Kongsberg EA640 User manual

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December2018©KongsbergMaritimeAS
EA640
Hydrographicsinglebeamechosounder
InstallationManual
Thismanualprovidesyouwithinformationrequiredtoinstallthe
KongsbergEA640Hydrographicsinglebeamechosounder.The
informationisintendedforqualiedpersonnelsuchasshipyard
engineersandskilledworkers.
Caution
TheEA640echosoundermustneverbepoweredupwhentheshipis
indrydock.Thetransducerwillbedamagedifittransmitsinopenair.
TopreventinadvertentuseoftheEA640,disconnectthemainspower
wheneverthevesselisindrydock.

KongsbergMaritimeAS
www.kongsberg.com
Documentinformation
•Product:KongsbergEA640
•Document:InstallationManual
•Documentpartnumber:413764
•Revision:B
•Dateofissue:December2018
Copyright
TheinformationcontainedinthisdocumentremainsthesolepropertyofKongsberg
MaritimeAS.Nopartofthisdocumentmaybecopiedorreproducedinanyformorby
anymeans,andtheinformationcontainedwithinitisnottobecommunicatedtoathird
party,withoutthepriorwrittenconsentofKongsbergMaritimeAS.
Warning
Theequipmenttowhichthismanualappliesmustonlybeusedforthepurposefor
whichitwasdesigned.Improperuseormaintenancemaycausedamagetothe
equipmentand/orinjurytopersonnel.Youmustbefamiliarwiththecontentsofthe
appropriatemanualsbeforeattemptingtooperateorworkontheequipment.
KongsbergMaritimedisclaimsanyresponsibilityfordamageorinjurycausedby
improperinstallation,useormaintenanceoftheequipment.
Disclaimer
KongsbergMaritimeASendeavourstoensurethatallinformationinthisdocumentis
correctandfairlystated,butdoesnotacceptliabilityforanyerrorsoromissions.
Supportinformation
Ifyourequiremaintenanceorrepair,contactKongsbergMaritime’s
supportorganisation.Youcanalsocontactususingthefollowingaddress:
[email protected].Ifyouneedinformationaboutourother
products,visithttps://www.km.kongsberg.com.

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Tableofcontents
ABOUTTHISMANUAL..............................................................5
EA640......................................................................................6
Systemdescription.............................................................................................................7
Systemdiagram..................................................................................................................8
Systemunits.......................................................................................................................9
OperatorStationdescription.....................................................................................9
WBTdescription......................................................................................................9
Single-beamtransducers.........................................................................................10
Scopeofsupply................................................................................................................11
Basicitemsprovidedwithastandarddelivery.......................................................11
Installationrequirements..................................................................................................13
Supplypowerrequirements....................................................................................13
Cablesandwiringrequirements.............................................................................13
Compassdeviationrequirements............................................................................14
Noisesources..........................................................................................................14
Networksecurity..............................................................................................................14
Supportinformation.........................................................................................................16
PREPARATIONS.....................................................................17
Installationsummary........................................................................................................18
Aboutinstallationdrawings.............................................................................................19
Tools,equipmentandconsumablesrequiredforEA640installation..............................19
Wheretoinstallthetransducer........................................................................................20
Introductiontotransducerlocation.........................................................................20
Mountthetransducerdeep.....................................................................................20
Avoidprotrudingobjectsnearthetransducer.........................................................21
Keepthetransducerfarawayfromthepropellers.................................................22
Mountthetransduceratasafedistancefrombowthruster(s)...............................22
Summaryandgeneralrecommendations...............................................................22
Acousticnoise..................................................................................................................25
Contributingfactors................................................................................................25
Selfnoise................................................................................................................27
Ambientnoise.........................................................................................................29
Electricalselfnoise................................................................................................29
Somemeanstoreduceacousticnoise....................................................................30
INSTALLINGTHEEA640HARDWAREUNITS..........................32
InstallingtheWBTusingtheintegratedbrackets............................................................33
InstallingtheWBTina19"cabinet.................................................................................34
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Installingacommercialcomputer....................................................................................35
MountingtheWBTCabinet............................................................................................37
