Furuno CH-300 Operator's Manual page 33

How to discriminate fish echoes from the bottom
The figure at the bottom of the page illustrates how two fish schools "a" and "b" are
displayed on the screen using three different tilt angles.
Using the above three cases, fish schools will be displayed as below.
Bottom
Fish school "b"
Case 1(Tilt angle 30° to 40 °):
Case 2(Tilt angle 10° to 20 °):
Case 3(Tilt angle 0° to 5 °):
Case 2
Case 1
(Case 1, 2 and 3 are relative to the bottom pictured above.)
Detecting beam and fish position
Bottom
Bottom
Fish school "b"
Fish school "a"
Case 1
Fish echo and tilt angle
Fish school "a" and "b" are just above the bottom echo.
Fish school "b" is clearly seen. Fish school "a" is behind
the bottom echo therefore it is difficult to discern.
Bottom echo is weak so fish school "b" is easily seen.
Fish school "a" is masked by the bottom echo so it is
difficult to discern. However, larger fish schools may
appear in this condition.
Case 3
Fish school "a"
Bottom
Fish school "b"
Case 2
2. HORIZONTAL MODE
Fish school "a"
Case 3
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