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EM 712
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Kongsberg EM 712 Installation Manual

KongsbergEM712
Multibeamechosounder
Installationmanual
401027/B
June2018©KongsbergMaritimeAS
Copyright
TheinformationcontainedinthisdocumentremainsthesolepropertyofKongsbergMaritimeAS.Nopart ofthisdocumentmaybecopiedorreproducedinanyformorbyanymeans,andtheinformationcontained withinitisnottobecommunicatedtoathirdparty ,withoutthepriorwrittenconsentofKongsberg MaritimeAS.Thedocument,oranypartofit,maynotbetranslatedtoanyotherlanguagewithoutthe writtenapprovalfromKongsbergMaritimeAS.
Disclaimer
KongsbergMaritimeASendeavourstoensurethatallinformationinthisdocumentiscorrectandfairly stated,butdoesnotacceptliabilityforanyerrorsoromissions.
Warning
Theequipmenttowhichthismanualappliesmustonlybeusedforthepurposeforwhichitwasdesigned. Improperuseormaintenancemaycausedamagetotheequipmentand/orinjurytopersonnel.Allusers mustbefamiliarwiththecontentsoftheappropriatemanualsbeforeattemptingtoinstall,operate, maintainorinanyotherwayworkontheequipment.
KongsbergMaritimeASdisclaimsanyresponsibilityfordamageorinjurycausedbyimproperinstallation, useormaintenanceoftheequipment.
Supportinformation
Ifyourequiremaintenanceorrepair,contactyourlocaldealer.Y oucanalsocontactususingthefollowing address:km.hydrographic.support@kongsberg.com.Ifyouneedinformationaboutourotherproducts, visithttp://www.km.kongsberg.com.
KongsbergMaritimeAS
www.kongsberg.com
Installationmanual
Tableofcontents
ABOUTTHISMANUAL..............................................................7
KONGSBERGEM712................................................................9
Systemdiagram0.5x0.5degreessystem.......................................................................10
Systemunits.....................................................................................................................12
Transducerdescription...........................................................................................12
TransmitterUnitdescription...................................................................................13
ReceiverUnitdescription.......................................................................................13
ProcessingUnitdescription....................................................................................14
HydrographicWorkStationdescription.................................................................14
PREPARATIONS.....................................................................15
Tools,equipmentandconsumablesrequiredforEM712installation.............................15
Personnelqualications...................................................................................................16
Sonarroomrequirements.................................................................................................17
Environmentalrequirements..................................................................................17
Sizeandaccessrequirements.................................................................................17
Requirementsforinsulation,heatingandventilation.............................................18
Requirementsforelectricalinstallations,cablesandcommunication...................18
Wheretoinstallthetransducer........................................................................................20
Introductiontotransducerlocation.........................................................................20
Mountthetransducerdeep.....................................................................................20
Avoidprotrudingobjectsnearthetransducer.........................................................21
Keepthetransducerfarawayfromthepropellers.................................................22
Chooseatransducerpositionfarawayfromthebowthruster(s)...........................22
Summaryandgeneralrecommendations...............................................................22
Acousticnoise..................................................................................................................24
Contributingfactors................................................................................................24
Selfnoise................................................................................................................25
Ambientnoise.........................................................................................................28
Electricalselfnoise................................................................................................28
Somemeanstoreduceacousticnoise....................................................................28
INSTALLINGTHETRANSDUCER.............................................31
Transducerdescription.....................................................................................................32
Transducerinstallationprinciples....................................................................................34
Introduction............................................................................................................34
Gondola..................................................................................................................36
Blister.....................................................................................................................37
Flushmounted........................................................................................................38
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Externalmountedwithfairings..............................................................................38
Transducerinstallationsummary.....................................................................................39
Manufacturingandinstallingthecasings........................................................................42
Designing,manufacturingandmountingthesteelconduits............................................44
Installingthemountingframes........................................................................................47
Installingthetransducersintothemountingframes........................................................49
Rulesfortransducerhandling..........................................................................................53
Paintingthetransducerface.............................................................................................54
Approvedanti-foulingpaints...........................................................................................56
INSTALLINGTHEEM712HARDWAREUNITS.........................58
TransmitterUnit...............................................................................................................59
InstallingtheTransmitterUnit...............................................................................60
RIO-Pboard-dipswitchsetting............................................................................62
ReceiverUnit...................................................................................................................63
InstallingtheReceiverUnit....................................................................................64
ReceiverUnit-dipswitchsetting..........................................................................66
ProcessingUnit................................................................................................................68
CBMFboard-dipswitchsetting...........................................................................69
DRAWINGFILE......................................................................70
216148EM712TransducerTX1dimensions.................................................................71
221048EM712TransducerTX2dimensions.................................................................73
219621EM712TransducerRX1dimensions.................................................................75
216146EM712TransducerRX2dimensions.................................................................77
223137EM712Transducermountingframe-0.5degrees............................................79
223139EM712Transducermountingframe-1degree.................................................81
223273EM712Transducermountingframe-2degrees...............................................83
317812EM712Casingw/mountingframe-0.5degrees...............................................85
320320EM712Casingw/mountingframe-1degree....................................................86
375817EM712Combinedcasingw/mountingframe-1degree...................................87
331369EM712Casingw/mountingframe-2degrees..................................................88
396402EM712TransmitterUnitdimensions.................................................................89
212984EM712TransmitterUnitmountingbracket.......................................................90
396428EM712ReceiverUnitdimensions.....................................................................91
385422ProcessingUnitdimensions................................................................................92
378828HydrographicW orkStationdimensions.............................................................93
371591Rackinstallationkitdimenisons.........................................................................95
370275RemoteControlUnit(K-REM)dimensions.......................................................96
373962RemoteControlUnit(K-REM)wiringdiagram.................................................98
DIMENSIONALSURVEYINGANDALIGNMENT........................99
Aboutdimensionalsurveyingandalignment................................................................100
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Dimensionalsurveying..................................................................................................100
Alignment......................................................................................................................101
Calibration.....................................................................................................................102
Vesselcoordinatesystem...............................................................................................102
CABLELAYOUTANDINTERCONNECTIONS...........................104
Readthisrst.................................................................................................................105
Cableplans.....................................................................................................................106
Cableplan,ProcessingUnit.................................................................................107
Cableplan,TransmitterUnit................................................................................108
Cableplan,ReceiverUnit,0.5degree..................................................................110
Topsidecableplan................................................................................................113
ListofEM712cables....................................................................................................113
Transmittransducercables.............................................................................................119
Receivetransducercables..............................................................................................123
Clocksynchronization(1PPS).......................................................................................127
Externalsynchronization...............................................................................................129
HydrographicWorkStationrearconnectors(MP5810)...............................................132
Cabledrawingsandspecications.................................................................................134
RS-232seriallineusingthreewiresandRJ45connector....................................135
RS-422seriallineusingvewiresandRJ45connector......................................136
AdapterforD-connectortoRJ45connectorforRS-422.....................................137
Clocksynchronisation(1PPS)usingacoaxcable...............................................138
Externalsynchronisation......................................................................................139
Remotecontroloverview.....................................................................................140
Remotecontrol.....................................................................................................142
RemoteControlusingK-Rem..............................................................................143
Dummyplugfornotusingremotecontrol...........................................................144
RemotecontrolofTransmitterUnit.....................................................................145
RemotecontrolofReceiverUnit..........................................................................147
TECHNICALSPECIFICATIONS..............................................151
Performancespecications............................................................................................152
Interfacespecications...................................................................................................154
Weightandoutlinedimensions......................................................................................158
Powerrequirements.......................................................................................................160
Environmentalrequirements..........................................................................................161
Alignmentspecications................................................................................................164
EQUIPMENTHANDLING.......................................................166
TransportingKongsbergMaritimeequipment...............................................................167
Liftingunitsandtransportationboxes...........................................................................168
Inspectionofunitsandtransportationboxesafterarrival..............................................170
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Specicationsforstoragepriortoinstallationoruse.....................................................171
Unpackinginstructions..................................................................................................173
Unpackingstandardpartsandunits......................................................................173
Unpackingmechanicalunits................................................................................174
Unpackingelectronicandelectromechanicalunits..............................................175
Unpackingtransducers.........................................................................................176
Specicationsforstorageafterunpacking.....................................................................178
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Aboutthismanual
Purposeofmanual
Thepurposeofthismanualistoprovidetheinformation,proceduresandbasicdrawings requiredforthephysicalinstallationoftheEM712.
Targetaudience

