Class rises to new challenges of shipboard noise

30 Sep 2011

Rising standards and expectations relating to crew habitability, occupational safety and passenger comfort have prompted closer attention to shipboard noise levels, as have considerations of the component damage that can result from excessive vibration, writes David Tinsley.

While onboard comfort for passengers is a vital competitive factor for cruise ship and, increasingly, ferry operators, the concept of crew habitability in relation to merchant vessels at large has assumed far greater importance in recent years. This reflects tougher regulatory criteria, and a greater appreciation of the fatigue-inducing effect and long-term health issues associated with protracted exposure to high levels of noise and vibration. The link between seafarer wellbeing and efficiency, the latter bearing on both operational efficacy and safety, is now accepted and understood, albeit more so in some maritime communities than others.

In addition, giving the heightened expectations of today’s generation of youngsters as regards working conditions, habitability is an issue in seafarer recruitment and retention.

The classification sector is very much to the fore in the drive for improvements in the shipboard environment, and not only in response to the commercial needs of the passenger ship specialists as regards customer comfort.

Exemplifying this proactive approach is ABS, which produced its Guide for Crew Habitability on Ships in 2001, and Guide for Crew Habitability on Offshore Installations in 2002. In mid 2011, the society produced an updated Guide for Crew Habitability on Workboats, first released in 2008. This defines noise criteria and verification methods with respect to attaining the society’s habitability notations for offshore support and supply vessels.

Addressing accommodation design, whole-body vibration, noise, indoor climate and lighting, the guide offers designers specific parameters against three levels of habitability and corresponding notations, namely HAB, HAB+ and the new HAB++ notation, denoting the premier standard. “By applying the habitability criteria in the Guide, operators have the means to help reduce crew fatigue, improve task performance, increase personnel and vessel safety, and assist with the every increasing challenges of crew recruiting and retention,” stated ABS.

A recent initiative in Japan has seen the release by ClassNK of an advisory document, the Noise and Vibration Guideline, and the creation of new notations endorsing ‘Noise and Vibration Comfort’(NVC) and ‘Mechanical Vibration Awareness’(MVA). The notations will be offered from the autumn of 2011 onwards.

The society’s move has been prompted both by the demand for improved shipboard working environments and the growing awareness of the potentially detrimental influences of excessive vibration on ships’ machinery and equipment. With technological advance and research in the field of noise and vibration attenuation, ClassNK felt that it was apposite to provide a new set of standards for the industry.

The German marine industries and maritime community have a longer track record than many in demonstrating an awareness of the overall safety and efficiency implications of high levels of shipboard noise and vibration. For its part, Germanischer Lloyd(GL)’s technical contributions in this field have lately included an analytical tool that can assess the noise and vibration characteristics of a newbuild design within a matter of days.

The PRE-CHECK service developed and provided by GL subsidiary FutureShip is intended to enable pre-emptive measures to be taken during the early stages of a newbuild project to avoid potential noise and vibration problems, rather than having to make changes or modifications later in the construction or when the ship is in service.

The procedure under PRE-CHECK not only considers direct effects but also takes into account the interaction between the various factors and parameters, such as the number of propeller blades, engine type, deck stiffeners, plate areas, the position of the deckhouse, and the ship’s key performance values.

As a result, the analytical tool helps identify prospective sources of excessive noise and vibration, and gives a grading that reflects the likelihood or otherwise of standards or requirements being met. The client then has a technical basis for deciding whether and where steps will need to be taken.

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ClassNK

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Germanischer Lloyd SE

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ABS

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