The American Club issued an alert focusing on the IMO guidance as set forth in the annex to the attached document MEPC.1/Circ.878, Guidance on the Development of a Ship Implementation Plan for the Consistent Implementation of the 0.50% Sulphur Limit Under MARPOL Annex VI.
Mainly, as it is reported, there’s no mandatory requirement to have an implementation plan. On the contrary, Port State Control authorities are to possible take the status of any plan, or the lack thereof, into consideration...
https://safety4sea.com/advises-on-imo-sulphur-cap-implementation/