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Furuno CH-300 User Manual

Page 53

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2. HORIZONTAL MODE

2-27

Sea surface reflections

To reduce sea surface reflections, set the tilt angle to 5

° or higher, so the upper edge of the

sonar beam does not hit the sea surface, or adjust TVG. When a decreased tilt angle is
used, sea surface reflections cover a large area as illustrated below.

Sea surface

Sea surface

10

°

Tilt angle
indication

Sea surface
reflections

10

°

Sea surface reflections

Wake

A wake produced by own ship or another ship can be a strong reflecting object when a
decreased tilt angle is used. As the wake appears as a thick continuous line, it can be easily
distinguishes from a fish school. A wake contains many air bubbles which attenuate
ultrasonic energy, making it difficult to sound beyond the wake.

Own
ship

Other
ship

Wake produced
by other ship

Own ship's
screw noise

Own ship's
screw noise

Own ship's wake
(produced when
own ship turned)

Wake