Aboutthismanual

Themanualisintendedfortechnicalpersonnel;suchasskilledshipyardworkers, electricians,qualiedengineersandnavalarchitects.Itisassumedthatyouunderstand thegeneralprinciplesofmaritimeelectronicequipment.Youmustalsobefamiliarwith computerhardware,interfacetechnologyandinstallationofelectronicandmechanical products.
Weassumethatyouarefamiliarwiththebasicacousticprinciplesofsoundinwater. Wealsoexpectthatyouhavesomeexperiencewithmultibeamand/orsinglebeamecho soundersinhydrographicapplications..
Installationinstructions
Youmustfollowtheinstructionsinthismanualtoensureoptimalperformance.Asa guide,installationproceduresarepresentedintheordertheymustbedone.
Theequipmentdescribedinthismanualincludesthecompletesystemwithrelevant cabinets.Unitsprovidedlocallybythecustomer,installationshipyardorlocal representativearenotdescribed.
Themanualalsodenestheequipmentresponsibility,andprovidesapplicable instructionsforunpackingandstorageofunits.
Note
Youmustfollowtheinstructionsgiveninthismanual.Ifnotitmayaffectthewarranty.
KongsbergMaritimeASwillacceptnoresponsibilityforanydamageorinjurytothe system,vesselorpersonnelcausedbyequipmentthathasbeenincorrectlyinstalledor maintained,orbydrawings,instructionsorproceduresthathavenotbeenprepared byus.
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KongsbergEM712Installationmanual
Installationdrawings
Theinstallationshipyardmustprovideallnecessaryinstallationdrawingsunless otherwisespeciedinthedeliverycontract.
KongsbergMaritimeASmay,onspecialorder,provideassistancetothesedrawings.
Note
Ifrequired,alldocumentsprovidedbytheshipyardforthephysicalinstallationof theEM712mustbeapprovedbythevessel’ snationalregistryandcorresponding maritimeauthorityand/orclassicationsociety.Suchapprovalmustbeobtainedbefore theinstallationcanbegin.Theshipownerandshipyarddoingtheinstallationare responsibleforobtainingandpayingforsuchapproval.
TheoutlinedimensionsoftheEM712unitsarefoundintheDrawinglechapter inthismanual.
Onlineinformation
ForinformationabouttheEM712andotherproductsfromKongsbergMaritime,visit ourwebsite.
•https://www.km.kongsberg.com
Registeredtrademarks
Observetheregisteredtrademarksthatapply.
Windows
®
isaregisteredtrademarkofMicrosoftCorporationintheUnitedStatesand
othercountries.
®
EM
isaregisteredtrademarkofKongsbergMaritimeASinNorwayandothercountries.
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KongsbergEM712
Topics
Systemdiagram0.5x0.5degreessystem,page10
Systemunits,page12

