Garmin GPS 152 Owner's Manual And Reference Manual page 69

• Heading— lets you select the reference used in calculating heading information. You can select
from 'Auto Mag Var', 'True', 'Grid' and 'User Mag Var'. 'Auto Mag Var' provides magnetic north heading
references which are automatically determined from your current position. 'True' provides headings
based upon a true north reference. 'Grid' provides headings based on a grid north reference (and
is used in conjunction with the grid position formats described on page 58). 'User Mag Var' allows
you to specify the magnetic variation at your current position and provides magnetic north heading
references based upon the variation you enter.
To enter a user defi ned magnetic variation:
1. With the 'Heading' fi eld set to 'User Mag Var', highlight the heading reference fi eld (immediately
to the right) and press ENTER/MARK.
2. Use the ARROW KEYPAD to enter the magnetic variation at your current position and press
ENTER/MARK.
WARNING: If 'User Mag Var' is selected, you must periodically update the magnetic
variation as your position changes. Using this setting, the unit will not automatically
calculate and update the magnetic variation at your present position. Failure to update
this setting may result in substantial differences between the information displayed on
your unit and external references, such as a magnetic compass.
• Distance, Speed and Altitude— lets you select the desired units of measure for distance, speed and
altitude readouts in 'Nautical' (nm, kt, ft), 'Statute' (mi, mh, ft) or 'Metric' (km, kh, mt) terms.
• Depth*— lets you select the desired units of measure for depth in Feet (ft), Fathoms (fa) or
Meters (mt).
• Temperature*— lets you select the desired units of measure for temperature in Fahrenheit (°F)
or Celsius (°C).
* You must be receiving proper sonar NMEA data from another device for this data to display. See pages 83-84.
Reference
Main Menu:
Units Tab
You may manually enter a magnetic variation.
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