Drydock
Drydock
Drydock
AmitTomar(marineramit@gmail.com)
DryDock/Hull
Q.Whatpreparationsneedtobedonebeforedrydock?
Preparednessfordrydockwillstartwellinadvanceofthedrydock.Thepreparednesswillincludethefollowing:
1)Howtochangeovermainengineandboilerindieseloil.
2)Howtochangetheshippowertoshorepowertakinginaccountofvoltageandfrequency.
3)RequirementofcoolingoffridgeandA/Cplant
4)Methodofsewagedisposal.
5)Securingofheavyweights.
6)Tanksandcofferdamstobesounded.
7)Chiefengineerandsecondengineerwhoaremanagementlevelpersonnelofengineroomdepartment,tomakearoughplantodelegate
responsibilityofvariousjobs.
8)Chiefengineerwilldelegateresponsibilityforarrangingsparesastheyarrive.
9)Personneltopreparetagsforvariousvalveswithjobnumberandfixthemonvalve.
10)Allsafetyaspectsdiscussedandsafetyprecautionstobefollowed.Allengineroompersonneltobebriefedaboutsafetyandaskedtocheckthe
shorepersonnelregardingsafeworkingculture.
11)Adaytodayworkreporttobemadeanddiscussedtocheckwhetheralljobsareproceedingasperscheduleorthereissomedelay.Ifsamelook
intothem.
12)Chiefengineerandsecondengineertodivideandcoordinatevarioussurveyswhichtheywilloversee.
Nowwhileundockingofvesselthereshouldbepropercoordinationbetweenshipandyardpersonnel.
1.Makearepairandmaintenancelist,createorobtainadrydockhandbookifrequired,andassignresponsibleshipstafftotheirdutiesonthelist.
Dividestaffintogroupstooverseetheworkcarriedoutbyyardgangs.
2.Allsparepartsmustbecheckedandrepairitemskeptreadyforuse.
3.Previousdrydockreportsshouldbestudiedandpreviousclearancemeasuresnoted.
4.Cleanengineroomtanktopandbilges.
5.Preparesewagetreatmenttanks,dirtyoiltanksandbilgetanks.
6.Flushingofbilgelinesistobecarriedoutpriortodrydock.
7.Theoilwaterseparatorfilterelementshouldberenewedandthesystemcheckedforsatisfactoryoperation.
8.Fortankers,allcargotanksarecleanedandgasfreed.
9.Minimumbunkers(FuelOilandFreshwater)andballastcarried.
10.Allheavyweightssecuredpriortodrydock.
11.Alltanksandcofferdamsmustbesoundedandrecorded.
12.Firefightingplansandsafetymeasuresdiscussedbeforedrydock
13.Firefightingequipmentonboardshouldbecheckedandkeptreadyforuse.
14.Emergencylightingandgeneratorshouldbetestedbeforeentry.
15.Escaperoutesmustbeclearlymarked.
16.Allvalvesandcheststobeoverhauledmustbeclearlymarked.
17.Shoreconnectionsforcoolingwaterandfirelinearetobereadied.
18.Mainengine,generators,andboilerarechangedovertodieseloil.
19.CO2totalfloodingsystemsaresecuredandlockedbeforeentry.
20.Vesselmustapproachdockwithevenkeel.
Q.Statefourmostimportantdrawingstohavebeforedrydocking.
shellexpansionplanplatenumbering
dockingplanitshowsthingslikedrainplugs,seaboxes,underwaterattachmentsetc.Additionalinformationlikeindicationswherehullrepairsare
requiredcanbeaddedtoit.Thisallowsthedrydockshipmanagerstoplacetheblocksonwhichthevesselwillsit.
tankcapacityplanlocation,GM,vol
fireplan
midshipplan
halfbreadthplan
hydrostaticcurvesshipstability,tpc,etc
Q.Whatisthesignificanceof"halfbreadthplan"ofshipindrydock?
Aplanofashipshowingoutlinesofhorizontalsectionsorwaterlinesatvariouslevels,fromthemaindecktothekeelonlytheleftorrighthalfisshown.
