Simrad ES38-12 - INSTALLATION REV A User manual

Installation manual
Simrad ES38-12
38 kHz split-beam transducer
TECHNOLOGY FOR SUSTAINABLE FISHERIES
www.simrad.com

SimradES38-12
Installationmanual
Thisdocumentprovidesageneraldescriptionofhowto
installtheSimradES38-12Splitbeamtransducer.The
informationmustberegardedasgeneralguidelinesand
recommendationsonly.Theinstallationshipyardmust
designandmanufactureinstallationhardwaretotthe
ES38-12transduceroneachindividualvessel.
344276/A
17.02.2010©KongsbergMaritimeAS

Documenthistory
Simraddocumentnumber:344276/ISBN-13:978-82-8066-119-7/Currentrevision:A
Rev.A15.022010Firstversion.
Copyright
©2010KongsbergMaritimeAS
TheinformationcontainedinthisdocumentremainsthesolepropertyofKongsbergMaritimeAS.Nopart
ofthisdocumentmaybecopiedorreproducedinanyformorbyanymeans,andtheinformationcontained
withinitisnottobecommunicatedtoathirdparty,withoutthepriorwrittenconsentofKongsberg
MaritimeAS.Thedocument,oranypartofit,maynotbetranslatedtoanyotherlanguagewithoutthe
writtenapprovalfromKongsbergMaritimeAS.
Disclaimer
KongsbergMaritimeASendeavourstoensurethatallinformationinthisdocumentiscorrectandfairly
stated,butdoesnotacceptliabilityforanyerrorsoromissions.
Warning
Theequipmenttowhichthismanualappliesmustonlybeusedforthepurposeforwhichit
wasdesigned.Improperuseormaintenancemaycausedamagetotheequipmentand/orinjury
topersonnel.Theusermustbefamiliarwiththecontentsoftheappropriatemanualsbefore
attemptingtoinstall,operateorworkontheequipment.
KongsbergMaritimeASdisclaimsanyresponsibilityfordamageorinjurycausedbyimproper
installation,useormaintenanceoftheequipment.
Supportinformation
Ifyourequiremaintenanceorrepair,contactyourlocaldealer.Youcanalsocontactususingthefollowing
address:[email protected].Ifyouneedinformationaboutourotherproducts,visitourwebsite.On
thewebsiteyouwillalsondalistofourdealersanddistributors.
KongsbergMaritimeAS
www.kongsberg.com

Installationmanual
Tableofcontents
ABOUTTHISMANUAL.......................................................5
SIMRADES38-12..............................................................6
WHERETOMOUNTTHETRANSDUCER...............................7
HOWTOINSTALLTHETRANSDUCER..............................11
Transducerinstallationinblister............................................................................11
Useamountingplatewheneverprovided.....................................................11
Smoothsurfaceisimportant........................................................................11
Example:Largecirculartransducer..............................................................12
Example:Mediumandlargetransducers,principle.......................................13
Example:Mediumandlargetransducers,detail............................................13
Commonguidelines....................................................................................14
Toe-in........................................................................................................14
Physicallocation.........................................................................................14
Transducerinstallationinboxkeel.........................................................................15
Usemountingplatewheneverprovided........................................................15
Smoothsurfaceisimportant........................................................................15
Example:Boxkeelinstallation....................................................................16
Transducerushmountedinasteeltank...............................................................16
Usemountingplatewheneverprovided........................................................16
Smoothsurfaceisimportant........................................................................16
Waterlled.................................................................................................16
Example:Flushmountinginasteeltank......................................................17
Transducerwithacousticwindow..........................................................................17
Usemountingplatewheneverprovided........................................................17
Smoothsurfaceisimportant........................................................................17
Example:Acousticwindow.........................................................................18
Transducermountedinsidethehull.......................................................................18
Usemountingplatewheneverprovided........................................................18
Smoothsurfaceisimportant........................................................................18
Example:Mountinginsidethehull..............................................................19
Transducermountedonadropkeel.......................................................................19
Retractabletransducer............................................................................................20
TOWEDBODYINSTALLATION.........................................21
Generalrequirements.............................................................................................21
Smoothsurfaceisimportant........................................................................21
Usemountingandclampingringswheneverprovided...................................21
Useamountingplatewheneverprovided.....................................................21
Installationinatowedbody...................................................................................22
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SimradES38-12
Example:Smalltransducer..........................................................................23
Example:Mediumandlargetransducers......................................................23
Example:Dualtransducerarrangement........................................................24
STEELCONDUIT..............................................................25
TRANSDUCERHANDLINGANDMAINTENANCE................26
Rulesfortransducerhandling.................................................................................26
Rulesfortransducermaintenance..........................................................................27
Approvedanti-foulingpaintsfortransducers.........................................................28
Usingself-lockingtaps...........................................................................................28
IntroductiontoEmugeself-lockingthreads...................................................29
Drawingstandard........................................................................................30
Tapsandgauges..........................................................................................30
Self-locktapsprovidedbySimrad...............................................................31
Supplierandmanufacturer...........................................................................31
TRANSDUCERCABLESPLICING.......................................32
DRAWINGFILE...............................................................33
Echosounderconnections......................................................................................33
Splicingthetransducercable.......................................................................33
GeneralPurposeTransceiver(GPT)wiring...................................................34
GeneralPurposeTransceiver(GPT)transducerplugassembly.......................35
ES38-12Outlinedimensionsandinstallationdrawings.........................................36
Outlinedimensions[111337].......................................................................37
Mountingplate[111492].............................................................................38
Installationprinciples[111495]....................................................................39
4344276/A