KongsbergEM712

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KongsbergEM712Installationmanual

Systemdiagram0.5x0.5degreessystem

ThesystemdiagramidentiesthemaincomponentsofabasicEM712system.Only themainconnectionsbetweentheunitsareshown.Detailedinterfacecapabilitiesand powercablesarenotshown.
AHydrographicWorkStation(HWS)
BInterfaces:
•Soundspeedsensor
•Tide
•Centerdepthoutput
CProcessingUnit(PU)
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DProcessingUnitinterfaces:
•Positioningsystems
•Attitude(roll,pitchandheave)
•Velocity
•Heading
•Clock
ProcessingUnitspecialinterfaces:
•Triggerinput/output
•Clocksynchronization(1PPS)
ETransmitterUnit
FReceiverUnit
GTransmittransducer
KongsbergEM712
HReceivetransducer
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Systemunits

Topics
Transducerdescription,page12
TransmitterUnitdescription,page13
ReceiverUnitdescription,page13
ProcessingUnitdescription,page14
HydrographicWorkStationdescription,page14

Transducerdescription

Atransducerisadevicethatconvertsoneformofenergytoanother.Inanechosounder systemthetransducerconvertsbetweenelectricenergyandsound.
TheEM712usesseparatetransducerarraysfor transmittingandreceivingsoundpulses.Both transducerarrayscanhaveoneormoremoduleswhich areassembledinmountingframes.
TheEM712transducermodulesareavailableinan icereinforcedversion.Formoreinformation,contact KongsbergMaritime.
Thetwotransducerarraysarenormallymountedas“T”or“L”congurationsunderthe vessel’shull(MillsCrossconguration).Thetransmittransducerarrayshouldbealigned paralleltothevessel’skeel.Thereceivertransducerarrayshouldbealigned90degrees onthekeel.Bothtransducerarraysshouldbehorizontalonaplaneonthekeel.
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TransmitterUnitdescription

TheEM712TransmitterUnithasalltransmitelectronics,likecontrolprocessors,power ampliers,powersupply,capacitorbatteryandEthernetinterface.
TheTransmitterUnitisawall-mountedsteelcabinet withintegratedshockandvibrationabsorbers,designed forbulkheadmounting.One19inchsub-rackis containedinthecabinet.Thenumberofcircuitboards inthesub-rackwilldependuponthechosentransducer conguration.
TwistedpairEthernetisusedfordatacommunication withtheProcessingUnit.
TheTransmitterUnitisnormallylocatedina"sonar room"closetothetransducerarrays.
Fora0.5degreetransducer,oneTransmitterUnitisused.

ReceiverUnitdescription

TheEM712ReceiverUnithasallreceiveelectronics,likecontrolprocessor,ampliers, Analog-to-DigitalConverters,powersupplyandEthernetinterface.
TheReceiverUnitisasmallwall-mountedsteelcabinet withintegratedshockandvibrationabsorbers,designed forbulkheadmounting.Thenumberofcircuitboards willdependuponthechosentransducerconguration. TwistedpairEthernetisusedfordatacommunication withtheProcessingUnit.
TheReceiverUnitisnormallylocatedina"sonar room"closetothetransducerarrays.
Fora0.5degreetransducer,twoReceiverUnitsare used.
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KongsbergEM712Installationmanual

ProcessingUnitdescription

TheEM712ProcessingUnitisprovidedtoprocessthesignalstoandfromthe TransmitterandReceiverUnits.
TheEM712ProcessingUnitisanindustrial computerusingbothCOTS(commercialoff-the-shelf) componentsandcustommadecomponents.Theunitis designedandtestedforruggeduse.
TheProcessingUnitperformsthereceiverbeamforming,bottomdetection,andmotion andsoundspeedcorrections.Itcontainsallinterfacesfortime-criticalexternalsensors suchasvesselattitude(roll,pitch,headingandheave),vesselpositionandexternal clock.Morethanonesensorofeachtypemaybeconnectedsimultaneously,withonein useandallofthemlogged.
TheProcessingUnitcontrolstheTransmitterandReceiverunitsviaEthernet communication,andisalsointerfacedtotheOperatorstationviaEthernet.
The48VoutputfromtheProcessingUnitcanbeusedforremoteon/offcontrolofthe TransmitterandReceiverUnits.