Aplanofonesideofashipshowingbyhorizontallongitudinalsectionstheformsofthevariouswaterlines,railanddecklinesattheside,theframe
stations,andthebuttocklines
Q.Whatisdockingplanandshellexpansionplan?
Q.Statethetoolsneededbeforedocking,indrydockandpropellerremoval.
Q.Asa2ndengineerwhatallpreliminarychecksyouwilldoaftershiphasentereddrydockandwaterispumpedout?
Q.Whatisharmonisedsystemofsurvey?Whatallthingsareharmonised?Indrydock,whataretheharmonisedsurveycarriedout?Whichallitemsto
besurveyedinengineroom?
HarmonisedSurveySystemforShipsadoptedin1998byIMO,cameintoforceonFebruary3,2000,inordertoalleviatetheproblemscausedby
surveydatesandintervalsbetweensurveyswhichdonotcoincide,coveringinternationalshippingregulationsincludingthecodesandconventionsof
Marpol,Solas,Loadline,IBCcode,BCHcode,IGCcode.
Thefeaturesofharmonizedsystemare:
1.Oneyearstandardintervalbetweensurveys,basedoninitial,annual,intermediate,periodicalandrenewalsurveysasappropriate
2.Amaximumperiodofvalidityoffiveyearsforcargoshipsandoneyearforpassengershipscertificates.
3.Threemonthsextensionforcargoshipcertificatesontheharmonisedsurveysystemforships(oronemonthforshortvoyages)toenabletheship
tocompleteitsvoyage.
4.Whenanextensionhasbeengranted,theperiodofvalidityofthenewcertificateistostartfromtheexpirydateoftheexistingcertificatebeforeits
extension.
5.Therenewalsurveymaybecompletedwithinthreemonthsbeforetheexpirydateoftheexistingcertificate.
6.Atleasttwoinspectionsarerequiredtobeexecutedoftheshipsbottominafiveyearperiodmaximumintervalbetweentheinspectionshasalso
beensetatnotmorethan36months.
7.AcombinedCargoshipSafetyCertificateinsteadofexistingsafetyequipment,safetyconstruction,safetyradiocertificates.
FollowingcertificatescomingunderHSSSarecalledstatutorycertificates:
PassengerShipSafetyCertificate,includingRecordofEquipment
CargoShipSafetyConstructionCertificate
CargoShipSafetyEquipmentCertificate,includingRecordofEquipment
CargoShipSafetyRadioCertificate,includingRecordofEquipment
CargoShipSafetyCertificate,includingRecordofEquipment
InternationalLoadLinesCertificate
InternationalLoadLinesExemptionCertificate
InternationalOilPollutionPreventionCertificate
InternationalPollutionPreventionCertificatefortheCarriageofNoxiousLiquidSubstancesinBulk
InternationalCertificateofFitnessfortheCarriageofDangerousChemicalsinBulk
InternationalCertificateofFitnessfortheCarriageofLiquefiedGasesinBulk
CertificateofFitnessfortheCarriageofDangerousChemicalsinBulk
HarmonisedsurveyinDrydock
tailshaft,
underwaterhull,
intermediateshaftbearing,
propeller,
rudder,
anchorchain,
boiler,
mainenginebearings,pumps,andmachineriesunderCMS.
Q.Explaindetailsofhullinspectionindrydock.
ACrackedweld:
01.InformClasssurveyor&seekhisopinion.
02.TracethelengthokcrackbyDPTest
03.Oneinchfrombothsidesdrillcrackarrestingholes.
04.Gasfreethetankfrominside
05.GaugingofCracktobecarriedoutbygaugingelectrodetillbottomofthecrackisreached
06.Weldingelectrode,welder&proceduretobeclassapproved.LowHydrogenElectrodesareused.
07.Theaffectedportiontobeheatedto200degCbyflametorch&temptobenotedbyIRsensor.
08.Carryoutweldingfromeitherside
09.Theweldisagaintobeheatedbyflametorelievestress&coveredwithinsulationtapestoreducecoolingrate.
10.Weldtobeinspected&arrestholestobewelded
11.Radiographytestistobecarriedout.
