MARPOL Annex VI

MARPOL Annex VI, added to the Convention by a 1997 Protocol and significantly strengthened by 2008 and subsequent amendments, regulates air pollution from ships. It sets limits on sulphur oxide (SOx) and nitrogen oxide (NOx) emissions from ship exhausts, controls the use of ozone-depleting substances, regulates shipboard incinerators, and establishes Emission Control Areas (ECAs) where stricter standards apply. The global sulphur cap, effective from 2020, limits fuel oil sulphur content to 0.50% m/m outside ECAs. For an officer of the watch, Annex VI compliance means verifying that the correct grade of fuel is in use when entering or departing an ECA — where the limit is 0.10% m/m — and maintaining records of fuel oil changeovers in the Engine Room Log. Ships using exhaust gas cleaning systems (scrubbers) as an alternative compliance method must operate and document them in accordance with flag state approval. Bunker delivery notes and fuel oil samples must be retained for a minimum period specified by the flag state and presented to port state control inspectors on request. NOx Technical Code certification applies to marine diesel engines above a certain power threshold. The Energy Efficiency Design Index (EEDI) and Ship Energy Efficiency Management Plan (SEEMP) — also required under Annex VI — are increasingly scrutinised as IMO's Carbon Intensity Indicator (CII) rating system comes into force.