we are steering for. This is how we are able to sail into the wind. Now, exceeding the windspeed is really cool. This is most easily done on a catamaran or a sailboard since they are very light and draw very little water.