Furuno GP-7000F Operator's Manual page 93

Marker-zoom display
The marker-zoom display expands a selected area of the normal sounder picture
to full vertical size of the screen on the left-half window. You may specify the
portion to expand by operating the VRM (Variable Range Marker), which you can
shift with the [ENTER] knob. The area between the VRM and zoom marker is
expanded.
Note 1: The VRM is set independently from other displays in case of multiple
displays.
Note 2: The range of the bottom-lock can be changed at BOTTOM LOCK
RANGE on RANGES menu.
Marker
zoom display
25.0
ft
Zoomed fish school
Marker-zoom display plus normal sounder display
Bottom discrimination display
The bottom discrimination mode displays the bottom echo to help you determine
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.
Note: The range of the bottom discrimination can be changed at BOTTOM
LOCK RANGE on RANGES menu.
Bottom discrimination
display
Seabed tail
Long tail: Hard bottom
Short tail: Soft bottom
Single frequency display
Fish school
20
12.8
30
40
50
50k
10
0
50
79.5
ft
Bottom discrimination display
10. VIDEO SOUNDER OPERATION
0
VRM
This area is zoomed.
50
Zoom marker
100
50k
0
Single
frequency
display
50
This area
is zoomed.
100
10-7