Carbon Intensity Indicator Rating
Abbreviation: CII
Operational efficiency rating A–E assigned annually to ships >5,000 GT under MARPOL Annex VI.
In practice
Operators monitor CII through the year via DCS data. C-rating triggers operational measures (slow steaming, hull cleaning); D and E ratings trigger SEEMP Part III corrective action plan. Charter parties increasingly reference CII rating in clauses.
Regulatory detail & full definition
Carbon Intensity Indicator Rating — an annual operational efficiency rating from A (best) to E (worst) assigned to ships of 5,000 GT and above under MARPOL Annex VI Reg. 28. CII is calculated as grams of CO2 per cargo-tonne nautical mile, derived from IMO Data Collection System fuel consumption data, and compared with a tightening reference line (annual reduction factors set in MEPC.355(78)). Three consecutive D ratings or a single E require a corrective action plan in the Ship Energy Efficiency Management Plan; charter parties increasingly include CII-related clauses.
Authoritative source: MARPOL Annex VI (Air pollution) ↗
Related
Source: MARPOL Annex VI Reg. 28; MEPC.355(78)
High confidence
Editorial confidence: how we grade.