IMO advances plan to cut ship noise

The revised guidelines themselves, issued as MEPC.1/Circ.906/Rev.1 and dated 15 November 2024, stated that the Marine Environment Protection Committee had approved amendments at MEPC 82 “pertaining to the inclusion of the underwater radiated noise planning reference chart.” The circular added that the revised guidelines “will take effect on 1 December 2024.”

In the preamble to the annexed guidance, IMO set out the policy rationale in direct terms, “Commercial shipping is one of the main contributors to underwater radiated noise, which has adverse effects on critical life functions for a wide range of marine life, including marine mammals, fish and invertebrate species.”

Against that baseline, SDC 12 also reported progress on technical outputs designed to make the guidance more usable in design and retrofit decisions.

It said the sub-committee had agreed “the draft technical guidance on co-optimising energy efficiency and underwater radiated noise at the design and retrofit stage with a view to approval by MEPC 84.”

The meeting summary described the associated circular as supplementary guidance “on integrating URN reduction with energy efficiency, recognising the synergies between the two frameworks” and “drawing on experience gained during EPB and the outcomes of URN-EE workshops held in 2023 and 2025.”

The revised URN guidelines, for their part, embedded an implementation tool intended to guide early-stage planning and iterative improvement.

Appendix 4 stated, “The Revised Guidelines are non-mandatory, and URN Management Planning is intended to be a flexible tool that allows for a customised approach which can be modified to address specific contexts.”

It added, “URN Management Planning is meant to be an iterative process with steps that reinforce one another.”

In May 2025, Riviera reported that the policy case for linking noise and efficiency had been made explicitly by the High Commission of Canada’s alternate IMO representative Michelle Sanders, who warned, “Underwater noise poses a serious threat to over 130 marine species.”

Ms Sanders also said, “It is important not to view underwater noise in a silo,” adding, “We know there are co-benefits to noise reduction and energy efficiency, and many of the solutions overlap.”

SDC 12 also set out a further workstream aimed at strengthening the evidence base for goal-setting and agreed draft terms of reference for an IMO-commissioned study on URN emissions.

It asked the IMO Secretariat to assess options to cover the cost of the study.

IMO noted that the study was intended to support target-setting by generating in-water estimates and to help establish baselines and projections, to help in determining a URN baseline for ships, as well as for contemporary and future projections of URN emissions.

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