Simrad ES80 User Manual

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Relatedtopics
Acousticnoise,page462
BITE:Noisepage,page409
Selfnoise
Anyvesselequippedwithahydroacousticsystem(forexampleechosounderorsonar)
willproducemoreorlessselfnoise.
Therearemanysourcesofsuchselfnoise.Wewillheregointosomedetailsinorderto
analysethedifferentsourcesofselfnoiseonavesselandhowtheymayinuenceupon
thenoiselevelofthehydroacousticinstruments.
Machinerynoise
Themaincontributortomachinerynoiseisusuallythemainengineonboardthevessel.
Thecontributionfromauxiliarymachinerymay,however,beconsiderable,especiallyif
itisinpoorshape.Themachinerynoisecanbetransmittedtothetransduceras:
•Structure-bornenoisethroughtheshipstructureandthetransducermountings
•Water-bornenoisethroughthehullintothewatertothetransducer
Electricalnoise
Modernvesselsarenormallyequippedwithalotofelectricinstrumentssuchas
hydroacousticsystems,radars,navigationsystems,andcommunicationequipment.
Anyelectricinstrumentsmayinsomecasescauseelectricalinterferenceandnoise.
Internationalregulationsandcerticationsareusedtocontrolandreducethis,buteven
thesearelimitediftheelectricalsystemsarepoorlyinstalledand/ormaintained.
Propellernoise
Propellernoiseisoftenthemainsourceofnoiseathighervesselspeeds.Variablepitch
propellersorfastmovingpropellersusuallymakemorenoisethanxedpropellersor
slowmovingpropellers.
Propellernoiseisusuallywater-borne.Insomecases,however,shaftvibrationsor
vibrationsinthehullnearthepropellermaybestructure-bornetothetransducer.Ifa
propellerbladeisdamaged,thismayincreasethenoiseconsiderably.
Propellercavitationisaseveresourceofnoise."Singing"propellersmightbeasourceof
noise,whichinterferesatdiscretefrequencies.Insomecasesstaticdischargefromthe
rotatingpropellershaftmaybequitedisturbing.
SimradES80ReferenceManual

Simrad ES80 Specifications

General

Brand	Simrad
Model	ES80
Category	Marine Equipment
Language	English