In 2014-2015, Level Acoustics & Vibration was part of a research team that investigated how to deal with noise exposure on old ships navigating the Rhine. This research was conducted in cooperation with DPA Cauberg-Huygen and Rubber Design. The results were presented in 2015 to the European comittee that is responsible for drafting the noise standards on ships (CESNI). Eventually, our proposals have been accepted, resulting in relaxation of noise standards for older ships. Noise standards already apply to ships built after April 1st, 1976. From 2020 onwards, ships built before 1976 were also expected to meet these stricter noise requirements. At the request of the Dutch Ministry for Infrastructure and Water Management, a different methodology will now be used for the measurements of noise levels on these ships, since it is technically and financially impossible for these older vessels to comply otherwise.
New measurement method
The proposal for the new measurement method is for a large part based on results of the research that Level Acoustics & Vibration has contributed to. The new method involves measuring the noise exposure during a weighted average of different RPM’s, instead of only at 95% of the engine power. This is more representative of the actual use of the motor. If noise levels still exceed maximum requirements, every measure that lowers noise levels, that can be reasonably expected to get executed, has to be taken. The exact definition of ‘reasonably’ will be determined in future by the ministry, in consultation with ILT, international branch organizations and other authorities. If there is still an exceedance of the allowed noise exposure after this investment, the prevailing sound levels will be permitted, provided that the exceedence is limited to a set number. Ultimately, if the noise level in the bedroom remains too high, a ship may not sail for more than 16 hours per day.
In the Netherlands alone, 2500 ships are saved from having to stop their activities thanks to the relaxation of the norms.
Also read our news item about the executed research from August 2014: