Azimuth Thruster

An azimuth thruster is a ship propulsion unit, mounted in a pod beneath the hull, whose propeller can be rotated through a full horizontal circle to provide thrust in any direction, making a separate rudder unnecessary. It exists in two basic forms: a mechanical version, in which a motor inside the hull drives the propeller through a right-angle gear train running down into the pod, and an electrical or podded version, in which an electric motor sits directly inside the pod and drives the propeller with no gearing at all. The English inventor Francis Ronalds described an early version of the idea in 1859, calling it a propelling rudder that combined a boat's propulsion and steering into one unit, but the modern mechanical azimuth thruster, using what is called a Z-drive gear train, was invented in 1951 by Joseph Becker, the founder of the German company Schottel, an achievement for which Becker later received the Elmer A. Sperry Award in 2004; a rival design was patented by Pleuger in 1955. The podded electric version, known as the Azipod, followed decades later, developed in the late 1980s by Wartsila Marine, Stromberg and the Finnish National Board of Navigation.