Reject control slowly clockwise until it is filtered out. If no noise is detected, the control should be left in the "MIN" position.
WHAT YOU SEE ON THE DISPLAY
A "Zero" line is always present on the dial. This indicates that the unit is transmitting a signal. Any additional light displayed indicates a reflected sonar signal. This could be the bottom or any object between
the surface and the bottom. The depth of the water is determined by comparing the leading edge of the bottom return to the number on the appropriate scale (inside or outside ring). The width of the bottom return and any surrounding flashes of light can give the user insight into texture, hardness, ground cover, etc.
Generally, a wider bottom return indicates a soft bottom. Soft sand and mud tend to allow the sonar signal to penetrate until there is sufficient density to reflect the signal. The result is a wider return signal display. Part of the signal bounces back immediately from the surface of the bottom, part of the signal penetrates slightly.
A hard bottom is generally displayed as a narrow return. All of the signal is reflected off the surface of the bottom simultaneously, so the returned signal arrives intact.
Terrain variation within the area of coverage will spread out the bottom representation. It may be difficult to differentiate a hard sloping bottom from a flat soft bottom.
