In use, the GHP 12 course computer sends steering commands over the boat's network, and this drive unit converts those commands into real mechanical force on the boat's existing hydraulic steering system, holding a course or executing autopilot manoeuvres like tacking without the helmsman touching the wheel. The standard Class B unit is rated for sailboats up to roughly 79,000 lbs of displacement, delivering up to 2,380 lbs of thrust over a 12-inch stroke -- enough force for a genuinely large, heavy cruising or offshore sailboat, distinguishing it from the smaller Class B Compact drive unit (rated to about 48,400 lbs displacement and 1,610 lbs of thrust) aimed at mid-size boats. As a purely mechanical/hydraulic actuator rather than an electronics unit, it's typically installed low in the boat near the existing steering ram or quadrant, plumbed into the vessel's hydraulic steering circuit rather than mounted at the helm.