Aboutthismanual
Aboutthismanual
Purpose
Thepurposeofthisinstallationmanualistoprovidethegenericdescriptionsand
illustrationsthatallowsyoutounderstandthebasicprinciplesforechosounder
transducerinstallation.
Abouttheinformationprovidedinthisdocument
Theinformationinthisdocumentmustberegardedasgeneralguidelinesand
recommendationsonly.Theinstallationshipyardmustdesignandmanufacture
installationhardwaretoteachindividualtransducerandvessel.
Approvalbymaritimeauthorities
Wheneverrequired,theinstallationshipyardmustalsohavetheinstallationapprovedby
theapplicablemaritimeauthorities.
Additionalinformation
Foradditionaldetailedinformationaboutthetransducertobeinstalled,refertothe
documentationprovidedwiththetransducer.Drawingsanddescriptionscanalsobe
obtainedfromht t p : / / w w w . s i m r a d . c o m .
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SimradES38-12
SimradES38-12
Thepurposeofthismanualistheprovidethebasicinformationrequiredtoinstallthe
SimradES38-12Splitbeamtransducer.
Transduceranddocuments
•SimradES38-12:KSV-111497
•Datasheet:164276
•Drawings:
–Outlinedimensions:111337
–Mountingplate:111492
–Installationprinciples:111495
Note
Althoughdrawingsareprovidedtoexplaintheinstallationprinciples,theinstallation
shipyardmustprovidethenaldrawingsrequiredtotthetransducertoeach
individualvessel.Also,whenapplicable,theinstallationshipyardmusthavethe
drawingsandinstallationapprovedbythepropermaritimeauthorities.
ThedrawingsspecicfortheES38-12transducerarelocatedintheDrawingleon
page33.
Technicalspecications
RefertotheSimradES38-12datasheet.Y oucanreadand/ordownloadthedatasheeton
h
t t p : / / w w w . s i m r a d . c o m .
Additionalpartsprovidedforinstallation
ThefollowingitemscanbesuppliedbySimradtofacilitateinstallation.Theitems
mustbeorderedseparately.
•Mountingplate:499–111492
6344276/A

