Why is mitigating underwater noise important for Shipowners and Operators?

Marine mammals and fish heavily rely on their sense of hearing for essential activities such as navigation, communication, and locating food sources. Each species exhibits sensitivity to specific frequency ranges within the spectrum, crucial for survival and environmental interaction. However, the increasing underwater noise from ships is disrupting this balance, prompting regulators globally to develop regulations to minimise its impact.

Regulatory frameworks

Since 2014, URN guidelines (MEPC.1/Circ.833, April 2014) have been available for commercial ships. These guidelines offer non-mandatory advice for designers, builders, and operators. Covering design, operational, and maintenance considerations, they are a valuable resource for enhancing URN management practices.

The 80th session of IMO's Marine Environment Protection Committee  (MEPC 80) approved new guidelines on URN have been providing additional insights into URN reduction approaches and technologies (MEPC.1/Circ.906) and (MEPC.1/Circ.907). MEPC80 also adopted a revised strategy aimed at achieving net-zero greenhouse gas emissions by or around 2050, with discussions on how Underwater Radiated Noise (URN) and measures to reduce shipping’s impact on them may also contribute to the GHG reduction targets set.

Discussions on establishing better data and knowledge on URN through an experience-building phase (EBP) and measurements have been ongoing. MEPC 81 encouraged the early uptake and implementation of MEPC.1/Circ.906 as part of an EBP, with an invitation for submissions to MEPC 82 on this topic. No further revisions to the URN Guidelines will be undertaken until the EBP has been completed. MEPC 81 also endorsed in principle the draft Action plan for reducing underwater noise from commercial shipping, with a view to further consideration and final approval at MEPC 82. 

While still non-mandatory, these guidelines offer detailed recommendations for existing and new ships, emphasizing the importance of creating an Underwater Noise Management Plan. This plan is set to align with the mandatory Energy Efficiency Management Plan, ensuring a holistic approach to environmental sustainability.

States are implementing local restrictions, and an increasing number of speed reduction zones and Particularly Sensitive Sea Areas (PSSAs) are being established. Ports also incentivise compliance, with initiatives like the Port of Vancouver offering significant fee discounts for vessels with LR's UWN-L notation.

Furthermore, the International Association of Classification Societies (IACS) has been actively working towards Unified Standards for measuring URN, enhancing consistency and reliability across the industry. A new set of recommendations was introduced, designated as Rec.176, effective from 1 September 2023, aimed at standardising the measurement of URN, addressing safety concerns when working with large ships in situ in open waters and leveraging practical experiences to offer a unified approach for the quantification of continuous underwater radiated noise.

Managing Underwater Radiated Noise (URN) for the Cruise Industry

Watch our on-demand webinar to learn how to reduce harbour fees with noise-compliant vessels and discuss underwater noise from cruise ships.

Partner with LR advisory expertise

Stay ahead of the curve with our guidance on navigating these regulatory changes and optimizing your URN management strategies. Our experience in underwater noise measurement has been gained working closely with navies around the world to help them ensure that their vessels meet stringent noise guidelines. This has also provided us with direct access to 'one of a kind' proven facilities and equipment that we are now able to make available to commercial operators, too.

  • URN Management Plan Development
  • Vessel’s URN Predictions
  • Energy Efficiency & URN Relationships
  • Environmental Impact at Specific Locations
  • Field Measurements
  • Rotor-Hull Interaction
  • URN Mitigation Advisory
Fleet Benefits
  • Increased efficiency
  • Environmental protection
  • Decreased onboard noise level
  • Decreased material damage