Z-Drive

A Z-drive is an azimuthing propulsion unit whose propeller can be steered through a full 360 degrees, transmitting engine power down a vertical shaft and out through a horizontal shaft via two right-angle gear sets, the Z-shaped path that names it. It replaces the rudder, giving omnidirectional thrust. Z-drives power most modern azimuth stern-drive (ASD) and tractor tugs, ferries, and offshore vessels, delivering high bollard pull and tight maneuvering. The competing scheme is the cycloidal Voith Schneider Propeller; both are forms of azimuth thruster.