3-24 hsb
2
PLUS Series LCD Display
Introduction to
MARPA
• Choppy sea state conditions exist yielding poor stability; own ship’s
headingdata is very unstable.
• Inadequate heading data
Symptoms of such conditions are that acquisitionis difficultand the
MARPA vectorsare unstable; the symbol wanders away from the target,
locksonto another targetor changes to a lost targetsymbol. If any of these
conditionsarepresent,acquisitionandtrackingmayneed tobere-initiated
or, in some cases be impossibleto maintain. Improving the quality of the
heading data will reduce the effect of the other conditions.
Risk Assessment
Eachtargetis monitored to see if it will be within a certain distance from your
own vessel within a certain time. If so, the target is designatedas dangerous
and you are warned withan audible alarmin addition to a warning on the
screen.Thetargetsymbolchangesandflashestoindicatethatitisa dangerous
target.Pressingany key silences the alarm and removesthe warning, but the
target symbol remains dangerous.
Both the distance (Own Vessel Safe Zone) and the time (Time to Safe Zone)
areselectable as described in Section 7.5.
If a target is lost, either because the MARPAsoftware has lost contact with it,
or because it has moved out of range, you are warned, againwith an audible
alarmandanon-screenwarning.Pressinganykeysilencesthealarm,removes
the warningand removes the lost target symbol from the screen.
Target Data
All MARPA targets are stored in a MARPA database list, which shows
bearing,range, course and speed of each tracked target.
For any one targeta pop-up data box can be placed on the screen,this shows
bearing,range, course, speed,CPA (Closest Point of Approach) and TCPA
(Time to ClosestPoint of Approach).The targetfor which data is displayedis
indicated by a circle around its symbol.
Each targetis displayedas a symbol to indicateits status:
Target is being acquired
Target is safe
Target is dangerous.
Target is Lost
The dangerous and lost symbols are shown flashing.
81186_3.book Page 24 Thursday, August 22, 2002 8:23 AM
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