An alternative view of EEXI

Edwin Pang, founder of UK consultancy Arcsilea and chair of RINA’s IMO Committee, reckons emissions cutting agreements agreed upon this month are more significant than many other commentators have suggested. In the first of a two-part series, he explains why.

There have been lots of pronouncements about MEPC 76 being a disappointment or low in ambition, in particular the outcomes of the short-term measures.

I wonder if the issue is that the headline numbers don’t really tell the whole story and the actual situation is more complex than it first appears.

Let’s take EEXI first. We agreed that for ships to which power limitations are used, PME should be calculated at 83% of MCR lim instead of 75% of MCR lim as is done for EEDI. Leaving aside for now the significant interpretation and consistency problems we now have in the calculation guidelines which will need to be resolved, this shift to 83% means that affected ships will have to limit their power by a further 10% than if 75% was used.

However, this is not the only issue. For ships which do not have acceptable documentary proof of their speed power curve (ie from sea trials or model tests, appropriately calibrated to EEDI draught, that is, at summer load line), speed (Vref) may be determined via a statistical method.

This method imposes a penalty of one knot or 5% of the speed (whichever is lower), and the statistical method may already under predict the speed before the penalty is applied. Now there are good reasons as to why this penalty was imposed, which is to try to avoid unfair over-prediction of speed. Taken together however, these make the EEXI a much more challenging standard to comply with, and effectively holds many existing ships to a higher standard than new ships under the EEDI framework.

It is perhaps easiest to illustrate what this means in practice by way of an example.

Let’s use a kamsarmax bulk carrier currently fitted with a 9,930 kW main engine. Prior to the deliberations at ISWG-GHG 8, this ship would have complied (arguably on paper) with a minor power restriction to 9,600 kW if we were able to use the speed power curve. Now after the change to 83% and assuming we had to also use the statistical method to comply, power needs to be restricted to 7,300 kW. That is 26.5% versus 3.3% power limitation, for the same ship, for want of a bit of paper that has a curve depicting the relationship between speed and power. That is a desperately un-level playing field, at least until the CII measure bites sufficiently to level things out (more on this tomorrow).

There are some who have observed that even at a 26.5% power reduction, operational speeds are barely affected. In some cases this is true, but on the other hand we also need to take into account power margins for weather and fouling. A case in point is the current situation with container shipping – the significant delays being incurred means ships being stationary for longer periods, increasing hull fouling. And there are also ship types and sizes (mainly the smaller and shortsea segments, which involves significant numbers of ships) that operate closer to design speed for which this has a significant impact.

And the timescale over which we will implement the EEXI requirements? Around one year from 2023 (though the prudent shipowner will be starting now) for possibly 30,000 existing ships. That will be a mammoth undertaking for everyone involved – from initial calculation, verification/approval to installation and certification of the power limits.

Pretty ambitious I’d say.


  1. Insightful. It is helpful having commentary from someone who has taken the time to actually understand the regulation and then determined its actual impact.

  2. Thanks for two good reads Edwin. A query – if I take 25% off the rated power of a kamsarmax, even if I acknowledge that the effect on service speed will be minimal, what is the effect on manoeuvrability, particularly in heavy weather? I’m imagining entering a crowded anchorage and trying to get the bow up into a stiff crosswind with only 75% of the power I used to have.

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