- What is EEXI?
The Energy Efficiency Existing Ship Index (EEXI) is an IMO regulation that came into force on 1 January 2023. It sets minimum technical efficiency standards for existing vessels to reduce CO₂ emissions.
- When did the EEXI enter into force?
The amendments to MARPOL Annex VI entered into force on 1 November 2022, with EEXI and CII certification requirements effective from 1 January 2023. Initial reporting occurred in 2023, with the first ratings issued in 2024.
- What improvement measures can help my vessel meet EEXI requirements?
Common measures include engine power limitation, shaft power limitation (SHaPoLi), engine derating, propulsion optimization, and energy-saving devices. For vessel-specific recommendations, consult your classification society or maritime advisory.
- When must my vessel be EEXI compliant?
Your vessel must have its EEXI Technical File approved and its International Energy Efficiency Certificate (IEEC) re-issued by your flag administration or Recognized Organization at the first annual survey after 1 January 2023.
- Which vessels does the EEXI apply to?
The EEXI applies to all cargo and cruise vessels above 400 GT that fall under MARPOL Annex VI. For ships with non-conventional propulsion (e.g. diesel-electric) or those undergoing major conversions, recalculation of the EEXI may be required. Refer to MARPOL Annex VI for specific exemptions and clarifications.
- Will EEXI requirements change in the near future?
A formal IMO review of the EEXI and CII regulations is underway and must be completed by 1 January 2026. Based on its findings, further amendments to MARPOL Annex VI may be adopted.
- Can I use any class to approve/verify the EEXI or do I need to use the vessel’s class?
The EEXI Technical File must be approved and the International Energy Efficiency Certificate (IEEC) issued by the vessel’s respective classification society1. You cannot use a different class for approval unless the vessel has formally changed class and the new society has taken over responsibility for statutory certification.
This ensures consistency with the ship’s existing compliance framework under MARPOL Annex VI.
- What is the required EEXI which my vessels have to fulfil?
The required EEXI is calculated using EEDI reference lines (Energy Efficiency Design Index) with reduction factors applied based on ship type and size. In most cases, this aligns with the required EEDI values from Phase 2 or Phase 3 of the EEDI framework.
Each vessel’s attained EEXI is then compared to this required value to determine compliance. The reduction factor is expressed as a percentage relative to the EEDI baseline, and varies depending on the vessel category.
Source: imo.org
- What documents must be submitted for class approval of EEXI compliance?
You must submit an EEXI Technical File to your vessel’s classification society. This file includes the calculation of the attained EEXI and supporting documentation. Maritime advisory services can assist with preparing the file if needed.
- Will EEXI approval affect statutory certificates?
Yes. Once the EEXI Technical File is approved by the vessel’s classification society, the International Energy Efficiency Certificate (IEEC) will be re-issued to reflect compliance with MARPOL Annex VI.
- What is the timeline for the re-issuance of the IEE Certificate?
The International Energy Efficiency Certificate (IEEC) is re-issued at the first annual survey after 1 January 2023, following approval of the vessel’s EEXI Technical File.
- Is Engine Power Limitation (EPL) the only way to meet EEXI requirements?
No. While EPL is a common method, other improvement measures such as shaft power limitation, propulsion optimization, and energy-saving technologies are also valid approaches under the EEXI framework. The most suitable option depends on the vessel’s design, operational profile, and compliance strategy.
- Are there specific rules from flag states or classification societies when limiting engine power?
Yes. Classification societies and flag states may have specific rules or conditions for engine power limitation, especially for vessels with additional requirements such as ice class certification. Operators should consult their respective classification society to ensure compliance with both EEXI and any other applicable standards.
- What about ice-classed vessels with minimum speed requirements in ice?
All requirements related to the vessel’s ice class must be taken into account when calculating the EEXI. If it is not possible to meet both the minimum speed requirements for ice navigation and the EEXI compliance threshold, additional technical or operational measures may be required.
Operators should consult their classification society or flag administration for guidance on balancing ice class obligations with EEXI compliance.
Source: imo.org
- How about engines which are already derated? Can this engine be limited to an even lower level?
You could further limit your engine output, for instance for a second time, if necessary to fulfil the requirements by installing Datum Electronics Shaft Power Meter and EEXI Control Panel Interface. Unlike rigid engine limiters, Datum’s EEXI system allows the vessel Master to retain full control of the engine output (for instances where safety is paramount, as defined by SOLAS), whilst still providing the essential data to support the regulatory needs.
- Would installing a diesel-electric engine exempt my vessel from EEXI requirements?
Not necessarily. While some vessels with non-conventional propulsion systems (such as diesel-electric) may be treated differently under EEXI rules, they are not automatically exempt. Notably, LNG carriers and cruise passenger ships with diesel-electric propulsion are still subject to EEXI requirements.
For full compliance guidance, vessel operators should consult their classification society or flag administration, as exemptions depend on ship type, propulsion configuration, and regulatory interpretation.
Source: imo.org
- What documentation is required after Engine Power Limitation (EPL) has been implemented?
After EPL installation, the following documents should be submitted to your classification society:
- EPL Report from the engine manufacturer
- Survey statement from the class surveyor confirming installation
- EPL Management Plan outlining operational procedures and limitations
- Can Engine Power Limitation (EPL) lead to operational issues like increased vibration?
Yes. Limiting engine power often reduces the operational revolution range, which can introduce resonance conditions and lead to increased structural or machinery vibrations. These may affect crew comfort, cause wear or damage, and impact machinery reliability. If power is limited by deactivating cylinders, it alters the engine’s dynamics, requiring reassessment of shaft torsional vibrations, firing frequency, and excitation forces.
Operators should assess these risks with their classification society or technical advisor to ensure safe and compliant operation.
- What is required to verify the performance improvement of an ESD?
It is recommended to carry out a model test to predict the performance improvement of the ESD before installation. This model test result will then be used for the calculation of the attained EEXI. The decision about the installation of an ESD should be based on a model test or CFD prediction.
- Why do “SHaPoLi” and “ShaPoLi” both appear, and which is correct?
The officially recognised styling is SHaPoLi. This is the capitalisation used in the IMO’s 2021 Guidelines on Shaft/Engine Power Limitation (Resolution MEPC.335(76)), where the term is defined as Overridable Shaft Power Limitation (SHaPoLi).
Because class societies and flag administrations align their circulars and advisories to those IMO texts, they also standardise on SHaPoLi, reinforcing it as the formal acronym in regulatory, technical, and certification contexts.
EEXI SHaPoLi Bridge Interface
Real-Time Shaft Power Monitoring for Streamlined EEXI Compliance.
Our Type Approved EEXI–SHaPoLi solution supports compliance with MARPOL Annex VI and IMO EEXI regulations relating to vessel air pollution and CO emissions.
By continuously recording shaft power using a secure data link from the Datum SPM, the system generates automatic voyage reports to support vessel optimisation and regulatory documentation. Power exceedance events are logged automatically, along with corresponding GPS location and date/time-stamping.
Featuring a 12-inch touchscreen LCD, the system provides a clear and efficient overview of engine performance. Intuitive software provides users with configurable warnings and exportable reports, while its offline architecture secures its data against cyber threats.
