Installation manual

SimradES70
Theinterioroftheblistermustbelledwithseawater.Usedrainageholesinthe
bottomandanairoutletonthetop.Thewaterpressurebehindthetransducerwillthen
compensatefortheoutsidepressureduringvesselmovementsinroughsea.
WerecommendthatlargediametertransducersarettedwithahorizontalU-shaped
supportbar.Thisbarcanthenbesecuredtothemountingringusingthreadedrods.
Thetransducercablepenetratesthehullinastufngtube.Leaveanadequateloopofthe
cablebehindthetransducerforeasymountingorremovalofthetransducer.
Toe-in
Theprimaryconsiderationmustbetoallowlaminarwaterow.Inmostcasesthisis
achievedbydesigningtheblisterinparallelwiththekeel.However,iftheblisteris
locatedclosetothebow,thefrontoftheblistermayhaveafewdegreestoe-intowards
thebow.
Figure31Toe-inprinciple
AKeel
BBlister
CToe-inangle
(CD17010C)
A
B
C
Theanglemustbechosentoallowformostefcientwaterow.Itwillvarywiththe
locationofthetransducer;thedepthbelowthehull,thedistancefromthebow,andthe
distancetothekeel.Typicalanglesarefrom0to3°ondeplacementhulls.Onplaning
hulls,theangleisnormallycloseto0°.
Physicallocation
Theblisterisplacedononeofthesidesofthehull,andthedistancefromthekeelisa
tradeoffbetweenaclosedistancegivingaturbulentowofwaterinanarrowpassage,
andalargedistancebringingthetransducerhigherupandalsomoreaffectedbyvessel
roll.Normallyadistanceofapproximately1misagoodcompromise.
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