A steering actuator control system configured to provide steering control commands to a steering actuator of a steering device on a piece of towed marine equipment, the towed marine equipment formed from a plurality of pieces, the control system comprising: a memory storing setpoint data including positional values for a desired position of each piece of towed marine equipment, and characterised in that the control system comprises: a process data calculation module configured to invoke a first mathematical model to calculate process data representing the calculated actual position of each piece of towed marine equipment in response to a prior steering control command; a control module configured to receive the setpoint data; receive the process data representing the calculated actual position of each piece of towed marine equipment; compute a difference between the received setpoint data and the received process data; and calculate a control command for the steering actuator of the steering device if there is a difference between the setpoint data and the process data; a disturbance adjustment calculation module configured to combine a disturbance value based upon a measured disturbance with a value of the process data and output a disturbance adjustment value, wherein the disturbance adjustment value is a quotient with the disturbance value in the numerator and the process data value in the denominator; and a correction calculator module that adds the disturbance adjustment value to the control command to create an adjusted control command for transmission to the steering actuator. a memory storing setpoint data including positional values for a desired position of each piece of towed marine equipment, and characterised in that the control system comprises: a process data calculation module configured to invoke a first mathematical model to calculate process data representing the calculated actual position of each piece of towed marine equipment in response to a prior steering control command; a control module configured to receive the setpoint data; receive the process data representing the calculated actual position of each piece of towed marine equipment; compute a difference between the received setpoint data and the received process data; and calculate a control command for the steering actuator of the steering device if there is a difference between the setpoint data and the process data; a disturbance adjustment calculation module configured to combine a disturbance value based upon a measured disturbance with a value of the process data and output a disturbance adjustment value, wherein the disturbance adjustment value is a quotient with the disturbance value in the numerator and the process data value in the denominator; and a correction calculator module that adds the disturbance adjustment value to the control command to create an adjusted control command for transmission to the steering actuator. a process data calculation module configured to invoke a first mathematical model to calculate process data representing the calculated actual position of each piece of towed marine equipment in response to a prior steering control command; a control module configured to receive the setpoint data; receive the process data representing the calculated actual position of each piece of towed marine equipment; compute a difference between the received setpoint data and the received process data; and receive the setpoint data; receive the process data representing the calculated actual position of each piece of towed marine equipment; compute a difference between the received setpoint data and the received process data; and calculate a control command for the steering actuator of the steering device if there is a difference between the setpoint data and the process data; a disturbance adjustment calculation module configured to combine a disturbance value based upon a measured disturbance with a value of the process data and output a disturbance adjustment value, wherein the disturbance adjustment value is a quotient with the disturbance value in the numerator and the process data value in the denominator; and a correction calculator module that adds the disturbance adjustment value to the control command to create an adjusted control command for transmission to the steering actuator.