Sonar Screen - Navman Fish 4430 Installation And Operation Manual

3-5 SONAR screen

Select MAIN MENU - SONAR to display the
SONAR screen.
This is a powerful feature and with some
experience, this screen can be used to identify
both the type of bottom and the fish species.
On the Sonar Echo section on the right side,
the strength of an echo at a particular depth
is shown by a horizontal line at that depth. A
strong echo produces a long line, whereas a
weak echo produces a short line. Below the
echoes the screen shows the Shading Bar. This
disappears from view after a few seconds, but
just press to re-display it.
The left side of the screen is the Fish History
section. Using the Shading Bar as a control, the
fishfinder interprets the echoes shown on the
Sonar Echo section and uses this information to
draw the Fish History section.
Recognising the Type of Bottom
The bottom trace is the strongest echo shown
in the lower part of the left side of the screen.
A bottom trace with a wide black layer is
indicative of a hard bottom, because a hard
bottom returns strong echoes. Conversely, a
soft bottom produces medium or weak echoes,
which are shown by a narrower trace.
Fish 4430/4431 Installation and Operation Manual
Small strong echo
(e.g. fish). This
usually flashes
on and off as the
ultrasonic pulse
strikes the fish.
Large strong signal
(e.g. bottom)
Shading Bar
Recognising the Type of Fish
Different species of fish have different sizes
and shapes of swim bladders. The air in the
swim bladder reflects the ultrasonic pulse, so
the strength of the echo varies between fish
species according to the size and shape of the
swim bladder. The sonar display is 70 pixels
wide, so it can show 70 levels of return echo
strength, which is a powerful feature.
When fishing among a school of fish and
catching them, note the fish species and the
strength of the echo that it returns on the
fishfinder on the Sonar Echo screen. Then,
the next time that particular return on the
fishfinder is seen, it is likely to be the same fish
species.
Adjusting the Shading Bar
The Shading Bar is displayed as a horizontal
bar in the lower half of the screen. Adjust the
Shading Bar so different strength echoes have
a different shade on the screen. Weaker echoes
can be shown as light grey, and the strongest
echoes shown as black.
Increase the black part of the Shading Bar by
pressing if there are too few long (strong)
echoes being displayed in black.
Decrease the black part of the Shading Bar by
pressing if there are too many long (strong)
echoes being displayed.
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