Raymarine LIGHTHOUSE 4 - Polar Laylines; Wind Shift Data

–Catamaran(leeway10°–20°)
Note:Ifyouselectaboattypeotherthanonewithstatedleeway
anglesthennoleewaycorrectionwillbeappliedinthecalculations.
•[Displaylaylinesonthischart]—Enablesanddisablesdisplayoflaylines
thecurrentChartappinstance
.
•[Adjustfortides]—Whenenabledlaylinecalculationswilltakeintoaccount
tidalflow.
Polarlaylines
Thefollowingoptionsareavailableforpolarlaylines:
•[Sailperformance]—Usethisoptiontoswitchtousingspecifiedangles
[Fix edangles]ortodisablelaylines[Notset].
•[Polar]—Browsethelisttofindtheboatmodelthatmostcloselymatches
yourownboat.Ifyourboatisnotlisted,orifyouhavepolardatayouwould
likeincluded,pleasesendanemailtopolars@raymarine.com.
•[Boattype]—Selectingtheappropriateboattypewillprovidemore
accurateleewaycalculations.Onlyselectoneofthefollowingboattypes:
–Sailcruiser(leeway5°–10°)
–Racesail(leeway(3°–5°)
–Catamaran(leeway10°–20°)
Note:Ifyouselectaboattypeotherthanonewithstatedleeway
anglesthennoleewaycorrectionwillbeappliedinthecalculations.
•[Displaylaylinesonthischart]—Enablesanddisablesdisplayoflaylines
thecurrentChartappinstance
.
•[Adjustfortides]—Whenenabledlaylinecalculationswilltakeintoaccount
tidalflow.
Windshiftdata
AsTrueWindDirection(TWD)isconstantlychanging,thepositionofthe
laylineschangesovertime.Thesechangesareshownaslightercolored
shadedtriangleswhichrepresentthevariationofTWDoveraspecifiedtime
period.
•WithTWDholdingatthehighendofitsrangeofvariation,thevesselcan
tacktostarboardandwilllaythewindwardorleewardmarkasitenters
theshadedarea.However,ifTWDshiftsbacktowardsthelowerendofits
rangeofvariation,thevesselwillfallshortofthelaylineandmayhaveto
performextratackstoreachthewaypoint.
•WithTWDholdingatthelowendofitsrangeofvariation,thevesselcan
tacktostarboardandwillonlylaythewindwardorleewardmarkwhenit
reachestheendoftheshadedarea.However,ifTWDshiftsbacktowards
thehighendofitsrangeofvariation,thevesselwilloverstandthewindward
orleewardmarkandmayneedtotravelfarthertoreachthewaypoint.
•Dependingonthesituation,thenormalcourseofactionwouldbetotack
whenthevesselishalfwaythroughtheshadedarea.Howeverthismay
notbetheshortestorquickestroute.
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