Features of the Wakes of Partly Immersed Wheels

The wakes of partly immersed wheels and paddlewheels are described. The wave trains are compared with boat wakes and are classified into displacement, transition and planing types. The effects that these wake forms can have on a wheel that is being used as a propulsion device are discussed. A significant feature of wheels at high rotational speeds is the stern fountain. Its formation and effects are discussed. Another feature is the overwhelming bow wave which is sometimes present at planing speeds. This is described and factors contributing to its formation are discussed. The control of this bow wave is noted as important particularly for high-speed paddlewheels since its presence limits the speed of operation. It is concluded that these wake features need to be taken into consideration in the design of wheel type propulsion devices. This study is part of a project that developed a type ofpaddlewheel that supports a load dynamically as it travels at speed over the water surface.