12.Hosetesttobecarriedout
13.Primer&painttobeapplied.
Severeindentationinwayofframe:
01.Itcannotbetoleratedsohastobecroppedoffalongwithbendframe&renewed.
02.Put2smallsizeplates&weldittoframe(tag)withactualsizeplate.
03.Heating&stressrereleasingtobecarriedout.
04.Radiography&Hosetestoftheweldtobecarriedout.
SurfacessufferingfromgeneralCorrosion:
01.Gaugingtobecarriedout&if20%iseatenawayplateneedstoberenewed.(decidedbyclasssurveyor)
02.Onlythingtobedoneiscleanthesurface,coatwithprimer,antifouling&anticorrosivepaints.
03.AddZincAnodes.
BilgeKeelFractured?
01.Cropthedamagedpart&renew.
Q.Explainprocedureofmeasurementofship'shullthicknessandroughnessatdifferentplaces.
hullroughnessanalyser
Q.Duringhullinspection,youfoundexcessivecorrosiononhullplateandframe,whatwillbeyourcourseofaction?
Q.Explainmethodsofsurfacepreparationofhull.
weathering,pickling,sandblasting
primer,binder(3coats)
Q.Whatchecksaredoneonanchors?
Allanchors>=76kg(wt.istakenincludingshacklebutexcludingstock)mustbetestedandissuedwithatestcertificate.
Weightischeckedif10%less,anchorshouldberenewed
Anchorheads,flukesandshanksshouldbesurfaceexaminedforcracks,corrosion,bends
Anchorheadcrownpinsandanchorshacklepinsshouldbehammertested,hardenedupifslack,orrenewedifexcessivelywornorbent
Swivelsiffitted,shouldbecloselyexaminedsofaraspossibleinwayofthethreadedconnection,asmanyhavebeenlostinserviceduetoconcealed
wastageinthisarea.Ifindoubttheswivelshouldberecommendedtoberemoved.
"U"typeconnectingshacklesshouldbeexaminedforexcessiveneckwear,slacknessinthepinsandforshearingofkeeperpins.Thepinmustbea
snugfitallaroundintheseshackles,otherwisethekeeperpinmayshearwhenastrainisputonthechain.
Initialtestscarriedoutonanchoraftermanufacture:
Allanchorsaresubjectedtoproofstrainandstresstest
Thefollowingtestsareconductedoncaststeelanchorsonly(wroughtironorforgedsteelanchorsarenotsubjectedtothesetestsastheyareforged
fromredhotslabbyhammering):
Droptest
Anchorisdroppedbothendonandsideonfrom12ftor3.6mheightonanironorsteelslab
Percussiontest
Thepiecemustbehammeredalloverbya3.2kgsledgehammer,noflawshoulddevelopandaclearsoundshouldcome.
Bendingtest
Anadditionalpieceofmetal20cmlongiscastwiththepiecetobetestedandiscutawayforthistest.Thispieceisthenturneddownto2.5cmin
diameterandbentcoldbyhammeringthroughanangleof90degoveraradiusof3.75cm,nofractureshouldappearatall.
Q.Whatarethechecksdoneanchorchaincables?
Approvedtestingestablishmentsaretheretoacceptchaininlengthof27.5m
3linkstobecheckedperchainlength(1chainlength=27.5m),ifmeandia<0.88D,chainlengthtoberenewed
checklength
lookforbrokenlinks,corrosion
Anchorchaincableshouldbesurfaceexamined,hammertestedandlooseormissingstudsreplacedbyweldingatoneendofthestudonly,atthe
endofthestudoppositethelinkbuttweld.
TherestofthechaincableshouldbefurtherexaminedforexcessivewearandgaugedifnecessarytoensurecontinuedcompliancewiththeRules.
Verifythatthenumberofshotsofanchorchainasfittedportandstarboard,equalthetotallengthrequiredbytheClassificationRuleEquipment
Numeral.
Q.Explainseachestinspection.
heatingcoil,
anode,
grating,
marinegrowth
MGPSsystem
steamnozzle
valve
Q.Howanodeisfittedtoshipshull?
