Towed body design
the sound energy, and may in worst cases block the sound
transmission totally. Therefore, design the towed body so that it
can operate in deep water.
Caution
Observe the maximum operational depth of the
transducer. Do not exceed this limitation.
Do not allow the towed body to hit the sea bed. This
may inflict permanent damage to the transducer(s).
Noise from protruding objects on the body
Objects protruding from the towed body, such as zinc anodes,
sonar transducers or even a rudder or a keel, may generate
turbulence and flow noise. Holes and pipe outlets are also
possible noise sources, as these may act as resonant cavities
amplifying the flow noise at certain frequencies. Do not place
an echo sounder transducer in the vicinity of such objects, and
especially not close behind them.
For the same reason, it is very important that the body area
adjacent to the transducer face is as smooth and level as possible.
Even traces of sealing compound, sharp edges, protruding bolts
or bolt holes without filling compound will create noise.
Inclination of the transducer face
Ideally, the transducer face should be mounted in parallel with
the sea surface when the towed body is in normal trim, as this
will provide the most accurate echo information. However, it is
also very important that the water flow over the transducer face
is laminar.
In order to ensure laminar flow, the transducer face may be tilted
slightly upwards in relation to the water flow. This allows the
flowing water to meet the face directly, and assures laminar flow.
The inclination angle must however be determined carefully. The
angle must be small on transducers with narrow beam angles. As
a rule of thumb, mount transducers with beam angles smaller
than seven degrees with minimum inclination angle. The smaller
beam angle your transducer has, the smaller the inclination angle
can be.
Ensure that you do not mount the transducer with a negative
inclination angle. This may cause turbulence under the transducer
face, and reduced echo sounder performance.
307121/A
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Summary of Contents for ES200-7CD - REV B
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