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Case Study – Impact of Installation of Rotor Sails on a Bulk Carrier


Reducing greenhouse gas emissions is a challenge each transportation sector is working to solve in various ways, and the marine shipping industry is no exception. Greenhouse gas emissions released by fuel-powered ships and other marine vessels have been on the rise in recent years, rising about 10% between 2012 and 2018, according to a 2020 study released by IMO.

According to the Fourth IMO GHG study, international shipping, in 2018, was responsible for approximately 2% of global carbon dioxide emissions. This may not sound a lot but is comparable to emissions from major GHG emitting countries, such as for example Germany.

Emission projections 2018 – 2050

  • Emissions are projected to increase from about 90% of 2008 emissions in 2018 to 90-130% of 2008 emissions by 2050 for a range of plausible long-term economic and energy scenarios (Figure 1).
  • Emissions could be higher (lower) than projected when economic growth rates are higher (lower) than assumed here or when the reduction in GHG emissions from land-based sectors is less (more) than would be required to limit the global temperature increase to well below 2 degrees centigrade.
  • Although it is too early to assess the impact of COVID-19 on emission projections quantitatively, it is clear that emissions in 2020 and 2021 will be significantly lower. Depending on the recovery trajectory, emissions over the next decades maybe a few percent lower than projected, at most. In all, the impact of COVID-19 is likely to be smaller than the uncertainty range of the presented scenarios.

Annex VI part of the MARPOL requirements deals with air pollutions and also regulates the energy efficiency of ships. It introduces different requirements that are coming into force and the shipowners need to take action in order to comply with the new rules.



One of the most important benefit that installing Rotor Sails brings, is the compliance with the short-term upcoming regulations regarding required EEXI that enters into force from January 1st 2023.

This case study highlights the applicability of harnessing wind power for ships. Economically, the results reveal that the use of Rotor Sails will contribute to considerable savings.


For 100 years, Rotor Sails, also known as Flettner Rotors, have been successfully used to harness wind power to assist vessel propulsion. This proven technology capitalizes on the aerodynamic phenomenon known as the Magnus Effect. They comprise vertical cylinders, driven by the wind to rotate and generate thrust. This increases efficiency by reducing fuel consumption, bunker costs and harmful emissions.


The purpose of this study is to assess the techno-economical aspects of installing two Rotor Sails on a handysize bulk carrier and their effect on the ship’s operation. The assessment includes – evaluation of the impact of the Rotor Sails on the ship structure and performance, estimate calculation of the total investment, and prediction to overcome the investment. CO2 reduction was also taken into consideration.

Ship Particulars 

  • Length o.a. – 190 m
  • Length b.p. – 185 m
  • Breadth mld. – 32.26 m
  • Depth mld. – 18.1 m
  • Designed draught mld – 11.2 m
  • Scantling draught mld – 12.7 m
  • Deadweight at designed draught (11.2m) – 47 400 t
  • Deadweight at designed draught (12.7m) – 55 900 t
  • Constant weight – 239 t

Rotor Sails to be installed

  • 2 Rotor Sails to be installed
  • Size – 18×3
  • Maximum Continuous Thrust Force 100kn each
  • Rotor sails efficiency – 90%

Rotor sails propulsion impact

  1. Propeller thrust relief – 18 %
  2. Main engine output relief – 15 %
  3. Fuel consumption saving – app. 15 %

Other calculations

For the purposes of the study, we have also taken into consideration other options of different hours of operation of the Rotor Sails. The results below show predictions if the vessels are operating 250 days per year.

If you want to learn more details regarding the results of the study contact us at office@ihbshipdesign.com 


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