
SimradMS70
Avoidallpropellers
Mountthetransducerfarawayfromthepropellers.
Thepropulsionpropelleristhedominantnoisesourceonmostshingvessels,research
vessels,merchantvesselsandpleasurecrafts.Thenoiseistransmittedthroughthesea
water.Forthisreason,thetransducershouldbeplacedfarawayfromthepropeller,
whichmeansontheforepartofthehull.Positionsoutsidethedirectlineofsightfrom
thepropellerarefavourable.
Onsmallvesselswithshortdistancesitisadvisedtomountthetransduceronthatsideof
thekeelwherethepropellerbladesmoveupwards,becausethepropellercavitationis
strongestontheotherside.Thecavitationstartsmosteasilywhenthewaterowsin
thesamedirectionasthepropellerblade,andthatistosomedegreethecaseatthatside
ofthekeelwherethepropellerbladesmovedownwards.
Avoidallbowthrusters
Mountthetransducerfarawayfromthebowthrusters.
Bowthrusterpropellersareextremelynoisy.Wheninoperation,thenoiseandcavitation
bubblescreatedbythethrustermaketheechosounderuseless,almostnomatterwhere
thetransducerisinstalled.Andwhennotinoperation,thetunnelcreatesturbulence,and
ifthevesselispitching,thetunnelmaybelledwithairoraeratedwaterintheupper
positionandreleasethisinthelowerposition.
Ingeneral,alltransducersmustbethereforeplacedwellawayfromthebowthruster.
However,thisisnotaninvariablerule.Certainthrusterdesignscombinedwithits
physicallocationonthehullmaystilloffersuitabletransducerlocationsnearthethruster.
Ifyouareindoubt,consultanavalarchitect.
Summaryandgeneralrecommendations
Someoftheaboveguidelinesareconicting,andeachcasehastobetreatedindividually
inordertondthebestcompromise.Generallythepropellernoiseisthedominantfactor,
andarecommendedtransducerlocationisintheforepartofthehull,withmaximum
distancefromthebowequaltoonethirdofthetotallengthofthehullatthewaterline.
Figure5Generalrecommendationfortransducerlocation
ATransducer
BInclinationangle
CHulllengthat
waterline
DMaximum1/3of
thehulllengthat
waterline(C)
24
331549/B
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