simrad pilot, ap44 vrf pack, heavy duty simrad simrad is44 heavy duty autopilot with virtual feedback includes is44 control head, nac-3 processor, and precision 9 compass the nac-3 autopilot computer is the brains behind your autopilot system. nac-3 contains the control algorithms developed to helm a yacht across a broad range of weather conditions and sea-states, alongside the electronics needed to operate a hydraulic or mechanical drive unit, while also interfacing with other components including heading sensors and rudder feedback units. the nac-3 was designed for boats 10 metres (33 feet) or greater in length and is rated to operate high-current hydraulic drives, mechanical drive units, and solenoid valves with a current rating of 30 amps continuous (50 amps peak).