Garmin GPS III Plus - Manual (Page 88)

Units Settings
Distance & Speed lets you select the desired units of measure for distance and speed
readouts in ‘Nautical’, ‘Statute’ or ‘Metric’ terms.
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 82). ‘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.
Altitude lets you select altitude readouts in ‘Feet’ or ‘Meters’.
To select a units setting:
1. Highlight the desired field and press ENTER to display the available options.
2. Select the desired option and press ENTER.
3. If ‘User Mag Var’ is selected in the ‘Heading’ field, highlight the heading reference field (immed-
iately to the right) and press ENTER. Enter the magnetic variation at your current position using
the rocker keypad and press ENTER.
WARNING: If ‘User Mag Var’ is selected, you must periodically update the magnetic
variation as your position changes. Using this setting, the GPS III+ 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 GPS III+ and external references, such as a magnetic compass.
Select nautical, statute or
metric units of measure from
the ‘Units’ settings.
The ‘User Mag’ option allows
you to define the magnetic
variation for your area. ‘Auto
Mag Var’ is the preferred set-
ting in most cases.
78
REFERENCE
Setup Menu: Units
I