Furuno GP-3500F - Manual (Page 185)

11. VIDEO SOUNDER OPERATION
11-13
11.4.2 Selecting display range
The basic range may be selected with the [RANGE] key, from the eight ranges
shown in the illustration below. (These eight ranges may be programmed as
desired. For details, see paragraph 11.15.)
1. Press the [RANGE] key to show the ECHO SOUNDER RANGE window.
ECHO SOUNDER
15 ft
30 ft
60 ft
120 ft
200 ft
400 ft
1000 ft
4000 ft
TURN KNOB TO SELECT
ECHO SOUNDER
RANGE.
Echo sounder range window
2. Rotate the [ENTER] knob to select a range.
Note:
This setting must be done within 10 seconds after pressing the [RANGE]
key, otherwise the window will be erased.