AFS Certification

AFS Certification

Amendments to the International Convention on the Control of Harmful Antifouling Systems on Ships (AFS Convention) adopted by the IMO ban the presence of cybutryne in hull coatings beginning January 1, 2023.


Cybutryne is a chemical compound used in some antifouling hull coatings systems. When used in the outermost layer of hull coatings, cybutryne exhibits biocidal properties which prevent marine life from attaching to the hull coating’s surface.


When used as an anti-fouling agent, cybutryne leaches, following the physical mechanism well known to self-polishing anti-fouling paints, and then becomes available in the environment, together with other degradation products of its original formulation that can also be characterized as toxic and persistent.


AFS Convention Amendments

Introduction of new amendments to the AFS Convention prohibits usage of cybutryne (CAS No. 28159-98-0) in anti-fouling systems for new applications as well as for ships those already have applied with an anti-fouling system which contain cybutryne.


The amendments to the convention apply as follows:

  • New construction vessels with delivery date after January 1, 2023, shall be delivered as cybutryne free which is required to be declared by paint/coating manufacturer at the time of vessel’s delivery.
  • Existing vessels in operation shall comply with this requirement by the next scheduled anti-fouling system renewal survey after January 1, 2023, but no later than 60 months following the last application to the ship of an anti-fouling system containing cybutryne.



AFS Certification

Vessels having AFS Certificate as of the effective date of the amendment to the AFS Convention to add Cybutryne to the list of banned substances (1 January 2023) shall undergo documentary verification and receive AFS Certificate in a new format within 2 years from the effective date (by 31 December 2024).


Refer to the Resolution MEPC.331(76) and to the PMDS Technical Circular TC-18-22 Control of Harmful AFS on ships.


Source IMO & ClassNK


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