As you move away from shore on
a deep lake, the bottom signal
will gradually
move around the
dial until it reaches zero. If the
dial is calibrated to a depth of 60
feet, the water is 60 feet deep.
Continue further, and the bottom
signal will start around again.
Add whatever figure it shows to
60 to get the correct depth. The
inside dial on the Eagle Model
Silent
Sixty 1 is calibrated from
60 to 120 feet to help you read
depths greater
than 60 feet.
Other Eagle models have dual
ranges that allow you to change
to a deeper scale when you go
deeper
than 60 feet.
SIGNAL INTERPRETATION
Because your Eagle is both ex-
tremely
sensitive and powerful,
it can give you an accurate pic-
ture of the kind of bottom over
which your boat is passing. A
bottom of firm sand, gravel,
shell, or hard clay returns a
bright, fairly
wide signal. If
you
are traveling
over such a bottom
and the signal weakens, it
means that you have moved over
a soft mud bottom. A soft bottom
absorbs the sound waves and re-
turns a weak signal. In this case,
simply turn up the sensitivity to
get a good bottom reading.
A level bottom with scattered
rocks returns the usual bottom
signal — plus secondary
signals
both above and below it. This is
caused by the different distances
the sound waves travel. Those
that go straight down, hit a rock,
and come back indicate, cor-
rectly, that the top of the rock is
above the level of the bottom.
But the sound waves that hit a
rock toward the outer edge of the
cone of sound waves and are re-
flected back to the transducer
travel further. Consequently,
their signals appear below the
tottom signal.
A smooth bottom of solid rock
returns a wide, bright signal.
Broken rock of various sizes
sends back an even wider one,
with occasional flashes above
and below
the level of the true
bottom, though these signals
aren't so distinct as the ones re-
turned
by scattered rocks on a
smooth
botto,m.
Big rocks or stumps on a smooth
bottom send back signals above
the level of a smooth
bottom,
the
distance depending
on their
height. If
you watch as you ap-
proach a post or a tree, however,
you will often see the signal
climb up, then descend the other
side as you continue.
A steep slope returns a wide sig-
nal, the steeper the wider, with
the signal returned
from a high
underwater cliff
being the
widest. The sure proof
of a
drop-off
is the sudden
change of
the regular depth signal to a
wide one, then back to the usual
width, but either more shallow
or deeper as the boat moves
past.
Brush will return flashes of
varying heights above the bot-
tom signal. Weeds also tie in
with the bottom, although they
return weaker signals than
brush or tree limbs. In most
lakes, weeds don't grow in water
more than 12 or 15 feet deep be-
cause of the lack of sunlight.
Weeds make a great many thin,
pale signals on the dial.
The nicest bottoms
to survey
with your
EAGLE are those that
return a clear, bright
signal, with no spikes
either above or below
it from scattered rocks.
This is the easiest bot-
tom signal of all to
read and fish at any
depth above it show up
plainly on the dial.
Nothing is more
gratifying than to find
a big school of
largemouth bass over
clean gravel or wall-
eyes over a smooth
sandbar — places that
these two popular fish
like and that are easy
to fish by the bottom-
bumping
technique.
It is easy to get mul-
tiple signals on the
dial from bottoms of
this type. If
you are
over water 20 feet
deep, for example, and
turn up the gain you'll
get signals at 20 and
40 feet.
9 10
DETECTING A SMOOTH BOTTOM
Gravel or Hard Clay
Fig. 14
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