HydrographicWorkStationdescription

TheHydrographicWorkStationistheoperatorstationfortheEM712.
Adedicatedmaritimecomputerisprovidedwiththe EM712Multibeamechosounder.Itissetupwith allnecessarysoftware.
TheHydrographicWorkStationisbasedonthe Microsoft
TheHydrographicWorkStationisnormallymounted neartheoperatorworkspace.
®
64-bitWindows®7operatingsystem.
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Preparations

Topics
Tools,equipmentandconsumablesrequiredforEM712installation,page15
Personnelqualications,page16
Preparations
Sonarroomrequirements,page17
Wheretoinstallthetransducer,page20
Acousticnoise,page24

Tools,equipmentandconsumablesrequired forEM712installation

InordertodotheEM712installation,allnecessarytoolsandequipmentformechanical work,cabinetinstallationandelectricalwiringmustbeavailable.
Itisnotpracticaltoprovideadetailedlistofallnecessarytoolsandequipment.Y oumust beequippedwithastandardsetoftools.Thistoolsetmustcomprisethenormaltoolsfor electronicandelectromechanicaltasks.Thisincludesdifferentscrewdrivertypes,pliers, spanners,acablestripper,asolderingironetc.Eachtoolmustbeprovidedinvarious sizes.Werecommendthatalltoolsaredemagnetizedtoprotectyourequipment.
However,youmustmakesurethatthefollowingspecializedtoolsareavailable.
•Allnecessarytoolsandconsumablesrequiredforwelding
•Allnecessarytoolsandconsumablesrequiredforphysicalinstallationofunits,
cabinetsandracks
•Allnecessarytoolsandconsumablesrequiredforelectricalinstallations
•AnarticulatedjackorsimilararrangementcapableofliftingtheindividualEM712
units
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Note
Wheneverspecicconsumablesorspecialtoolsortestinstrumentsarerequired,these areidentiedintherelevantprocedure(s).
Relatedtopics
Weightandoutlinedimensions,page158
Personnelqualications
TheinstallationoftheEM712isademandingtask.Itisveryimportantthatthe personnelinvolvedintheinstallationtasksarecompetentandexperiencedcraftsmen.
Asaminimum,thefollowingcertiedcraftsmenmustbeavailable.
•ServiceengineerfromKongsbergMaritime
•Welders
•Electricians
Note
Thequalityoftheweldingiscriticaltothesafetyofthevessel.Weldingmustonlybe donebyacertiedwelder.
Ifapplicable,thenalinstallationweldsmustbeapprovedbythevessel’ snational registry,thecorrespondingmaritimeauthorityand/orclassicationsociety.Observethe relevantrulesandregulationsrelatedtowelding.
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Preparations

Sonarroomrequirements

Topics
Environmentalrequirements,page17
Sizeandaccessrequirements,page17
Requirementsforinsulation,heatingandventilation,page18
Requirementsforelectricalinstallations,cablesandcommunication,page18

Environmentalrequirements

TheEM712unitsmustbeinstalledinadryanddust-freeenvironment.Theunitsarenot fullyprotectedagainsthumidity,dustorwater.
Itisimportantthatthesonarroomiskeptdry.TheEM712unitsmustnotbeexposed toexcessivetemperatures,moistureorhumidity.Suchconditionscancausecorrosive attacksandsubsequentfailurestotheelectroniccircuitry.Visitthesonarroomat regularintervalstochecktemperatureandhumidity,andtakethenecessaryactions iftheenvironmentalconditionsarepoor.
ObservetheenvironmentalspecicationsrelatedtotheEM712units.
Relatedtopics
Environmentalrequirements,page161

Sizeandaccessrequirements

Awelldesignedsonarroomwithawellttedsizeandeasyaccessreducestheriskof corrosion,andsimpliesmaintenance.Thisincreasessystemreliability.
Thesonarroommustbelargeenoughtohouseallthesystemunits.Theroommust provideenoughspacetoallowefcientmaintenance.Youmustbeabletokeepallthe cabinetdoorsfullyopenwithoutunduerestrictiontoyourmovements.
1Theroommustnotbeusedforanyotherheavymachinery.
2Theroommustnotbeunnecessarilyobstructedbygirders,pipesetc,whichmay
causeinstallationproblemsorimpedemaintenance.
3Thesonarroommustbeaccessibleunderallconditionsatseaorataberth.
4Alldoorsorhatchesmustbedesignedsothatthetoolsandequipmentcanbe
removedwithoutbeingdisassembled.
Relatedtopics
Weightandoutlinedimensions,page158
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KongsbergEM712Installationmanual

Requirementsforinsulation,heatingandventilation

Thebulkheadsinthesonarroomshouldbeinsulatedandprovidedwithaninteriorwall tothedeck.Theroomshouldbeequippedwithheaterandconnectedtothevessel's ventilationsystem.
Heatingrequirements
Heatingisaneffectivemethodforreducinghumidity.Theheaterinthesonarroommust dimensionedtomaintaintheequipmentwithinitsenvironmentaltolerances.
ObservetheenvironmentalspecicationsrelatedtotheEM712units.
Ventilationrequirements
Thesonarroomshouldbeconnectedtothevessel'sventilationsystemtoensureasupply ofcoolingair.Ifaventilationsystemisnotavailable,installtwo3”pipesfromthesonar roomtoasuitablefreshairlocationondeck.
Thefreshairshouldentertheroomasclosetotheooraspossible,andshouldbe extractedfromashighaspossible.Afunnelshapeddrip-collectormustbemounted belowtheventpipestodivertmoisturetothebilge.Onthemaindeck,thebest ventilationisprovidedwhentheoutletpipeisatleastfourmetershigherthantheinlet pipe.Tokeepoutseawater,rainandspray,theventilationpipesmustbettedwith goosenecksoranequivalentdesign.
Note
Ifthevesselislikelytooperateintropicalconditions,asuitableairconditioningsystem mustbeinstalled.Theairconditioningsystemmustbeabletoprovideanambient temperaturethatdoesnotexceedthemaximumoperatingtemperaturesoftheEM712 unitsthatareinstalledintheroom.
Relatedtopics
Environmentalrequirements,page161

