Fish schools

A fish school appears as a mass of echoes on the screen. The color of the mass shows the density of fish schools on the sonar beam. To find distribution and center point of a fish school, try several different tilt angles.

(A) Sea surface fish

Tilt angle: 0˚ to 10˚

Fish school

Sea surface reflections

(B) Midwater, bottom fish Tilt angle: 30˚ or more

Fish echo which appears before bottom can be detected.

Bottom

Tilt angle: 0˚ to 20˚

Fish echo which appears together with or after bottom can be detected.

Fish school

Bottom echo not displayed because

of decreased tilt angle. Sea surface reflections are present.

Fish school

Large midwater fish school is present.

Bottom

When the tilt angle is shallow, the reflection echo from bottom is weak and the fish echo which appears from bottom

is easy to find.

Figure 2-22 Fish schools

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Image 43
Furuno CH-250 manual Fish schools, Bottom