Simrad 38-200 COMBI C - REV D User manual

Installation manual
Simrad 38/200 Combi W
Dual frequency echo sounder transducer
TECHNOLOGY FOR SUSTAINABLE FISHERIES
www.simrad.com

Simrad38/200CombiW
Installationmanual
Thisdocumentprovidesageneraldescriptionofhow
toinstalltheSimrad38/200CombiWDualfrequency
transducer.Theinformationmustberegardedasgeneral
guidelinesandrecommendationsonly.Theinstallation
shipyardmustdesignandmanufactureinstallationhardware
totthe38/200CombiWtransduceroneachindividual
vessel.
Observethemaximumpowerratingsforthis
transducer!
164986/D
13October2009

Documenthistory
Documentnumber:164986/ISBN-13:978-82-8066-035-0
Rev.A08.11.04Firstversion.
Rev.B20.05.05Addedinformationaboutcableglands.
Rev.C06.06.05Correctederrorontheoutlinedimensiondrawingonpage29.
Thecorrectouterdiameteris180mm.
Rev.D06.10.09Additionalinformationadded.
Copyright
©2009KongsbergMaritimeAS
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.
Support
Ifyourequiremaintenanceorrepair,contactyourlocaldealer.Youcanalsocontactususingthefollowing
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Installationmanual
Tableofcontents
ABOUTTHISMANUAL.......................................................5
SIMRAD38/200COMBIW................................................6
WHERETOMOUNTTHETRANSDUCER...............................7
HOWTOINSTALLTHETRANSDUCER..............................11
Transducerinstallationinblister............................................................................11
Usemountingandclampingringswheneverprovided...................................11
Smoothsurfaceisimportant........................................................................11
Example:Smallcirculartransducer..............................................................12
Commonguidelines....................................................................................12
Toe-in........................................................................................................13
Physicallocation.........................................................................................13
Transducerinstallationinboxkeel.........................................................................14
Usemountingandclampingringswheneverprovided...................................14
Smoothsurfaceisimportant........................................................................15
Example:Boxkeelinstallation....................................................................15
Transducerushmountedinasteeltank...............................................................15
Usemountingandclampingringswheneverprovided...................................15
Smoothsurfaceisimportant........................................................................16
Waterlled.................................................................................................16
Example:Flushmountinginasteeltank......................................................16
Transducerwithacousticwindow..........................................................................17
Usemountingandclampingringswheneverprovided...................................17
Smoothsurfaceisimportant........................................................................17
Example:Acousticwindow.........................................................................18
Transducermountedinsidethehull.......................................................................18
Usemountingandclampingringswheneverprovided...................................19
Smoothsurfaceisimportant........................................................................19
Example:Mountinginsidethehull..............................................................19
Transducermountedonadropkeel.......................................................................20
Retractabletransducer............................................................................................21
TRANSDUCERCABLEGLANDSANDSPLICING.................22
Aboutcableglands.................................................................................................22
Cableglandforsteelhulls......................................................................................23
CableglandforwoodenandGRPhulls.................................................................24
Cableglandsforsmallhulls...................................................................................25
Transducercablesplicing.......................................................................................26
Ordernumbers........................................................................................................26
STEELCONDUIT..............................................................27
164986/D3

Simrad38/200CombiW
TRANSDUCERHANDLINGANDMAINTENANCE................28
Rulesfortransducerhandling.................................................................................28
Approvedanti-foulingpaints..................................................................................29
Usingself-lockingtaps...........................................................................................29
IntroductiontoEmugeself-lockingthreads...................................................30
Drawingstandard........................................................................................31
Tapsandgauges..........................................................................................31
Self-locktapsprovidedbySimrad...............................................................32
Supplierandmanufacturer...........................................................................32
DRAWINGFILE...............................................................33
Echosounderconnections......................................................................................33
Splicingthetransducercable.......................................................................33
GeneralPurposeTransceiver(GPT)wiring...................................................34
Transducercablepairs.................................................................................34
GeneralPurposeTransceiver(GPT)transducerplugassembly.......................35
Outlinedimensionsandinstallationdrawings........................................................36
Outlinedimensions[208889].......................................................................37
Mountingring[208846]..............................................................................38
Clampingring[204677]..............................................................................40
Recommendedarrangement[204678]..........................................................42
4164986/D