Q.Aftergroundingvesselrefloated,as2/EwhatallchecksyouwillcarryoutonM/E?
Q.Indrydock,tankplughasbeenrenewedandonly2hoursleftforflooding,howwillyouchecktheintegrityoftheplug?
Q.FinalInspectionbeforeUndocking?
Checkforfollowing:
Paintworkiscompleted.
Hullrepairiscompleted.
AllTankplugsareinplace.
AllAnodesarefitted,grease/paperusedtocoverthemduringpaintingisremoved.
EchoSounderTransduceriscleanedofpaper&grease.
Propellerropeguardisfittedproperlyinplace.
Oilisnotleakingfromsterntube.
Propellerisfreefrompaint&freefromanyotherobject.
Checkfreedomofmovementofrudderwithsteeringgear,smoothmovement.
Jumping&Pintleclearancestaken.
Rudderplugsareinplace.
SeaGridsareinplace&securedproperly.
Ensureallseav/v'sareshut.
Ensurealltanksareatsamelevelaswhenentry~tomaintainsametrimwhenrefloating.
Propeller
Q.Incontrollablepitchpropellertypes,whichoneisthebest,bossoneortailshaftoneandwhy?
Q.What3typesofpropellersareinuse?Givematerialofeach.Whyisdifferentmaterialforsmallshippropeller?
Q.Howtofindpitchofthepropellerindrydock?
Q.Discussdesigningaspectsoftakingthecantileverloadofpropeller.
Q.Explainkeylessandkeyedpropeller.
AdvantagesofKeylesspropeller:
thestressraisersatthefwdendoftheshaftkeywaydonotexist,shaftisstrongerandhasgreaterfatigueresistance
anincreaseinthecoefficientoffrictionavailablefortorquetransmission
acontrolleddegreeofinterferencefit
areductionintheallowancerequiredfortemp.ascoefficientofexpansionforC.I.sleeveasthatoftheshaft
fittingandbeddingiseasy,shaftoflesserdiawillsufficeforsameengineandship
Q.Explainremovalmethodofkeylesspropeller(pilgrimnutmethod).
Q.Howiskeylesspropellerfitted,explaintighteningprocedureswithgraphsanddiagrams.Whatparameterstocheckwhiletightening?
Q.Propellerfitbyshorepeople,howwillyouconfirmthatfittingiscorrect?Whatallchecksyouwillcarryout?
Q.Whatwillyoucheckasa2ndengineerbeforefittingakeyedpropeller?
Thefithastobecheckwithkeyinplace
2.thesealtostopwateringressmustbethoroughlychecked
Q.Whatisbeddingofpropeller?
Toachieveagoodgrip,agoodbeddingcontactbetweensleeveandshaftisobtainedbeforemountingthesleeveinthepropellerboss.After
machining,thesleeveispushedontothetailshaftandthenjackedoff,anyhighspotsareidentifiedandremovedfromthesleevebyhandgrinding.
Theprocessmayberepeateduntilbeddingcontactofatleast85%ofthetotalareaofthetaperedsurfaceofthepropellershaftisachieved.Priorto
finalpushupthefittingsurfacearehandrubbedwith100gritemeryclothandthendegreased.
Q.Whatisinterfencefitinpropeller?
Q.Whatallchecksarecarriedoutonpropellerindrydock?
ropeguard
lossofblades
bendingofblades
cracks(dyepenetrationtest)
pittingandcavitationmarks
corrosionanderosion
propellerdrop
Q.Whatispropellerdrop?Whereandhowtomeasure?Stateitsmaximumvalue.
PropellerDrop:1mm/160mmdiameterofshaft
measuredbyPokerGauge
Q.Propellerfittedbyahorepeople,howtocomfirmthatfittingiscorrect?
Byseeingpushuptravel
Afterfittingpropellerurpushup,oilpressurewillbeengravedonboss...afterfittingjusnotethetempandseethemakersgraph,fromwhichu
checktherespectivehydrailicpressureandpushup...nwthisvaluehastomatchwiththeengravedvalue
Rudder
Q.Whyrudderangleisrestrictedto35degrees?
dragforceinc.turningforcedec.
