Eagle CUDA 250 S/Map Installation And Operation Instructions Manual page 92

Weak bottom echo, digital readings erratic or no fish signals:
1. Make sure the transducer is pointing straight down. Clean the face of
the transducer. Oil, dirt and fuel can cause a film to form on the trans-
ducer, reducing its effectiveness. If the transducer is mounted inside
the hull, be sure it is shooting through only one layer of fiberglass and
that it is securely bonded to the hull. Use only LEI epoxy.
2. Electrical noise from the boat's motor can interfere with the sonar.
This causes the sonar to automatically increase its Discrimination or
noise rejection feature. This can cause the unit to eliminate weaker
signals such as fish or even structure from the display.
3. The water may be deeper than the sonar's ability to find the bottom.
If the sonar can't find the bottom signal while it's in the automatic
mode, the digital sonar display will flash continuously. It may change
the range to limits far greater than the water you are in. If this hap-
pens, place the unit in the manual mode, then change the range to a
realistic one, (for example, 0-100 feet) and increase the sensitivity. As
you move into shallower water, a bottom signal should appear.
4. Check the battery voltage. If the voltage drops, the unit's transmitter
power also drops, reducing its ability to find the bottom or targets.
Bottom echo disappears at high speeds or erratic digital read-
ing or weak bottom echo while boat is moving
1. The transducer may be in turbulent water. It must be mounted in a
smooth flow of water in order for the sonar to work at all boat speeds. Air
bubbles in the water disrupt the sonar signals, interfering with its ability
to find the bottom or other targets. The technical term for this is cavitation.
2. Electrical noise from the boat's motor can interfere with the sonar.
This causes the sonar to automatically increase its Discrimination or
noise rejection feature. This can cause the unit to eliminate weaker
signals such as fish or even structure from the display.
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