MountingthedrawersintheWBTCabinet.....................................................................39
Designing,manufacturingandmountingthesteelconduit.............................................41
Installingthetransducer(s)...............................................................................................43
Installingthetransduceronablisterordropkeel............................................................44
Installingthetransduceronasteelhull............................................................................46
CABLELAYOUTANDINTERCONNECTIONS.............................48
Cableplan........................................................................................................................49
Listofcables....................................................................................................................50
InstallingtheEA640cables.............................................................................................51
ConnectingoneormoretransducerstotheWBT..................................................51
ConnectingpowerandgroundtotheWBT............................................................55
ConnectingtheWBTandtheOperatorStation......................................................56
ConnectingasynchronizationcabletotheOperatorStationusinganRS-232
serialinterfaces..................................................................................................56
Cabledrawingsandspecications...................................................................................58
Transducer..............................................................................................................58
Auxiliaryconnectorforsynchronization................................................................59
RS-232usedassynchronizationtrigger(inputoroutput).....................................60
DRAWINGFILE......................................................................61
388697WBToutlinedimensions....................................................................................62
400930WBTCabinetoutlinedimensions.......................................................................64
TECHNICALSPECIFICATIONS................................................68
Performancespecications..............................................................................................69
Interfacespecications.....................................................................................................70
Weightandoutlinedimensions........................................................................................73
Powerrequirements.........................................................................................................73
Environmentalspecications...........................................................................................74
EQUIPMENTHANDLING.........................................................75
TransportingKongsbergMaritimeequipment.................................................................76
Liftingunitsandtransportationboxes.............................................................................77
Inspectionofunitsandtransportationboxesafterarrival................................................78
Specicationsforstoragepriortoinstallationoruse.......................................................79
Unpackinginstructions....................................................................................................80
Unpackingstandardpartsandunits........................................................................81
Unpackingmechanicalunits..................................................................................82
Unpackingelectronicandelectromechanicalunits................................................82
Unpackingtransducers...........................................................................................83
Specicationsforstorageafterunpacking.......................................................................85
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Aboutthismanual
Purposeofmanual
Thepurposeofthismanualistopresentthedescriptionsanddrawingsrequiredtoinstall
theEA640Hydrographicsinglebeamechosounder.
Targetaudience
Themanualisintendedfortechnicalpersonnel;suchasskilledshipyardworkers,
electricians,qualiedengineersandnavalarchitects.Y oumustalsobefamiliarwiththe
installationofelectronicandmechanicalproducts.
Onlineinformation
ForinformationabouttheEA640andotherproductsfromKongsbergMaritime,visitour
website.
https://www.km.kongsberg.com
Registeredtrademarks
Observetheregisteredtrademarksthatapply.
Windows®isaregisteredtrademarkofMicrosoftCorporationintheUnitedStatesand
othercountries.
Aboutthismanual

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EA640
Topics
Systemdescription,page7
Systemdiagram,page8
Systemunits,page9
Scopeofsupply,page11
Installationrequirements,page13
Networksecurity,page14
Supportinformation,page16
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Systemdescription
EA640isahighperformancehydrographicwidebandsinglebeamechosounder.The
echosounderisdevelopedforhydrographicuseindeeptomediumdepthwaters.
Formaximumexibilityandeaseofoperation,theEA640echosoundersusesthe
MicrosoftWindows®7operatingsystem.TheEA640softwarecanberunonany
mediumrangeWindowscompatiblecommercialcomputer.
Widebandfrequencysweep(FM)incombinationwithadvancedsignalprocessinggives
anexceptionallygoodsignaltonoiseratioandrangeresolution.
TheEA640offersinternalstorageofallrawsampledata.Thisincludesallexternalinput
sensordataforreplaypurposes.Ahighlyexibleprocessingregimemakesitpossible
tologhighdensitycomplexrawdataforadvancedpost-processing.Werecommend
usinganadditionalexternalstoragedevice.
Youcansetupthedisplaytosuityourspecialneeds.Youcanchoosedifferent
presentationsonthescreenforechograms,digitaldepthandotherfeatures.Saveuser
settingsfordifferentoperationsandusethemagainforsimilaroperations.
EA640supportsawiderangeofinputsfromthirdpartysensorsandyoucanalsoexport
thesedataanddatafromEA640toawiderangeofdifferentoutputs.
Availablefrequenciesspanfrom10to500kHz.Avarietyofhighlyefcienttransducers
areavailabletosuitallyouroperationalneedsfromshallowtofullwaterdepths.
