L-3 Communications Navigation Echosounder LAZ 5100 - Manual (Page 64)

Page 5-1
L-3 ELAC Nautik
5 INSTALLATION, CARE AND MAINTENANCE
5.1 INSTALLATION
The display and control unit can be panel, bulkhead, deckhead or console mounted. The system is
delivered with mounting brackets as specified by the user. Install the display and control unit in
accordance with the relevant section of the Installation Drawing Number EZ 52 590 8001 to 8010
which can be found in chapter 6 "DRAWINGS" of this handbook.
The mounting place should assure, that no direct sun light influences the visibility of the display
and for clear display readings a viewing angle of ± 50° perpendicular to the display is
recommended.
The echosounder performance is limited by the acoustic in-water characteristics. These are mainly
influenced by the transducer mounting position, the operating frequency and the efficiency of
electrical-acoustical conversion.
The transducer position must be selected in a way that the radiating surface is mounted in an area
virtually free of turbulence and air bubbles. The sound waves are reflected by any layers of air
bubbles or turbulence that strong, that the sound can not pass the layers and thus echosounding is
prevented.
Because of this fact the transducers should be mounted within the ship's bow area. In case of an
existing bow thruster, the transducer must be mounted ahead or below the thruster outlet. If
mounted behind the bow thruster, the performance of the echosounder will be degraded by
turbulence and air bubbles. Even a total echosounding break down is possible.
During bow thruster operation echosounding is not possible because a wide area around the
thruster´s outlet is saturated with turbulence and air bubbles.
On ships equipped with a bulb bow the transducer must be mounted ahead as far as possible,
because the bulb generates a layer of air bubbles that heavily reduces the transducer /
echosounder performance.
A transducer mounted in the vicinity of the ship's stern can be operated only while drifting, at the
pier or at very low speed. The reason is that the stern area is generally disturbed by turbulence
and air bubbles, dependent on ship's speed. Additionally vibrations and engine noise may be a
source of disturbances. The sound signal cannot penetrate this layer, the bottom echo fades away
and the digital display shows the zero echo ( 1 - 1.5 m) or "?". For this reason only the front
transducer must be used while sailing.