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GPSMAP 192C Owner’s Manual
U
SING
S
ONAR
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U
NDERSTANDING
S
ONAR
Whiteline
The Sounder Module can help you determine whether the bottom is
hard or soft. When the sonar sound waves are reflected back by the
bottom, a hard bottom returns a stronger signal than a soft bottom.
A thin whiteline indicates a softer bottom, while a thick whiteline
indicates a harder bottom. Normally, a red line is used to show the
point where water meets the bottom. This line follows the bottom
contour, along with any significant objects lying on the bottom.
The unit uses the whiteline function to make the bottom layer
information easier to distinguish.
Whiteline Off
Whiteline On
Thick
Whiteline:
Hard bottom
Thermoclines
A rough definition of a thermocline is a break in water where
the water temperature changes faster than the water above it.
Thermoclines are shown as the weakest colors.
One of the unique features offered by Garmin is See-Thru
®
technology, which allows the GPSMAP 192C to hear both weak
and strong signals simultaneously so as to identify fish returns
under the toughest conditions, such as suspended in thermoclines
or even hiding near structures. See-Thru technology allows the
Sounder Module to see through thermoclines and locate fish.
Thermocline
