Humminbird 917C Installation And Operation Manual page 28

6. Test and Finish the Installation
Once you have installed both the control head and the transom transducer, 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 POWER once to turn the control head on. If the unit does not
power up, make sure that the connector holder is fully seated in the
receptacle and that power is available.
2. If all connections are correct and power is available, the
Humminbird® control head will enter Normal operation.
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'
but less than the depth capability of the unit, and that the transducer
is fully submerged, since the sonar signal cannot pass through air.
NOTE: The transducer must be submerged in water for reliable transducer
detection.
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.
5. If you have the correct angle set on the transducer, yet lose a bottom
reading at high speed, adjust the height and the running angle in
small increments to give you the ideal transducer position for your
boat. First, adjust the height in small increment.
NOTE: The deeper the transducer is in the water, the more likely that a rooster
tail of spray will be generated at high speeds, so make sure that the transducer
is as high as it can be and still be submerged in the water.
If you are still not getting good high speed readings, you may need
to disassemble the transducer mounting assembly and re-position
the ratchets.
If you do change the transducer position, re-trace the position of the
mounting bracket before proceeding.
NOTE: It is often necessary to make several incremental transducer adjustments
before optimum high speed performance is achieved. Due to the wide variety of boat
hulls, however, it is not always possible to obtain high speed depth readings.
6. Once you have reached a consistently good sonar signal at the
desired speeds, you are ready to lock down the transducer settings.
Force the pivot to the Up position to gain access to the mounting
screws, then re-align the mounting bracket against the transom of
the boat to match the traced silhouette. Check the bracket position
with the level again to make sure it is still level, then mark the third
mounting hole using a pencil or marker. Unscrew and remove the
mounting screws and the transducer assembly and set aside.
7. Drill the third mounting hole, using a 5/32" drill bit. Use a marine-
grade silicone sealant to fill all three drilled mounting holes,
especially if the holes penetrated the transom wall.
NOTE: On fiberglass hulls, it is best to use progressively larger drill bits to reduce
the chance of chipping or flaking the outer coating.
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