Slow steaming application for short-sea shipping to comply with the CII regulation

Burak Zincir*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

10 Citations (Scopus)


Slow steaming is an effective operational measure that reduces fuel consumption and thus emissions on board. With the Carbon Intensity Indicator (CII) regulation coming into force in 2023 from the International Maritime Organization (IMO), ships will have to reduce their CO2 emissions even more. The practice of slow steaming is an important measure to comply with this regulation. In this study, real voyage data of a general cargo ship was used. The changes in fuel consumption, CO2, CH4, N2O, and BC emissions, 20-year global warming potential (GWP20), and 100-year global warming potential (GWP100) of the ship were analysed under different scenarios (75%, 38%, 27%, and 19% main engine load), and the voyage expenses and cost-benefit ratio were calculated. At 38% main engine load, 31.5% less emissions were released than at 75% main engine load. At 27% and 19% main engine load, the emission reduction was 40.6% and 50.1%, respectively. The CO2 reduction target of 40% by 2030 and 50% by 2050 compared to 2008 levels in the IMO Initial GHG Strategy was achieved with slow steaming. As CO2 emissions decreased due to the application of slow steaming, this had a positive impact on the ship's CII rating and it remained at the A rating without further action. Nevertheless, it remains at the A rating with slow steaming, the amount of emissions varies depending on the rate of application of slow steaming in three different scenarios, and this shows that the environmental impact of each A rating is not the same. The results of the economic analysis show that operating costs increase and fuel costs decrease when the travel time is extended with slow steaming. As a result, the total voyage expenses decreased by up to 23.3%.

Original languageEnglish
Pages (from-to)21-38
Number of pages18
Issue number2
Publication statusPublished - 1 Mar 2023

Bibliographical note

Publisher Copyright:
© 2023, University of Zagreb Faculty of Mechanical Engineering and Naval Architecture. All rights reserved.


The author wishes to thank to Seahorse Shipping and Engineering Co. Ltd. and DD Shipping Ltd. to provide their ship data and voyage information for this study. The author also wishes to thank again to Seahorse Shipping and Engineering Co. Ltd. for the financial support for the publication.

FundersFunder number
Seahorse Shipping and Engineering Co. Ltd.


    • carbon intensity index
    • maritime transport
    • short-sea shipping
    • slow steaming


    Dive into the research topics of 'Slow steaming application for short-sea shipping to comply with the CII regulation'. Together they form a unique fingerprint.

    Cite this