Raymarine c97 - MARPA Overview

16.8MARPAoverview
MARPA(MiniAutomaticRadarPlottingAid)
improvescollisionawarenessbytrackingacquired
targetsandcalculatingtheirspeedandcourseto
enableriskanalysis.
Pre-requisites:
•ForeffectiveMARPAoperation,yourMFDmust
haveaccurateheadingandspeeddataforyour
vessel.
•InTrueMotionmode,SpeedOverGround(SOG)
andCourseOverGround(COG)informationis
requiredtoshowtruetargetcourseandspeed.
•InRelativeMotionmode,headingandspeed
informationisrequired.
Eachtargetcanbedisplayedwithagraphic
indicatingtheClosestPointofApproach(CPA),and
TimetoClosestPointofApproach(TCPA).The
calculatedtargetdatacanalsobedisplayed.Each
targetiscontinuallyassessedandanaudiblealarm
issoundedifatargetbecomesdangerous,orislost.
Thenumberoftargetsthatyoucantrackatanyone
timeisdependentonthemodelofradarscanner
thatyouareusing.
1 2 3 4
D12219-2
ItemTargetsymbolDescription
1Acquiredtarget
2Dangeroustarget
3Targetbeginacquiring
4Losttarget
Safetynotices
Note:Itisyourresponsibilitytoexercisecommon
prudenceandsoundnavigationaljudgement.
Thereareconditionswhereacquiringatargetmay
becomedifcult.Thesesameconditionsmaybea
factorinsuccessfullytrackingatarget.Someofthe
conditionsare:
•Thetargetechoisweak.Thetargetisveryclose
toland,buoysorotherlargetargets.
•Thetargetoryourownvesselismakingrapid
manoeuvres.
•Choppyseastateconditionsexistandthetargetis
buriedinexcessiveseaclutterorindeepswells.
•Choppyseastateconditionsexistyieldingpoor
stability;ownvessel’sheadingdataisvery
unstable.
•Inadequateheadingdata.
Symptomsofsuchconditionsinclude:
•targetacquisitionisdifcultandtheMARPA
vectorsareunstable;
•thesymbolwandersawayfromthetarget,locks-on
toanothertarget,orchangestoalostsymbol
target.
Inthesecircumstances,targetacquisitionand
trackingmayneedtobere-initiatedandinsome
casesitmaynotbepossibletomaintainacquired
targets.Betterqualityheadingdatamightimprove
performanceinthesecircumstances.
MARPAriskassessment
Eachtargetismonitoredtoascertainwhetheritwill
bewithinacertaindistancefromyourvesselwithin
acertaintime.Ifso,thetargetisdesignatedas
dangerous,andanaudiblewarningissoundedand
awarningdisplayed.Thetargetsymbolchangesto
thedangeroustargetsymbolandashestoindicate
thatitisadangeroustarget.Acknowledgingthe
alarmwillremovethewarning.
Ifatargetislost,eitherbecausetheMARPAsoftware
haslostcontactwithit,orbecauseithasmoved
outofrange,anaudiblealarmissoundedanda
warningisdisplayed.Thesymbolwillchangetothe
losttargetsymbol.Acknowledgingthewarningwill
silencethealarmandremovethewarningandthe
losttargetsymbol.
MARPAtargetsrange
MARPAtargetacquisitionisonlyavailableatRadar
rangescalesofupto12nm,althoughtracking
continuesatallranges.
Ifyouchangetoasmallerrangescale,targetsmay
bebeyondtherangeofyourRadarscannerandwill
belost.Insuchcases,awarningindicatesthatthe
targetisoff-screen.
MARPAcontextmenu
WhenaMARPAtargetisselectedthecontextmenu
whichprovidesthefollowingpositionaldataand
menuitems.
Positionaldata
•CPA
•TCPA
•COG
•SOG
Menuitems:
Radarapplication
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