Trans RINA, Vol 157, Part A3, Intl J Maritime Eng, Jul-Sep 2015
their resonance with the lowest vibration modes of the hull reinforcements.
Table 1. Average
experimentally [1]. Type of engine
RPM Average
Control room
110- 200
Maximum 95- 110
89- 100
69- 80
noise levels
Slow Medium Group 1
200-400 95-110 90-107 70-80
400-600 98-115 95-110 74-80
in dB(A)
Medium Group 2
Medium Group 3
600- 1.000
99-117 97-112 80-86
obtained Fast
1.000- 1.800
105- 122
97- 113
87-88
Table 1 shows that noise emission increases with engine speed and that the values are above 95 dB(A). It may therefore be stated that the permissible continuous exposure limit is exceeded in all motor vessels in the engine room and that there is a need for a suitable control room.
The different types of noise emission generated by a
diesel engine are the following: exhaust gas noise (due to gas pulsations), airborne noise (noise generated in the engine room) and structural noise (due to vibration in the engine bedplate) (figure 1).
The fan itself and its motor. Air ducts and ventilation rates. Air entering the system due to suctioning. Air exiting the system through diffusers.
The noise in the ducts is due to two main factors: air speed and abrupt changes of direction in the elbows and intersections.
3. NOISE STANDARDS
There is a need to differentiate between what is called health and safety on board and safety of life at sea.
Occupational health and safety on board falls within the scope of the prevention of occupational hazards. The legal scope of this occupational legislation is mainly the competence of national and EU authorities.
Regulations on Safety of Life at Sea are international in scope, while still forming part of Occupational Health and Safety.
3.1
INTERNATIONAL MARITIME ORGANIZATION (IMO)
To achieve its objectives, the IMO has adopted more than 40 Conventions and Protocols, which are binding legal instruments and, once put
into force, their
provisions must be implemented by all States that have signed them.
Once they have entered into force, the implementation of IMO conventions depends on the Governments of the States Parties.
The IMO also adopts many non-treaty instruments such as codes and recommendations. These codes and recommendations are
not mandatory instruments;
although Member States are expected to implement the provisions laid down in them.
There are currently over 800 codes, covering all areas of navigation. These include the Code on noise levels on board ships A.468 (XII)(81) [3], adopted by the IMO in 1981.
3.2 NEW IMO REGULATION MSC 337. (91).
Figure 1. Types of noise emission generated by slow diesel engines on ships [2]
2.3 VENTILATION AND AIR CONDITION
Forced ventilation and air conditioning systems are often the third major source of noise. This noise originates from:
A-136
Seeing as the previous regulation dated from 1981, in October 2007 the Maritime Safety Committee (MSC) decided to revise the code (MSC83). The revision was completed in November 2012 and its amendment entered into effect in July 2014. The revised noise limits distinguish between two ship sizes:
1,600 up to 10,000 GT 10,000 GT and above
The purpose of the Code is to limit noise levels and reduce worker exposure. The Code is not intended to be
©2015: The Royal Institution of Naval Architects
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