Q.Whatisturningmomentandwhyitismoreinaheadthanasterndirection?
Q.Indrydock,whatallrudderchecks&maintenancetobedone,differentclearanceswithvaluesin%ofitssize,maximumvalues?
Rudder:
1.WhenDockingistakingplaceobserverudderifanywateriscomingout.
2.Aftercompletionofdockingremovetop&bottomplug&checkforwater.
3.Hammerrudderplatetochecksound&conditionofrudderplates.
4.Ifshipismorethan5yrs.oldClassSurveyormayinsistonGuagingreport
5.CheckconditionofZnblockfittedontherudder.Ifcompletelywornedoutaddfewmorethanlasttime.
6.CouplingbetweenRudder&RudderStockcementtobechecked,chipoffthecement&checkconditionofPalmBolts.
7.PutRudderinmidshipposition&seeactualpositionoftherudderw.r.t.shipthiswillhelpidentifytwistingofrudderstock.
8.Pintleclearancetocheck.
9.JumpingClearance
10.Weardown&RudderdroptobecheckedinDryDock.
11.Visualinspectionforruddercorrosion,pitting,cracksetc.
ShellPlating:
01.CheckforBuckling,Corrosion,Dents&Cracks.
02.CheckconditionofAnodes:Ifcompletelywornout~moreisrequired/Ifnotworn~notconnectedproperly
03.CheckSeagrowth:Ifhigh~Antifoulingpaintwasineffective.
Rudderrepair
SlotWeldingtobecarriedout.Plates,Weldingrods,weldersQualification&procedureofrepairingmustbeapprovedbyclasssurveyor.Secondplate
iscalledWrappingPlate/CoverPlate.Plateispreparedbymarkingoftheframesonit&thenslotsarecut.Thentheplateisbendontheframework&
isweldedtotheframes.Slotsarefilledwiththeweld.Theseweldsareground&madesmooth.
PressureTestingofRudder:
1.Gravitymethod:Fillwaterinrudderupto2.46mabovetopofrudder&observeit.Waterlevelshouldnotdrop.
2.HoseTest:Drainplughastoremoved&hoseisappliedontheslotwelds&observeifwateriscomingfromthedrainplug.Thisistobedone
beforegravitymethod.
3.Coating:Opentopplug,putbottomplugwithcock.Fill50%waterinside&20%withpaint.Drainwaterslowlybycock.Thisiscalledfloatcoat
painting.
Q.Stateallclearancesofrudder,theirsignificanceandmax.values.Whatisjumpingclearanceanditssignificance?Whereisjumpingbarlocated?
JumpingClearance:6mm,allowanceatRhapsonslide:16~19mmPintleClearance:1.1~3.3mm
Q.Whatdoesrudderdropindicate?Howtotakerudderdrop,wheredowemeasureitandtoolformeasuringit?
trammelgauge
Q.Whattakestheweightofrudder?Howmanypintlesandtheiruse?Ifpintleweardownishigh,howtorepairit?
Q.Howtoreplaceruddercarrierbearing?
SternTube/Shaft
Q.Discusssterntube/tailshaftsurveyindetails.Whyheadis2.46monly?
Q.Explainsterntubesealingarrangementindetail.Drawcrosssectiondiagramoflipseal.Howleakageisavoided?
Sterntubeissupportedbyaftpeakbulkheadandsternframe,andalongthelengthbynarrowfloorsorbracketstowhichaftframingisattached
Q.Explainshaftseallinerfittingarrangement.Whatisthematerialofliner?Howtoremoveandcheckstobemade?
Q.Statesterntubebearingclearances.
Q.Howwillyoucometoknowifshaftsealisleaking?Howwillyourectifytheleakageinport,(youcantgotodrydockandhavenospareseal,
underwaterrepairisallowed)?
Maintainlowhead.
Usehigherviscousoil.
Replenishperiodicallytocounterfortheoilloss.Drainoffthewaterperiodically.Trytoremoveforeignparticlesbychangingdirectionofshaft.
Q.Howtailshafttaperendandkeyedareaischecked?Whyinterferencefitboltsareprovided?