Kongsberg Simrad SU90 Operator's Manual page 186

Simrad SU90 Operator Manual
d Read the noise value from the noise circle.
e For every knot the speed is reduced, read the noise.
(If you find it more convenient, type the data directly into the spreadsheet.)
f Fill in the result table.
9 When all the measurements have been made, type the data (speed and noise) into a
spreadsheet to create the curve.
10 Hoist the transducer back up to its upper position.
Result
Speed
20
19
18
17
16
15
14
13
12
11
10
9
184
Speed/Frequency/Noise
Frequency
Noise level
381291/D