okeanos - Stiftung für das Meer
Our Blog
Monday, January 23rd, 2012 . 1:48 pm | No Comments

Shipping Noise—Progress Since Okeanos Foundation’s 2008 Workshop

The “International Workshop on Shipping Noise and Marine Mammals” took place April 21-24, 2008, in Hamburg, hosted by the Okeanos Foundation. It was a congregation of experts from biology and ship technology, the former dealing with the biological receiver, the latter presenting their knowledge of underwater noise generation of ships. The unique atmosphere of the workshop provided for free exchange of knowledge and opinion, resulting in two statements on the issue, one from the biological side and the other from the technology side.

All participants were aware of the enormity of the research task of finding the cause and effects of noise and ultimately reducing it. We know that shipping dominates noise in most of the oceans at frequencies below 300 Hz, whether there is a ship in close vicinity or not. This could render especially large baleen whales nearly unable to communicate with each other against the rumbling noise from ship propellers. We do not know how severe the effect is on the survivability of the whales. If we find one day that this noise has a critical impact on the life of a whale, there will be no quick cure. There are more than 50,000 larger, ocean-going ships at sea at any given time and their life span is around 30 years. We cannot stop shipping to lower noise levels. Until now we do not even know what the effect would be. Background noise levels have risen by 10 dB from the 1960s to 1990s. Since then it seems that the rise is at a slower pace, however, compared to the 1960s, the range at which a whale could hear his companion has been reduced to a quarter: if a blue whale could hear the other at 100 miles earlier, now it is down to 25 miles and shrinking.Large Ship leaving Port of Napier
Large Ship leaving Port of Napier, New Zealand © Napier City Council, New Zealand

The reaction to the workshop’s finding was immediate. The International Maritime Organisation (IMO) took up the issue in the same year and founded a Correspondence Group as part of the Marine Environment Protection Committee (MEPC). Since then, the Group has collected information available from experts from around the world which now awaits processing in a next step towards a Working Group within one of the technical Committees in IMO.

The European Union has taken up the issue in their European Marine Strategy Framework Directive (MSFD), also in 2008. EU member states are required to achieve or maintain good environmental status (GES) in all European seas by 2020. All marine states of the EU must implement the Directive by developing and implementing national strategies. This also covers anthropogenic noise as one form of energy introduced into the environment. In 2010, MSFD Task Group 11 addressed impulsive noise and low frequency continuous noise as the main attributes of environmental conditions in terms of noise. Germany, in particular, started to issue programs to collect preliminary information on the background noise status of her Exclusive Economic Zone and particularly the Marine Protected Areas. Related activities will result in stationary sound observatories to continuously monitor acoustic conditions. Quality criteria to judge acoustic conditions have yet to be developed.Noise recording
Underwater noise measurements of ships at sea will be increasingly important to understand noise radiation of ships © DW-ShipConsult

In 2010 the EU started a well-funded research project on noise from ocean transport. This is the first program directly related to shipping noise research and may quickly yield very important information on the basics of shipping-related noise generation.

In 2011, unnoticed by the public, the International Towing Tank Conference (ITTC), a congregation of all hydrodynamic institutes dealing with ships and offshore structures, founded a Specialist Committee on Hydrodynamic Noise. This is essential as we know that ship propellers are the main low frequency noise sources in ships, and the Towing Tanks (also referred to as Ship Model Basins) play a key role when designing and model-testing propellers. The particular contribution of noise output has not been considered in propeller design in the past, but we know from Okeanos-funded research that noise production is also observable in model scales. Such examinations are a prerequisite to a fast and efficient approach towards understanding the underlying physical processes and ultimately, the methods for mitigation of underwater noise.
Ship Propeller
Cavitation, evaporating water at the low pressure side of ship propellers, is the dominant cause of sound in the oceans © DW-ShipConsult

After all, it is vital that incentives are devised to help the ship owner and the ship designer consider underwater radiated noise as a design parameter and that an environmentally friendly ship may have (hopefully minor if negative) effects on other features. With current knowledge we have to expect that the effect on propulsive efficiency will not be such that it results in direct investments in new sound reduction technologies. However, good environmental status in the ocean also with respect to noise is of public interest, and IMO, along with other bodies, based on serious research may come up with acceptable proposals of what a quiet ship for the future means.

All papers that were produced from the International Workshop on Shipping Noise and Marine Mammals or related papers can be found on the Okeanos website.

Blog authors: Dr. Dietrich Wittekind, DW-Shipconsult GmbH and Lindy Weilgart,
Okeanos – Foundation for the Sea

Further information can be found here:

NOAA symposiums
IFAW report on vessel quieting

Arctic Marine Shipping Assessment (AMSA)

EU Marine Strategy Framework Directive
The International Towing Tank Conference ITTC

Above information list by courtesy of Amy Scholik-Schlomer, NOAA (National Oceanic and Atmospheric Administration)

* Mandatory field