Humminbird ] 981 - Manual (Page 23)

TEST AND FINISH THE TRANSDUCER INSTALLATION
When you have installed both the control head, the transducer, and accessories and
have routed all the cables, you must perform a final test before locking the transducer
in place. Testing should be performed with the boat in the water, although you can
initially confirm basic operation with the boat out of the water.
1. Press the POWER/LIGHT key once to turn the control head on. There will be an
audible chirp when the key is pressed correctly. If the unit does not power-up,
make sure that the connector holder is fully seated and that power is available.
2. If all connections are correct and power is available, the control head will enter
Normal operation. If no transducer is detected (or one is not connected), the
unit will go into Simulator mode and will indicate this by displaying the word
Simulator on the control head display.
NOTE: The transducer must be submerged in water for reliable transducer detection.
3. If the bottom is visible on-screen with a digital depth readout, the unit is
working properly. Make sure that the boat is in water greater than 2 ft (.6 m) but
less than the depth capability of the unit, and that the transducer is fully
submerged, since the sonar signal cannot pass through air.
4. If the unit is working properly, gradually increase the boat speed to test high-
speed performance. If the unit functions well at low speeds but begins to skip
or miss the bottom at higher speeds, the transducer requires adjustment.
Angling the rear of the transducer downward and/or lowering the transducer
farther into the water will help achieve depth readings at high speeds. If the left
side of the fish arch is longer than the right side, then the back of the transducer
is angled too far downward. If the right side of the fish arch is longer than the
left side, then the back of the transducer is angled too far upwards.
NOTE: It may not always be possible to get symmetrical fish arches and high speed depth
readings at the same time. Due to the wide variety of boat hulls, however, it is not always
possible to obtain high speed depth readings.
NOTE: It is often necessary to make several incremental transducer adjustments before
optimum high speed performance is achieved.
Once you have reached a consistently good sonar signal at the desired speeds, you are
ready to lock down the transducer settings.
5. Mark the transducer bracket location on the transom with a pencil, then pop up
the bracket to reveal the mounting screws. Tighten the stainless steel mounting
bracket screws to secure in place.
Hand-tighten only!
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