In an autopilot system, the drive unit is what actually moves your rudder or outboard, under control of the autopilot computer. Like the computer, the drive unit you’ll need depends on the size of your boat and the sort of steering system it has.

• On smaller runabouts with a cable-steering system, an electronic helmdrive unit replaces the existing mechanical gearbox and connects to the existing steering cables
• On sterndrive (inboard/outboard) boats, a mechanical servo drive replaces the steering cable from the helm
• Outboard or in board vessels with power assisted hydraulic steering need a hydraulic reversing or constant running pump
• For sailing boats, a linear hydraulic drive is required to operate the steering quadrant