Aboutthismanual
ABOUTTHISMANUAL
Purpose
Thepurposeofthisinstallationmanualistoprovidethegeneric
descriptionsandillustrationsthatallowsyoutounderstandthe
basicprinciplesforechosoundertransducerinstallation.
Caution
Observethemaximumpulsepowerratingforthis
transducer:
•38kHz:400W
•200kHz:250W
Maximumcontinuouspowerratingis:
•38kHz:4W
•200kHz:2,5W
DONOTapplymorepowerthantheratedmaximum!
Exceedingthepowerinputwillpermanentlydamage
thetransducer.
Abouttheinformationprovidedinthisdocument
Theinformationinthisdocumentmustberegardedasgeneral
guidelinesandrecommendationsonly.Theinstallationshipyard
mustdesignandmanufactureinstallationhardwaretoteach
individualtransducerandvessel.
Approvalbymaritimeauthorities
Wheneverrequired,theinstallationshipyardmustalsohavethe
installationapprovedbytheapplicablemaritimeauthorities.
Additionalinformation
Foradditionaldetailedinformationaboutthetransducerto
beinstalled,refertothedocumentationprovidedwiththe
transducer.Drawingsanddescriptionscanalsobeobtainedfrom
h
t t p : / / w w w . s i m r a d . c o m .
164986/D5

Simrad38/200CombiW
SIMRAD38/200COMBIW
Thepurposeofthismanualistheprovidethebasicinformation
requiredtoinstalltheSimrad38/200CombiWDualfrequency
transducer.
Transduceranddocuments
•Simrad38/200CombiW:KSV-208845
•Datasheet:165019
•Drawings:
–Outlinedimensions:834-208889
–Mountingring:499-208846
–Clampingring:820-204677
–Mountingarrangement:820-204678
Note
Althoughdrawingsareprovidedtoexplaintheinstallation
principles,theinstallationshipyardmustprovidethenal
drawingsrequiredtotthetransducertoeachindividual
vessel.Also,whenapplicable,theinstallationshipyardmust
havethedrawingsandinstallationapprovedbytheproper
maritimeauthorities.Thedrawingsspecicforthe38/200
CombiWtransducerarelocatedintheDrawingleon
page33.
Technicalspecications
RefertotheSimrad38/200CombiWdatasheet.Youcanread
and/ordownloadthedatasheetonh t t p : / / w w w . s i m r a d . c o m .
Additionalpartsprovidedforinstallation
ThefollowingitemscanbesuppliedbySimradtofacilitate
installation.Theitemsmustbeorderedseparately.
•Mountingring:ES1-208847
•Clampingring:ES1–203672
•Transducercable(forextension):642-078215
6164986/D

Wheretomountthetransducer
WHERETOMOUNTTHETRANSDUCER
Asingleanswertothequestionwheretolocatethetransducer
cannotbegiven.Itdependsverymuchonthevessel’s
construction,howthehullisshapedandhowthewaterruns
alongthehull.Therearehoweveranumberofimportantguide
lines,andsomeoftheseareevenconicting.
Mountthetransducerdeep
Mountthetransduceratadeeppositiononthehull.Considerthe
situationswhenthevesselisunloaded,andwhenitispitching
inheavyseas.
Thereareseveralreasonsforthis.
1Theupperwaterlayersoftheseacontainamyriadofsmall
airbubblescreatedbythebreakingwaves.Inheavyseasthe
upper5to10metresmaybelledwithair,andthehighest
concentrationswillbenearthesurface.Airbubblesabsorb
andreectthesoundenergy,andtheymayinworstcases
blockthesoundtransmissionaltogether.
2Anotherreasontogodeepisthecavitationinfrontof
highpowertransducers.Cavitationistheformationof
smallbubblesinthewaterduetotheresultinglocal
pressurebecomingnegativeduringpartsoftheacoustic
pressurecycles.Thecavitationthresholdincreaseswiththe
hydrostaticpressure.
3Thetransducermustneverbeliftedfreeofthewatersurface.
Transmittingintoopenairmaydamagethetransducer
beyondrepair.Mountingthetransduceratadeepposition
onthehullpreventsthis.
4Ifthetransducerisliftedupfromthewaterduringheavy
seas,itmaybedamagedwhenthehullstrikesbackatthe
seasurface.Thisisespeciallyimportantforlowfrequency
transducerswithlargefaces.
Mountthetransducerawayfromprotruding
objectsonthehull
Objectsprotrudingfromthehull,suchaszincanodes,sonar
transducersoreventhevessel’skeel,generateturbulenceand
ownoise.Holesandpipeoutletsarealsoimportantnoise
sources.Theymayactasresonantcavitiesamplifyingtheow
noiseatcertainfrequencies.Donotplaceanechosounder
transducerinthevicinityofsuchobjects,andespeciallynot
closebehindthem.Forthesamereason,itisveryimportant
thatthehullareaaroundthetransducerfaceisassmoothand
levelaspossible.Eventracesofsealingcompound,sharpedges,
protrudingboltsorboltholeswithoutllingcompoundwill
createnoise.
164986/D7

