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WATER TEMPERATURE
AND THERMOCLINES
OPERATION
Water
temperature
has an
important-if
not
controlling-influence
upon
the activities
of all fish. Fish are cold
blooded and their bodies
are
always
the
temperature
of the
surrounding
water.
During
the
winter,
colder water slows down their
metabolism. At this
time, they
need
about
a fourth as much food as
they
consume in the summer.
Most
fish don't
spawn
unless the
water
temperature
is within
rather
narrow limits.
A surface
temperature
meter such
as Lowrance's
LDT-
3000
helps identify
the desired surface water
spawning
temperatures
for various
species.
Trout can't survive in streams
that
get
too warm.
Bass and other fish
eventually
die out when stocked
in
takes
that remain
too cold
during
the summer.
While some fish have
a wider
temperature
tolerance than
others,
each has a certain
range
within
which it tries to
22
SENSITIVITY
When first turned
on,
the X-20 is in the AUTO
SEARCH mode.
The
micro-computer
automatically adjusts
the
sensitivity
and
range
to find
and
lock onto the bottom. The
digital depth
flashes
"0" until it finds and
locks onto
the bottom. You
can leave the
sensitivity
in the automatic
mode or
manually adjust
it to
suit conditions.
You
may
need to increase
the
sensitivity
to show fish
symbols
when
the
unit is in automatic.
To do
this,
first
press
the
SENS.
key.
The letters
"SENS" will flash on the
right
side of the
display.
A vertical bar
appears
on
the left side of the screen.
(
See
below.)
This indicates the sensi-
tivity
level.
To increase the
sensitivity, press
and
hold the
up
arrow
key
until
the
sensitivity
is at the desired
level. The down
arrow
key
de-
creases
sensitivity
in the same manner.
Notice how
the
sensitivity
bar
moves
as
you
change settings.
It will move
up
when the
sensitivity
is
increased.
You'll also see the
change
on the
display.
After
you've
finished
setting
the
sensitivity
level,
the letters 'SENS" and
the sensitiv-
ity
bar
will
disappear
after
eight
seconds.
When the Fish
l.D. feature is
off,
the
sensitivity
can be
increased
more,
even
if the unit's automatic feature
is on. This will
help display
fish and
other small
detail. When automatic
is turned
off,
the
sensitivity
level can
be increased to
its
maximum
level.
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