68 GPSMAP
®
4000/5000 Series Owner’s Manual
Radar
Radar Targeting
Radar targeting enables you to identify and track objects.
About MARPA
MARPA is primarily used for collision avoidance, through object targeting and tracking.
To use MARPA, you must assign a MARPA tag to a target. The radar system automatically monitors the
tagged object and provides you with information about the object, including the range, bearing, speed, GPS
heading, nearest approach, and time to nearest approach. MARPA indicates the status of each tagged object
(acquiring, lost, tracking, or dangerous), and the chartplotter can sound a collision alarm if the object enters
your safe zone.
MARPA Targeting Symbols
➊
➋
➎
➍
➌
Symbol Description
➊
Acquiring a target� Concentric, dashed green rings radiate from the target while the radar is
locking onto it�
➋
Target has been acquired� A solid green ring indicates the location of a target that the radar
has locked onto� A dashed green line attached to the circle indicates the projected course over
ground or the GPS heading of the target�
➌
Closest point of approach and time to closest point of approach to a dangerous target�
➍
Dangerous target is in range� A red ring ashes from the target while an alarm sounds and
a message banner appears� After the alarm has been acknowledged, a solid red dot with a
dashed red line attached to it indicates the location and the projected course over ground or
the GPS heading of the target� If the safe-zone collision alarm has been set to Off, the target
ashes, but the audible alarm does not sound and the alarm banner does not appear (page
17)�
➎
Target has been lost� A solid green ring with an X through it indicates that the radar could not
lock onto the target�
