As with all electromechanical systems, the course that the autopilot steers is only as accurate as the input of its sensors — in this case, the most critical data is the vessel’s compass course. While fluxgate compasses provide accurate azimuth information, their reporting rates of 1-10 hertz are sluggish to report course changes compared to today’s nine-axis compasses, which feature updated rates in the ballpark of 10-30 hertz, or that number of times per second. Moreover, the new breed of compasses are accurate to roughly plus or minus 2 degrees magnetic, and also deliver pitch, roll and yaw information, and in some systems, even heel angle. All this data means the autopilot’s CPU and algorithms can more efficiently stay on course. When networked with other onboard devices, the data can also account for vessel motion and the affect it has on wind angle and speed data. As a result, nine-axis compasses have largely usurped fluxgate compasses.