Prerequisites
The SU90 system is turned on and operates normally. The vessel is at sea. Recommended minimum depth is 100 metres. If the SU90 system is operated from any other compartment than the bridge, an open two-way oral communication channel with the bridge
is required. You need the following equipment:
If you wish to do the test with a "silent ship" the following prerequisites must be met:
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The water must be as deep as possible. Recommended minimum depth is 100 metres. |
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There must be no other vessels in the vicinity. |
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As much machinery as possible must be turned off. It is particularly important to turn off electrical motors, as well as cooling systems and hydraulic pumps that may cause
electric noise. |
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To prevent interference, all other hydroacoustic instruments must be turned off. |
If you do this tests in a busy harbour, or with noise sources present, the sensitive receivers will detect all the noise in
the nearby waters.
Context
Since the noise will vary with each ping, you must make five measurements for each vessel speed, and then calculate the average
noise.
TipIf you record all the raw data during the noise test, you can repeat the test later using the replay file.
You may wish to make the noise/speed curve under realistic conditions. This means that all relevant vessels systems are in normal use. If you experience very high noise levels, you may wish to repeat the test with "silent ship" settings. To isolate noise sources, turn individual vessel systems off, and check for any changes in the noise level.
NoteWhen the transducer is fully lowered, the speed of the vessel must not exceed the maximum speed permitted for the hull unit. This maximum speed depends on the physical size of the transducer, the mechanical construction of the hull unit, and how far
down the transducer has been lowered. The System Protection page allows you to define a limit that triggers an alarm if the maximum speed is exceeded. The System Protection page is located in the Installation dialog box.
Illustration:
Read the noise value from the noise circle. Use the mean value of the readouts at 0 degrees (straight up).