Ducted propeller

A Kort nozzle is a tapered, airfoil- like profiled ring surrounding the propeller of a ship and was developed in the 1930s by the Italian aeronautical engineer Luigi Stipa and the German naval architect Ludwig Kort.

By the use of the Kort nozzle, the flow losses can be reduced at the ends of the propeller blades and generates a higher mass flow. This leads to an increase in efficiency which results in practice in a higher static pull. By the quieter wake shore and soles of inland waters are less affected.

Kort nozzles are often used on tugs and barges. You can pivoted and thus directly used as a rudder. In the recreational boating one uses Kort nozzles often as protector of the propeller against damage from floating debris. In these cases, however, the hydrodynamic effect is not very pronounced.

Gallery

Starr built Kort nozzle