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Systemdiagram
ThesystemdiagramidentiesthemaincomponentsofabasicEA640system.Only
themainconnectionsbetweentheunitsareshown.Detailedinterfacecapabilitiesand
powercablesarenotshown.
ThebasicEA640Hydrographicsinglebeamechosounderconsistsofonetransducerand
oneWBT.Additionaltransceiversandtransducerscanbeaddedtomeetyouroperational
andfunctionalrequirements.Youalsoneedacomputerandadisplay.Thesecanbe
deliveredbyKongsbergMaritimeorboughtseparately.
AOperatorStation
BEthernetswitch
CWBT
DTransducer
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Systemunits
Topics
OperatorStationdescription,page9
WBTdescription,page9
Single-beamtransducers,page10
OperatorStationdescription
TheOperatorStationmaybeapanelcomputeroraseparatecomputerwithadisplay.
Thecomputerisbasedonacommercialdesign,
butthesoftwareandhardwarehasbeenspeciedby
KongsbergMaritimetosuittheEA640requirements.
WBTdescription
TheWBTisprovidedtotransmitacousticenergythroughwater.Thistransmissionand
receptionarecommonlyreferredtoasaping.Aftereachtransmission,thetransceiver
receivestheechoesfromthetargetsinthewaterand/ortheseabed.Theseechoesare
lteredandamplied,andthenconvertedtodigitalformat.
TheWideBandTransceiver(WBT)comprisesarugged
boxprovidingallnecessarytransmitterandreceiver
electronics.Thereceiverisdesignedforlownoise,
anditcanhandleinputsignalsspanningaverylarge
instantaneousdynamicamplituderange.
AhighqualityEthernetcableconnectstheWideBand
Transceiver(WBT)totheOperatorStation.ThedistancebetweentheOperatorStation
andthetransceivercanbeextendeduptomaximum70meters.Ifalongercableis
required,cutitinhalf,andinsertanEthernetswitchtoprovidebufferamplication.
Note
IfmorethanoneWideBandTransceiver(WBT)isused,asmallhighcapacityEthernet
switchisrequiredtoconnectthetransceiverstotheOperatorStation.
TheWideBandTransceiver(WBT)requiresanexternalpowersupplyoffering12to
15Vdc,minimum5A.Asuitablepowersupplyisprovidedwiththedelivery.The
transceivercanalsobepoweredbyalargecapacitybattery.
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Single-beamtransducers
TheEA640Hydrographicsinglebeamechosoundercanbeusedwithourefcient
single-beamtransducers.
KongsbergMaritimecanprovidealargerangeof
efcientandaccuratesingle-beamtransducersfor
underwatermappingapplications.Alargenumber
ofoperationalfrequenciesisavailable.Formore
informationaboutKongsbergMaritimetransducers,
seeourwebsite.
https://www.km.kongsberg.com
Theinstallationofthetransducer(ortransducers)isnotdescribedindetailinthis
manual.Seethedocumentationprovidedwitheachtransducer.
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Scopeofsupply
Topics
Basicitemsprovidedwithastandarddelivery,page11
Basicitemsprovidedwithastandarddelivery
ToassembleacompleteEA640system,youwillneedasetofsystemunits.Themain
unitsrequiredareprovidedwiththestandarddelivery.
WhenyouunpackthepartsprovidedwiththeEA640delivery,makesurethatthe
followingitemsareincluded.
WBT
•1WBT
•1Powersupply
•1Powercable
•14–pinConXconnector—ForbatteryorUPS
•1Ethernetcable
•16–pinPCBconnector
•24–pinPCBconnectors
•1Panelcover
•2Cableglands–Forcableswithdiameter8-12mm
•3Cableglands–Forcableswithdiameter5.5-9.5mm
•3Blindplugs
•4Nuts
Transducers
Alargerangeoftransducersisavailableforthedifferentoperationalfrequencies.For
ordernumbers,seeourwebsite.
TransducersFrequency(kHz)Beamwidth(degrees)Cablelength(m)
12–16/601216x1620
15–171517x1715
18–111811x1120
38–7387x720
38–9389x920
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TransducersFrequency(kHz)Beamwidth(degrees)Cablelength(m)
50–185018x1820
50–7507x720
120–2512010x1025
200kHzSidescan2000.5x4920
200–9G200915
200–28E2007x725
200–352003x325
38/200CombiD38/20013x21/7x715
50/200CombiD50/20010x16/7x715
500Sidescan5000.5x6015
500–3G500310
OperatorStation
ContactyourKongsbergMaritimerepresentativeforinformationaboutthecurrent
modelthatisdeliveredwithyourEA640system.
