scope:

This International Standard specifies a method of measurement and reporting of underwater sound radiated from merchant ships in deep-water, where the depth of the water is equal to or greater than 1,5 times the horizontal distance between the hydrophone and CPA. The method is suitable for survey purposes to be used by marine engineers in obtaining data on the characteristics of underwater noise radiated from merchant ships.

NOTE A separate International Standard will be developed for a method of measurement in waters where the depth is less than 1,5 times the horizontal distance between the hydrophone and CPA.

The result of the measurement according to this International Standard is described as an underwater radiated noise level, which is corrected for measurement distance, but affected by the existence of free surface of water, bottom of water and other physical objects.

NOTE Informative Annex A describes the measurement uncertainty.

Underwater sound radiated from merchant ships depends largely on the operational conditions of the ship, such as draught, speed, operation of the engine(s), etc. Therefore, the ship's condition during measurement should be as close as possible to the actual operating conditions (e.g. loaded or ballasted) to which data are sought.

If statistical data for precision of the measurement is to be obtained, it is recommended to repeat measurements under the same condition, or to deploy more hydrophones for a measurement, or to refer to ISO/PAS 17208.

This International Standard does not specify or provide any criteria for adverse effects of underwater sound radiated from ships to the marine ecosystem.