Simrad38/200CombiW
Mountthetransducerattheforwardpartofthe
hulltominimisetheeffectsfromtheboundary
waterlayer
Whenthevesselforcesitswaythroughthesea,thefriction
betweenthehullandthewatercreatesaboundarylayer.The
thicknessoftheboundarylayerdependsuponvesselspeedand
theroughnessofthehull.Objectsprotrudingfromthehull,and
dentsinthehull,disturbtheowandincreasethethicknessof
theboundarylayer.Theowinthisboundarylayermaybe
laminarorturbulent.Alaminarowisanicelyordered,parallel
movementofthewater.Aturbulentowhasadisorderlypattern,
fullofeddies.Theboundarylayerincreasesinthicknesswhenthe
owgoesfromlaminartoturbulent.Thegurebelowillustrates
theboundarylayerofavesselmovingthroughthewater.
Figure1Boundarywaterlayer
ATurbulentow
BLaminarow
CAirbubblesinthewater
Furthermore,airbubblesintheseawaterarepresseddownbelow
thehullandmixedintotheboundarylayer.Theboundarylayer
isthinunderneaththeforwardpartofthevessel,andincreasesin
thicknessasitmovestowardsaft.Ifthesidesofthehullaresteep,
someoftheairbubblesintheboundarylayermayescapetothe
seasurfacealongthevesselsides.Itisourexperiencethatawide
andatbottom,witharisinganglelessthanaround13degrees,
ispronetogivingairproblemsforthetransducer.Inanycasea
transducerlocationintheforwardpartofthehullispreferredin
ordertominimisetheinuenceoftheboundarylayer.
8164986/D

Wheretomountthetransducer
Mountthetransducerfarawayfromthepropellers
Thepropulsionpropelleristhedominantnoisesourceonmost
shingvessels,researchvessels,merchantvesselsandpleasure
crafts.Thenoiseistransmittedthroughtheseawater.For
thisreason,thetransducershouldbeplacedfarawayfromthe
propeller,whichmeansontheforepartofthehull.Positions
outsidethedirectlineofsightfromthepropellerarefavourable.
Onsmallvesselswithshortdistancesitisadvisedtomountthe
transduceronthatsideofthekeelwherethepropellerblades
moveupwards,becausethepropellercavitationisstrongeston
theotherside.Thecavitationstartsmosteasilywhenthewater
owsinthesamedirectionasthepropellerblade,andthatisto
somedegreethecaseatthatsideofthekeelwherethepropeller
bladesmovedownwards.
Mountthetransducerfarawayfromthebow
thrusters
Bowthrusterpropellersareextremelynoisy.Wheninoperation,
thenoiseandcavitationbubblescreatedbythethrustermake
theechosounderuseless,almostnomatterwherethetransducer
isinstalled.Andwhennotinoperation,thetunnelcreates
turbulence,andifthevesselispitching,thetunnelmaybelled
withairoraeratedwaterintheupperpositionandreleasethisin
thelowerposition.Ingeneral,alltransducersmustbetherefore
placedwellawayfromthebowthruster.However,thisisnot
aninvariablerule.Certainthrusterdesignscombinedwithits
physicallocationonthehullmaystilloffersuitabletransducer
locationsnearthethruster.Ifyouareindoubt,consultanaval
architect.
Mountthetransducerwithaslightlyinclined
transducerface
Ideally,thetransducerfaceshouldbemountedinparallelwiththe
seasurfacewhenthevesselisinnormaltrim,asthiswillprovide
themostaccurateechoinformation.However,itisalsovery
importantthatthew
a t e r  o w overthetransducerfaceislaminar.
Inordertoensurelaminarow,thetransducerfacemaybetilted
slightlyupwardsinrelationtothewaterow.Thisallowsthe
owingwatertomeetthefacedirectly,andassureslaminarow.
Theinclinationanglemusthoweverbedeterminedcarefully.The
anglemustbesmallontransducerswithnarrowbeamangles.As
aruleofthumb,mounttransducerswithbeamanglessmaller
thansevendegreeswithminimuminclinationangle.Thesmaller
beamangleyourtransducerhas,thesmallertheinclinationangle
canbe.Ensurethatyoudonotmountthetransducerwitha
negativeinclinationangle.Thismaycauseturbulenceunderthe
transducerface,andreducedechosounderperformance.
164986/D9