Operationalsoftware
Operationalsoftwareisprovidedonasuitablemedia.IftheOperatorStationis
purchasedfromKongsbergMaritime,theoperationalsoftwareisinstalledonthe
OperatorStation,andreadyforuse.
Enduserdocumentation
End-userdocumentationisprovidedonpaperand/ordigitalformats.Alldocumentation
relatedtooperationandinstallationcanbedownloadedfromourwebsite.
https://www.km.kongsberg.com
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Installationrequirements
Topics
Supplypowerrequirements,page13
Cablesandwiringrequirements,page13
Compassdeviationrequirements,page14
Noisesources,page14
Supplypowerrequirements
Observethegeneralrequirementsrelatedtothesupplypower.
Thesupplyvoltagetotheequipmentmustkeptwithin±10%oftheinstallation’snominal
voltage.
Maximumtransientvoltagevariationsonthemainswitchboard’sbus-barsarenotto
exceed-15%to+20%ofthenominalvoltage(exceptunderfaultconditions).
•Makeandmodel:KongsbergWBT
•Voltagerequirement:12–15VDC,5A
•Powersupply:
–Voltagerequirement:115/230V AC,47to63Hz,singlephase,nominal
–Maximumvoltagedeviation:15%
–Maximumtransient:20%ofnominalvoltage,recoverytime3s
–Powerconsumption:100V A(Approximately)
Cablesandwiringrequirements
CorrectwiringiscrucialfortheoperationalperformanceoftheEA640.
Allcablesrunningbetweensystemcabinetslocatedindifferentroomsand/orondifferent
decksmustbesupportedandprotectedalongtheirentirelengthsusingconduitsand/or
cabletrays.Notethatthecablesmustnotbeinstalledinthevicinityofhigh-power
suppliesandcables,antennacablesorotherpossiblesourcesofinterference.
Alltransducercablesmustberuninsteelconduits.
Formoredetailedinformationaboutcablesandwiring,refertothebasiccable
requirements.
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Compassdeviationrequirements
EA640unitsthatareinstalledonthebridgemayhaveaneffectonthecompass.
Oncetheinstallationiscomplete,thevesselmustbeswungwiththeEA640inboth
operativeandinoperativemodes.
Theshipownerandcaptainareresponsibleforupdatingthecompassdeviationtable
accordinglywithregardtothevessel’snationalregistryandcorrespondingmaritime
authority.
Noisesources
TheoperationalperformanceoftheEA640Hydrographicsinglebeamechosounder
dependsonthenoiseconditions.Itisessentialthatthenoisesignatureisaslowas
possible.
Thevessel’shull,rudder(s)andpropeller(s)mustbethoroughlyinspectedindrydock
priortoinstallation.
Roughnessbelowthewater-linedeformitiesintheshellplatingandprotrudingobstacles
cancreateunderwaternoise.Thesesourcesofturbulencemustbesmoothedorremoved
asbestaspossible.
Note
Itisespeciallyimportantthatthepropeller(s)arenotpittedordamaged.
Networksecurity
IfaEA640systemisconnectedtoalocalareanetwork,datasecurityisimportant.
EquipmentmanufacturedbyKongsbergMaritimeisfrequentlyconnectedtothevessel's
localareanetwork(LAN).Whenyouconnectacomputertoalocalareanetworkyou
willalwaysexposethedataonthatcomputer.Allothercomputersconnectedtothesame
networkmaybeabletoaccessyourdata.Severalthreatsmayimmediatelyoccur:
•Remotecomputerscanreadthedata.
•Remotecomputerscanchangethedata.
•Remotecomputerscanchangethebehaviourofthecomputer,forexampleby
installingunwantedsoftware.
Usually,twoparametersareusedtodenethethreatlevel:
1Thelikelihoodthatanyremoteconnectionwilldoanyoftheabove.
2Thedamagedoneifaremoteconnectionsucceedsdoingthis.
KongsbergMaritimehasnoinformationregardingthecompletesysteminstallationon
anyvessel.SystemsprovidedbyKongsbergMaritimeareregardedasstand-aloneofine
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systems.Theyarestand-aloneeventhoughtheymaybeconnectedtoanetworkfor
sensorinterfacesand/ordatadistribution.