Requirementsforelectricalinstallations,cablesand communication

Theelectricalinstallationsinthesonarroommustmeetminimumrequirementsto providesuitablelightsandsupplypower.
Lightrequirements
Thesonarroommustbeequippedwithsuitablelightingtosimplifytheinstallation andtoaidfuturemaintenance.
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Communicationrequirements
Thesonarroomshouldbeequippedwithatelephone,anintercomsystem,oranyother meansoforalcommunicationbetweenthesonarroomandthebridgeand/orcontrol room(s).
Powerrequirements
Eachunitinthesonarroomshouldbeprovidedwithaseparatecircuitbreakeronthe mainssupply.
Propervesselgroundmustbeprovided.
Aminimumnumberofadditionalelectricaloutletsmustbeprovidedforotherequipment.
Cablingrequirements
ThesonarroomunitsareconnectedtootherEM712unitslocatedindifferent compartmentsonthevessel.Theunitsmayalsobeconnectedtoperipheraldevices.If thesecablespassthroughhatchesorareaswheretheymaybedamaged,theymustbe runinconduits.Minimum2”conduitisrecommended.
Makesurethatallsystemcablesareproperlyconnectedandsecured,andinstalled withsomeslack.Theslackisessentialtowithstandvibrations,andtofacilitatefuture maintenanceandreplacements.
Relatedtopics
Powerrequirements,page160
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KongsbergEM712Installationmanual

Wheretoinstallthetransducer

Topics
Introductiontotransducerlocation,page20
Mountthetransducerdeep,page20
Avoidprotrudingobjectsnearthetransducer,page21
Keepthetransducerfarawayfromthepropellers,page22
Chooseatransducerpositionfarawayfromthebowthruster(s),page22
Summaryandgeneralrecommendations,page22

Introductiontotransducerlocation

Asingleanswertothequestion"wheretoinstallthetransducer"cannotbegiven.
Thephysicallocationofthetransducerdependsonthevessel'sdesignandconstruction, howthehullisshaped,andhowthewaterrunsalongthehull.Therearehowevera numberofimportantguidelines,andsomeoftheseareevenconicting.
Note
Theinformationheremustbeconsideredasgeneraladvice.EachEM712installation mustbehandledseparatelydependingonthehulldesignandtheotherelectricaland mechanicalsystemsinstalledonthevessel.

Mountthetransducerdeep

InordertoachievethebestpossibleEM712performance,mountthetransduceras deepaspossibleunderthevessel’shull.
Thereareseveralreasonsforthisrecommendation.
Flownoise
Considerthesituationswhenthevesselisunloaded,andpitchinginheavyseas.The vesselisridinghigh,andthebowmayevenbeliftedoutofthewater.Thiswillcausea lotofairtofollowtheshapeofthehull.
Theupperwaterlayersoftheseacontainamyriadofsmallairbubblescreatedbythe breakingwaves.Inheavyseastheupper5to10metresmaybelledwithair,andthe highestconcentrationswillbenearthesurface.Airbubblesabsorbandreectthesound energy,andtheymayinworstcasesblockthesoundtransmissionaltogether.
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Cavitation
Cavitationistheformationofsmallairbubblesclosetothetransducerface.Thebubbles appearbecausethelocalpressurebecomesnegativeduringpartsoftheacousticpressure cycles.Thecavitationthresholdincreaseswiththehydrostaticpressure.Thenoiseis madewhenthebubblesimplode.
Transmittinginair
Thetransducermustneverbeliftedfreeofthewatersurface.Ifthetransduceris activatedwhenoutofwateritmaybedamagedbeyondrepair.Mountingthetransducer atadeeppositiononthehullwillinnormallypreventthis.
Slamming
Slamminghappensifthevesselhullclimbsoutofthewaterinheavyseas.Theforceof thewaterwhenthehullfallsdownmaypushthetransducerup,andmaycausedamage bothtothetransducerandtoitsmounting.Thisisespeciallyimportantforlowfrequency transducerswithlargefaces.Theeffectofslammingcanbereducedbymountingthe transducerasdeepaspossibleonthehull.
Note
KongsbergMaritimeAStakesnoresponsibilityforanydamagestothetransducer,the cableorthemountingarrangement,causedbyslamming.

Avoidprotrudingobjectsnearthetransducer

Objectsprotrudingfromthehullwillgenerateturbulenceandownoise.Thiswill reducetheEM712performance.
Protrudingobjectsmaybezincanodes,transducersoreventhevessel'skeel.Holesand pipeoutletsarealsoimportantnoisesources,aswellasroughsurfacescausedbybad welding.Eventracesofsealingcompound,sharpedges,boltsoremptyboltholeswill createnoise.Alltheseprotrudingobjectsmayactasresonantcavitiesamplifyingthe ownoiseatcertainfrequencies.
Donotplaceatransducerinthevicinityofprotrudingobjects,andespeciallynotclose behindthem.Makesurethatthesurfaceofthetransducerface,thehullplatingandputty aroundthetransducerisasevenandsmoothaspossible.Mountingscrewsorboltsmust notbeextrudingfromthetransducer,theinstallationhardwareorthehullplating.If necessary,grindandpolishallsurfaces.
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KongsbergEM712Installationmanual