Simrad38/200CombiW
Summaryandgeneralrecommendations
Someoftheaboveguidelinesareconicting,andeachcasehas
tobetreatedindividuallyinordertondthebestcompromise.
Generallythepropellernoiseisthedominantfactor,anda
recommendedtransducerlocationisintheforepartofthehull,
withmaximumdistancefromthebowequaltoonethirdofthe
totallengthofthehullatthewaterline.
Figure2Generalrecommendationfortransducerlocation
ATransducer
BInclinationangle
CHulllengthatwaterline
DMaximum1/3ofthehulllengthatwaterline(C)
Ifthevesselhullhasabulbousbow,thismaywellbeagood
transducerlocation,butalsoheremustbetakenintoconsideration
theowpatternoftheaeratedwater.Oftentheforemostpart
ofthebulbispreferable.
Figure3Recommendedlocationofthetransduceronabulbous
hull
AThruster
BTransducerlocation
10164986/D

Howtoinstallthetransducer
HOWTOINSTALLTHETRANSDUCER
Therearemanydifferentwaystomountthetransducer.These
aretherecommendedmethodstomountacirculartransducer.
Transducerinstallationinblister
Withatransducerwithcircularhousing,onerecommended
installationmethodisbyusingablister.Thetransducerblister
mustbedesignedandmanufacturedbytheinstallationshipyard
totthevessel’ssizeandhullshape.
Usemountingandclampingrings
wheneverprovided
Circulartransducersmaybeprovidedwithmountingand
clampingrings,orwithdrawingstoallowforlocalproduction
ofthese.Themountingringisweldedtotheholepreparedfor
thetransducer,whiletheclampingringtsaroundtheedgeof
thetransducerbody.Boltsthroughtheclampingringintothe
mountingringwillsecurethetransducerbetweenthem.Note
thatseveraltransducersusedirectionguidestoallowcorrect
mounting.
Smoothsurfaceisimportant
Mountingscrewsorboltsmustnotbeextrudingfromthe
transducerortheareaimmediatelyaroundit.Makesurethatthe
surfaceofthetransducerface,theinstallationhardwareusedto
mountit,thehullplatingandtheputtyaroundthetransduceris
asevenandsmoothaspossible.Obstructionsonthesesurfaces
willcreateproblemswithturbulentow.
164986/D11

Simrad38/200CombiW
Example:Smallcirculartransducer
Theillustrationbelowshowsatypicaltransducerblisterdesigned
forasmalltransducer.Thesameblisterdesignprinciplesasfora
largetransducerapply.
Figure4Smallcirculartransducer
AStreamlined
blister
BMountingring
CClampingring
DGuide
EAiroutlet
FForward
GTransducer
cable
EE
A
C
G
D
F
B
(CD017010B)
Notethatthetransducercablemustbeprovidedwithacableloop
insidetheblister.Observetheverticalforwardedgeoftheblister.
Thiswillguidethewatertoeachsideoftheblister.
Commonguidelines
Thebestperformanceisobtainedwithablisterheightof40cm
ormore.Astreamlinedshapeandroundededgesreducetheow
noise.Averticalleadingedgeorfrontwillguidetheaerated
watertothesidesoftheblister.Theorientationoftheblister
shouldfollowthewaterow.
12164986/D

