Simrad Simrad SP70, Installation Manual

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Final tests and measurements
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Speed
(Knots)
Bearing 0 degrees
(Knots)
Stable speed Acceleration Retardation
0
2
4
6
8
10
12
14
Table 9 Noise verification
4 Make a dashed line plot of the acceleration noise into the
Noise/speed plot , and a dotted line for the retardation noise.
By comparing these three plots it should be possible to sort out if
the main noise is caused by flow noise or engine/propeller noise.
If the main noise is caused by flow noise, the ship’s hull should be
thoroughly inspected during next docking. If the noise is caused by
the engine propeller, ensure that the propeller is not chipped or
corroded.