What happens when you add a bulb to a rudder?

20 November 2022

A rudder bulb is a streamlined component that is fixed at the leading edge of a rudder. It is designed to improve the water flow in front of the rudder and fills the vacuum behind the centre of the propeller. Furthermore, a bulb reduces propeller induced cavitation, which results in an extended lifetime of the rudder by less cavitation damage in propeller hub area.

Computational Fluid Dynamics calculations together with tank tests have proven fuel savings up to 1,5% when a bulb is applied to a rudder, depending on the ship type and its steering behaviour. This energy saving device is best suited to seagoing vessels with large propeller hub sizes and high thrust loads, such as bulk carriers, container ships, chemical tankers and cruise ships. A bulb can be installed in new-build and existing ships (retrofit).