Keepthetransducerfarawayfromthepropellers

Thepropulsionpropellersisthedominantnoisesourceonmostvessels.Thenoise iseasilytransmittedthroughthewater.Thisnoisemayoftenreducetheoverall performanceofyourEM712.
Thetransducermustbeinstalledasfarawayfromthepropellersaspossible.Thebest positionsarethereforeontheforepartofthehull.Positionsoutsidethedirectlineof sightfromthepropellersarebest.
Onsmallvesselswerecommendmountingthetransduceronthatsideofthekeelwhere thepropellerbladesmoveupwards.Thisisbecausethepropellercavitationisweakest onthatside.Thecavitationstartswhenthewaterowsinthesamedirectionasthe propellerblades.Thisiswherethepropellerbladesmovedownwards.

Chooseatransducerpositionfarawayfromthebow thruster(s)

Bowthrusterpropellersareextremelynoisy.Whenyoudecidewheretoplacethe transducer,youmustconsiderthenoisecreatedbymostbowthrusters.
Wheninoperation,thenoiseandcavitationbubblescreatedbythethrustermaymake yourEM712Multibeamechosounderuseless,almostnomatterwherethetransduceris installed.Whenthebowthrustersarenotinoperation,thetunnelcreatesturbulence.If yourvesselispitching,thetunnelmaybelledwithairoraeratedwaterintheupper positionandreleasethisinthelowerposition.
Ingeneral,thetransducershouldthereforebeplacedwellawayfromthebowthruster(s).
However,thisisnotaninvariablerule.Certainthrusterdesigns-combinedwiththeir physicallocationsonthehull-maystillofferasuitablelocationforthetransducer,even closetothethruster.Ifyouareindoubt,consultanavalarchitect.

Summaryandgeneralrecommendations

Someoftheinstallationguidelinesprovidedfortransducerlocationmaybeconicting. Forthisreason,eachvesselmustbetreatedindividuallyinordertondthebest compromise.
Ingeneral,themostimportantfactoristoavoidairbubblesinfrontofthetransducer face.Forthisreason,therecommendedtransducerlocationisnormallyintheforepartof thehull,wellaheadofthenoisecreatedbythebowwave.
Themaximumdistancefromthebowisnormallyequaltoonethirdofthetotalwater linelengthofthehull.
Ifthevesselhullhasabulbousbow,thismaywellbeagoodtransducerlocation,but alsointhiscasetheowpatternoftheaeratedwatermustbetakenintoconsideration. Theforemostpartofthebulbisoftenagoodlocation.
Thisappliestothevesselinnormaltrimandspeed.
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Important
Thetransducermustneverbetiltedbackwardswhenthevesselismovingatnormal speed.
Donotplaceatransducerinthevicinityofprotrudingobjects,andespeciallynotclose behindthem.
Makesurethatthesurfaceoftheresultinginstallationisassmoothandstreamlinedas possible.
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KongsbergEM712Installationmanual

Acousticnoise

Aswithanyotherhydroacousticsystems,thequalityoftheEM712echodataand presentationsaresubjecttounwantedacousticnoise.Theechoesfromanylargeand smalltargetmustbedetectedinsidethenoise.
Itisimportantthatwekeepthenoiselevelaslowaspossible.Theisnecessarytoobtain longrangeanddependableinterpretationsoftheechoes.Evenwiththeadvancednoise lteringofferedbytheEM712,wemustaddressthenoisechallenge.Thisisimportant duringtheplanningandpreparationsfortheEM712installation.
Topics
Contributingfactors,page24
Selfnoise,page25
Ambientnoise,page28
Electricalselfnoise,page28
Somemeanstoreduceacousticnoise,page28

Contributingfactors

Severalfactorsarecontributingtotheperformanceofthehydroacousticequipment usedonboardavessel.
Factorscontributingtotheperformanceofthehydroacousticequipmentusedonboarda vesselare:
•Thequalityandpropertiesofthetransmittedsignal
•Thequalityofthereceivingsystem
•Theoperationalsettingsmadeduringoperation
•Thepropertiesofthetarget(s)
•Thesignal-to-noiseratio
Themajorityofthesefactorscanneitherbecontrollednorimprovedbymeans ofinstallationmethodsortransducerlocations.Thequalityandpropertiesofthe transmittingandreceivingsystemsarekeyfactorsduringourproductdevelopment,while ourenduserdocumentationaimstohelptheusertomaketherightltersettingsduring operation.Asforthetargetproperties,thereisnothinganyofuscandowiththose.
Thesignal-to-noiseratio,however,canbeimprovedbymakingthecorrectchoices duringinstallation.
Signal-to-noiseratio(oftenabbreviatedSNRorS/N)isameasureusedin scienceandengineeringthatcomparesthelevelofadesiredsignaltothelevelof backgroundnoise.Itisdenedastheratioofsignalpowertothenoisepower,often expressedindecibels.Aratiohigherthan1:1(greaterthan0dB)indicatesmore
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signalthannoise.WhileSNRiscommonlyquotedforelectricalsignals,itcan beappliedtoanyformofsignal[...].
http://en.wikipedia.org/wiki/Signal_to_noise_ratio(September2013)
Thesignalistheechothatwewanttoknowsomethingabout,whilethenoiseisany unwantedsignalsordisturbances.Theechomustbedetectedinthenoiseandthereforeit isnecessarytokeepthenoiselevelisaslowaspossibleinordertoobtainlongrange anddependableinterpretation.
Thenoisethatcontributestothesignaltonoiseratiomaybedividedintothefollowing typesofnoise:
•Selfnoise
•Ambientnoise
•Electricalnoise
•Reverberation
AThetransducercanpickupnoisefrom
•Biologicaldisturbances
•Interference
•Cavitation
•Propellernoise
•Flownoise
•Acousticnoisefromotherhydroacousticsystems
BThetransducercableislong,andmaypickupelectricnoisefromgenerators,
pumps,coolingsystemsandotherelectricorelectromechanicaldevices.
CThepreampliersareverysensitive,andtheycaneasilypickupelectricalnoise
frominternalandexternalpowersupplies.Thepreampliersarealsovulnerablefor analoguenoisecreatedbytheirownelectroniccircuitry.Digitalnoisecreatedby theconverterandprocessingcircuitrycanalsocreateproblems.
DConverterstransformtheanalogueechoestodigitalformat.
ESignalprocessingcircuitrycancreatedigitalnoise.

