Kongsberg Simrad MF90, Installation Manual

Page: 57 / 426

476671/B
55
Important considerations related to noise
The operational performance of all hydroacoustic systems depend on the noise conditions. It
is essential that the noise signature is as low as possible. Careful planning of the installation
may reduce the acoustic noise.
The installation trunk must be mounted so that it remains vertical during normal operating
conditions. The fairing around the installation trunk must be streamlined. The transducer
must be protruding far enough down to reach out of the boundary layer.
The primary sources of underwater disturbance (other than a vessel’s main propeller and
bow/stern thruster) that have a negative effect on the performance are:
• Main or bilge keels
• Sacrificial anodes
• Cooling elements protruding from the hull
• Transducers
• Pilot tubes
• Sea chests
• Overboard discharges
• Dents in the hull
Important
All appendages to the hull, indentations, physical damage and pipes are potential sources of
underwater noise. These may act as resonant cavities amplifying noise at certain frequencies,
create cavitation or turbulence. The installation trunk and hull unit must not be located in
the vicinity of such objects, and especially not immediately aft of them.
Related topics
Preparations, page 42
Choosing the best location for the hull unit, page 51
Preparations