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Avoid protruding objects
Objects protruding from the hull will generate turbulence and flow noise. This will reduce
the ES38-18/200–18C performance.
Such objects may be zinc anodes, sonar transducers or even the vessel's keel. Holes and
pipe outlets are also important noise sources, as well as rough surfaces caused by bad
welding. All these protruding objects may act as resonant cavities amplifying the flow
noise at certain frequencies.
Do not place a transducer in the vicinity of such objects, and especially not close behind
them. For the same reason, it is very important that the hull area around 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.
Stay far away from the propellers
The propulsion propellers is the dominant noise source on most vessels. The noise
is transmitted through the sea water, and may often reduce the performance of your
ES38-18/200–18C system.
For this reason, the transducer must be placed far away from the propellers, which means
on the fore part of the hull. Positions outside the direct line of sight from the propellers
are favourable.
On small vessels with short distances it is advised to mount the transducer on that side
of the keel where the propeller blades move upwards, because the propeller cavitation is
strongest on the other side. The cavitation starts most easily when the water flows in the
same direction as the propeller blade, and that is to some degree the case at that side of the
keel where the propeller blades move downwards.
Choose a position far away from the bow
thruster(s)
Bow thruster propellers are extremely noisy.
When in operation, the noise and cavitation bubbles created by the thruster may make your
ES38-18/200–18C system useless, almost no matter where the transducer is installed.