Furuno NAVNET GD-1920C Operator's Manual page 125

4. VIDEO SOUNDER OPERATION
Bottom-zoom display
The bottom-zoom display expands bottom and bottom fish echoes by the zoom range
selected on the SOUNDER RANGE SETUP menu (see paragraph 7.9.3), and is useful for
determining bottom hardness. A bottom displayed with a short echo tail usually means it is
a soft, sandy bottom. A long echo tail means a hard bottom.
Bottom-lock display
The bottom-lock display provides a compressed normal picture on the right half of the
screen and a 10 or 20 feet (3 or 6 meter) wide layer in contact with the bottom is expanded
onto the left half of the screen. This mode is useful for discriminating bottom fish from the
bottom echo. You may select the bottom lock range from the SOUNDER RANGE SETUP
menu. For details, see paragraph 7.9.3.
Fish
school
4-4
Bottom
80
BOTTOM-ZOOM
DISPLAY
Bottom-zoom display plus normal sounder display
10
-
-
-
8
-
-
-
6
- -
-
4
-
-
-
2
10
-
-
80
-
0
BOTTOM-LOCK
DISPLAY
Bottom-lock display plus normal sounder display
- 0
-
0
- -
-
20.0
-
- -
-
10
- -
50
-
-
- -
-
20
-
- -
100
- -
-
-
30
HF
NORMAL DISPLAY
0
-
-
-
-
Zoom marker
50
-
-
This part
-
is zoomed.
-
100
-
-
HF
NORMAL DISPLAY
Zoom marker