Sound advice – how to reduce vessel underwater noise and onboard vibration.
Jun. 8 2021
By Vincent Lamaison, acoustic and vibration project manager, BV Solutions M&O
This year’s UN World Ocean Day takes place on June 8 with the theme of “The Ocean: Life and Livelihoods”. It is an appropriate time for us all to consider the impact our activities have on our waters around the world and the steps we can take to preserve this essential life source.
There are growing concerns about the increasing levels of noise and vibration affecting marine life globally. The European Life-PIAQUO project, which is supported by Bureau Veritas Marine & Offshore (BV M&O), says the average levels of noise in our busiest seas have increased by almost 20dB in the past 50 years. That’s 100 times more sound power over a 10 times wider range. Furthermore, the EU Marine Strategy Framework Directive identified energy and noise (including underwater noise) as one of the 11 descriptors of environmental status for which good status was to be achieved by 2020.
Protecting our seas
The rise in commercial sea traffic over the years has been cited as one of the main reasons for the increase in underwater radiated noise (URN)
No international mandatory regulations currently exist to solve this issue. However, localised initiatives are underway. For example, the Port of Vancouver, Canada, is championing coordinated management approaches working with ship owners, and is actively involved within the international community of port authorities, policy makers, marine engineering and class societies, and BV Solutions M&O is also playing an active part in addressing international URN issues, and developing robust classification regulations.
Ensuring Health, safety and comfort onboard
However, noise and vibration problems are not merely confined to underwater. They represent a challenge onboard vessels too, and can have a significant impact on the health, safety and comfort of both crew and passengers. Vibrations can also impair the performance of onboard equipment.
The International Maritime Organization (IMO) has established mandatory on board noise regulations, including minimum sound insulation thickness between cabins, for vessels over 1,600 gross tonnage. In addition, several countries or flags have their own additional standards for noise and vibrations, such as noise and vibration exposure criteria in France and vibration levels in accommodation for Danish ships.
Two problems, one solution
Noise and vibrations underwater and onboard may appear to be separate issues but one answer to solving them is interconnected and starts with the very early stages of any vessel-building project.
Engaging an appropriate technical advisory, asset management and assurance solutions partner at the outset can ensure all anticipated design issues can be resolved before fabrication and construction begin.
As an example, BV Solutions M&O supports asset owners all the way from the design phase to ensure optimal acoustic and architectural performance. In addition to providing modelling recommendations based on existing measurements and addressing the full range of noise frequencies, Bureau Veritas Solutions M&O engineers play a key role in factory acceptance testing alongside manufacturers. This includes frequent visits to shipyards while vessels are under construction.
There are several sources of vessel noise underwater and onboard, including the main engine, HVAC equipment, generators and exhausts. But one of the main causes is often the vessel’s propeller. An appropriate advisory organisation such as BV Solutions M&O will be able to provide bespoke recommendations on the best propeller architecture and other solutions to reduce noise and vibrations. Addressing these issues early on in the design phase will avoid considerable and costly operational issues once the vessel is in service.
The challenges and solutions to noise and vibration pollution both above and below the waterline have never been more important as we look to balance the future security of our seas alongside growing commercial demands. This will be the theme of an upcoming BV Solutions M&O webinar. Details will follow shortly.
Learn more about our noise and vibration services here.