Humminbird 931C Installation And Operation Manual page 19

93x_Man_531370-1_A - vs4.qxd 2/18/2005
15" (380 mm)
Level
from prop(s)
3. Using a pencil or punch, mark the three mounting holes on the transom. Do not
mark or drill any other holes at this time.
4. Using a 5/32" (4.0 mm) bit, drill the three holes to a depth of approximately
1" (25 mm). On fiberglass hulls, it is best to use progressively larger drill bits to
reduce the chance of chipping or flaking the outer coating. Use a marine-grade
silicone sealant to fill the drilled holes.
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To mount the transducer
bracket to the boat
(Dual frequency unit):
1. Remove the transducer mounting
template from this manual. See
Appendix B for the Dual Frequency
Transducer Mounting Template.
2. Hold the template on the transom of
the boat in the location where the
transducer will be installed. Align the
template vertically, matching the lower
edge of the transom with the bottom
corner of the template. If your propeller
moves clockwise as the boat moves
forward, mount the transducer on the
starboard side, and use the bottom left
corner of the template. If your propeller
moves counter-clockwise as the boat
moves forward, mount the transducer on
the port side, and use the bottom right
corner of the template.
14
5. Align the metal mounting bracket with the mounting
holes. The center slot should be above the two outer
slots. (This bracket and all other hardware supplied is top
quality stainless steel for maximum strength and
corrosion protection.) Insert the three 1" (25 mm) flat
head wood screws into the drilled holes, but do not
completely tighten.
Attaching the Bracket
To attach the pivot to the transducer (Dual frequency unit):
1. Attach the pivot to the transducer body, using the two 1/4"-20 x 5/8" (16 mm)
machine screws, toothed washers, and square nuts. The toothed washers must
fit on the inside of the transducer ears, between the pivot and the ears. The
square nuts will be prevented from rotating by the pocket in the back of the
pivot. An Allen wrench is provided which fits all the 1/4"-20 screws, but do not
fully tighten the screws at this time.
2
1
1 Insert the square nuts
2
Toothed Washer
3
Pivot
4 Machine Screw
3
4
Attach the Pivot