Wheretomountthetransducer
Wheretomountthe
transducer
Asingleanswertothequestionwheretolocatethetransducercannotbegiven.It
dependsverymuchonthevessel’sconstruction,howthehullisshapedandhowthe
waterrunsalongthehull.Therearehoweveranumberofimportantguidelines,and
someoftheseareevenconicting.
Mountthetransducerdeep
Mountthetransduceratadeeppositiononthehull.Considerthesituationswhenthe
vesselisunloaded,andwhenitispitchinginheavyseas.
Thereareseveralreasonsforthis.
1Theupperwaterlayersoftheseacontainamyriadofsmallairbubblescreatedbythe
breakingwaves.Inheavyseastheupper5to10metresmaybelledwithair,and
thehighestconcentrationswillbenearthesurface.Airbubblesabsorbandreectthe
soundenergy,andtheymayinworstcasesblockthesoundtransmissionaltogether.
2Anotherreasontogodeepisthecavitationinfrontofhighpowertransducers.
Cavitationistheformationofsmallbubblesinthewaterduetotheresultinglocal
pressurebecomingnegativeduringpartsoftheacousticpressurecycles.The
cavitationthresholdincreaseswiththehydrostaticpressure.
3Thetransducermustneverbeliftedfreeofthewatersurface.Transmittinginto
openairmaydamagethetransducerbeyondrepair.Mountingthetransducerata
deeppositiononthehullpreventsthis.
4Ifthetransducerisliftedupfromthewaterduringheavyseas,itmaybedamaged
whenthehullstrikesbackattheseasurface.Thisisespeciallyimportantforlow
frequencytransducerswithlargefaces.
Mountthetransducerawayfromprotrudingobjectsonthehull
Objectsprotrudingfromthehull,suchaszincanodes,sonartransducersoreventhe
vessel’skeel,generateturbulenceandownoise.Holesandpipeoutletsarealso
importantnoisesources.Theymayactasresonantcavitiesamplifyingtheownoise
atcertainfrequencies.Donotplaceanechosoundertransducerinthevicinityofsuch
objects,andespeciallynotclosebehindthem.Forthesamereason,itisveryimportant
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SimradES38-12
thatthehullareaaroundthetransducerfaceisassmoothandlevelaspossible.Even
tracesofsealingcompound,sharpedges,protrudingboltsorboltholeswithoutlling
compoundwillcreatenoise.
Mountthetransducerattheforwardpartofthehulltominimisetheeffectsfrom
theboundarywaterlayer
Whenthevesselforcesitswaythroughthesea,thefrictionbetweenthehullandthe
watercreatesaboundarylayer.Thethicknessoftheboundarylayerdependsuponvessel
speedandtheroughnessofthehull.Objectsprotrudingfromthehull,anddentsinthe
hull,disturbtheowandincreasethethicknessoftheboundarylayer.Theowinthis
boundarylayermaybelaminarorturbulent.Alaminarowisanicelyordered,parallel
movementofthewater.Aturbulentowhasadisorderlypattern,fullofeddies.The
boundarylayerincreasesinthicknesswhentheowgoesfromlaminartoturbulent.The
gurebelowillustratestheboundarylayerofavesselmovingthroughthewater.
Furthermore,airbubblesintheseawaterarepresseddownbelowthehullandmixed
intotheboundarylayer.Theboundarylayeristhinunderneaththeforwardpartofthe
vessel,andincreasesinthicknessasitmovestowardsaft.Ifthesidesofthehullare
steep,someoftheairbubblesintheboundarylayermayescapetotheseasurfacealong
thevesselsides.Itisourexperiencethatawideandatbottom,witharisingangleless
thanaround13degrees,ispronetogivingairproblemsforthetransducer.Inanycasea
transducerlocationintheforwardpartofthehullispreferredinordertominimisethe
inuenceoftheboundarylayer.
Figure1Boundarywaterlayer
ATurbulentow
BLaminarow
CAirbubblesinthewater
8344276/A

Wheretomountthetransducer
Mountthetransducerfarawayfromthepropellers
Thepropulsionpropelleristhedominantnoisesourceonmostshingvessels,research
vessels,merchantvesselsandpleasurecrafts.Thenoiseistransmittedthroughthesea
water.Forthisreason,thetransducershouldbeplacedfarawayfromthepropeller,
whichmeansontheforepartofthehull.Positionsoutsidethedirectlineofsightfrom
thepropellerarefavourable.Onsmallvesselswithshortdistancesitisadvisedtomount
thetransduceronthatsideofthekeelwherethepropellerbladesmoveupwards,because
thepropellercavitationisstrongestontheotherside.Thecavitationstartsmosteasily
whenthewaterowsinthesamedirectionasthepropellerblade,andthatistosome
degreethecaseatthatsideofthekeelwherethepropellerbladesmovedownwards.
Mountthetransducerfarawayfromthebowthrusters
Bowthrusterpropellersareextremelynoisy.Wheninoperation,thenoiseandcavitation
bubblescreatedbythethrustermaketheechosounderuseless,almostnomatterwhere
thetransducerisinstalled.Andwhennotinoperation,thetunnelcreatesturbulence,
andifthevesselispitching,thetunnelmaybelledwithairoraeratedwaterinthe
upperpositionandreleasethisinthelowerposition.Ingeneral,alltransducersmust
bethereforeplacedwellawayfromthebowthruster.However,thisisnotaninvariable
rule.Certainthrusterdesignscombinedwithitsphysicallocationonthehullmaystill
offersuitabletransducerlocationsnearthethruster.Ifyouareindoubt,consultanaval
architect.
Mountthetransducerwithaslightlyinclinedtransducerface
Ideally,thetransducerfaceshouldbemountedinparallelwiththeseasurfacewhen
thevesselisinnormaltrim,asthiswillprovidethemostaccurateechoinformation.
However,itisalsoveryimportantthatthew
a t e r  o w overthetransducerfaceislaminar.
Inordertoensurelaminarow,thetransducerfacemaybetiltedslightlyupwardsin
relationtothewaterow.Thisallowstheowingwatertomeetthefacedirectly,and
assureslaminarow.Theinclinationanglemusthoweverbedeterminedcarefully.The
anglemustbesmallontransducerswithnarrowbeamangles.Asaruleofthumb,mount
transducerswithbeamanglessmallerthansevendegreeswithminimuminclination
angle.Thesmallerbeamangleyourtransducerhas,thesmallertheinclinationanglecan
be.Ensurethatyoudonotmountthetransducerwithanegativeinclinationangle.This
maycauseturbulenceunderthetransducerface,andreducedechosounderperformance.
Summaryandgeneralrecommendations
Someoftheaboveguidelinesareconicting,andeachcasehastobetreatedindividually
inordertondthebestcompromise.Generallythepropellernoiseisthedominantfactor,
andarecommendedtransducerlocationisintheforepartofthehull,withmaximum
distancefromthebowequaltoonethirdofthetotallengthofthehullatthewaterline.
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SimradES38-12
Figure2Generalrecommendationfortransducerlocation
ATransducer
BInclinationangle
CHulllengthat
waterline
DMaximum1/3of
thehulllengthat
waterline(C)
Ifthevesselhullhasabulbousbow,thismaywellbeagoodtransducerlocation,but
alsoheremustbetakenintoconsiderationtheowpatternoftheaeratedwater.Often
theforemostpartofthebulbispreferable.
Figure3Recommendedlocationofthetransducer
onabulboushull
AThruster
BTransducerlocation
10344276/A

