Sailing Employing Wind and Water

The wind and water are moving in the same direction on a calm and clear day. Movement is difficult in this situation as there is not a godo amount of energy to be extraced. The wind and water together create a difference in motion, which is then captured by the boat in energy. The sailboat captures this energy by utilizing the sail(s) and the hull(s).

There are usually two different directions, the sailboat and the wind, and both of these create a relative or apparent wind. A sail uses this apparent wind and generates lift. This is an example of an airfoil, and using Bernoulli's Principle the airfoil creates lift much like an airplane does. In fact, depending on the orientation of the sailboat, its point of sail, and its design it could conceivably obtain a speed faster than the true windspeed.

The sail is used by the boat to move in the water. Being able to move in the water is only helpful if a direction can be chosen. To help direct the boat an underwater component is required, such as a centerboard, underwater foil, keel, or even the hull itself can be employed. The boat can move in any direction, except into the wind, with the combination between the underwater component and the sail.

The tacking angle ranges from 35 to 80 degrees and is also known as the angle of the boat's movement relative to the true wind. Using a 35 degree tacking angle, on either side of the wind, a sailboat could cover over 290 degrees of the boat compass. Sailing into the wind can be accomplished indirectly by sailing close-hauled, about 45 degrees, and then tacking and sailing in a zigzag fashion. Moving together in a given direction is acheived with both the underwater component of the boat and the sail.

Understanding the dynamics between capturing and using the energy from the motions of wind and water can help answer the following questions:

1)How do sailboats move?

2)How can a sailboat sail upwind?

3)How can a boat sail faster than the wind?

Most sailors are not physicists but they are undoubtedly cognizant of the physical principles that govern basic movements in the water when sailing. The crew of a boat would be stuck in the water, if it wasn't for these principles.