Kongsberg Simrad CP200-5C, Installation Manual, Page: 53 / 110

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Some means to reduce acoustic noise
Several factors are contributing to the performance of the hydroacoustic equipment used on
board a vessel. Careful planning of the installation may reduce the acoustic noise.
Unfortunately, it is impossible to simply provide a number of specific procedures to reduce
the noise.
An important factor is the physical location of the transducers. This depends on the vessel's
design and construction, how the hull is shaped, and how the water runs along the hull.
Other factors deal with other equipment mounted on board, and this will also be vessel
dependant. At moderate ship speeds the machinery noise is usually dominant. At medium
speeds the flow noise increases more rapidly and takes over, while at higher speed the
propeller noise will be the main contributor.
Note
The information here must be considered as general advice. Each system installation must
be handled separately depending on the hull design and the other electrical and mechanical
systems installed on the vessel.
Reducing flow noise
The shape of the transducer (or dome around it) must be
as streamlined as possible. The hull plating in front of the
transducer must be as smooth as possible.
Important
Be especially aware of bilge keels and sacrificial anodes.
The keel must be rounded off without sharp edges. Neither
extruding objects nor abrupt transitions must be present.
Each transducer must be mounted with a small inclination
angle (approximately 2 degrees).
Reducing machinery noise
• Each transducer must be installed as far away from the engine room as possible.
• The main engine and relevant auxiliary engines and equipment must be fixed to rigid
foundations to avoid vibrations.
• Any hull structure that may vibrate must be damped or coated to reduce the vibrations.
The use of shock absorbers or floating rafts may sometimes reduce this noise. The
structure-borne noise may be reduced by isolation, for example by providing vibration
clamping between the transducer and the hull structure.
Preparations