Light boats with plenty of propulsive power can ride and skim on the surface of the water, supported by dynamic pressure. The slower-moving or sta­tionary boat is supported by the static pressure of the water, summed up in the one word ‘buoyancy’. When a boat planes, the dynamic water pressure is higher than the static, with the result that her weight is supported by a smaller area in contact with the water. Friction and Drag are thus reduced and speed increases. Sailing dinghies, which have suitably shaped hulls and sail areas which are large for their weight, can ‘get on the plane’ in a fresh wind, though they do not quite reach the condition of a planing power boat. (see also: Displacement hull.)