Selfnoise

Anyvesselequippedwithahydroacousticsystem(forexampleechosounderorsonar) willproducemoreorlessselfnoise.
Therearemanysourcesofsuchselfnoise.Wewillheregointosomedetailsinorderto analysethedifferentsourcesofselfnoiseonavesselandhowtheymayinuenceupon thenoiselevelofthehydroacousticinstruments.
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Machinerynoise
Themaincontributortomachinerynoiseisusuallythemainengineonboardthevessel. Thecontributionfromauxiliarymachinerymay,however,beconsiderable,especiallyif itisinpoorshape.Themachinerynoisecanbetransmittedtothetransduceras:
•Structure-bornenoisethroughtheshipstructureandthetransducermountings
•Water-bornenoisethroughthehullintothewatertothetransducer
Electricalnoise
Modernvesselsarenormallyequippedwithalotofelectricinstrumentssuchas hydroacousticsystems,radars,navigationsystems,andcommunicationequipment.Any electricinstrumentsmayinsomecauseelectricalinterferenceandnoise.International regulationsandcerticationsareusedtocontrolandreducethis,buteventheseare limitediftheelectricalsystemsarepoorlyinstalledand/ormaintained.
Propellernoise
Propellernoiseisoftenthemainsourceofnoiseathighervesselspeeds.V ariablepitch propellersorfastmovingpropellersusuallymakemorenoisethanxedpropellersor slowmovingpropellers.
Propellernoiseisusuallywater-borne.Insomecases,however,shaftvibrationsor vibrationsinthehullnearthepropellermaybestructure-bornetothetransducer.Ifa propellerbladeisdamaged,thismayincreasethenoiseconsiderably .
Propellercavitationisaseveresourceofnoise."Singing"propellersmightbeasourceof noise,whichinterferesatdiscretefrequencies.Insomecasesstaticdischargefromthe rotatingpropellershaftmaybequitedisturbing.
Cavitation
Cavitationistheformationofsmallairbubbles closetothetransducerface.Thebubblesappear becausethelocalpressurebecomesnegative duringpartsoftheacousticpressurecycles. Thecavitationthresholdincreaseswiththe hydrostaticpressure.Thenoiseismadewhen thebubblesimplode.
Cavitationnoisemayappearnearextruding objectsathigherspeeds,butmoreoftenitis causedbythepropellers.Propellercavitationisaseveresourceofnoise.Thecavitation startswhenthewaterowsinthesamedirectionasthepropellerblades.Thisiswhere thepropellerbladesmovedownwards.
Insomecasesaresonantphenomenonissetupinaholenearthehull.Thissoundwill haveadiscretefrequency,whileallotherownoisewillhaveawidefrequencyspectrum.
(ImagefromU.S.Navyinthepublicdomain.)
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Flownoise
Theupperwaterlayersoftheseacontainamyriadofsmallairbubblescreatedbythe breakingwaves.Whenthehullmovesthroughwateritwillcauseadisturbance,andthis willgeneratefriction.Thefrictionzoneiscalledtheowboundarylayer.Theowin thisboundarylayermaybelaminarorturbulent.
•Thelaminarowisanicelyordered,parallelmovementofthewater.
•Theturbulentowisadisorderlyowpattern,fullofeddies.
ATurbulentow
BLaminarow
CAirbubbles
Airbubblesabsorbandreectthesoundenergy,andtheymayinworstcasesblockthe soundtransmissionaltogether.
Theboundarylayerincreasesinthicknesswhenitbecomesturbulent.Theboundary layeristhinintheforwardpartofthevesselhull,andincreasesasitmovesaft.The thicknessdependsonshipsspeedandontheroughnessofthehull.Allobjectssticking outfromthehull,ordentsinthehull,willdisturbtheowandwillincreasethethickness oftheboundarylayer.Whentheowspeedishigh,theturbulencecanbeviolentenough todestroytheintegrityofthewater.Smallvoidsorcavitiesinthewaterwilloccurand thisiscalledcavitation.
Rattlenoise
Rattlenoisemaybecausedbylooseobjectsinthevicinityofthetransducer,likexing bolts.Therattlemayalsocomefromlooseobjectsinsidethehull.
Interference
Interferencefromotherhydroacousticequipmentonboardthesamevesselmaybean annoyingsourceofdisturbance.Unlessthesamefrequencyisusedformorethanone pieceofequipmentonlythetransmittedpulsewillcontributetotheinterference.
Inphysics,interferenceisthephenomenoninwhichtwowavessuperposeeach othertoformaresultantwaveofgreaterorloweramplitude.Interferenceusually referstotheinteractionofwavesthatarecorrelatedorcoherentwitheachother, eitherbecausetheycomefromthesamesourceorbecausetheyhavethesameor
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nearlythesamefrequency.Interferenceeffectscanbeobservedwithalltypesof waves,forexample,light,radio,acoustic,surfacewaterwavesormatterwaves.
https://en.wikipedia.org/wiki/Interference_(wave_propagation),April2016

