Rudder Roll Stabilization

This stabilizer makes use of the existing rudder to control roll motion rather than adding some other stabilizer.

Principle: The rudder angle changes slow enough to reduce roll and fast enough not change the yaw angle.The Rudder angle is the input & 1)Ships Heading & 2) Roll Reduction are 2 outputs respectively.

Physics for controlling Heading motion is as follows:
The rudder induced force FR appears immediately, once the rudder has reached the starboard position. The rudder force FR now generates a clockwise moment MR that rolls the ship inwards. It should be noted that the rudder induced force FR also results in a sideway kick phenomenon. Since the size of the ship is significantly larger than that of the rudder, the hull induced force FH due to existence of drift angle built up much slowly. However once FH comes in, a counter clockwise moment MH is generated that outweighs the rudder-induced moment MR and an outward roll is generated. When the ship gradually rolls outwards, a restoring moment is generated to counteract the hull force induced moment MH. Eventually, the ship will reach a steady outward roll angle when the restoring moment is equal but in opposite direction to the hull force induced moment MH.

:?::?:I want to know about the physics as to how Rudder controls the Rolling motion????

 

Are you a student? Is this a question from an assignment or an exam? I'll assume the answer to those questions is yes so I won't provide an answer. But I will ask a question which might help you find the answer yourself.

How fast does a vessel roll compared to change heading? Think about that as you read the information you provided.

 

That system would work better with a rudder where the shaft had a pronounced angle. The old finkeel boats with angled rudders would have a pronounced roll when steered hard.