Ship Energy Efficiency Management Plan (SEEMP): Parts I, II and III Guide

For a technical superintendent, the Ship Energy Efficiency Management Plan is no longer the box-ticking document it once was. Since the Carbon Intensity Indicator took effect, the SEEMP has become the operational backbone of a vessel's compliance with MARPOL Annex VI — the plan that has to demonstrate, with real fuel data, that each ship will actually hit its required carbon intensity year after year or face a downgrade. It now comes in three parts that work together: Part I sets the energy-efficiency measures the ship will use, Part II defines exactly how fuel consumption data is collected for the IMO Data Collection System, and Part III — mandatory since January 2023 — sets the CII targets and the implementation plan to meet them. And the requirements keep tightening: a revised Part II and an updated Part III covering the 2026–2028 period had to be on board and verified by 1 January 2026, with enhanced data granularity now required. The thread running through all three parts is data: accurate, continuous, verifiable fuel and operational data, because a SEEMP is only as good as the figures behind it. This guide explains each part, how they connect to CII, the operational measures that move the rating, and the data foundation that makes the whole plan work. To see how the fuel and CII data behind your SEEMP can be tracked automatically, book a Marine Inspection demo.

What the SEEMP Is — and Who Needs Which Parts

The SEEMP is a mandatory, ship-specific plan under MARPOL Annex VI that establishes a cost-effective mechanism for improving a vessel's energy efficiency and managing its emissions. Which parts a ship must carry depends on its size, and getting that scope right is the starting point. See SEEMP tracking in a demo.

Part I — The Energy-Efficiency Management Plan

Part I is the operational heart of the SEEMP: a ship-specific plan describing the measures the vessel will use to improve fuel efficiency, from how it is navigated to how it is maintained. It is where good practice is turned into a documented, repeatable routine.

The key to Part I is that it must be lived, not filed. For the measures to count, the master and officers have to integrate them into daily operations, and the company has to provide the training, resources, and support to make that possible. A SEEMP kept only for inspection delivers nothing.

Part II — The Fuel Consumption Data Collection Plan

Part II is the data engine. It mandates that ships of 5,000 GT and above collect and report fuel oil consumption, distance travelled, and hours underway, feeding the IMO Data Collection System. It defines exactly how that data will be gathered, so the figures are consistent and verifiable. See fuel data logging in a demo.

The reporting cycle is fixed: data is collected throughout the year, aggregated at year-end, submitted to the flag state or verifier by 31 March, verified with a Statement of Compliance issued by 31 May, and transferred to the IMO's GISIS database by 30 June. Every step depends on the underlying data being accurate and complete — which is exactly where manual logging tends to fail.

Part III — The CII Implementation Plan

Part III, mandatory since 1 January 2023, is what made the SEEMP a performance contract rather than a statement of intent. It ties the ship to its Carbon Intensity Indicator and sets out, concretely, how the required rating will be achieved and held over a three-year horizon. It must contain four defined elements.

Part III is a living document. Each year it must be updated with the prevailing fuel-consumption data so the ship can track its CII performance and the effectiveness of its measures. Ships delivered before August 2025 with an existing Part III had to revise it to cover the 2026–2028 period and have the updated plan on board by 1 January 2026, under the latest IMO verification guidelines.

How CII Ratings Drive the Whole Plan

The reason Part III gives the SEEMP its teeth is the rating consequence. The CII grades each ship from A to E on its operational carbon intensity, and a poor grade carries real obligations that the implementation plan exists to avoid.

A ship rated D for three consecutive years, or E for a single year, must develop a plan of corrective actions as part of its SEEMP to return to compliance. Because the required CII threshold tightens each year under the IMO's reduction factors, a vessel that stands still on efficiency will see its rating slip over time — which is precisely why the three-year implementation plan, refreshed annually with real data, is the mechanism that keeps a ship on the right side of the line. See CII tracking against target in a demo.

The Data Foundation That Makes It Work

Across all three parts, one requirement is constant: accurate data. A SEEMP cannot demonstrate efficiency measures, report consumption, or prove CII performance without reliable figures, and the quality of those figures decides whether the plan survives verification.

This is where the practical difference is made. The fleets that handle the SEEMP well are not those with the best-written document but those with the best data behind it — captured continuously, tracked against target through the year, and ready for verification on demand. Turning the SEEMP from a binder into a live, data-driven management tool is what actually moves the CII rating and keeps the vessel compliant. Book a demo to see it on your fleet.

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