Purpose of the Sonar Whiteline or Edge Feature

Garmin chartplotters and fishfinders with sonar have a feature that allows the sonar to display the signal from the bottom to help define the hardness or softness of the return. On some models, the function is called Whiteline, and on other series, it is called Edge. When the Whiteline or Edge feature is enabled, the surface layer of the bottom displays with a white stripe underneath it.

The thickness of the white stripe depends on the strength of the returning echo. A rigid or rocky bottom generates a stronger echo, resulting in a thick white line. A soft, sandy, or muddy bottom displays a thin white line.

Directions to turn on or off the Edge feature on current GPSMAP¹ series devices: from within a sonar page, select Options > Sonar Setup > Appearance > Edge, then press the option to turn on or off. A green light will indicate settings for the Edge feature.

¹  Legacy chartplotters, and Striker series devices see owner's manual for steps Finding the Owner's Manual for a Garmin Device