Garmin GMR 21 - Manual (Page 15)

GMR 21/41 Owner’s Manual 11
GMR 21/41 O
PERATION
> T
HE
R
ADAR
A
DJUSTMENT
M
ENU
To move the center location of the VRM:
1. Use the Rocker to highlight Move and press ENTER.
2. Using the Rocker, move the center point of the VRM to the
selected location.
3. Press ENTER to set the new location.
To use the VRM/EBL, expand the diameter of the VRM so that the
outer edge touches the target. Rotate the EBL until it intersects the
VRM at the target location. The measured range and bearing are
displayed in the lower left corner of the screen.
MARPA
The Mini Automatic Radar Plotting Aid (MARPA) function helps
with collision avoidance. MARPA can track up to ten designated
targets. Detailed information including Bearing, Range, Course,
Speed, Closest Point of Approach, and Time to Closest Point of
Approach for each target is displayed in the MARPA list.
NOTE: The MARPA function requires the use of a heading
sensor. The heading sensor must output the NMEA sentence HDM
or HDG at format 0183, v2.30 or higher. The Gamin Marine
Network has been tested using the KVH ® 1000 heading sensor
using 6 second dampening.
MARPA relies on a Heading Sensor to provide accurate own vessel
heading information. Accurate heading data enhances MARPA’s
performance. Each target being tracked by MARPA is represented by
a symbol. The symbols indicate the current state of the target.
Acquiring target
Target is safe
Target is dangerous
Lost target
For each target, a number and Vector Line is displayed with the
symbol. The number is the MARPA list ID number. The Vector Line
is a visual reference of the target’s course and speed.
To designate a MARPA target:
1. Use the Rocker to highlight Acquire Target and press
ENTER.
2. On the Radar Page, using Rocker, move the pointer to the
target, and press ENTER.
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