Select > Installation, select the name of the stereo, then select Zones > Speed Vs Volume > Speed Source.

Engine Speed

Uses the RPM reading provided by a supported NMEA 2000^® engine. The volume increases as the engine RPM increases from the set Minimum speed to the set Maximum speed. If multiple supported engines are connected, the stereo uses the average RPM reading from all engines.

Speed Over Ground

Uses the speed over ground (SOG) reading provided by a supported NMEA 2000 GPS antenna or chartplotter with an internal GPS antenna. The volume increases as the SOG increases from the set Minimum speed to the set Maximum speed.

Speed Through Water

Uses the speed through water (STW) reading provided by a supported NMEA 2000 water-speed sensor. The volume increases as the STW increases from the set Minimum speed to the set Maximum speed.

Wind Speed

Uses the wind speed reading provided by a supported NMEA 2000 wind-speed sensor. The volume increases as the wind speed increases from the set Minimum speed to the set Maximum speed.