Humminbird 998c SI - Manual (Page 41)

31 Transom Mount - Side Imaging®
Adjusting the running position of the transducer
The transducer mounting bracket allows height and tilt adjustment, while
the pivot bolt allows angular adjustment. These adjustments will help
reduce cavitation. Initially, adjust the transducer as described in the
following paragraphs. Further adjustment may be necessary to refine the
installation after high-speed testing.
1. First, adjust the pivot angle of the transducer body, so it is parallel
with the length of the hull of the boat.
2. Fully tighten the two pivot screws, using the supplied Allen wrench.
Access to the pivot screws is provided by the lower holes in the side
of the mounting bracket. It may be necessary to re-tighten the pivot
bolt after initial use as the plastic may still be conforming to the
pressure from the lock washers.
3. Adjust the height of the assembly so the face
of the transducer is 1/8" (3 mm) to 1/4" (6 mm)
beneath the bottom of the transom, and fully
tighten the three mounting screws.
4. In order to gain access to the mounting
screws, the transducer assembly must be
pivoted up in the bracket as shown. Be careful
not to alter the running angle as some force is
necessary to pivot the assembly.
5. If access to the top mounting hole is not possible due to the selected
height of the transducer, fully tighten the two lower screws, then
simply remove the headed pivot pin and the transducer assembly,
and tighten the top screw, then reassemble.
6. Confirm that the pivot angle has not changed and that all mounting
screws are fully tightened.
Tighten the Mounting
Screws
Normal Cavitation Cavitation that will cause
erratic sonar readings