Garmin GMR 20 - Manual (Page 17)

GMR 20/40 Owner’s Manual 13
GMR 20/40 O
PERATION
> T
HE
R
ADAR
A
DJUSTMENT
M
ENU
MARPA Setup Menu
To change a MARPA field option:
1. Using the ARROW KEYPAD, highlight the desired field and
press the ENTER key to activate the field selections.
2. Using the ARROW KEYPAD, highlight the desired selection.
3. Press the ENTER key to accept the change.
Vector Length—predicts the target’s approximate position at a set
time interval. This setting determines the length of the Vector Line,
based on the time interval setting and the target’s speed. The time
interval settings range from .05 minutes to 60 minutes.
Target History—is a trail showing a targets movement. Target
History can be turned On or Off.
Own Vessel Safe Zone—is a circular area defined by a range setting
that is centered on your own vessel. If a target enters the defined area
an alarm is sounded. The Safe Zone can be set to a distance between
.01 and 2 nautical miles.
Time To Safe Zone—sounds an alarm if MARPA determines that a
target will intersect the Own Vessel Safe Zone within the defined time
interval. The time interval settings range from 3 to 24 minutes.
Safe Zone Ring—displays a ring on the Radar page depicting the
Own Vessel Safe Zone.
Velocity Reference—has two settings, Absolute and Relative. This
setting determines how speed and direction are displayed on the
MARPA List. Relative calculates target speed and direction relative to
your own. Absolute displays the target’s actual speed.
Hide/Show Navigation Features
This setting hides or shows navigation features such as Waypoints, a
Bearing Line and a Course Line on the Radar page. See page 16 for
more information on selecting the Navigation Features.
Additional Adjustment Menu Items
There are three additional items available on the Adjustment Menu:
Map Cursor On/Off, Setup, and Enter Standby/Begin Transmitting.
continued