MUD BOTTOM CAUSES THE SIGNAL TO FADE

When you are hunt-
ing fish, with the gain
adjusted properly to
return a clear, bright
signal from a bottom
of gravel, sand,
or
shell, you will some-
times see the signal
disappear.
This doesn't
mean that you have
suddenly come to ex-
tremely deep water —
the dial would have
shown the drop-off
with a wide band of
signals in this case.
Instead, your
boat is
now above a mud bot-
tom. Mud absorbs the
sound waves. Thrn up
the gain. The bottom
signal may be faint
from a bottom of de-
caying vegetation
under deep water. Fish
will still show on the
dial, however. Back
over a hard bottom,
you'll get multiple
signals. Fig. 17
the mounting holes at the top
of the slots in the bracket.
6. Mount the assembly
to the
transom with two #10 screws.
Align the face of the trans-
ducer with
the bottom of the
hull with a straight edge.
Tighten all screws.
7. Route the transducer cable to
the depth
sounder unit. Do
not cut the transducer cable.
If it is too long, coil and store
the excess in an out-of-the-
way location.
S. Make a test run to determine
the results. Some boat hulls
require lowering
the back
edge of the transducer 2° to
6°. If the run was satisfactory,
drill two more holes in the
• bottom of the slots and install
two more #10 screws. Note:
The transducer must be
• against the transom for good
results. After locking
in place,
fill any voids between the
transom and the transducer
with caulking compound,
epoxy, or silicone adhesive.

OPERATION

SENSITIVITY AND
"ON-OFF" KNOB
This knob operates in a manner
similar to the volume control on
a radio. Thrning the knob
clockwise will turn the unit on,
and turning the knob back the
full counterclockwise
position
will turn the unit off. Thrning
the knob in a continued
clockwise manner will increase
the receiver sensitivity and
weaker echos from deeper water
can and will be observed on the
dial. After mounting the trans-
ducer, turn the unit on by turn-
ing the sensitivity knob
clockwise. You will see the con-
stant surface signal at zero. Be-
fore long, you will see another
signal — at ten feet if the water
is ten feet deep. This signal
indi-
cates the bottom. It, too, should
always show.
Continue turning
the Sensitivity
control toward the right and you
will see a second bottom signal
at double the depth of the first,
or 20 feet. The sound waves have
hit bottom, bounced
back, hit the
surface of the water, then
bounced
down and up again.
Over a firm bottom
you can in-
crease the sensitivity until the
dial shows three or four bottom
signals at multiples of true
depth.
The sensitivity is adjustable and
you should always set it to re-
turn a steady
bottom signal —
nearly as bright as the zero sig-
nal — regardless
of
depth. 'Ilirn
the knob counterclockwise when
you begin
to get the double bot-
tom signal; clockwise when the
bottom signal begins to fade. lb
show fish the sensitivity control
should be set to show a strong,
bright
bottom signal. Many
fishermen prefer to run the sen-
sitivity control very high with
the second bottom signal
show-
13 6
Mud and decayed vegetation
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