GATE RUDDER® System – Performance Advantages

The GATE RUDDER® System from Kamome Propeller turns hydrodynamic forces that would otherwise be resistance into rudder thrust. The rudder blades around the propeller act like a duct with a special section shape, creating a velocity difference in the flow and using the resulting lift as propulsive force. Performance was verified by comparing the gate rudder vessel *Shigenobu* with a sister ship fitted with a flap rudder.

Energy savings

• Sea trials: 14% lower main engine output at the same ship speed
• One year in service: about 20% lower fuel consumption than the flap-rudder sister ship, stable across seasons
• Side-by-side trial off Kobe on 30 December 2021: at the same engine output, the gate rudder ship was clearly faster

Course-keeping and turning

• Two asymmetric rudders each set to the appropriate angle give a smaller turning circle at low speed and linear response at small rudder angles
• Outperformed the flap rudder in low-speed harbor tests; meets the IMO turning circle requirement at maximum speed

Noise reduction

• Flow straightening suppresses cavitation, reducing onboard noise in the steering gear room by 5 dB at the same speed
• Lower underwater radiated noise, especially at high frequencies, reducing effects on sonar and marine life

Controls

A dedicated joystick provides intuitive maneuvering when berthing and in narrow channels; an improved rudder blade shape enables true sideways movement, confirmed in coastal tanker trials.