Installation manual

SimradES38-12
thatthehullareaaroundthetransducerfaceisassmoothandlevelaspossible.Even
tracesofsealingcompound,sharpedges,protrudingboltsorboltholeswithoutlling
compoundwillcreatenoise.
Mountthetransducerattheforwardpartofthehulltominimisetheeffectsfrom
theboundarywaterlayer
Whenthevesselforcesitswaythroughthesea,thefrictionbetweenthehullandthe
watercreatesaboundarylayer.Thethicknessoftheboundarylayerdependsuponvessel
speedandtheroughnessofthehull.Objectsprotrudingfromthehull,anddentsinthe
hull,disturbtheowandincreasethethicknessoftheboundarylayer.Theowinthis
boundarylayermaybelaminarorturbulent.Alaminarowisanicelyordered,parallel
movementofthewater.Aturbulentowhasadisorderlypattern,fullofeddies.The
boundarylayerincreasesinthicknesswhentheowgoesfromlaminartoturbulent.The
gurebelowillustratestheboundarylayerofavesselmovingthroughthewater.
Furthermore,airbubblesintheseawaterarepresseddownbelowthehullandmixed
intotheboundarylayer.Theboundarylayeristhinunderneaththeforwardpartofthe
vessel,andincreasesinthicknessasitmovestowardsaft.Ifthesidesofthehullare
steep,someoftheairbubblesintheboundarylayermayescapetotheseasurfacealong
thevesselsides.Itisourexperiencethatawideandatbottom,witharisingangleless
thanaround13degrees,ispronetogivingairproblemsforthetransducer.Inanycasea
transducerlocationintheforwardpartofthehullispreferredinordertominimisethe
inuenceoftheboundarylayer.
Figure1Boundarywaterlayer
ATurbulentow
BLaminarow
CAirbubblesinthewater
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