Technical Manual LAZ 5100 / ES 5100
GENERAL INSTALLATION INSTRUCTION FOR ECHO SOUNDERS
TH 52 603 8001 EN Rev.: S
Technical Manual LAZ 5100 / ES 5100
2-1
2
GENERAL INSTALLATION INSTRUCTION FOR ECHO SOUNDERS
2.1
General Remark to Hydro Acoustic Equipment
Even with a carefully selected transducer position and proper installation, the function
of hydro acoustic equipment can be impaired by turbulence, acoustic noise or aerated
water.
As main causes, the following can be stated:
Propeller(s)
running
reversed;
Thruster(s) in operation, especially at low speed ahead;
Engine noise, transferred to the transducer either by the hull structure or through
the water, the latter especially as bottom-reflection in shallow water.
Loosing sonar contact with the water at extremely bad weather, as a result of
violent pitching.
Hot water discharges from power plants;
Rising cold water in several sea areas.
The list above is not complete; we will be pleased to assist with further information
on request, see also chapter 5.1.
2.2
Transducer Installation
The performance of an echo sounder is limited by the acoustic propagation of sound
in water. This is mainly influenced by the
transducer mounting place
, the
operational frequency
and the
transducer efficiency
.
The transducer mounting place must be selected in such a way, that the transducer
surface is free of air bubbles and turbulence. Air bubbles and turbulence will reflect
the sound energy so that no echoes from the bottom will be returned.
Therefore transducers in general have to be installed in ship's bow.
If the ship has a bow thruster, the transducer has to be mounted ahead of it.
Otherwise the turbulence caused by the thruster hole will disturb echo sounding
operation.
While the bow thruster is operating, no echo sounding is possible because of the
propeller rotation. On ships with bulbous bow the transducer must be mounted as far
ahead as possible.
Transducers mounted in ship's aft normally are limited in function during travelling,
because this area is very noisy. Due to engine noise, propeller rotation and air
bubbles, the transducers are only effective during low speed travelling.
An indication for this is the disappearing of echoes, digital reading will indicate surface
reverberation (1-1.5 m) or “?”.
While sailing only the front transducer should be used.
