Kongsberg Simrad SU90 Operator's Manual page 181

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.
Tip
If 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.
Note
When 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
that triggers an alarm if the maximum speed is exceeded. The
is located in the
Installation
Illustration:
Read the noise value from the noise circle. Use
the mean value of the readouts at 0 degrees
(straight up).
Procedure
1 Make sure that you have sufficient water
depth below the keel before you lower the
transducer.
2 Lower the transducer to its bottom position.
3 If necessary, establish a separate
communication line with the bridge to
verify the vessel speed during the test.
4 Make the following preparations.
a At the bottom of the display presentation, select Bow Up presentation mode,
and activate the Horizontal view.
b Open the
Operation
1 Set
Operation
381291/D
System Protection
dialog box.
menu.
to Normal.
Maintenance procedures
page allows you to define a limit
System Protection
page
179