Air boats (sometimes spelled airboats) are watercraft powered by large propellers mounted on the rear. Early air boats used aircraft engines to spin their props, but most modern air boats use standard automotive V-8 engines for power. The gas-powered engine turns a crankshaft, which in turn spins the propeller up to 3000 rpms or more. The propeller draws air from the front and pushes it through the back to create forward momentum.
Because air boats do not need underwater rudders or blades, their bottoms can be very flat. This means that air boats can reach areas usually inaccessible to traditional boats, such as very shallow water, swamps and stump-filled inlets. Air boats can also travel over most land surfaces, as long as the propeller can produce enough power to overcome the added friction. The bottom and sides of many air boats are covered with a thick layer of polymer plastic to absorb the damage of gravel and concrete surfaces.
Air boats are generally used for recreation and fishing, but many coastal cities also employ them for rescue operations. In places like the Florida Everglades, air boats are much more practical than traditional boat designs. Weeds and grasses slip below the flat bottom of the air boat and the propeller never contacts the water. Pilots of air boats control direction through the use of a handheld rudder and 'brake' by cutting power to the engine with a throttle control.
Some say that Alexander Graham Bell actually designed the first air boats in 1905, although countless numbers of amateur boat builders also attached aircraft engines and propellers to flat-bottomed boats. Most air boats built before the 1980s still employed aircraft engines, but proper maintenance proved to be difficult. With the switch to standard automotive engines like a Chevy 350 V-8 or 454, most mechanics can easily make repairs to air boats with readily available parts.