Specifications

Weak bottom
echo,
digital readings erratic,
or no
fish,
signals (cont.):
2. Electrical noisefromthe boat's
motorcan interfere with the sonar. This causes
the sonar to
automatically
increase its
Discrimination or noise
rejection
feature.
This can cause the unit to eliminate
weakersignals
such as fish or even structure
from the
display.
3. The water
may
be
deeper
than
the sonar's
ability
to find the
bottom. If the
sonar can't find the bottom
signal
while it's in the automatic
mode,
the
digital
will
flash
continuously.
It
may change
the
range
to limits far
greaterthan
the water
you
are in. If this
happens, place
the unit in the manUal
mode,
then
change
the
range
to a realistic
one,
(forexample,
0-100
feet)
and increase the
sensitivity.
As
you
move into shallower
water,
a bottom
signal
should
appear.
4. Check the
battery voltage.
If the
voltage drops,
the unit's transmitter
power
also
drops, reducing
its
ability
to find the
bottom or
targets.
Bottom echo
disappears
at
hIgh speeds
or erratic
digital reading
or weak
bottom echo while boat Is
moving -
1, The transducer
may
be in
turbulent water. It must be mounted in a smooth
flow of water in order for the sonar to
work at all boat
speeds.
Air bubbles In the
water
disrupt
the sonar
signals, interfering
with its
ability
to find the bottom or
other
targets.
The technical term for
this is Cavitation'.
2. Electrical noisefromthe boat's motorcan
interfere with the sonar. This causes
the
sonar to
automatically
Increase its
Discrimination or noise
rejection
feature.
This can cause the unit to eliminate
weakersignals
such as fish or even structure
from the
display. Try using resistorspark plugs
or
routing
the sonar unit's
power
and transducer cables
away
from other
electrical
wiring
on the boat.
No fish arches when the Fish ID
feature Is off:
1. Make certain transducer is
pointing
straight
down. This is the most
common
problem
if a
partial
arch is
displayed.
See the Fish Arch section in
your owner's,
manual for more
information.
2. The
sensitivity may
not be
high enough.
In
orderforthe unit to
display
a fish
arch,
it has to be able to receive
the fish's echo from the time it enters the cone
until it leaves, If the
sensitivity
is not
high enough,
the unit
displays
the fish
only
when it is in the center of the
cone.
3. Use the Zoom
feature. It is much easierto
display
fish arches when
zoomed
in on a small
range
of water
than a
large
one. For
example, you
will have
muth
better luck
seeing
fish arches with
a
30 to
60 foot
range
than a 0 to 60 foot
range.
This
enlarges
the
targets, allowing
the
display
to show much more detail.
To
change
the
ASF,
first
press
the
MENU
key
while
a loran screen is
displayed.
Now,
press
the
key adjacent
to the
"CHANGE SETUP"
label. Press
the MENU
key
one more
time,
then
press
the
key
adlacent
to the "ADJUST ASF" label. The
screen shown beloW
appears.
This menu lets
you change
the ASF
using
TD offsets or
latitude/longitude
correction.
Entering
the
ASF correction automati-
cally
turns the ASF feature on.
Latitude/Longitude
ASF Correction
__________________
Use the
latIlong
ASF correction if the _____________________
latitude/longitude position
shown on
the
display
is
slightly
different than
your known, precise
position. (If
the
displayed position
is off
by
a
large
margin,
the
Alternate/Primary
feature
may
need to be
switched.)
For
example, suppose your
actual
tatitude/
longitude
is
38-25-40/81-34-10,
but
the UltraNav
displays
38-24-30/81-35-
20.
Simply
enter
your
actual
position,
and the lJltraNav will handle the
rest. ________
To
change
the
ASF
using
the
latitude/longitude correction,
you
first
must be in the location
you
are
changing. Next,
press
the
key adja-
cent to the "ENTER
LAT/LONG CORRECTION"
label. The screen at
the
top
of the
next
page appears.
IMPORTANTI
ASF
corrections entered
by
the user are
good only
for
the stations
in use at the time
and location
being
corrected, If
you
travel
away
from the
area,
the ASF correction
may
not be valid. ASF
correc-
tions
may
not be usable if
you change stations,
or if
the unit auto-
matically
changes
stations. This
especially
holds true if
you
enter a
latitude/longitude position
to
change
ASF. The
UltraNav
will
only
apply
the
ASF correction to the stations in use
-
not all of them.
Remember,
if
you
change
stations,
especially
if
you change GRI's,
the ASF will have to
be re-entered.
--TO k
LAT
/LQN
a
ri ',..n
MORE'
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