Interpreting The Display - Furuno GP-1670F Operator's Manual

7. FISH FINDER OPERATIONS
[RANGES]: The default range settings are suitable for most applications. However,
you can customize the ranges to suit your needs, with [RANGE 1] - [RANGE 8]. Set
the ranges in descending order. Be sure that each range is higher than its preceding
range.
7.18

Interpreting the Display

Zero line
The zero line (transmission line) shows
the position of the transducer. The line
disappears from the screen when the
range is 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.
Second
bottom echo
7-22
Difference in depth
15 ft
30 ft
60 ft
120 ft
200 ft
400 ft
1000 ft
1500 ft
30 ft
30 ft
Range shifted
Difference in sensitivity
Zero
line