A steering system for a marine vessel comprises a helm, a control head, and a joystick. The helm and control head may respectively provide user inputted steering commands and user inputted shift and throttle commands on a first CAN network. The joystick and the control head may respectively provide user inputted steering commands and user inputted shift and throttle commands on a second CAN network. The helm may provide user inputted steering commands on the first CAN network. The control head may provide user inputted shift and throttle commands on the second CAN network. The joystick may provide user inputted steering commands and user inputted shift and throttle commands on either the first CAN network or the second CAN network.

A boat includes a planing hull, a propeller, a main rudder, and a pair of flanking rudders. The planing hull has port and starboard sides, a transom, a hull bottom, and a centerline running down the middle of the boat, halfway between the port and starboard sides. The propeller is positioned forward of the transom and beneath the hull bottom. The main rudder is positioned aft of the propeller. The main rudder has a rotation axis about which the main rudder rotates. The flanking rudders are positioned forward of the propeller. One of the flanking rudders is positioned on the port side of the centerline, and the other flanking rudder is positioned on the starboard side of the centerline.

A working oil chamber sealing system of a rotary vane steering gear actuator having a top end face of a respective segment of a housing that holds a segment top face horizontal seal. The segment top face horizontal seal having a sealing face which touches a rear face of a top cover. The top cover rear face holds an upper ring seal, a sealing face of which touches an outer circumferential edge of an upper end face of a rotor and also touches a sealing face inner edge of the segment top face horizontal seal and a sealing face inner edge of an upper horizontal vane seal of a rotor vane, respectively.

A working oil chamber sealing system of a rotary vane steering gear actuator having a top end face of a respective segment of a housing that holds a segment top face horizontal seal. The segment top face horizontal seal having a sealing face which touches a rear face of a top cover. The top cover rear face holds an upper ring seal, a sealing face of which touches an outer circumferential edge of an upper end face of a rotor and also touches a sealing face inner edge of the segment top face horizontal seal and a sealing face inner edge of an upper horizontal vane seal of a rotor vane, respectively.

A steering system for a marine vessel, the steering system comprises a first steering apparatus having a first steering actuator for steering the first steering apparatus and a second steering apparatus having a second steering actuator for steering the second steering apparatus. There is a mechanical steering linkage operatively connecting the first steering apparatus to the second steering apparatus so the steering apparatuses are steered synchronously. A user input device provides user inputted steering commands. A control apparatus operatively connects to the actuators and to the user input device. The control apparatus controls the steering of the steering apparatuses so both of the steering apparatuses are simultaneously steered the same amount.