NorthStar Navigation Multi-Function Unit M84 - Manual (Page 87)

Northstar M121/M84 Installation and Operation Manual 86
19-13 Setup > Calibrate
Press
MENU
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
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 19-11.
NavBus
NavBus is the preferred method for connecting
the Instrument to other Northstar instruments.
Select this if the instruments are connected
using NavBus.
NavBus Group
Use this when a group of Northstar instruments
are connected together using NavBus, to
specify a group of instruments for backlighting,
if required. Then, if the backlight setting on one
instrument in the group is adjusted, the other
instruments change automatically. Otherwise,
select 0. See section 20-10.