Interpreting The Display - Furuno MFD12 Operator's Manual

7. Fish Finder
7.16

Interpreting the Display

Color bar
The color bar at the left edge of the display shows the range of colors used to display
different echo strengths. The top color (reddish-brown) is the strongest color and the
lower colors the weaker colors. Use the bar as a reference to estimate the density of
a school of fish, fish species and the hardness of the bottom.
STRONG
R-BRN
RED
ORANGE
YELLOW
GREEN
LIGHT-BLUE
BLUE
DEEP BLUE
WEAK
No Signal
49.6
ft
Zero line
The zero line shows the position of the transducer. The line disappears from the
screen when the range is shifted, or is shown at the draft depth when the draft of the
vessel is entered.
Zero Line
Range shifted
Bottom echoes
The strongest echoes are from the bottom, and are normally shown in reddish-brown
or red. The colors and the width change with bottom material, depth, sea condition,
installation, frequency, pulse length and sensitivity.
Bottom contour
The tail from a hard bottom is longer than the tail from a soft bottom, because the hard
bottom reflects more of the ultrasonic pulse. An echo from shallow water gives a stron-
ger reflection than the echo received from deep water. A longer bottom tail appears
on slopes, because of the difference in travel time at both edges of the beam angle.
For the rough bottom, echoes are reflected on many different planes, which displays
echoes in many layers, which gives a 3D effect.
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