Installation manual
TransducerInstallation
Figure21Boundarywaterlayer
ATurbulentow
BLaminarow
CAirbubblesinthewater
Furthermore,airbubblesintheseawaterarepresseddownbelowthehullandmixed
intotheboundarylayer.Theboundarylayeristhinunderneaththeforwardpartofthe
vessel,andincreasesinthicknessasitmovestowardsaft.Ifthesidesofthehullare
steep,someoftheairbubblesintheboundarylayermayescapetotheseasurfacealong
thevesselsides.Itisourexperiencethatawideandatbottom,witharisingangleless
thanaround13degrees,ispronetogivingairproblemsforthetransducer.Inanycasea
transducerlocationintheforwardpartofthehullispreferredinordertominimisethe
inuenceoftheboundarylayer.
Mountthetransducerfarawayfromthepropellers
Thepropulsionpropelleristhedominantnoisesourceonmostshingvessels,research
vessels,merchantvesselsandpleasurecrafts.Thenoiseistransmittedthroughthesea
water.Forthisreason,thetransducershouldbeplacedfarawayfromthepropeller,
whichmeansontheforepartofthehull.Positionsoutsidethedirectlineofsightfrom
thepropellerarefavourable.Onsmallvesselswithshortdistancesitisadvisedtomount
thetransduceronthatsideofthekeelwherethepropellerbladesmoveupwards,because
thepropellercavitationisstrongestontheotherside.Thecavitationstartsmosteasily
whenthewaterowsinthesamedirectionasthepropellerblade,andthatistosome
degreethecaseatthatsideofthekeelwherethepropellerbladesmovedownwards.
Mountthetransducerfarawayfromthebowthrusters
Bowthrusterpropellersareextremelynoisy.Wheninoperation,thenoiseandcavitation
bubblescreatedbythethrustermaketheechosounderuseless,almostnomatterwhere
thetransducerisinstalled.Andwhennotinoperation,thetunnelcreatesturbulence,
andifthevesselispitching,thetunnelmaybelledwithairoraeratedwaterinthe
upperpositionandreleasethisinthelowerposition.Ingeneral,alltransducersmust
bethereforeplacedwellawayfromthebowthruster.However,thisisnotaninvariable
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