Sailing: Harnessing the Power of 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 sailboat captures the energy that is created from the difference in motion of the wind and water. 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 boat will be able to move about in the water by utilizing the sail. Being able to move the boat is half the battle, the other half being able to chose a direction. 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. Sailing directly into the wind cannot be done, but the combination of the sail and underwater component let the boat move in any other direction.

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. There is a relationship built between the sail and underwater component to move the boat in a specific direction.

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.