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Magnetic
variation
961 Operations and Reference Manual Rev. D
2. Press the CURSOR PAD left or right or press the LEFT
ARROW or RIGHT ARROW keys to select either AUTO or
MAN (for manual).
3. When done, press the ACCEPT key (or CANCEL to leave
the option unchanged).
4. Press RETURN to go back to the SETUP MENU screen.
Magnetic compasses naturally point to the magnetic north
pole, which is several hundred miles from the Earth's geo-
graphic north pole. The difference between the angles to the
two poles is called magnetic variation. To coincide with a mag-
netic compass, the 961 defaults to the AUTO setting for mag-
netic variation. Under most conditions, you'll want the 961 to
automatically calculate the variation for your position, which
is usually entirely adequate; however, the 961 lets you choose
select automatic or manual magnetic variation, or else true
north.
True north setting
If you select true north, no corrections will be applied to your
course and bearings. True north usually is required if you're
using a gyrocompass.
Automatic setting
If you select automatic variation, the 961 calculates magnetic
variation automatically, according to your position, to coincide
with a magnetic compass.
Manual setting
If you select the manual setting, you can enter from 0
°
180
, East or West, in the MAG VARIATION field. The manual
setting is available for those times when the CHART screen
must match an older or less accurate chart, or in remote areas
as when you're above 70
961's variation calculations can be off by a significant amount.
To change the magnetic variation setting:
Chapter 13 - Customizing Setup Functions
°
north latitude, where, locally, the
°
to
Page 13-21
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