Hydrofoils and How They Work :: Hydrofoil Physics Boat Boating Watercraft

What is a hydrofoil? A hydrofoil is a watercraft that is supported on ski-like pontoons while in motion, with the bulk of the hull remaining entirely above the water (Encarta Encyclopedia 2002). Hydrofoils were first seen about in 1869. Emmanuel Denis Farcot was issued a patent on a boat that he had developed to go faster through the water because of less resistance. If you look at his design, he was using many little foils along the side of his boat to lift it out of the water in order to reduce the drag on the hull of the boat. Hydrofoils are not only used on boats. Guidoni and Croco took the idea of hydrofoils and put then on seaplanes. Their main reason for puting foils on the plane was to make the landings smoother and to make takeoffs much quicker. The plane can get out of the water much faster with foils because there is less drag inhibiting the plane from gaining speed to get airborn. This is useful when taking off of short lakes or in rough water. There are many purposes for hydrofoils. The main reason people or buisnesses install hydrofoils onto their watercraft is to decrease the drag of the boat as it travels through the water. By decreasing the drag, the watercraft is able to travel at higher speeds while burning less fuel. This makes use of the watercraft much more economical and provides a smoother, more comfortable ride because the watercraft rides above the reach of most of the waves. Another reason to use hydrofoils is because they are fun. The picture below shows a water ski that has been transformed into something that you sit on with your feet in front of you while you are "floating on air" behind a ski boat. When used on sail boats, hydrofoils can increase the top speed by quite a bit. Once the hull of the sail boat is out the the water the drag from the water is much less. Simply explained, there is less surface area "rubbing" on the water to slow the boat down. This means that even with gentle winds, a small boat can really get moving. Most hydrofoils lift the watercraft that they are supporting in the same way that airplane wings keep the plane supported in the air. With enough lift on the water foils, the hull of the watercraft is lifted out of the water.