The Maritime and Port Authority of Singapore (MPA) on Thursday (17 July) issued Shipping Circular No. 4 of 2025 regarding resolutions adopted by the 83rd session of the Maritime Safety Committee (MEPC83) of the International Maritime Organization (IMO), which was held from 7 to 11 April 2025:

This circular informs the shipping community of the resolutions adopted by MEPC 831 and urges the shipping community to prepare for the implementation of these resolutions.

MEPC 83 adopted the following mandatory resolutions:

Resolution MEPC.397(83) – Amendments to the NOX Technical Code 2008 (Use of multiple engine operational profiles for a marine diesel engine, including clarifying engine test cycles)

This resolution adopts amendments to the NOX Technical Code 2008, concerning the use of multiple engine operational profiles for a marine diesel engine, including clarifying engine test cycles. The amendments will enter into force on 1 March 2027 and will be given effect through the Prevention of Pollution of the Sea (Air) Regulations.

Notably, the amendments shall enter into effect as follows:

• for a new individual engine or a parent engine of an engine family or engine group that has not been previously certified, the said amendments apply no later than 1 January 2028, based on the issue date of the Engine International Air Pollution Prevention (EIAPP) Certificate for the individual engine or parent engine;

• in the case of a new member engine to an engine family or engine group for which the parent engine was certified before 1 January 2028, prior to the certification of that member engine it would need to be shown that the engine family or engine group complied with the said amendments no later than 1 January 2030 based on the issue date of the EIAPP Certificate for that member engine;

• the said amendments do not apply to a marine diesel engine which already has an EIAPP Certificate except:
• in the case of an engine that is subject to substantial modification on or after 1 January 2028, the said amendments would apply as specified in the definitions of “substantial modification” set out in amended paragraph 1.3.2 of the NOx Technical Code 2008 based on the issue date of the EIAPP Certificate for that engine; and
• in the case of an identical replacement engine installed on or after 1 January 2028, the version of the NOx Technical Code 2008 at the time of issuance of the EIAPP Certificate to the original engine

applies, unless the replaced engine is already equipped with multiple engine operational profiles, in which case the provisions of the new chapter 8 of the NOx Technical Code 2008 apply.

Resolution MEPC.398(83) – Amendments to the NOX Technical Code 2008 (Certification of an engine subject to substantial modification or being certified to a Tier to which the engine was not certified at the time of its installation)

This resolution adopts amendments to the NOX Technical Code 2008 concerning the certification of an engine subject to substantial modification or being certified to a tier to which the engine had not been certified at the time of its installation. The amendments will enter into force on 1 September 2026 and will be given effect through the Prevention of Pollution of the Sea (Air) Regulations.

MEPC 83 also adopted the following resolutions:

Resolution MEPC.399(83) – 2025 Guidelines on Selective Catalytic Reduction (SCR) Systems

This resolution adopts the 2025 Guidelines on SCR systems. These Guidelines supersede the 2017 SCR Guidelines, adopted by resolution MEPC.291(71) and amended by resolution MEPC.313(74).

Resolution MEPC.400(83) – Amendments to the 2021 Guidelines on the Operational Carbon Intensity Reduction Factors Relative to Reference Lines (CII Reduction Factors Guidelines, G3) (Resolution MEPC.338(76))

This resolution adopts amendments to the 2021 Guidelines on the operational carbon intensity reduction factors relative to reference lines (CII reduction factors guidelines, G3), updating the reduction factors for the required annual operational CII of ship types including for years 2027 to 2030.

Resolution MEPC.401(83) – Amendments to the 2024 Guidelines for the Development of a Ship Energy Efficiency Management Plan (SEEMP) (Resolution MEPC.395(82))

This resolution adopts amendments to the 2024 Guidelines for the development of a SEEMP, in relation to the methodology for collecting data on fuel oil consumption, distance travelled and hours under way and other items.

Resolution MEPC.402(83) – Guidelines for Test-Bed and Onboard Measurements of Methane (CH4) and/or Nitrous Oxide (N2O) Emissions from Marine Diesel Engines

This resolution adopts the Guidelines for test-bed and onboard measurements of CH4 and/or N2O emissions from marine diesel engines.

Resolution MEPC.403(83) – Amendments to the 2022 Guidelines on Survey and Certification of the Energy Efficiency Design Index (EEDI)

This resolution adopts amendments to the 2022 Guidelines on survey and certification of the EEDI, updating the references to the International Towing Tank Conference Recommended Procedure 7.5-04-01-01.1 Preparation, Conduct and Analysis of Speed/Power Trials 2024 edition and ISO 15016: 2025 edition.

Resolution MEPC.405(83) – Amendments to the 2023 Guidelines for the Development of the Inventory of Hazardous Materials (Resolution MEPC.379(80))

This resolution adopts amendments to the 2023 Guidelines for the development of the Inventory of Hazardous Materials, clarifying the relevant threshold values in respect of cybutryne when samples are directly taken from the hull or when samples are taken from wet paint containers.

Any queries relating to this circular should be directed to MPA Shipping Division via email at [email protected].

Photo credit: Maritime and Port Authority of Singapore
Published: 18 July, 2025