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FP5

NORMA Résumé de rapport

Project ID: G3RD-CT-2001-00393
Financé au titre de: FP5-GROWTH
Pays: Norway

Criteria for external and underwater noise from high-speed vessels

Underwater noise requirements for high-speed crafts:
The proposed limits were derived based on comparison of measured underwater noise levels from selected high-speed vessels and criteria used for other marine activities. The best-documented underwater noise criteria were the proposed ICES criteria.

A mammal warning limit of 180dB and the fisheries research limit were superimposed on these measured data. The fisheries research limit has been converted from the indicated constant bandwidth noise levels to 1/3-octave band noise levels. The mammal warning limit is indicated at a frequency of 1kHz, thereby avoiding the frequency ranges of high sensitivity for most of the commercial types of fish except herring.

Not surprisingly, the measured data exceed the fisheries research limits in the low frequency part of the spectrum, since the fisheries research limits are based on a 20 m avoidance reaction distance. A 20m limit would be not only unrealistic but also unreasonable for a vessel not engaged in fisheries research. Increasing the avoidance reaction zone to 200m would appear to be more appropriate and this would result in a limit, which is 20dB higher than the recommended fisheries research limit. The corresponding curve for the 200m requirements was found to be realistic. The selected water jet driven vessels satisfy this requirement with clear margins.

The selected propeller driven craft exceeds, however, the suggested limit in the low frequency end of the spectrum and at the 1/3 octave band including the propeller blade passing frequency the noise level is only 5dB below the ”mammal warning limit” of 180dB.

The indicated limits are therefore proposed as suitable underwater noise criteria for high-speed vessels.

External airborne noise limits for high speed vessels:
Similarly measured data for a number of vessels have been studied and compared to criteria applied to other modes of transportation. The analyses have resulted in the following recommendations:
- LAeq, T=24 h = 55dB(A) at facade of dwelling and / or;

- LAFmax = 70dB(A) close to dwelling;

- Measured in accordance with ISO 2922.

Contact

Kai ABRAHAMSEN, (Principal Engineer)
Tél.: +47-67577495
Fax: +47-67579911
E-mail