Ambientnoise

Ambientnoiseisusuallynotalimitingfactortotheperformanceofsonarsandecho sounders.
Theambientnoisemaybesplitupasfollows:
•Seanoise:Airbubbles,seismicdisturbances,waves,boundaryturbulence,etc.
•Biologicalnoise:Fish,mammals
•Manmadenoise:Othervessels,interference
•Precipitationnoise:Heavyrainorhail
Insomeareas,wheremanyvesselsoperatetogether,theengineandpropellernoisefrom othervesselsmaybedisturbing.Interferencefromhydroacousticinstrumentslocated inothervesselsmayalsobealimitingfactor.Theseanoisedependsontheweather conditions.Inbadweathertheseanoisecanbequitehighduetothewaves.

Electricalselfnoise

Electricalorelectronicselfnoiseispickeduporgeneratedinanyotherpartofthe equipmentthanthetransducer.
Humpickedupbythetransducercablesorpickedupfromthepowersupplyisusually themostcommonsourceofelectricalselfnoise.Athigherfrequencies–whererather widebandwidthsarenecessary–thenoisefromcomponents,transistorsorother analogueelectronicmaybealimitingfactor.

Somemeanstoreduceacousticnoise

Severalfactorsarecontributingtotheperformanceofthehydroacousticequipment usedonboardavessel.CarefulplanningoftheEM712installationmayreducethe acousticnoise.
Unfortunately,itisimpossibletosimplyprovideanumberofspecicproceduresto reducethenoise.
Animportantfactoristhephysicallocationofthetransducers.Thisdependsonthe vessel'sdesignandconstruction,howthehullisshaped,andhowthewaterrunsalong thehull.Otherfactorsdealwithotherequipmentmountedonboard,andthiswillalsobe vesseldependant.Atmoderateshipspeedsthemachinerynoiseisusuallydominant.At mediumspeedstheownoiseincreasesmorerapidlyandtakesover,whileathigher speedthepropellernoisewillbethemaincontributor.
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Note
Theinformationheremustbeconsideredasgeneraladvice.EachEM712installation mustbehandledseparatelydependingonthehulldesignandtheotherelectricaland mechanicalsystemsinstalledonthevessel.
Reducingownoise
•Theshapeofthetransducer(ordomearoundit)mustbeasstreamlinedaspossible.
•Thehullplatinginfrontofthetransducermustbeassmoothaspossible.
Important
Beespeciallyawareofbilgekeelsandzincalloyanodes.Thekeelmustberoundedoff withoutsharpedges.Neitherextrudingobjectsnorabrupttransitionsmustbepresent.
Reducingmachinerynoise
•Themainengineandrelevantauxiliaryenginesandequipmentmustbexedtorigid
foundationstoavoidvibrations.
•Anyhullstructurethatmayvibrateshouldbedampedorcoatedtoreducethe
vibrations.
Theuseofshockabsorbersoroatingraftsmaysometimesreducethisnoise.The structure-bornenoisemaybereducedbyisolation,forexamplebyprovidingvibration clampingbetweenthetransducerandthehullstructure.
Reducingpropellernoise
•Sufcientclearancebetweenthepropellersandthehull,therudderandthekeelmust
beprovided.
•Placethezincalloyanodesinplaceswherethewaterowistheleastdisturbed.
•Ensurethatthepropellersbladesarecorrectlydesignedandwithoutdamages.
•Theuseofabafebetweenthepropellersandthetransducermayreducenoise
appreciably.
•Staticdischargescausedbytherotatingpropellershaftmayberemovedbyproper
groundingorbymountingacoalbrushfromtheshafttovesselground.
Reducingrattlenoise
Ensurethatnopartsnearthetransducerscanrattleasaresultofwateroworvibrations.
Reducinginterference
Interferencefromthetransmissionpulsesfromotherhydroacousticinstrumentson boardthevesselisdifculttoavoid.Theproblemmaybereducedbychoosingthe workingfrequenciescarefullyandtosomeextentbyseparatingthedifferenttransducers. Onvesselswithalargenumberofseparatehydroacousticsystemsinstalledandin
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simultaneoususe,aseparatesynchronizingsystem(forexampletheK-Sync)should beconsidered.
Reducingelectricalnoise
•Makesurethatallunitsareproperlygrounded,asthisisimportanttoavoidelectrical
noise.
•Useshieldedcableswithcorrectgrounding.
•SeparateEM712cablesfromothercableswithhighvoltages,largecurrentsor
transients.
•Placeallhighvoltagepowercablesinmetalconduits.
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