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Whiteline, Thermoclines – Garmin GPSMAP 296 User Manual

Page 138

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Whiteline

The GSD 20 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 296 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 GSD 20

Sounder Module to see through thermoclines and helps locate fish

where they live.

Thermocline

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GPSMAP 296 Pilot’s Guide

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