Eagle Electronics SeaFinder 250 DF User Manual

Page 64

Weak bottom echo, digital readings erratic, or no fish signals:
1. Make certain the transducer is pointing straight down. Clean the

face of the transducer. Oil, dirt and fuel can cause a film to form on the

transducer, reducing its effectiveness. If the transducer is mounted in-

side the hull, be sure it is shooting through only one layer of fiberglass

and that it is securely bonded to the hull. Do NOT use RTV silicone
rubber adhesive or Marine-Tex

 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 happens, place the unit

in the manual mode, then change the range to a realistic one, (for exam-

ple, 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 sig-

nals such as fish or even structure from the display.