Note
NonetworksafetyapplicationsareinstalledonanyKongsbergMaritimecomputers.
Thecomputersarethusnotprotectedagainstviruses,malwareorunintentionalaccess
fromexternalusers.
SecuringtheEA640systemitselfhasnomeaningunlessthereisapolicyinplacethat
securesallcomputersinthenetwork.Thispolicymustincludephysicalaccessby
trainedandtrustedusers.Thecustomer/enduseroftheEA640systemwillalwaysbe
inchargeofdeningandimplementingasecuritypolicy,andprovidingtherelevant
networksecurityapplications.
Note
KongsbergMaritimewillnotacceptanyresponsibilityforerrorsand/ordamagescaused
byunauthorizeduseoraccesstotheEA640.
IfyouwishtoconnecttheEA640systemtotheship'slocalareanetwork,youmust
implementthesamesecuritymechanismsontheEA640computer(s)asfortherestof
thenetwork.Thisisataskforthenetworkresponsiblepersononboard.Somekey
elementsheremustbe:
•Thesameanti-virusprotectiononallcomputers,includingroutinesforupdating
thisprotection.
•Thesamesettingsfortherewallonallcomputers.
•Controlledphysicalaccesstocomputersonthenetwork.
•Trustedandtrainedoperators.
•Log-inaccessmechanisms.
•Samepolicyforattachingperipheralequipmenttothecomputers(USBdevices,
harddrivesetc).
•Installationofprogramsonanycomputerinthenetwork,vericationthateach
programisauthentic.
•Denitionofwhichprogramsareallowedtorunoneachcomputer.
•Loggingmechanismofcomputeractivity,andinspectionoftheselogs.
Howtodeneandimplementtheserulesdependsoneachenduser'snetworksystem
conguration,whichagainmustbearesultofthepoliciesandthreatlevelstheenduser
hasdenedforthecompleteinstallation.Forsomeproductsthenetworkconsistsofonly
processorunitsand/orworkstations,transceiversandafewsensors.Onothervessels,
largercomputersystemscanbeinstalledtoincludenumerousproductsanddatasystems.
Theremustbeoneresponsiblepersonforthesecurityofthesystem,largeorsmall.
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Supportinformation
ShouldyouneedtechnicalsupportforyourEA640youmustcontactaKongsberg
Maritimeofce.Alistofallourofcesisprovidedonourwebsite.Youcanalsocontact
ourmainsupportofceinNorway.
•Companyname:KongsbergMaritimeAS
•Address:Strandpromenaden50,3190Horten,Norway
•Telephone(24hsupport):[phone]
•Website:https://www.km.kongsberg.com
•E-mailaddress:[email protected]
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Preparations
Topics
Installationsummary,page18
Aboutinstallationdrawings,page19
Tools,equipmentandconsumablesrequiredforEA640installation,page19
Wheretoinstallthetransducer,page20
Acousticnoise,page25
Preparations

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Installationsummary
InstallationoftheEA640isademandingtaskthatrequirescarefulpreparations,a
numberofspecicprocedures,wiringandrequiredsystemsettings.
Context
Anoverallinstallationprocedureisprovided.
Note
InordertoobtainmaximumsafetyandEA640performance,itisveryimportantthatthe
installationproceduresinthismanualarecompliedto.Youmustdothetasksintheorder
theyaredescribed.Thevesselownermustmakesurethattheinstallationshipyardholds
theapplicablecompetencetoperformtheinstallation,andthattheapplicablemaritime
authoritiesareavailabletoverifyandcertifytheinstallation.
Procedure
1Determinethephysicallocationofthetransducer(ortransducers).
Necessaryconsiderationsmustbetakentoavoidacousticandelectricdisturbances.
2Installeachtransducer.
Eachtransducerwillpenetratethehull.Forthisreason,thisisacrucialpart
oftheinstallation.Theinstallationshipyardmustprovideallnecessarydesign
andinstallationdrawings,aswellastherelevantworkstandardsandmounting
procedures.Ifrequired,alldocumentsprovidedbytheshipyardforthephysical
installationoftheEA640mustbeapprovedbythevessel’snationalregistryand
correspondingmaritimeauthorityand/orclassicationsociety.Suchapprovalmust
beobtainedbeforetheinstallationcanbegin.Theshipownerandshipyarddoingthe
installationareresponsibleforobtainingandpayingforsuchapproval.
