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Shaft power limitation

The shipping industry is facing increasingly strengthened environmental regulations, in particular those concerning decarbonization. At the MEPC 75, the amendment to MARPOL Annex VI to introduce the Energy Efficiency Existing Ship Index (EEXI) as a technical measure and Carbon Intensity Indicator (CII) rating as an operational measure was approved as a short-term measure of the IMO GHG Strategy.

Once adopted, EEXI and CII will be the most imminent measures to be met by the shipping industry with expected implementation in 2023. The majority of pre-EEDI ships do not satisfy the EEXI requirements. Such non-compliant vessels will require additional measures such as limitation of engine power (EPL/ShaPoLi) and/or installation of energy saving devices (ESD).


Preparation For EEXI

The required EEXI is the maximum amount of CO2 emitted by a vessel per capacity (deadweight) tonne mile under reference conditions according to its type and capacity. To comply with the regulation, the attained EEXI for a vessel must be less than or equal to the required EEXI.

The majority of pre-EEDI ships do not satisfy the EEXI requirements. Such non-compliant vessels will require additional measures such as limitation of engine power (EPL/ShaPoLi) and/or installation of energy saving devices (ESD).

In this regard, shipowners will need to check the current status of EEXI and CII of their ships as soon as possible and find the most cost effective solution that would be suitable for their ships.

ABA*MAR has developed a Shaft power limitation (SHaPoLi), EEXI Shaft Power Acquisition Module, that when integrated with ABA*MAR Shaft Power Meter, provides verified shaft power data.

ABA*MAR EEXI Shaft Power Acquisition Module provides a continuous logs of RPM, Torque and power with the exact date and time as well as the reason for the power exceedance, provided it integrates bridge navigation equipment information.

Voyage reports are automatically produced in support of the regulatory port authority documentation requirements, providing the most convenient way to evidence EEXI compliance system to limit the engine power.

In exceptional circumstances where the Ships Master or OICNW need to override the EEXI power limiter (for events such as Adverse Weather, Ice-Navigation, Rescue Operations, Avoidance of Pirates and Engine Maintenance), ABA*MAR EEXI Shaft Power Acquisition Module logs the exact reason for the power exceedance.

Shaft power limitation Key Points

The benefits

ABA*MAR EEXI shaft power acquisition system beyond being cost effective and easy to install, presents many other benefits to shipowners.

  • Ensure compliance with EEXI requirements.
  • A standardised and low-cost solution.
  • Non-intrusive and quick retrofit installation.
  • Integrates with existing ABA*MAR shaft power meters and ABA*MAR DSSP systems.
  • Does not limit operational flexibility for vessels with multiple shaft lines or multiple engines per shaft.
  • Can be integrated to third party shaft power meter systems.
  • Automated and simple EEXI report generation.
  • Continuous GPS positioning linked to power events.

The software

Easy to understand user interface for monitoring and recording power breaches.

The system implements strict RBAC rules to prevent any user to tamper with software configurations as well as data logging. Where and if data are presented to the user, it is done in a read only way.

Automatic data logging 

The data logging is automatic and cannot be stopped by the user.

 Guaranteed timestamps for data logging

The timestamp affixed to every row of the data log is synchronized with ship’s GPS, which satellites use internal atomic clocks.

Data log manipulation prevention systems

The entire data log is encrypted using an AES-256 algorithm, which is the standard for bank-level data encryption.

Software updating

New software versions will be developed, edited and issued in accordance with development routines according to ISO 9002 for the work process. All changes to software will be documented and tested prior to release so that traceability is maintained within software releases.

Minimum data report and export requirements

The system supports the exporting of the entire data log or of a selected section of it using standard formats (i.e., XLSX format), mainly for the use by inspectors and verifiers.

Backup and recovery of information:

The system makes continuous backup of the data log on a secondary storage unit.

The Process

At the point of any Power Reserve threshold breach, the EEXI Interface main screen will provide a visual and audible alarm, highlighting to the ships Master or OICNW when:

  • the vessels Power Reserve limit is close to be reached and
  • when Power Reserve limit has been breached.

Power reserve breach record
The Datum SHaPoLi EEXI Interface not only continuously records all Shaft Power data, but also creates a Power Reserve Breach Event
Record whenever the Shaft Power exceeds the Power Reserve threshold

Justification notes
Every Power Reserve Breach Event requires the ships Master or OICNW to justify the reasons for the use of Power Reserve, as per regulation 3.1 of MARPOL Annex VI (e.g. operating in adverse weather and ice-infested waters, participation in search and rescue operations, avoidance of pirates and engine maintenance)

Data recorded in accordance to regulation
In case of having used the Power Reserve, the ship should without delay notify its Administration or RO responsible for issuing the relevant certificate and the competent authority of the relevant port of destination with the information recorded in accordance with MEPC.335(76), paragraph 3.2:

Digital voyage report automatically recorded in-line with EEXI legislation.

Shaft power limitation How It Works

The ABA*MAR EEXI SHaPoLi system seamlessly integrates to existing vessel hardware, LAN and electronics infrastructure.


Torque Meter

On Board Data Acquisition system

D-SSP System

Fleet Management solution

Shaft power limitation

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derived from our 40 year expertise in Power measurment and ship performance

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