Garmin GMR 21/41, Owner'S Manual, Page: 18 / 26

12 GMR 21/41 Owner’s Manual
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MARPA Sub Tab
The MARPA sub tab contains settings for Vector Length, Target
History, Own Vessel Safe Zone, Tine To Safe Zone, Safe Ring Zone,
and Velocity Reference.
The available MARPA sub tab options are:
• 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 target’s 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 shown on
the MARPA list. Relative calculates target speed and direction
relative to your own.
Absolute
shows the target’s actual speed.