Howtoinstallthetransducer
Theinterioroftheblistermustbelledwithseawater.Use
drainageholesinthebottomandanairoutletonthetop.The
waterpressurebehindthetransducerwillthencompensatefor
theoutsidepressureduringvesselmovementsinroughsea.
Werecommendthatlargediametertransducersarettedwitha
horizontalU-shapedsupportbar.Thisbarcanthenbesecured
tothemountingringusingthreadedrods.
Thetransducercablepenetratesthehullinastufngtube.Leave
anadequateloopofthecablebehindthetransducerforeasy
mountingorremovalofthetransducer.
Toe-in
Theprimaryconsiderationmustbetoallowlaminarwaterow.
Inmostcasesthisisachievedbydesigningtheblisterinparallel
withthekeel.However,iftheblisterislocatedclosetothebow,
thefrontoftheblistermayhaveafewdegreestoe-intowards
thebow.
Figure5Toe-inprinciple
AKeel
BBlister
CToe-inangle
(CD17010C)
A
B
C
Theanglemustbechosentoallowformostefcientwaterow.
Itwillvarywiththelocationofthetransducer;thedepthbelow
thehull,thedistancefromthebow,andthedistancetothekeel.
Typicalanglesarefrom0to3°ondeplacementhulls.Onplaning
hulls,theangleisnormallycloseto0°.
Physicallocation
Theblisterisplacedononeofthesidesofthehull,andthe
distancefromthekeelisatradeoffbetweenaclosedistance
givingaturbulentowofwaterinanarrowpassage,andalarge
distancebringingthetransducerhigherupandalsomoreaffected
byvesselroll.Normallyadistanceofapproximately1misa
goodcompromise.
164986/D13

Simrad38/200CombiW
Observethehorizontalandverticaldistances(CandD)between
thekeelandthetransducerblister.Onamediumsizedvessel,the
horizontaldistance(C)shouldbeapproximately1meter.The
verticaldistance(D)mustingeneralbeassmallaspossible.This
isimportanttopreventthekeelfromshadowingthetransducer
beaminshallowwaters.
AKeel
BTransducer
blister
CHorizontal
distance
betweenkeel
andblister
DVertical
distance
betweenthe
blistersurface
andthekeel
Transducerinstallationinboxkeel
Vesselswithaboxkeelmayusethisfortransducerinstallation.
Theboxkeelisalreadythedeepestpartofthevessel.Ifthe
boxkeelistoonarrowtoaccommodatethetransducer,itcanbe
widened,eithersymmetricallyortoonesideonly.Inthelast
casetheinstallationcouldalsobedescribedasablistermerged
intothekeel.
Usemountingandclampingrings
wheneverprovided
Circulartransducersmaybeprovidedwithmountingand
clampingrings,orwithdrawingstoallowforlocalproduction
ofthese.Themountingringisweldedtotheholepreparedfor
thetransducer,whiletheclampingringtsaroundtheedgeof
thetransducerbody.Boltsthroughtheclampingringintothe
mountingringwillsecurethetransducerbetweenthem.Note
thatseveraltransducersusedirectionguidestoallowcorrect
mounting.
14164986/D

Howtoinstallthetransducer
Smoothsurfaceisimportant
Mountingscrewsorboltsmustnotbeextrudingfromthe
transducerortheareaimmediatelyaroundit.Makesurethatthe
surfaceofthetransducerface,theinstallationhardwareusedto
mountit,thehullplatingandtheputtyaroundthetransduceris
asevenandsmoothaspossible.Obstructionsonthesesurfaces
willcreateproblemswithturbulentow.
Example:Boxkeelinstallation
Thegurebelowillustratesasymmetricalboxkeelinstallation.
Figure6Boxkeelinstallation
ABoxkeel
BU-shaped
support
bar(only
recommended
onlarge
transducers)
CStufngtube
DCableinsteel
conduit
ECableservice
loop
(CD1701 1A)
A
B
D
C
E
Transducerushmountedinasteeltank
Flushmountingisusedonverylargevesselswithahullsodeep
thatnoairbubblesarefoundbelowthehull,andonvessels
operatinginshallowharboursorwaters,whereaprotruding
blistercannotbeaccepted.
Thestandardprocedureforushmountingonasteelvesselis
toweldasteeltankinsidethehull,andmountthetransducer
intothistank.
Usemountingandclampingrings
wheneverprovided
Circulartransducersmaybeprovidedwithmountingand
clampingrings,orwithdrawingstoallowforlocalproduction
ofthese.Themountingringisweldedtotheholepreparedfor
thetransducer,whiletheclampingringtsaroundtheedgeof
thetransducerbody.Boltsthroughtheclampingringintothe
164986/D15