Howtoinstallthetransducer
Howtoinstallthetransducer
Therearemanydifferentwaystomountthetransducer.Thesearetherecommended
methodstomountalargeandmediumsizedtransducerusingamountingplate.
Topics
•Transducerinstallationinblisteronpage11
•Transducerinstallationinboxkeelonpage15
•Transducerushmountedinasteeltankonpage16
•Transducerwithacousticwindowonpage17
•Transducermountedinsidethehullonpage18
•Transducermountedonadropkeelonpage19
•Retractabletransduceronpage20
Transducerinstallationinblister
Onerecommendedtransducerinstallationmethodisbymeansofablister.Theblister
mustbedesignedandmanufacturedbytheinstallationshipyardtotboththetransducer
body,andthevessel’ssizeandhullshape.
Useamountingplatewheneverprovided
Certaintransducersmaybeprovidedwithamountingplate,orwithdrawingstoallow
forlocalproductionofthis.
Themountingplateisweldedtotheholepreparedforthetransducer.Boltsthroughthe
transducerbodyintothemountingplatewillsecurethetransducer.
Smoothsurfaceisimportant
Mountingscrewsorboltsmustnotbeextrudingfromthetransducerorthearea
immediatelyaroundit.
Makesurethatthesurfaceofthetransducerface,theinstallationhardwareusedtomount
it,thehullplatingandtheputtyaroundthetransducerisasevenandsmoothaspossible.
Obstructionsonthesesurfaceswillcreateproblemswithturbulentow.
344276/A11

SimradES38-12
Example:Largecirculartransducer
Theillustrationbelowshowsatypicaltransducerblisterdesignedforalargetransducer.
Notethatduetothephysicalsizeofthetransducer,aU-shapedsupportbar(E)isused
tosupportthetransducer.Thepurposeofthissupportistopreventthetransducerfrom
beingpushedupintotheblisterinheavyseas.
Figure4Largecirculartransducer
AStreamlinedblister
BStiffeningrib
CDrainageholes
DInclinationangle
EU-shapedsupportbar(recommended
onlargetransducers)
FForward
GCableserviceloop
HStufngtube
IMinimum400mm
JRoundedcorners
KAiroutlet
12344276/A

Howtoinstallthetransducer
Example:Mediumandlargetransducers,principle
Figure5Mediumandlargetransducers
usingmountingplate
Thisillustrationshowsthe
installationprincipleofamedium
orlargetransducerusingamounting
plate.
AAiroutlet
BStreamlinedblister
CTransducercable
DTransducer
EMountingplate
FForward
Example:Mediumandlargetransducers,detail
Figure6Installationprinciple,
mediumandlargetransducers
AMountingring/plate
BHullplatingontowedbody
CTransducer
D“Clampingring”functionality
facilitatedbytransducerbody
EBolt
Thisillustrationshowstheinstallation
principleofamediumorlargetransducers
usingamountingringor-plate.Note
thataclampingringisnotrequired,asthe
transducerbodyisshapedtofacilitatethis
function.
344276/A13

