Installation manual
Wheretomountthetransducer
Wheretomountthe
transducer
Asingleanswertothequestionwheretolocatethetransducercannotbegiven.It
dependsverymuchonthevessel’sconstruction,howthehullisshapedandhowthe
waterrunsalongthehull.Therearehoweveranumberofimportantguidelines,and
someoftheseareevenconicting.
Mountthetransducerdeep
Mountthetransduceratadeeppositiononthehull.Considerthesituationswhenthe
vesselisunloaded,andwhenitispitchinginheavyseas.
Thereareseveralreasonsforthis.
1Theupperwaterlayersoftheseacontainamyriadofsmallairbubblescreatedbythe
breakingwaves.Inheavyseastheupper5to10metresmaybelledwithair,and
thehighestconcentrationswillbenearthesurface.Airbubblesabsorbandreectthe
soundenergy,andtheymayinworstcasesblockthesoundtransmissionaltogether.
2Anotherreasontogodeepisthecavitationinfrontofhighpowertransducers.
Cavitationistheformationofsmallbubblesinthewaterduetotheresultinglocal
pressurebecomingnegativeduringpartsoftheacousticpressurecycles.The
cavitationthresholdincreaseswiththehydrostaticpressure.
3Thetransducermustneverbeliftedfreeofthewatersurface.Transmittinginto
openairmaydamagethetransducerbeyondrepair.Mountingthetransducerata
deeppositiononthehullpreventsthis.
4Ifthetransducerisliftedupfromthewaterduringheavyseas,itmaybedamaged
whenthehullstrikesbackattheseasurface.Thisisespeciallyimportantforlow
frequencytransducerswithlargefaces.
Mountthetransducerawayfromprotrudingobjectsonthehull
Objectsprotrudingfromthehull,suchaszincanodes,sonartransducersoreventhe
vessel’skeel,generateturbulenceandownoise.Holesandpipeoutletsarealso
importantnoisesources.Theymayactasresonantcavitiesamplifyingtheownoise
atcertainfrequencies.Donotplaceanechosoundertransducerinthevicinityofsuch
objects,andespeciallynotclosebehindthem.Forthesamereason,itisveryimportant
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