Ship roll stabilization system

A ship stabilization system which utilizes the rudders to compensate for wave and wind induced roll motions, comprises:

• a hydraulic control means connected to the rudders for controlling the position of the rudders;
• a pump means coupled to the hydraulic control means for controlling the flow of fluid thereto to produce a predetermined rudder movement;
• a roll rate sensor for producing roll rate signals (a');
• flow control means connected to the pump means for controlling the flow rate of fluid through the pump means;
• a first actuation means having a first input for receiving said roll rate signal and a second input for receiving helm steering command signals and being connected to the flow control means for translating helm steering command signals into control impulses for the flow control means;
• a second actuation means connected to the flow control means for forming a roll reduction control signal from said roll rate signal translating said helm steering command signals and helm roll reduction control signals into a control impulse for the flow control means;
• and
• coupling means connected to the first and second actuation means and the flow control means for disengaging the first actuation means from the flow control means during the period of time that the second actuation means is operating.