Simrad ES 18 - DATASHEET REV C, Installation Manual

Page: 57 / 88

404770/B
55
Transducer installation inside the hull
The transducer can be mounted inside the hull. This installation method forces the
transducer to send and receive the acoustic pulses through the hull plating. This requires
a good acoustic contact between the transducer face and the hull.
In order to install the transducer like this, you must design and build a tank around the
transducer. The tank must be filled with a liquid. Hydraulic oil is well suited for this
purpose. It contains no gas bubbles and is non-corrosive.
Note
Placing the transducer inside the hull will reduce the transmit power and the reception
sensitivity.
Typical values of the two way loss are 3 dB for polyester, 6 dB for aluminium and
10 dB for steel.
The loss varies with the distance between transducer face and the hull. The best result is
obtained when the distance is half a wavelength.
In addition to the loss, the beam pattern is degraded, because a larger area of the hull is
set into vibrations.
Hulls made of wood or a sandwich type with foam in the middle attenuate the sound so
much that through hull sounding must be regarded as impossible.
If this is your only option for transducer installation, consult Kongsberg Maritime for
advice.
The transducer shown in the figure below is mounted inside the hull. The tank is filled
with oil.
A
Steel tank
B
Oil
C
Hull plating
D
Cable service loop
E
Bushing
F Cable in steel
conduit
G
Hole for oil filling
H Air outlet
Using the mounting ring
This large circular is transducer is designed to be mounted using the integrated flange
and a mounting ring.The mounting ring is welded to the hole prepared for the transducer.
Bolts through the transducer flange into the mounting ring will secure the transducer
in place.
Transducer installation principles