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Northstar Explorer 657 Installation and Operation Manual72
Press twice, then select Calibrate:
Speed
This calibrates the speed from a paddlewheel
sensor connected to the 657. 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
.
17-12 Setup > Calibrate
Speed filter
Waves and wind cause the boat speed from the
paddlewheel transducer to fluctuate slightly. To
give stable readings, the 657 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 17-10).
Temperature filter
Water turbulence and currents cause the water
temperature to fluctuate slightly. To give stable
readings, the 657 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).