A Voith Schneider unit varies the angle of vertical blades as they orbit, allowing thrust to change direction quickly and precisely. The idea originated as a turbine system for hydroelectric dams. Its maneuvering capability made the system attractive for tugboats and ferries before azimuthing pods became common. The planned auxiliary units for the German carrier Graf Zeppelin illustrate the design tradeoff. Harbor maneuverability was useful, but the installation added considerable expense and mechanical complication to an already complex warship when simpler methods could provide control.
Chapter · 26:09-28:10
Voith Schneider propulsion buys precision with complexity
Cycloidal blades give tugs and ferries immediate, finely directed thrust, but impose machinery burdens that are difficult to justify on a large warship.