SimradES38-12
Commonguidelines
Thebestperformanceisobtainedwithablisterheightof40cmormore.Astreamlined
shapeandroundededgesreducetheownoise.Averticalleadingedgeorfrontwill
guidetheaeratedwatertothesidesoftheblister.Theorientationoftheblistershould
followthewaterow.
Theinterioroftheblistermustbelledwithseawater.Usedrainageholesinthe
bottomandanairoutletonthetop.Thewaterpressurebehindthetransducerwillthen
compensatefortheoutsidepressureduringvesselmovementsinroughsea.
WerecommendthatlargediametertransducersarettedwithahorizontalU-shaped
supportbar.Thisbarcanthenbesecuredtothemountingringusingthreadedrods.
Thetransducercablepenetratesthehullinastufngtube.Leaveanadequateloopofthe
cablebehindthetransducerforeasymountingorremovalofthetransducer.
Toe-in
Figure7Toe-inprinciple
AKeel
BBlister
CToe-inangle
Theprimaryconsiderationmustbetoallow
laminarwaterow.Inmostcasesthisis
achievedbydesigningtheblisterinparallel
withthekeel.However,iftheblisteris
locatedclosetothebow,thefrontofthe
blistermayhaveafewdegreestoe-in
towardsthebow.
Theanglemustbechosentoallowformostefcientwaterow.Itwillvarywiththe
locationofthetransducer;thedepthbelowthehull,thedistancefromthebow,andthe
distancetothekeel.Typicalanglesarefrom0to3°ondeplacementhulls.Onplaning
hulls,theangleisnormallycloseto0°.
Physicallocation
Theblisterisplacedononeofthesidesofthehull,andthedistancefromthekeelisa
tradeoffbetweenaclosedistancegivingaturbulentowofwaterinanarrowpassage,
andalargedistancebringingthetransducerhigherupandalsomoreaffectedbyvessel
roll.Normallyadistanceofapproximately1misagoodcompromise.
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Howtoinstallthetransducer
Figure8Physicallocationofblister AKeel
BTransducerblister
CHorizontaldistancebetweenkeeland
blister
DV erticaldistancebetweentheblister
surfaceandthekeel
Observethehorizontalandvertical
distances(CandD)betweenthekeeland
thetransducerblister.Onamediumsized
vessel,thehorizontaldistance(C)should
beapproximately1meter.Theverticaldistance(D)mustingeneralbeassmallas
possible.Thisisimportanttopreventthekeelfromshadowingthetransducerbeam
inshallowwaters.
Transducerinstallationinboxkeel
Vesselswithaboxkeelmayusethisfortransducerinstallation.
Theboxkeelisalreadythedeepestpartofthevessel.Iftheboxkeelistoonarrowto
accommodatethetransducer,itcanbewidened,eithersymmetricallyortoonesideonly.
Inthelastcasetheinstallationcouldalsobedescribedasablistermergedintothekeel.
Usemountingplatewheneverprovided
Certaintransducersmaybeprovidedwithamountingplate,orwithdrawingstoallow
forlocalproductionofthis.
Themountingplateisweldedtotheholepreparedforthetransducer.Boltsthroughthe
transducerbodyintothemountingplatewillsecurethetransducer.
Smoothsurfaceisimportant
Mountingscrewsorboltsmustnotbeextrudingfromthetransducerorthearea
immediatelyaroundit.
Makesurethatthesurfaceofthetransducerface,theinstallationhardwareusedtomount
it,thehullplatingandtheputtyaroundthetransducerisasevenandsmoothaspossible.
Obstructionsonthesesurfaceswillcreateproblemswithturbulentow.
344276/A15

