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Ships oriented Innovative soLutions to rEduce Noise & Vibrations

Final Report Summary - SILENV (Ships oriented innovative solutions to reduce noise and vibrations)

Transports are well known to be major contributors to noise pollution. Noise and vibration (N&V)s abatement naturally appears as an important objective for the greening of surface transports.

The SILENV project is a response to this requirement for the maritime domain.

The consequences of N&V emissions from the ships are multiple. N&V emissions constitute a disturbance for both passengers and harbour area residents, and in some cases it may be a health issue for crew members. Moreover, the increasing ship traffic-generated underwater noise causes ecological nuisances on marine wildlife. This project proposes a holistic approach to reduce ship-generated N&V pollution.

After a definition of realistic target levels, existing experimental data from main types of ships and on-site measurements will be analysed to identify the most critical sources of N&V. Innovative solutions will be listed and individually assessed on technical and economic criteria. These solutions shall subsequently be virtually tested and refined on numerical models of entire ships, thus allowing us to scientifically grade N&V improvements.

SILENV's final main deliverable is a 'green label' proposal that includes recommended target levels for N&V and associated design guidelines.

Project context and objectives:

The SILENV project was proposed in the context of the transport theme in the Seventh Framework Programme (FP7). The project focuses on reduction of the environmental impact of ships. Noise generated by transport systems is a major component of the noise pollution emitted into the environment. A number of studies aim to find ways of reducing the noise annoyance generated by road, rail and air transport. Sea transport is also concerned by this objective.

N&V generated by ships have multiple consequences. First of all, they are a potentially major annoyance for the crews, on any type of ship. Prolonged exposure to high N&V levels causes fatigue, alters effectiveness in work and can lead to hearing degradation. N&V are the principal causes of discomfort for the persons on board passenger-carrying ships. The current regulations generally specify limits not to be exceeded on board. However, some aspects are not covered by present standards and require further study.

Noise pollution, the noise emitted by ships into the outside environment, is another important research priority for the project. The growth in sea traffic is leading to increased ambient noise in the oceans. The harmful consequences of this underwater noise pollution on the fauna have already been demonstrated. Marine mammals use sound for finding their way around, looking for food and communicating.

The noise emitted into the air by ships in harbour or during manoeuvres close to ports is also a growing source of annoyance for residents of adjacent urban areas. In Europe, there are national or local regulations which impose noise limits in the neighbourhood of port areas, but the rules that have been examined are very varied.

The SILENV project proposes a global approach to investigate all of these noise-related annoyances. The ultimate aim of the project is to establish an 'acoustic green label' including target N&V levels associated with design recommendations for achieving these targets. The interest of this project is its very broad spectrum: all types of annoyance are taken into consideration, but also the specific features of the various categories of ship: passenger, cargo and fishing vessels are covered by these studies.

The SILENV project is broken down into five interrelated work packages (WP) including the study tasks; one WP is dedicated specifically to project management and the last WP to communication activities.

The first phase (WP1) included an in-depth analysis of previous studies and of international, national and local regulations on the various topics covered. At the conclusion of this analysis, WP1 identified the improvements needed and thus provided guidelines for the subsequent phases of the project.

The objective of WP2 is to collect as much experimental data as possible in order to obtain a clear view of the state of the art for all the topics covered and the various types of ship. The collected information also forms a very rich database for the subsequent studies. Some of the data are obtained from information available from the project partners. Series of specific measurements are also made to supplement the project database, in particular where insufficient data is available from the partners.

WP3 aims to identify and analyse potential solutions for improving the N&V performance of ships.

WP4 has two objectives. The first is to develop and validate calculation methods for determining N&V levels emitted on board and into the environment by ships. The impacts on persons on board ships and on marine mammals will be quantified. In a second phase, the calculation methods will be used to assess the usefulness of the principal solutions identified.

Lastly, WP5 will include the summary of the studies and the definition of the acoustic green label.

In addition to this green label, several results of great interest will also be produced by the various WPs: analysis and summarising of the studies and present regulations on N&V in the marine field; database of measurements and associated analysis; studies on solutions for reducing noise levels on board and in the environment of ships; development and assessment of innovative calculation methods specific to ships.

