Hydroplane - easy speedster. When moving glider, due to a specially designed hull shape having a flat bottom, or ledges on the bottom in the form of steps - Redan, there hydrodynamic force compensating portion of gravity and causes significant total ascent of a ship which "goes on the step" (as it to skim the surface of the water - glides). As a result, significantly reduced the area of contact with the bottom of the water (in sports courts several times), reduced viscous resistance to movement by reducing the wetted surface and increases speed. Planing set light internal combustion engines, gas turbines, some types of gliders used sails. This type of vessel / movement is very sensitive to the load. A slight increase in load or weight distribution change can lead to the fact that the ship will not reach the planing mode, and will continue to move in a gas-guzzling displacement mode when the Froude number of about 1. propulsor are rowing (less air) screws, water cannons. Gliders are used for the carriage of passengers, security service, sports races, walks.