Garmin GPSMAP 235 Sounder - Manual (Page 55)

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GETTING START-
ED
Using the GOTO
Key
Map Page Options (con’t.)
From the map configuration page, you can also access another options menu by
highlighting any of the items and pressing O . There are five options:
•Enable or Disable a Row?: Allows you to turn an entire row on or off.
To turn an entire row on or off:
1. Use the R keypad to select the desired map item.
2. Press the O key.
3. Select the ‘Enable Row?’ or ‘Disable Row?’ option and press T .
•Calibrate the Map?: The map configuration options page also features a map calibra-
tion feature that allows you to calibrate the map display using your exact physical sur-
roundings or correct data from older charts. Before using the map calibration feature,
check to make sure that your map datum selected on the GPS matches the datum on the
chart you are using (see page 80). To calibrate the map display, you must know exactly
where you are, and understand that the correction is generally valid only in a limited
range from the point of correction.
Map calibration should only be performed while the vessel is still, and should
never be used to attempt SA corrections, which can degrade accuracy up to 330’
(100 meters). The maximum correction is 16,400 feet (5000m).
To calibrate the map:
1. Select the ‘Calibrate the Map?’ option and press T .
2. Use the R keypad to move the arrow cursor from the satellite position (indicated
by the satellite symbol) to your exact position. The bearing, distance and position
will be indicated in the data window.
3. Press T to confirm the calibration offset.
SECTION
4
MAP PAGE
Enable/Disable Rows
and Map Calibration
A B
A. To calibrate the map, highlight the ‘Calibrate the
Map?’ option and press EDIT/ENTER.
B. A satellite icon will remain on the map to indi-
cate the GPS position, while the boat marker will
reflect the calibration changes.
CAUTION!
The map calibration feature should never be used
to attempt to correct Selective Availability errors.
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