Project results:

Since the beginning of the SILENV project, three reports have been produced by WP1, covering the three principal topics of the SILENV project: N&V on board ships, noise pollution in the environment of ports, and noise radiated in the water.

The first report confirms that the subject of N&V on board ships has received a great deal of attention from the marine world since the 1980s, which has resulted in a complex and substantial body of regulations.

However, this does not mean that the subject is fully under control and covered by the regulations. Further investigation is needed on the parameters and the mechanisms that have the greatest influence on crew health and passenger comfort. Possible future trends in this field include better handling of transient noises and of the frequency content of noise.

Regarding airborne noise in port areas, two cases can be distinguished: noise generated by sailing close to the coast, and noise emitted by ships in harbour. After analysis and summarising of the present regulations and previous projects, the preliminary study resulted in the proposal of limiting values and recommendations on measurement methods.

With regard to the third topic, the survey of studies and publications confirmed that underwater noise, in which sea traffic is a major component, has an impact on marine fauna. Awareness of this problem is recent and knowledge remains limited, but the trend in national and international regulations is clearly to reduce this impact. Subsequently, in the project, the aim will be to use modelling to determine the interferences between traffic noise and communications for several species of marine mammal.

In parallel, an N&V database has been compiled in WP2 using information acquired by the partners, most of which have substantial experience in the fields under study. As expected at the beginning of the project, a lack of experimental data on noise in ports and underwater noise was confirmed. With a view to populating the database, a major series of measurements at sea has been conducted on various types of ship. Afterwards, the experimental data collected have been analysed in order to determine the most critical noise sources. Finally the improvement required to reach the future 'Green label' has been identified.

The work of WP3 has been broken down into four principal tasks according to the type of noise source: propellers and thrusters, engines, exhausts and ventilation, hull-structures. The first phase of this WP consisted in surveying the various noise reduction solutions for each type of source. The four deliverables produced give an overview of possible mitigating solutions for each type of noise source. The last step has been to summarise all the potential solutions and assess their interest for meeting the preliminary objectives defined from the results of WP1. The evaluated solutions synthesis is presented in the fifth deliverable of this WP.

In WP4, affordable suitable tools to simulate the large spectrum of effects related to N&V phenomena in the maritime ambit have been obtained, both tuning and validating available methods, and developing new approaches for particular applications.

The use of above tools permitted to check the identified solutions and to assess their adequacy in relation with requirements. The effectiveness of the solution has been assessed in quantitative terms through the synergic use of simulations and experimental data from sea trials.

Finally, in the frame of WP5, the acoustic green label proposal has been elaborated, basing on the results of previous WP. This label includes target levels related to N&V onboard, airborne and underwater radiated noise, and associated design guidelines.

At the end of the project, it can be concluded that the result of the studies is in line with the initial objectives.

Potential impact:

The main result of this project is the definition of the 'N&V green label' applicable to the most prevalent type of ships. This is a first important step in the N&V abatement process.

Additionally to the green label, the intermediate results issued from the WPs constitute significant progress beyond the state of the art. The following main deliveries can be highlighted: collecting and analysis of N&V experimental data, studies of innovative solutions to reduce noise pollution, definition and validation of N&V calculations tools dedicated to ship design.

The potential impacts of the decrease of N&Vs emitted from ships are multiple:

- improvement of health and safety for sea workers especially fishermen;
- improvement of comfort for the users of maritime transports;
- reduction of noise pollution for populations living around ports, and close to inner waterways;
- reduction of underwater noise pollution and its effects on the marine ecosystem.

The green label will be used as a reference by members of SILENV consortium in their respective activities: measurement, design, ship classification, N&V consulting. We also expect that a large part of members of the maritime community, (including national and international regulating authorities) will use the green label as a reference to reduce ship acoustic pollution.

To promote the project's results and to guarantee a wide dissemination of the acoustic 'green label' the following dissemination activities have been achieved:

- communicate with the end users network (shipyards, ship owners and public organisations);
- disseminate the results in the maritime community;
- obtain feedback from the targeted end users;
- develop dissemination material to reach the intended target audiences;
- organise local dissemination activities such as presentations and publications;
- implement and maintain a project web server for global dissemination.

The target audiences for the external communication are ship owners, shipyards, port authorities, classification organisations, scientists from maritime domain, and public institutions in charge of environment.

Project website: