Raymarine RC520, Owner'S Handbook Manual

Page: 142 / 218

128 HSB Series LCD Display
Units
You can set the units for speed, depth and temperature. The units you set will be
used to display all data, including information received from other instruments
on the system. However, the distance units do not affect the instrumented range
of the radar, which is always in nautical miles.
Variation Source
The variation value is the difference between True and Magnetic direction data
for heading or bearing values. The Variation Source option provides soft keys
for selecting Auto or Manual variation mode, displays the current variation
value for each and highlights the currently selected mode.
Auto Mode
If you select Auto mode, the radar obtains the value of variation automatically,
normally from received data. The variation value that is used depends on the
data available, and is selected in the following order of priority:
1. Variation value from the same source as the heading data:
- If heading data is being taken from NMEA, then variation is also
taken from NMEA
- If heading is taken from SeaTalk, then SeaTalk variation is used
2. Variation value from a different source:
- If heading data is being taken from NMEA, but no NMEA variation
is available, then variation is taken from SeaTalk
- If heading is taken from SeaTalk, but no SeaTalk variation is available,
then variation is taken from NMEA
3. A calculated variation value, using position data, if no SeaTalk or NMEA
value is available
4. The current manual variation value, if no SeaTalk or NMEA value and no
position data is available
Manual Mode
If you select Manual mode, by pressing either of the
MANUAL
keys, you can
specify the local variation value according to the area in which you are
operating. Press the appropriate
MANUAL
key to adjust the variation up or
down, to a maximum of 30° East or West.
This value is then transmitted to any other SeaTalk instruments on your system.
It is retained if you turn the display off and on again.
SystemSet Up
Parameters