Racing boats have to basic hull designs, displacement and planing. Motorboats with displacement hulls ride in the water, and planing skim along the surface on a cushion of air. Most motorboats with displacement hulls are known as flatbottoms. These boats have gently slopped sides and range from 2.5 to 5 meters long. Flatbottoms may have inboard or outboard motors. Inboard engines are inside the hull. Outboard engines are outside, usually at the rear of the boat. Flatbottoms with outboard engines are called runabouts. The driver of a flatbottom is in front of the engine. The driver sits in inboards or kneels in most outboards. The design of hydroplanes allows the pressure of the water to lift the boat and keep it on the surface of the water as long as the boat moves rapidly. A short float called a sponson on each side of the hull helps lift the nose of the boat out the water and increases the speed. Some hydroplanes reach speeds of 320 kilometers per hour, how ever they need a lot of room to make turns. Hydroplanes range from 3.5 meters to 8.5 meters in length.
Racing motorboats are powered by petrol, diesel, jet or turbine engines. Most boats operate with only one engine, but some have up to four. Some racing categories require stock engines, which are made in a factory and are not allowed to be modified. Some racing categories allow engines to be modified. In most races, inboard racing boats must use standard car engines. Large inboard hydroplanes may be powered by aircraft engines. Outboard motorboats can only use specific marine engines. The propeller is one of the most important pieces of equipment on any boat. Propellers are designed to increase the boat's speed and to provide efficient handling. They may have two, three or four blades.