Northstar
FISH 457/467
Installation and Operation Manual
44
Press
twice, then select
Calibrate
:
Speed
This calibrates the speed from a paddlewheel
sensor connected to the Instrument. Calibration
may be required because different hull shapes
have different flow characteristics. Obtain an
accurate measurement of the boat’s speed from
a GPS receiver; or by following another boat
travelling at a known speed; or by making a timed
run over a known distance.
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
.
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.
8-8 Setup > Calibrate
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 8-6.
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).
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
