Lowrance electronic LMS-337C DF - Manual (Page 168)

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The distance from your current position to the smaller ring (the ring's
radius) is 25 miles (always 1/4 the zoom range). With the arrow keys
and map cursor, you can scroll the map to see the third and fourth
rings. In this example, the distance to the third ring is 75 miles and
distance to the fourth ring is 100 miles from your current position.
To set range rings: From the Map Page, press MENU |
↓ to
M AP
D ATA
| ENT . Press
↓ to
D RAW M AP B OUNDARIES
|
→ to
R ANGE R INGS
. With the
option highlighted, press ENT to check it (turn on) and uncheck it (turn
off.) After the option is set, press EXIT | EXIT to return to the page display.
To set Lat/Long Grid: From the Map Page, press MENU |
↓ to
M AP
D ATA
| ENT . Press
↓ to
P OPUP M AP I NFORMATION
|
→ to
L AT /L ON G RID L INES
.
With the option highlighted, press ENT to check it (turn on) and un-
check it (turn off.) After the option is set, press EXIT | EXIT to return to
the page display.
Map Datum Selection
Maps and charts are based on a survey of an area covered by the map
or chart. These surveys are called "Datums." Maps using different da-
tums will show the same latitude/longitude in different locations.
All datums are named. The GPS system is based on the WGS-84 da-
tum, which covers the entire world. Other datums may also cover the
entire world, or just a small portion of it. By default, your unit uses the
WGS-84 datum. However, it can show your position using any of 191
datums. Different datums can be selected. To change the datum:
1. Press MENU | MENU |
↓ to
GPS S
ETUP
| ENT |
↓ to
D
ATUM
S
ELECTION
| ENT .
2. Scroll
↓ or ↑ to select the desired datum, then press
ENT .
3. To return to the last page displayed, press EXIT | EXIT .
A list of the datums used by this unit is in the back of this manual.
The Map Datum Menu.