Fish History And Zoom Screens - Navman FISH 450 Tricolor Installation And Operation Manual

3-2 Fish History and Zoom Screens

Fish History screen
The Fish History screen displays the most recent
signals on the right of the screen, and the oldest
signals on the left. Vertically, this screen always
displays between the surface and the selected depth
range. This screen is often used to find fishing spots.
Fish symbol,
with depth
Object (e.g.
seaweed)
Bottom
Depth of
Bottom
Water Surface
Temperature
Note 1: This screen can be customised. (see Setup
- Display section 4-6)
Note 2: The Depth of Bottom can be adjusted for
Keel Offset. (see Setup - Depth section 4-3)
Fish detection
The FISH450 Tricolor analyses all received echos
and recognises the characteristic patterns returned
by fish. These echos are displayed on the screen
as a fish symbol. The default setting is for an
associated depth to be shown with fish symbols.
Advanced users sometimes prefer to turn off the
fish symbol feature and interpret the echo patterns
themselves. The following is an example with fish
symbols turned off:
Small
school of
fish
Bottom
NAVMAN
FISH450 Tricolor FISHFINDER Installation and Operation Manual
Selected
range
e.g. 0-30 m
Zoom Bar
Speed
Alarm symbols, see the
Alarms section 3-1.
Large
school of
fish
Single fish
Zoom screen
The Zoom screen is used to view greater detail in
an area of interest (e.g. fish close to the bottom).
The right portion is the Full Range Section and
the left is the Zoom Section.
The Zoom Bar, located on the very right of the
screen, determines the depth range of the Zoom
Section and the amount of magnification:
The Full Range Section illustrated is 0 to 30 m and
the Zoom Bar is between 14 and 29m. Therefore
the area between 14 and
29m is enlarged in the
Zoom Section.
To set the depth of the
Zoom Section, move the
Zoom Bar up or down by
pressing the Cursor Up
or Down key. To make
the Zoom Bar smaller (to
increase magnification),
press the Cursor Left
key. To make the Zoom
Bar bigger (to decrease
magnification), press the
Cursor Right key.
The Zoom Bar can be adjusted in the Fish History
screen before switching to the Zoom screen.
Strength of returned echos
The three colours indicate differences in the
strength of the returned echo: blue is the strongest,
red is medium strength and green is the weakest.
There are several reasons why the strength of the
returned echo varies:
• The size of the fish, school of fish or other
object.
• The depth of the fish or object.
• The location of the fish or object. The area
covered by the ultrasonic beam is
approximately cone-shaped and strongest in
the centre.
• The clarity of water. Particles or air in the
water reduce the strength of the returned
echo.
• The composition or density of the object. Soft
mud produces weaker echos than rock.
Planing hulls at speed produce air bubbles and
turbulent water that bombard the transducer. The
resulting ultrasonic noise may be picked up by the
transducer and obscure the real echos.
Zoom
Full
Section
Range
Section
Zoom Bar
14
29
7