Simrad38/200CombiW
mountingringwillsecurethetransducerbetweenthem.Note
thatseveraltransducersusedirectionguidestoallowcorrect
mounting.
Smoothsurfaceisimportant
Mountingscrewsorboltsmustnotbeextrudingfromthe
transducerortheareaimmediatelyaroundit.Makesurethatthe
surfaceofthetransducerface,theinstallationhardwareusedto
mountit,thehullplatingandtheputtyaroundthetransduceris
asevenandsmoothaspossible.Obstructionsonthesesurfaces
willcreateproblemswithturbulentow.
Waterlled
Asforablister,theinteriorofthetankmustbelledwithwater.
Thiscanbeaccomplishedbyairreleasethroughasteeltube,
whichisextendedeithertoopenair1.5mabovethewaterline
ortothewateroutsidethehullatapointhigherthanthetank
interior.
Ifthetubeisextendedtoopenair,drainagemustbeprovided
withleakageatthetransducerangeoraseparateholeinthe
tankbottom.
Example:Flushmountinginasteeltank
Transducermountinginasteeltankisshowninthegurebelow.
Figure7Flushmountinginasteeltank
ASteeltank
BWater
CDrainagehole
DCableservice
loop
ESteeltubefor
airoutlet
FStufngtube
GCableinsteel
conduit
(CD17012A)
B
A
G
C
D
E
F
16164986/D

Howtoinstallthetransducer
Transducerwithacousticwindow
Vesselsoperatinginarcticwatersneedspecialattentionon
transducerinstallation.Floatingblocksoficemaydamageeven
aushmountedtransducerface.ForthissituationSimradoffers
arctictanksindifferentsizes.
Usemountingandclampingrings
wheneverprovided
Circulartransducersmaybeprovidedwithmountingand
clampingrings,orwithdrawingstoallowforlocalproduction
ofthese.Themountingringisweldedtotheholepreparedfor
thetransducer,whiletheclampingringtsaroundtheedgeof
thetransducerbody.Boltsthroughtheclampingringintothe
mountingringwillsecurethetransducerbetweenthem.Note
thatseveraltransducersusedirectionguidestoallowcorrect
mounting.
Smoothsurfaceisimportant
Mountingscrewsorboltsmustnotbeextrudingfromthe
transducerortheareaimmediatelyaroundit.Makesurethatthe
surfaceofthetransducerface,theinstallationhardwareusedto
mountit,thehullplatingandtheputtyaroundthetransduceris
asevenandsmoothaspossible.Obstructionsonthesesurfaces
willcreateproblemswithturbulentow.
164986/D17

Simrad38/200CombiW
Example:Acousticwindow
Thetransducershowninthegurebelowismountedinsidethe
tankbehindastrongacousticwindowwhichcouldbemadeof
polycarbonate.
Thetankislledwithoil.
Figure8Acousticwindow
ASteeltank
BOil
CAcoustic
window
DCableservice
loop
EStufngtube
FCableinsteel
conduit
GOilinlet
(CD017012B)
B
A
C
G
D
E
F
Transducermountedinsidethehull
Thetransducercanalsobemountedinsidethehull.
Aninstallationofthetransducerinsidethehull,andsounding
throughthehull,requiresagoodacousticcontactbetweenthe
transducerfaceandthehull.Buildatankaroundthetransducer
andllitwithaliquid.Oilusedinhydraulicsystemsisawell
suitedliquidforthispurpose.Itcontainsnogasbubblesand
isnon-corrosive.
Typicalvaluesofthetwowaylossare3dBforpolyester,6dB
foraluminiumand10dBforsteel.Hullsmadeofwoodora
sandwichtypewithfoaminthemiddle,attenuatethesoundso
muchthatthroughhullsoundingmustberegardedasimpossible.
Thelossvarieswiththedistancebetweentransducerfaceand
thehull.Thebestresultisobtainedwhenthedistanceishalfa
wavelength.ConsultSimradforadvice.Inadditiontotheloss,
thebeampatternisdegraded,becausealargerareaofthehullis
setintovibrations.
18164986/D