3 Making a noise/speed curve to determine vessel noise

The performance of the EK80 system will always be limited by different noise sources. During this test, noise measurements are done for different vessel speeds. The weather and sea conditions for the noise measurements will be those at the time of the test.

Prerequisites

The EK80 system is turned on and operates normally. All the relevant transceivers have been set up, and they are operational with their respective transducers.

Make a note of the sea state and wind at the time of the test.

You need the following equipment:

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The EK80 must be correctly setup for noise measurements.

1 Set up the EK80 for noise measurements

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Personal computer

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Spreadsheet program

Context

It is important to log noise data which is related to different movements of the vessel. Factors which will impact the noise differently are for instance the sheep speed, propeller rpm and pitch. This procedure focuses on checking the noise estimate at different vessel speeds ranging from 0 kts to 12 kts. In addition you will be reporting the propeller rpm and frequency of each transducer and as such get a more full picture of what noise to expect during similar circumstances. To reduce the number of combinations, focus on the ships standard survey speeds. If possible, turn off all acoustic transmitters during noise data collection.

Tip

If you record all the raw data during the noise test, you can repeat the test later using the replay file.

Procedure

Create a noise/speed table for noise estimate results.

Enter wind state, sea state and water depth.

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Wind state is measured using the Beaufort wind force scale.

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Sea state is measured using the WMO (World Meteorological Organization) sea state table.

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Water depth is measured using meters.

Enter the ship's different parameters in the table.

Start raw data recording.

Read and record the Noise Estimate values for 10 different pings for each vessel speed.

Open the Setup menu.

Select Diagnostics to open the dialog box.

Select Noise to open the page.

Read and record the Noise Estimate values for 10 different pings for each vessel speed.

Calculate an average value of the readings for the10 pings and enter in the noise/speed table.

Stop the recording.Save the data using a unique file name that identifies context, date, time and vessel. Attach the data file to the electronic copy of the test report.

When all the measurements have been made, type the data (speed and noise) into a spreadsheet to create the curve.

Result

Speed/Noise

Wind state			Sea state (re WMO)				Depth [m]
Tag	[knots]	Propeller rpm	Propeller Pitch	Noise Estimate [dB]
Tag	[knots]	Propeller rpm	Propeller Pitch	18 kHz	38 kHz	70 kHz	120 kHz	200 kHz	333 kHz	EC150-3C



Use this table to record the values. Alternatively, you can type the values straight into a spreadsheet. Make the necessary copies so that you have one table for each channel.

Test requirements	Results
A noise/speed curve is created.
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