Installation manual

Simrad38-7
Example:Acousticwindow
Thetransducershowninthegurebelowismountedinsidethe
tankbehindastrongacousticwindowwhichcouldbemadeof
polycarbonate.
Thetankislledwithoil.
Figure8Acousticwindow
ASteeltank
BOil
CAcoustic
window
DCableservice
loop
EStufngtube
FCableinsteel
conduit
GOilinlet
(CD017012B)
B
A
C
G
D
E
F
Transducermountedinsidethehull
Thetransducercanalsobemountedinsidethehull.
Aninstallationofthetransducerinsidethehull,andsounding
throughthehull,requiresagoodacousticcontactbetweenthe
transducerfaceandthehull.Buildatankaroundthetransducer
andllitwithaliquid.Oilusedinhydraulicsystemsisawell
suitedliquidforthispurpose.Itcontainsnogasbubblesand
isnon-corrosive.
Typicalvaluesofthetwowaylossare3dBforpolyester,6dB
foraluminiumand10dBforsteel.Hullsmadeofwoodora
sandwichtypewithfoaminthemiddle,attenuatethesoundso
muchthatthroughhullsoundingmustberegardedasimpossible.
Thelossvarieswiththedistancebetweentransducerfaceand
thehull.Thebestresultisobtainedwhenthedistanceishalfa
wavelength.ConsultSimradforadvice.Inadditiontotheloss,
thebeampatternisdegraded,becausealargerareaofthehullis
setintovibrations.
18
130003/D