The ratio of sail to vessel is an important factor in determining how stable, maneuverable and fast a sailboat will be. If you're up for the challenge, construct some mini sailboats -- these can be made of wooden sticks and candy wrappers. What is significant is not the size of the boat, but the proportions of your construction. Some factors to consider are: vessel length, width at the beam and weight in relation to ballast size. Experiment with various measurements, and then determine which design plans make the most sense. You should be able to easily recreate your findings for the science fair.
To navigate in varying sea conditions, a mainsail must be flexible enough to take on different shapes. In light winds, a sail can be rather loose or full. In faster winds, however, the sail should be pulled taut, taking on a flat shape. In addition, the angle of a mainsail sheet can vary -- from a short, stocky triangle shape, to a tall, slender shape, to a triangle with a rounded side. Try constructing different mainsail shapes, but keep all other conditions constant. You could even get adventurous with square and star-shaped sails. Then figure out which shapes take sail, which capsize and which could win races.
Did you know that salt water is more viscous, meaning thicker, than fresh water? Olympic swimmers love to time themselves in salt water because they often record their fastest times. But is the same true of sailboats? Keeping all other factors the same, such as wind speed and the boat, experiment to find out whether sailboats are faster in salt water or in fresh water. Set up two small tubs to recreate your findings for those who come to your booth at the science fair.
Fiberglass, the construction material of most modern-day sailboats, was not invented until the late 19th century, which means that large sailing vessels of old had to be made of wood. Other construction materials can vary too: What happens if the sail is made of cotton instead of polyester or some other fabric? What happens if the wood is coated in wax instead of polyurethane? You could even experiment to find out whether the type and color of paint impact the boat in any way. Which color boats are the fastest? Which materials are the most durable? Use science to explain which materials have historically been used for which kinds of sailboats and why. You'll be a budding sailboat expert before you know it!