Smaller box ships have been hit by the new mandatory requirements for a reduction in noise and vibration levels in crew areas.
The mandatory Maritime Safety Committee requirement 337 (91) was adopted by Solas for nearly every sea-going ship with a newbuilding contract from 1 July 2014 onwards. The previous directive in this area – IMO A.468(XII) – was only a recommendation. The new mandatory directive dictates that noise levels in crew areas on-board, including cabins, hospitals, messes, offices and recreation rooms, must be reduced by five decibels compared to the voluntary recommendation, if the vessel is above 10,000 gt, which DNV GL maritime senior engineer Stefan Semrau commented was “quite a lot”.
Mr Semrau said that the ship type most affected by the requirement are smaller container ships, just over the 10,000 gt mark. “These vessels have high engine power and propeller speed, and so while they were already critical for the old voluntary standard, many would not meet the new requirements. We have given lots of advice in this area,” Mr Semrau said.
DNV GL offers a noise prediction analysis service to its customers (shipyards and ship operators) to estimate the noise levels from machinery, including the propeller and engines as well as looking at how the crew areas are arranged and insulated. “If we find a situation where the sound requirements are not fulfilled, then we propose counter-measures such as optimising the insulation or isolating the noise sources,” commented Mr Semrau.
This directive is particularly topical because many of the first vessels affected by this new standard are in the final stages of construction or have recently been delivered.