PRODUCT SOLUTION

Ultimate Rudder Bulb

The World’s Closest Rudder Bulb to the Propeller

There are three main mechanisms by which rudder bulbs improve propulsion efficiency:
1. Suppressing the generation of hub vortices
2. Uniformizing the wake flow and gaining wake benefit
3. Improving the interaction between the propeller and rudder

Because the closer the rudder bulb is to the propeller, the more effective it becomes, the Ultimate Rudder Bulb achieves this optimal placement by rounding the shape of the cap, allowing the bulb to be positioned as close as possible to the propeller.

Energy Recovery and 6% Efficiency Improvement

With a conventional rudder, strong hub vortices—which are a source of energy loss—form at the trailing edge of the cap and flow toward the rudder's port side. These vortices reduce negative pressure on the rudder's main body, increasing rudder drag.
The Ultimate Rudder Bulb recovers this vortex energy through the bulb head, increasing the negative pressure at the leading edge of the rudder and thereby reducing drag.
Self-propulsion tests using a 208BC model vessel confirmed a 5–6% or greater improvement in propulsion efficiency. Even during rudder angle variation tests, the lift-to-drag ratio remained comparable to the case without a rudder bulb.

Track Record of Installations

The Ultimate Rudder Bulb has been adopted on multiple vessels, many of which are now in active service.
It has been successfully applied to both low-speed and high-speed ships and is compatible with both fixed-pitch and controllable-pitch propellers.