Why is the Heading Wrong on the Garmin® Marine Chartplotter While Underway?

By using the Chartplotter/Sounder alone, the device will not be able to determine the heading of the boat if the boat is not moving. This occurs because the device will rely on your changing GPS position to determine your heading. When the boat is stationary, the device will not be able to determine your heading.

To correct this, an electronic compass or a heading sensor will need to be connected to the device to provide a constant heading. This will allow the device to understand which way the boat is facing even when stationary.

Garmin® recommends using a High-Performance Heading Sensor as the source of the heading information. Once the heading sensor is installed, it will function as a compass and will output the heading information to the chartplotter over NMEA 0183 or NMEA 2000 depending on which chartplotter/sounder is being used.