Back to the CIIs – does the CII rating has anything to do with fuel efficiency?

 

On the last MEPC it was agreed that vessels were to reduce CO2 emissions by 11% by 2026 (compared to the 2019 level) on the operational level. The CII to determine this is defined as the Annual Efficiency Ratio (AER) and it is a quite simple performance parameter that can be derived from the ships IMO DCS reporting.

If you look at the CII (without any exemptions yet) and the target setting for a year, you would aim to get a rating C or better for your ships.

 

There are different ways to get a good rating

• Operate a vessel with a good design which means that it in principle has a good fuel efficiency
• Maintain the vessel with respect to the technical state, a clean hull and the good antifouling paint
• Operate the vessel reasonably and ensure the good voyage efficiency

 

 

All three factors can be exemplified through a case study. As an example, a representative fleet of bulk carriers can be evaluated for a year and viewed in the CII ratings scheme.

 

As it can be seen in the figure above the ratings vary from vessel to vessel and from vessel class to vessel class.

Looking specifically at the Kamsarmax class, it can be seen that some vessels are rated A and some are rated E. A few samples can be taken out to identify the reasons for the rating.

Three vessels are taken out, where one vessel (vessel #1) has a fuel-efficient design, and two other vessels (vessels #2 & #3) are less efficient and similar to each other.

Vessel	CII (AER)	Built year	Fuel efficient design	CO2 emissions for the year
#1	Rating A	2014	YES	16998 ton
#2	Rating E	2012	NO	18168 ton
#3	Rating E	2010	NO	23834 ton

Vessel #2 and vessel #3 have the approximately the same CII but vessel #3 emits around 30% more CO2 than vessel #2 and in principle vessel #2 should be rewarded for emitting less CO2. Vessel #1 emits the less CO2 and is rewarded with a rating A. If looking in detail at the vessels and their operations, you can find some factors that affects the CII and when designing the rules, probably not was the purpose.

Specifically you can look at vessel #2 and #3:

Vessel	At Sea mean speed	Average draught	Number of voyage legs	Sailed distance
#2	11.4 knots	9.4 m	31	42251 nm
#3	10.9 knots	10.3 m	24	55369 nm

 

 

So, it is obvious that what makes vessel #2 to get the E rating even though the CO2 emission is so low. The vessel sails the less distance compared to vessel #3, it has a considerable idle time (almost half of the year), 30% more voyage legs and the higher average speed when it is at sea. In this case the operational profile is the driver for the CII rating.

If we then look at the fuel-efficient vessel #1 and compare it to vessel #3, then we get the following

Vessel	At Sea mean speed	Average draught	Number of voyage legs	Sailed distance
#1	11.0 knots	10.4 m	17	61533 nm
#3	10.9 knots	10.3 m	24	55369 nm

 

In this case the time distribution is more or less the same, the draught and speed likewise, but the distance is around 10% higher for vessel #1. This along with the higher percentage of sailing time in ballast and the better fuel efficiency for vessel #1 makes the rating better than vessel #3. In this case the fuel efficiency the main driver for the CII rating.

In general, the CII rating as it is defined by IMO does not always favour the fuel-efficient vessels. It is possible to speculate in the operations to control the rating, as shown in the above. It can even be an advantage to categorize routes from the benefit of the CII, an example is shown in two routes selected below.

Where the route with the orange dots is the CII favourable route with long distances equal split in ballast/laden voyages. The route with the blue dots has a large number of voyage legs and a lot of idle time and is the CII non favourable route.

To summarize, it is always favourable for a shipowner to operate fuel efficient vessel. They operate with lower costs and emits less CO2 to the benefit for the environment. They will also come out with a good rating but since the CII is defined as it is, there might be some issues even with the best vessels in cases of bad operations.

Therefore, it is important to have control over this, first of all when you as owner set the CII target for the coming year but also during the year, so you can control that you meet the targets when you meet the end of the years ratings.

We can of course help you with this in VesOPS. Contact us  and try to work with our software tools and discover the benefits of being in control of you fleets performance – from costs to compliance.

 

Phone: +45 2939 2960

Email: info@vesops.dk