3.RudderandcoursecontrolRudderandrudderforceTurningabilityDirectionalstabilityTestofmaneuverabilityIMOinterimstandardsforshipManeuverability

3.1rudderandrudderforce

RudderRuderforce3.1.1RudderconventionalrudderBeckerorflaprudderJastramrotorrudderSchillingrudder3.1.1RudderBeckerorflaprudderFig.3.2Beckerflaprudder3.1.1RudderJastramrotorrudderFig.3.3Jastramrotorrudder3.1.1RudderTheSchillingrudder3.1.1therudderforce

3.1.1therudderforcePN＝576.2ARυR2sinδ

χ/b＝0.195+0.305sin

3.1.3steeringwiththerudder

TherudderitselfdoesnotprovidetheentireforcerequiredforachangeofcourseFig.3.5SteeringwithRudder3.1.3steeringwiththerudderStall3.2Turningability

TurningCircle

Factorsaffectingturn

PivotpointCoupledmotionwhenturn3.2.1TurningCircle

3.2.1TurningCircleAdvanceTransferTacticaldiameterFinaldiameterKickDriftangleDriftangle

3.2.2FactorsaffectingturnEquationforturning3.2.2Factorsaffectingturn

Structuraldesignandlength

Draughtandtrim

MotivepowerDistributionandstowageofcargo

Evenkeelorlistover

Availabledepthofwater

Rudderangle

Driftangleandinfluencingforces

3.2.2FactorsaffectingturnStructuraldesignandlength--Thelongertheshipgenerally,thegreatertheturningcircle--ThesmallertheclearancebetweenrudderandhullthemoreeffectivetheturningactionBlockcoefficient3.2.2FactorsaffectingturnMotivepower

Theturningcirclewillnotincreasebyanyconsiderablemarginwithanincreaseinspeed,becausethesteeringeffectisincreasedoverthesameperiodTheeffectsofspeed3.2.2FactorsaffectingturnDistributionandstowageofcargo

noeffectsontheturningcircle;butthevesselwillrespondmorereadilyifloadsarestowedamidships3.2.2FactorsaffectingturnDraughtandtrim--Thetrimbytheheadwilldecreasethediameterofturningcircle

--Thedeeperdraftwillmakethevesselmoresluggish3.2.2FactorsaffectingturnEvenkeelorlistover

Ifavesseliscarryingalist,itcanbeexpectedtomakealargerturningcirclewhenturningtowardsthelist,andvice-versa3.2.2FactorsaffectingturnAvailabledepthofwater:theadvance,thecorrespondingfinaldiameter,thetransferwillbeincreasedasthedepthofwaterbeshallowerRudderangle

rudderangle:small,alargeturningcirclewillresult,withlittlelossofspeed;largerudderangle,accompaniedbyalossofspeed.3.2.2Factorsaffectingturn3.2.2FactorsaffectingturnWhencompletingaturningcircle,becauseoftheangleofdrift,thesternquartersareoutsidetheturningcircleareawhilethebowareaisinsidetheturningcircle.3.2.3Pivotpoint

apointonthecenterlineaboutwhichtheshipturnswhentherudderisputover.?ofthelengthfromtheforward(orstern)

Fig.3.7ThePivotPointPP1/4L1/4La)Shipstopped,onevenkeelb)Makingheadwayc)Makingsternway3.2.4Coupledmotionwhenturn

Lossofspeedonturn

Heelonturn

3.2.4CoupledmotionwhenturnLossofspeedonturn3.2.4CoupledmotionwhenturnHeelonturn

Fig.3.9ForcesproducingheelwhenturningGFrFhRudderHKEHeelonturn3.2.5theuseofturningcircleelementsinshiphandlingTheadvanceThediameterofturningcircleThekick:manoverboardThereach:thelatestpointwheretheruddermebeused

3.3Directionalstability

Inherentdynamicstability

Initialturningability,

Coursekeepingabilityandyawcheckingability

3.3Directionalstabilitydynamicstabilitystaticalcoursestability3.3.1dynamicstabilityFig.3.10PathofstableandunstableshipUnstableshippathStableshippathUnstableshippathstaticalcoursestabilityTheresolutionoftheequation3.3.2Factorsaffectinginherentdynamicstability

3.3.2FactorsaffectinginherentdynamicstabilityT=IZZ/amassanditsdistributiontheunderwaterformofhull

trimDraftblockcoefficients3.3.3Initialturningability,

Coursekeepingabilityandyawcheckingability

Initialturningability:thechange-of-headingresponsetoamoderatehelm;course-changeabilityCourse-keepingability:ameasureoftheabilityofthesteeredshiptomaintainastraightpathinapredeterminedcoursedirectionwithoutexcessiveoscillationsofrudderorheadingYawcheckingability:

ameasureoftheresponsetocounter-rudderappliedinacertainstateofturningFactorsaffectingthe3.3.43.3.4factorsaffectingcoursekeepingandchangingandyawcheckingability

Factorsaffecting…3.3.4factorsaffecting…RudderangleRudderareaLoadingconditionSpeedwind,current,wave,shallowwaterandevenhullfouling3.4Testofmaneuverability

ModeltestTestconditions

Trialofsomerequiredmaneuvers

Spiralmaneuver

Pull-outmaneuver

3.4Testofmaneuverability3.4Testofmaneuverability3.4Testofmaneuverability3.4Testofmaneuverability3.4.1TestconditionsEnvironment

Deepunrestrictedwater:morethan4timesthemeandraught.Wind:nottoexceedBeaufort5.Wave:nottoexceedseastate4.Current:uniformonly.3.4.1TestconditionsLoading

Fullloaddraughtandevenkeel

5%deviationfromthatdraughtandevenkeelOrinaballastconditionwithaminimumoftrim3.4.1Testconditionsspeed:atleast90%oftheship'sspeedcorrespondingto85%ofthemaximumengineoutput3.4.1TestconditionsHeading:headtothewindduringtheapproachrunEngine:bekeptconstant(exceptedrequired)Approachrun:

conditionsmustbefulfilledforatleasttwominutesprecedingthetest3.4.2Turningcirclemaneuversteadycourseandspeed

recordingofdatamaximumrudderangleRudderandenginecontrolsarekeptconstantduringtheturn3600~720°changeofheading3.4.3

Zig-zagmaneuver

SteadycourseandspeedTherecordingofdatastartsRudderisorderedto100tostarboard/portWhentheheadinghaschangedby100offthebasecourse,therudderisshiftedto10°toport/starboardWhentheheadingis100port/starboardoffthebasecourse,rudderisreversedasbefore.Theprocedureisrepeatednolessthantwice3.4.3

Zig-zagmaneuver3.4.4Spiralmaneuver

steadycourseandspeeddatarecordingrudderisturnedabout15°andhelduntilth