SimradES38-12
Example:Boxkeelinstallation
Figure9Boxkeelinstallation
Thegureillustratesa
symmetricalboxkeelinstallation.
ABoxkeel
BU-shapedsupportbar
(onlyrecommendedonlarge
transducers)
CStufngtube
DCableinsteelconduit
ECableserviceloop
Transducerushmountedinasteeltank
Flushmountingisusedonverylargevesselswithahullsodeepthatnoairbubblesare
foundbelowthehull,andonvesselsoperatinginshallowharboursorwaters,where
aprotrudingblistercannotbeaccepted.
Thestandardprocedureforushmountingonasteelvesselistoweldasteeltankinside
thehull,andmountthetransducerintothistank.
Usemountingplatewheneverprovided
Certaintransducersmaybeprovidedwithamountingplate,orwithdrawingstoallow
forlocalproductionofthis.
Themountingplateisweldedtotheholepreparedforthetransducer.Boltsthroughthe
transducerbodyintothemountingplatewillsecurethetransducer.
Smoothsurfaceisimportant
Mountingscrewsorboltsmustnotbeextrudingfromthetransducerorthearea
immediatelyaroundit.
Makesurethatthesurfaceofthetransducerface,theinstallationhardwareusedtomount
it,thehullplatingandtheputtyaroundthetransducerisasevenandsmoothaspossible.
Obstructionsonthesesurfaceswillcreateproblemswithturbulentow.
Waterlled
Asforablister,theinteriorofthetankmustbelledwithwater.
16344276/A

Howtoinstallthetransducer
Thiscanbeaccomplishedbyairreleasethroughasteeltube,whichisextendedeither
toopenair1.5mabovethewaterlineortothewateroutsidethehullatapointhigher
thanthetankinterior.
Ifthetubeisextendedtoopenair,drainagemustbeprovidedwithleakageatthe
transducerangeoraseparateholeinthetankbottom.
Example:Flushmountinginasteeltank
Figure10Flushmountinginasteeltank
ASteeltank
BWater
CDrainagehole
DCableserviceloop
ESteeltubeforairoutlet
FStufngtube
GCableinsteelconduit
Thegureillustratesthe
installationprincipleswhenthe
transducerismountedinasteel
tank.
Transducerwithacousticwindow
Vesselsoperatinginarcticwatersneedspecialattentionontransducerinstallation.
Floatingblocksoficemaydamageevenaushmountedtransducerface.Forthis
situationSimradoffersarctictanksindifferentsizes.
Usemountingplatewheneverprovided
Certaintransducersmaybeprovidedwithamountingplate,orwithdrawingstoallow
forlocalproductionofthis.
Themountingplateisweldedtotheholepreparedforthetransducer.Boltsthroughthe
transducerbodyintothemountingplatewillsecurethetransducer.
Smoothsurfaceisimportant
Mountingscrewsorboltsmustnotbeextrudingfromthetransducerorthearea
immediatelyaroundit.
Makesurethatthesurfaceofthetransducerface,theinstallationhardwareusedtomount
it,thehullplatingandtheputtyaroundthetransducerisasevenandsmoothaspossible.
Obstructionsonthesesurfaceswillcreateproblemswithturbulentow.
344276/A17

SimradES38-12
Example:Acousticwindow
Figure11Acousticwindow
ASteeltank
BOil
CAcousticwindow
DCableserviceloop
EStufngtube
FCableinsteelconduit
GOilinlet
Thetransducershowninthegureis
mountedinsidethetankbehindastrong
acousticwindow.
Thewindowistypicallymadeof
polycarbonate.Thetankislledwithoil.
Transducermountedinsidethehull
Thetransducercanalsobemountedinsidethehull.
Aninstallationofthetransducerinsidethehull,andsoundingthroughthehull,requiresa
goodacousticcontactbetweenthetransducerfaceandthehull.Buildatankaroundthe
transducerandllitwithaliquid.Oilusedinhydraulicsystemsisawellsuitedliquid
forthispurpose.Itcontainsnogasbubblesandisnon-corrosive.
Typicalvaluesofthetwowaylossare3dBforpolyester,6dBforaluminiumand10dB
forsteel.Hullsmadeofwoodorasandwichtypewithfoaminthemiddle,attenuate
thesoundsomuchthatthroughhullsoundingmustberegardedasimpossible.Theloss
varieswiththedistancebetweentransducerfaceandthehull.Thebestresultisobtained
whenthedistanceishalfawavelength.ConsultSimradforadvice.Inadditiontothe
loss,thebeampatternisdegraded,becausealargerareaofthehullissetintovibrations.
Usemountingplatewheneverprovided
Certaintransducersmaybeprovidedwithamountingplate,orwithdrawingstoallow
forlocalproductionofthis.
Themountingplateisweldedtotheholepreparedforthetransducer.Boltsthroughthe
transducerbodyintothemountingplatewillsecurethetransducer.
Smoothsurfaceisimportant
Mountingscrewsorboltsmustnotbeextrudingfromthetransducerorthearea
immediatelyaroundit.
18344276/A