The GATE RUDDER® consists of two uniquely shaped rudders placed in parallel either side of the propeller instead of placing behind the propeller, which reduces resistance of rudder and create thrust to improve the energy consumption of 14% during the sea trial of the vessel. This is a completely new type of rudder system developed by new concept.
※The Nippon Foundation supported the development of the gate rudder.
Characteristics
A New Energy Saving System, confirming 14% Energy Saving On Actual Ship
By the speed difference of the stream facing to the duct with unique cross-section surrounding the propeller create dynamic lift, which is utilized as propulsion power. 14% of energy consumption during the sea trial of the real ship and some other superior features were achieved.
3 Property was confirmed by comparing with the sister ship
By comparing the data of MV SHIGENOBU equipped with the GATE RUDDER® SYSTEM
and its sister ship equipped with a flap ladder, several excellent performances were confirmed.
❶ Comparatively high energy saving
14% Energy Saving during the sea trial Comparing the sister ship during sea trial at the same ship speed, it is achieved that main engine output was 14% lower, which is really significant.
20% yearly Energy Saving on the actual commercial operation of the vessel Energy saving of the vessel with GATE RUDDER® was achieved steady regardless of the season, and confirmed about 20% less per year than the sister ship with the flap rudder.
❷ Excellent course keeping and turning performance
Excellent course keeping By steering two unsymmetrical rudders at appropriate angle, at a lower ship speed the turning circle could be smaller comparing with the sister ship with the flap rudder and turn linearly even at small rudder angle.
Less than the turning radius required by IMO (Considering the operation in harbor, during the test at a lower ship speed the turning circle could be smaller comparing with the sister ship with the flap rudder.) And also, at full speed, the turning circle of the vessel fulfilled the requirement of IMO.
❸ Enhance silence
Inboard Noise reduction By the equalization effect on the propeller inflow velocity, the occurrence of cavitation volume is suppressed and the noise in the steering gear room could be reduced 5 dB at the same ship speed comparing with the sister ship.
Underwater Radiated Noise(URN) reduction Reduced noise levels at high frequencies, which are particularly important for URN. Therefore, the influence to the measurement instrument like sonar and the marine life could be reduced.
Energy Saving Mechanism
3 Mechanism of GATE RUDDER® for achieving energy saving
Rudder placed in parallel both sides of the propeller reduce not only the resistance by the rudder, but also cavitation and toe angle of offset rudder (counter-steering) and these advanced mechanism affects multiply during the operation of the vessel to achieve fuel (energy) saving.
❶ Reduce resistance of rudder
Instead of placing behind the propeller, which is conventional construction, by placing two unsymmetrical rudder blades in parallel both sides of the propeller, reduce resistance of rudder and by the rudder blades create thrust to reduce hull resistance on self-propulsion condition.
❷ Suppress cavitation
Since GATE RUDDER® SYSTEM could create thrust, necessary thrust of propeller (to make same ship’s speed) could be reduced and cavitation could also be reduced, Further more by rectifying the stream facing to the propeller, the occurrence of cavitation is suppressed. Furthermore, since speed of the stream facing to the propeller is also rectified, torque nonuniformity is reduced to improve fuel consumption of main engine.
❸ Reduce counter-steering
During the operation in the ocean, it has turned out that there is a certain tendency for bow of vessel with GATE RUDDER® not to sway from side to side, which reduce the counter steering and contribute save energy operation of the vessel.
Excellent Safety
Create High safety operation GATE RUDDER®SYSTEM create excellent safety
Location of the rudder blades on crabbing mode made turn around at a point and move horizontally available.
Crabbing mode made Turn around & Move horizontally Available
By crabbing mode of GATE RUDDER®, one of standard modes, which two rudder blades are turned behind the propeller, vessel could be turned around on the spot and also move horizontally. If vessel operate bow thruster together with crabbing mode, it is easier to birthing and unberthing in the harbor.
Vessel could be operated with only one rudder blade working Even if one side of rudder isout of order, vessel could turn around even with only one rudder blade working normally.
Structural design considering safety
In order to have safe and appropriate structure, FEM is applied for the calculation. the strength calculation of the rudder (rudder blade and rudder stock) has been approved by Class NK.
By newly dedicated Auto pilot, the vessel equipped GATE RUDDER@ could be maneuvered in the same way
as other vessels with ordinary rudder
Auto pilot (dedicated by Tokyo Keiki Inc.) controls two rudder blades to have best performance of the vessel operation.
The crew of the vessel (installed GATE RUDDER@) can operate the vessel without any special feeling because of two rudder blades to reduce the stress of the crew.
Auto pilot PR-9000-GT specially dedicated for GATE RUDDER@ SYSTEM