3InstalltheEA640systemunits.
NotethatsomeEA640systemunitsmaybecommercial.Unlessorderedspecically
thesearenotincludedinthedelivery,andmustbepurchasedlocally.
4InstallthecablesbetweentheEA640systemunits.
Observetherelevantcableplan,procedures,aswellasthegeneralrequirementsfor
cabling.
5PoweruptheEA640forthersttime,andsetittowork.
Note
InordertopowerupoftheEA640inasafeandcorrectmanner ,therelevant
proceduresmustbecompliedto!
6Connecttheperipheralunits.
7DoacompleteEA640systemtest.
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Aboutinstallationdrawings
Theinstallationshipyardmustprovideallnecessarydesignandinstallationdrawings,as
wellastherelevantworkstandardsandmountingprocedures.
Note
Ifrequired,alldocumentsprovidedbytheshipyardforthephysicalinstallationofthe
EA640mustbeapprovedbythevessel’ snationalregistryandcorrespondingmaritime
authorityand/orclassicationsociety.Suchapprovalmustbeobtainedbeforethe
installationcanbegin.Theshipownerandshipyarddoingtheinstallationareresponsible
forobtainingandpayingforsuchapproval.
KongsbergMaritimeoffersfreeadviceforinstallationplanning.Proposedarrangements
maybesentforcommentaryorsuggestions.Thefollowingdrawingsshouldbe
submittedshouldassistanceberequested:
•Generalarrangement
•Bodyplananddrawingsoftherelevantcompartment
•Linesplan
Tools,equipmentandconsumablesrequired
forEA640installation
InordertodotheEA640installation,allnecessarytoolsandequipmentformechanical
work,cabinetinstallationandelectricalwiringmustbeavailable.
Itisnotpracticaltoprovideadetailedlistofallnecessarytoolsandequipment.Youmust
beequippedwithastandardsetoftools.Thistoolsetmustcomprisethenormaltools
forelectronicandelectromechanicaltasks.Thisincludesdifferentscrewdrivertypes,
pliers,spanners,acablestripper,asolderingiron,etc.Eachtoolmustbeprovidedin
varioussizes.Werecommendthatalltoolsaredemagnetizedtoprotectyourequipment.
However,youmustmakesurethatthefollowingspecializedtoolsareavailable.
•Allnecessarytoolsandconsumablesrequiredforwelding
•Allnecessarytoolsandconsumablesrequiredforphysicalinstallationofunits,
cabinetsandracks
•Allnecessarytoolsandconsumablesrequiredforelectricalinstallations
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Wheretoinstallthetransducer
Topics
Introductiontotransducerlocation,page20
Mountthetransducerdeep,page20
Avoidprotrudingobjectsnearthetransducer,page21
Keepthetransducerfarawayfromthepropellers,page22
Mountthetransduceratasafedistancefrombowthruster(s),page22
Summaryandgeneralrecommendations,page22
Introductiontotransducerlocation
Asingleanswertothequestion"wheretoinstallthetransducer"cannotbegiven.
Thephysicallocationofthetransducerdependsonthevessel'sdesignandconstruction,
howthehullisshaped,andhowthewaterrunsalongthehull.Therearehowevera
numberofimportantguidelines,andsomeoftheseareevenconicting.
Note
Theinformationheremustbeconsideredasgeneraladvice.EachEA640installation
mustbehandledseparatelydependingonthehulldesignandtheotherelectricaland
mechanicalsystemsinstalledonthevessel.
Mountthetransducerdeep
InordertoachievethebestpossibleEA640performance,mountthetransducerasdeep
aspossibleunderthevessel’shull.
Thereareseveralreasonsforthisrecommendation.
Flownoise
Considerthesituationswhenthevesselisunloaded,andpitchinginheavyseas.The
vesselisridinghigh,andthebowmayevenbeliftedoutofthewater.Thiswillcausea
lotofairtofollowtheshapeofthehull.
Theupperwaterlayersoftheseacontainamyriadofsmallairbubblescreatedbythe
breakingwaves.Inheavyseastheupper5to10metresmaybelledwithair,andthe
highestconcentrationswillbenearthesurface.Airbubblesabsorbandreectthesound
energy,andtheymayinworstcasesblockthesoundtransmissionaltogether.
EA640InstallationManual