Garmin gmr 21 User Manual

GMR 21/41 O

PERATION

 > 

T

HE

 R

ADAR

 A

DJUSTMENT

 M

ENU

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.

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.

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. 

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.