Safety notices
Note: It is your responsibility to exercise common
prudence and sound navigational judgement.
There are conditions where acquiring a target may
become difcult. These same conditions may be a
factor in successfully tracking a target. Some of the
conditions are:
• The target echo is weak.
• The target is very close to land, buoys or other
large targets.
• The target or your own vessel is making rapid
manoeuvres.
• Choppy sea state conditions exist and the target is
buried in excessive sea clutter or in deep swells.
• Choppy sea state conditions exist yielding poor
stability; own vessel’s heading data is very
unstable.
• Inadequate heading data.
Symptoms of such conditions include:
• target acquisition is difcult and the MARPA
vectors are unstable;
• the symbol wanders away from the target, locks-on
to another target, or changes to a lost symbol
target.
In these circumstances, target acquisition and
tracking may need to be re-initiated and in some
cases it may not be possible to maintain acquired
targets. Better quality heading data might improve
performance in these circumstances.
MARPA risk assessment
Each target is monitored to ascertain whether it will
be within a certain distance from your vessel within
a certain time. If so, the target is designated as
dangerous, and an audible warning is sounded and
a warning displayed. The target symbol changes to
the dangerous target symbol and ashes to indicate
that it is a dangerous target. Acknowledging the
alarm will remove the warning.
If a target is lost, either because the MARPA software
has lost contact with it, or because it has moved
out of range, an audible alarm is sounded and a
warning is displayed. The symbol will change to the
lost target symbol. Acknowledging the warning will
silence the alarm and remove the warning and the
lost target symbol.
MARPA targets range
MARPA target acquisition is only available at Radar
range scales of up to 12 nm, although tracking
continues at all ranges.
If you change to a smaller range scale, targets may
be beyond the range of your Radar scanner and will
be lost. In such cases, a warning indicates that the
target is off-screen.
MARPA context menu
When a MARPA target is selected the context menu
which provides the following positional data and
menu items.
Positional data
• CPA
• TCPA
• COG
• SOG
Menu items:
• Cancel target
• CPA Graphic
• Target Data
• Slew thermal camera (Only available when
thermal camera is connected and operating.)
Accessing the context menu
1. Non-touchscreen and HybridTouch displays:
i. Move the cursor over the area or object and
pressing the OK button.
2. HybridTouch and Touch only displays:
i. Select and hold on an area or object, or
ii. With the Chart Call-out displayed select the
Call-out box.
Acquiring a MARPA target
From the Radar application:
1. Select the target to be acquired.
The context menu is displayed.
2. Select Acquire Target.
The “acquiring target” symbol is displayed. If the
target is present for several scans, the Radar
locks-on to the target, and the symbol changes to
the “acquired target” symbol.
Cancelling an individual MARPA target
From the Radar application:
1. Select the relevant acquired MARPA target.
The MARPA context menu is displayed.
2. Select Cancel Target
Cancelling all MARPA targets
You can cancel all tracked MARPA targets using the
Tracked targets list
The location of the Tracked target list is dependent
on the application and Overlays you have enabled:
• Radar application: Menu > Tracked Targets.
• Chart application with Radar and AIS overlays
enabled: Menu > Radar & AIS > Tracked Targets
• Chart application with only the Radar overlay
enabled: Menu > Radar > Tracked Targets
• Chart application with only the AIS overlay
enabled: Menu > AIS > Tracked Targets
1. Select the Radar tab.
2. Select Cancel All Targets.
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