Trans RINA, Vol 157, Part A3, Intl J Maritime Eng, Jul-Sep 2015


constitute a niche market for shipyards that take these requirements into account and will suppose a challenge for shipbuilding in Spain, which will need to adapt its processes so as to meet standards imposed at a global level to reduce noise pollution.


IMO requirements concerning the use and instruction to use hearing protection should be included among the operational procedures of the ISM Code for


Operation of Ships, leading to increased awareness on the part of crews and effective control on the part of maritime agencies when performing audits.


We also highlight the differences that exist with respect to workers on land, especially during periods of rest.


From the data on noise levels in Section 4, it can be seen that:


 The level of noise in the different workspaces on merchant ships routinely exceeds recommended levels in the governing regulations. We believe this is why the Classification Societies permit tolerances of compliance.


 In general, the requirements of Classification


Societies are more demanding (except with respect to Grade 3) than IMO requirements. Thus, if the average level measured on board is close to the IMO limit, the noise level may be


considered


“improvable”, while if the average level is 5 dB or below this value, the noise level may be considered “acceptable”. Obviously, values exceeding these limits are totally unacceptable and corrective measures must be taken.


 In general, the places on the vessel where these recommended levels are systematically exceeded are machinery spaces. This is


compounded when


considering that the IMO has set a level of 110 dB(A) on for all machinery spaces. This is seriously harmful for engine room staff. This amendment to the regulations for machinery spaces will require mandatory actions in new construction ships


in the limit in the


accommodation spaces of vessels of 10,000 GT, although we understand that it should also apply to vessels of below 10,000 GT.


 These standards and recommendations do not pay due attention to vibration (closely related to noise) or to the frequency spectrum to determine whether there are tonal components, impulse noise or


low frequency noise, reverberation, setting only the


maximum overall equivalent continuous levels in dB(A) and, in some cases, the NR (Noise Rating) feature. In our opinion, therefore, other criteria, such as RC Mark II [22], used by ASHRAE [23] for interior spaces, should be employed so as to take into account the subjective degree of discomfort for people due to noise, in addition to its level. Neither


©2015: The Royal Institution of Naval Architects the Safe


do the standards take into account indicators on the intelligibility of communications, such as the SIL index [24].


In line with the results obtained in the SILENV project [15]), we may state that:


 Strict compliance with IMO (noise) and ISO (vibration) requirements on the ships making up the current fleet (regardless of the compliance of some vessels in particular) is not achievable in the short to medium term.


 Attempts to apply more stringent limits than current standards to the existing fleet will entail higher percentages


of incompliance, given that the


European merchant fleet does not generally comply with this new environmental regulatory framework. This will dictate corrective policies.


Possible strategies to improve the situation include:


 Specific policy actions to reduce the environmental impact of ships.


 A gradual renewal of the fleet is more feasible, given that the average age of the fleet means that modifications to improve the environmental impact of its vessels is not economically viable and the technical execution of such measures is likewise problematic.


 Any project promoted by the EU should reconcile three environmental issues: energy efficiency, gas emissions and noise emissions.


Thanks to the policies that are being developed within the European Union, the improvement in radiated noise in port and underwater


accompanied by an improvement in the noise level inside the vessel, and vice versa.


of


1,600 GT and above to avoid exceeding the level of 80 dB(A) of daily exposure to noise.  There is an improvement


The EU’s regulatory framework for noise and vibration needs to be further developed to achieve lower levels of noise and vibration emitted by ships both at sea and in port, integrating ports into their cities, as pollutant source, for incorporating it into of strategic noise maps.


6. REFERENCES


1. HERNANDEZ, R. Ruido y Vibraciones a bordo de los buques.. Course notes University of Cadiz, 2005.


2.


Diesel Engines and the Environment-Noise. MAN diesel, Martin's 2002.


Marine Engineering,


3. Resolution A.468 (XII). Code on Noise Levels On Board Ships. IMO, 1981.


4. Resolution MSC. 337(91). Appendix 1. Adoption of the Code on Noise Levels On Board Ships, 2012.


5. MITSON. R. B. et al, Underwater noise of research vessels. Review and recommendations.


A-143 radiated noise will also be


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