Garmin GPSMAP 3010C - Manual (Page 71)

GPSMAP 3006C/3010C Owner’s Manual 63
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• Map Datum—manually select the datum reference used to determine
a given location. The default setting is WGS 84. The unit automatically
selects the best datum depending on your chosen position format. Datums
are used to describe geographic locations for surveying, mapping, and
navigation and are not actual maps built in the unit. Although more than
100 datums are available, you should change the datum only if you are
using a map or chart that specifies a different datum.
WARNING: Selecting the wrong map datum can result in substantial
position errors. When in doubt, use the default WGS 84 datum for best overall
performance.
• temperature—set the units of measure for temperature in Fahrenheit (°F)
or Celsius (°C). You must be receiving NMEA Sonar temperature data or
using a Garmin Sonar Module for the temperature to appear.
• Distance, Speed, and Elevation—set the units of measure for distance,
speed and elevation readouts in Nautical (nm, kt, ft), Nautical (nm, kt, m),
Statute (mi, mh, ft), or Metric (km, kh, m) terms.
• Pressure—set the units of measure you want to use for weather readouts
in Inches Mercury (in), Millibars (mb), or Hectopascals (hPa). You must be
using a Garmin weather product for this data to appear.
• heading—set the reference used in calculating heading information. You
can select Auto Mag Var, true, Grid, and User Mag Var. Auto Mag
Var provides magnetic north heading references that are automatically
determined from your present location. True provides headings based
on a true north reference. Grid provides headings based on a grid north
reference. User Mag Var allows you to specify the magnetic variation at
your present location and provides magnetic north heading references
based on the variation you enter.
WARNING: If you select User Mag Var, you must periodically update the
magnetic variation as your location changes. When using this setting, the
GPSMAP 3006C/3010C unit does not automatically calculate and update the
magnetic variation at your present location. Failure to update this setting can
result in substantial differences between the information displayed on your unit
and external references, such as a magnetic compass.
To enter a user-defined magnetic variation:
1. With the Heading field set to User Mag Var, highlight the heading
reference field (immediately to the right), and press ENTER.
2. Enter the magnetic variation at your current location, and press ENTER.
Time Sub Tab
Use the Time sub tab to adjust the time format, enter a time zone, and adjust for
Daylight Saving Time to show the correct local time.