2
Select the location of the outer guard zone circle.
3
Select the location of the inner guard zone circle to define
the width of the guard zone.
Defining a Partial Guard Zone
You can define the boundaries of a guard zone that does not
completely encompass your boat.
1
From the sentry screen, select
Menu
>
Radar Menu
>
Sentry Setup
>
Adjust Guard Zone
>
Adjust Guard Zone
>
Corner 1
.
2
Touch and drag the location of the outer guard-zone corner
À
.
3
Select
Corner 2
.
4
Touch the location of the inner guard-zone corner
Á
to
define the width of the guard zone.
Radar Targeting and MARPA
Radar targeting enables you to identify and track objects.
Mini-automatic radar plotting aid (MARPA) is primarily used for
collision avoidance. To use MARPA, you assign a MARPA tag
to a target. The radar system automatically tracks 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
Acquiring a target. Concentric, dashed green rings radiate from
the target while the radar is locking onto it.
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.
Dangerous target is in range. A red ring flashes 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
flashes, but the audible alarm does not sound and the alarm
banner does not appear.
Target has been lost. A solid green ring with an X through it
indicates that the radar could not lock onto the target.
Closest point of approach and time to closest point of approach
to a dangerous target.
Assigning a MARPA Tag to an Object
Before you can use MARPA, you must have a heading sensor
connected and an active GPS signal. The heading sensor must
provide the NMEA 2000 parameter group number (PGN)
127250 or the NMEA® 0183 HDM or HDG output sentence.
1
From the Harbor, Offshore, or Cruising Radar screen, select
an object or location.
2
Select
Acquire Target
>
MARPA Target
.
Viewing Information about a MARPA-tagged Object
You can view the range, bearing, speed, and other information
about a MARPA-tagged object.
1
From a radar screen, select a targeted object.
2
Select
MARPA Target
.
Removing a MARPA Tag from a Targeted Object
1
From the Radar screen, select a MARPA target.
2
Select
MARPA Target
>
Remove
.
Viewing a List of AIS and MARPA Threats
From any Radar screen or the Radar overlay, you can view and
customize the appearance of a list of AIS and MARPA threats.
1
From a Radar screen, select
Menu
>
Radar Menu
>
Other
Vessels
>
AIS & MARPA List
>
Show
.
2
Select the type of threats to include in the list.
Showing AIS Vessels on the Radar Screen
AIS requires the use of an external AIS device and active
transponder signals from other vessels.
You can configure how other vessels appear on the Radar
screen. If any setting (except the AIS display range) is
configured for one radar mode, the setting is applied to every
other radar mode. The details and projected heading settings
configured for one radar mode are applied to every other radar
mode and to the Radar overlay.
1
From a Radar screen or the Radar overlay, select
Menu
>
Radar Menu
>
Other Vessels
>
Display Setup
.
2
Select an option:
• To indicate the distance from your location within which
AIS vessels appear, select
Display Range
, and select a
distance.
• To show details about AIS-activated vessels, select
Details
>
Show
.
• To set the projected heading time for AIS-activated
vessels, select
Projected Heading
, and enter the time.
VRM and EBL
The variable range marker (VRM) and the electronic bearing
line (EBL) measure the distance and bearing from your boat to
a target object. On the Radar screen, the VRM appears as a
circle that is centered on the present location of your boat, and
the EBL appears as a line that begins at the present location of
your boat and intersects the VRM. The point of intersection is
the target of the VRM and the EBL.
Showing the VRM and the EBL
The VRM and the EBL configured for one mode are applied to
all other radar modes.
From a Radar screen, select
Menu
>
Radar Menu
>
Show
VRM/EBL
.
Adjusting the VRM and the EBL
Before you can adjust the VRM and the EBL, you must show
them on the Radar screen (
page 13
).
You can adjust the diameter of the VRM and the angle of the
EBL, which moves the intersection point of the VRM and the
EBL. The VRM and the EBL configured for one mode are
applied to all other radar modes.
1
From a Radar screen, select a new location for the
intersection point of the VRM and the EBL.
2
Select
Drop VRM/EBL
.
3
Select
Stop Pointing
.
Measuring the Range and Bearing to a Target Object
Before you can adjust the VRM and the EBL, you must show
them on the Radar screen (
page 13
).
1
From a Radar screen, select the target location.
2
Select
Measure Distance
.
Radar
13
