Manual Sounder Operation; Selecting The Manual Mode; Selecting Display Range; Adjusting The Gain - Furuno NAVNET 1722 Operator's Manual

4.4

Manual Sounder Operation

Manual operation is useful for observing fish schools and bottom using fixed gain
setting.
The gain, range and range shifting functions used together give you the means
to select the depth you can see on screen.
4.4.1

Selecting the manual mode

1. If not displayed, press the [HIDE/SHOW] key to show the sounder soft keys.
2. Press the AUTO/D. BOX soft key to show the auto mode window.
3. Select OFF (MANUAL).
4. Press the RETURN soft key.
4.4.2

Selecting display range

Press the [RANGE +] or [RANGE -] key to select a range. The default ranges in
feet, meters, fathoms and passi/braza are as below. Note that range cannot be
changed in the automatic sounder mode.
Range 1
15 ft
5 m
3 fa
3 PB
4.4.3

Adjusting the gain

Normally, set the gain to the point where excessive noise does not appear on
screen. Use a higher gain setting for greater depths and a lower setting for
shallow waters.
Default sounder ranges
Range 2 Range 3 Range 4
30 ft 60 ft 120 ft
10 m 20 m 40 m
5 fa 10 fa 20 fa
5 PB 10 PB 30 PB
Gain too high
Examples of proper and improper gain
4. VIDEO SOUNDER OPERATION
Range 5 Range 6
200 ft 400 ft
80 m 150 m
40 fa 80 fa
50 PB 100 PB
Gain proper Gain too low
Range 7 Range 8
1000 ft 1200 ft 1500 ft
300 m 4000 m 4500 m
150 fa 650 fa 900 fa
200 PB 700 P/B 900 P/B
4-9