Operation Manual

8120 Installation and Operation Manual68
Note: for accurate calibration:
• The speed from a GPS receiver should be
greater than 5 knots.
• The speed from another paddlewheel
transducer should be between 5 and 20
knots.
• Best results are achieved in calm
conditions where there is minimal current
(best at high or low tide).
Calibrating speed:
1 Travel at a constant, known speed.
2 In the Calibrate menu, select Speed.
3 Press
or
to change the displayed
speed to the true value.
4 Press
ENTER
.
Speed filter
Waves and wind cause the boat speed from
the paddlewheel transducer to fluctuate
slightly. To give stable readings, the
Instrument calculates these values by taking
several measurements and averaging them.
Set the Speed filter to the lowest value which
gives stable readings. The range is 1 to 30
seconds or Off (0).
Temperature
The factory settings should be sufficiently
accurate for normal usage. To calibrate the
temperature readout, first measure the water
temperature with a thermometer known to
be accurate.
Use the cursor keys to display the
temperature readout box, then increase or
decrease the value to match the measured
temperature. The temperature can be set
from 32° to 99.9°F (0° to 37.7°C) with a
resolution of 0.1° unit.
To change the units between °F (Fahrenheit)
or °C (Celsius), see section 17-9.
Temperature filter
Water turbulence and currents cause the
water temperature to fluctuate slightly.
To give stable readings, the Instrument
calculates these values by taking several
measurements and averaging them. Set the
Temperature filter to the lowest value which
gives stable readings. The range is 1 to 30
seconds or Off (0).
Fuel
See section 17-5, Calibrate.
Keel Offset
A depth transducer measures depths below
where the transducer is mounted on the
boat, usually the bottom of the boat. The
Instrument calculates the depths to display by
adding the keel offset to all measured depths.
A Have a zero keel offset to display depths
below the transducer.
B Enter a positive keel offset to increase the
displayed depth. For example to display
the total depths below the surface, enter
the depth of the transducer below the
surface.
C Enter a negative keel offset to decrease the
displayed depth. For example, to display
the depths of clear water below the boat,
enter minus the depth of the deepest part
of the boat below the transducer.
Transducer;
depths measured
below here
A
B
C
Depths measured
below here
Depths measured
below here
Speed range
The maximum reading to display on an
analog boat speed gauge (see section 10).
Choose a range suitable for your boat.
Max fuel flow
The maximum fuel flow from the fuel tank.
Max RPM
The maximum engine RPM. Enter a value you
have attained rather than the manufacturer’s
value.