A control system for a marine vessel having one or more engines and a transmission associated with each engine is disclosed. The control system includes one or more control stations, each having a control arm and arm position means coupled to the control arm for providing an electrical signal that represents a position of the control arm within its operating range. The system includes one or more electronic control units, each of which is electro-mechanically coupled to an engine and a transmission. A first electronic control unit (ECU) includes input means for receiving the electrical signal, control means for controlling a throttle of a first engine and shift position of a first transmission based on the electrical signal, and output means for providing a control signal that represents a current position of the control arm to a second ECU. The second ECU is coupled to the first ECU via the communications link, and includes input means for receiving the control signal from the first ECU, and control means for controlling the throttle of a second engine and the shift position of a second transmission based on the power train control signal.