Simrad PI, Руководство по установке

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Simrad PI Catch monitoring system / Trawl hydrophone
6
851--164472 / Rev.B
When not in operation, bow/sternthruster tunnels create
turbulence and hence underwater noise when a vessel is under
way. Also, as a vessel pitches in heavy weather, thruster tunnels
may fill with air or aerated water which can disturb hydrophone
reception when released. Hydrophone installation should take
into regard the noise and down stream disturbances found
around and aft of thrusters.
Note:
Hydrophone installation must take into regard the noise and
down stream disturbances found around and aft of thrusters.
Noise from protruding objects and other sources
The primary sources of underwater disturbance (other than a
vessel’s main propeller and bow/sternthruster) that affect
hydrophone reception are:
•
Main or bilge keels
•
Zinc anodes
•
Cooling elements protruding from the hull
•
Equipment such as sonar hydrophones and pitot tubes
•
Sea chests
•
Overboard discharges
•
Dents in the hull
All appendages to the hull, indentations and pipe outlets are
potential sources of underwater noise. They may act as resonant
cavities amplifying noise at certain frequencies, create cavitation
or turbulence. Hydrophones should not be located in the vicinity
of such objects and especially not immediately aft of them.
Minimum distance to sonar and echo sounder
transducers
To avoid interference, PI hydrophone(s) must be installed as far
away as possible from other sources of underwater acoustical
energy such as active sonars and echo sounder transducers.
Hydrophones should be placed at least two meters from such
equipment when ever possible and distances of less than one
meter avoided. Hydrophones installed in close proximity to
underwater acoustical sources should be located as far aft as
possible from them, and most importantly, not be subjected to
direct (frontal) transmission from such equipment.