Furuno CSH-7 - Manual (Page 11)

1-4
Seabed echo and tilt angle
Case 1: Tilt angle 30 to 40 degrees
This tilt angle will display the entire seabed since it is captured
by the full width of the beam.
Case 2: Tilt angle 10 to 20 degrees
This tilt angle will only display half the seabed since it is only
captured by the lower half of the beam.
Case 3: Tilt angle 0 to 10 degrees
This tilt angle may or may not capture the seabed since the re-
turning echo is weak.
How to discriminate fish echoes from the seabed
The figure below illustrates how two fish schools a and b are
displayed on the screen using three different tilt angles.
Case 1: Tilt angle 30 to 40 degrees. Fish school is obscured by
the seabed.
Case 2: Tilt angle 10 to 20 degrees. Fish school is located above
the seabed (midwater).
Case 3: Tilt angle 0 to 10 degrees. Fish school is located close to
the seabed.
Case 1 Case 2 Case 3
Fish school a
Seabed
Fish
school
b
Case 3 Case 1 Case 2
Fish school a Fish school a
Seabed
Seabed
Figure 1-3 Fish echo and tilt angle