Paper "On the working principles of Energy Saving Devices" by Van Terwisga

An interesting paper explaining the physics behind the hydrodynamic energy saving devices.
On the working principles of ESDs.pdf (381.4 KB)


Hi @Paraschos.Liadis,

Thanks for sharing this interesting paper!

I find really helpful also this report coming from the specialist committee to the ITTC. This report includes a graph showing the CO2 emission reduction potential from individual measures, classified into the 5 main categories of

  1. hull design
  2. power & propulsion system
  3. alternative fuels
  4. alternative energy sources
  5. operation

The Specialist Committee on Energy Saving Methods Final Report and Recommendations to the 29th ITTC


@Stela.Spiraj very interesting!

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Thank you for sharing both!! I suspect some of these ESDs cost a lot of money. How do shipowners cover these costs? If a vessel is not compliant with EEXI in 2023, is there an immediate impact?

Hi @Pauline.Liadi

Indeed the ESDs cost a lot of money for installation. However, it is expected to improve the ships’ efficiency and reduce the fuel oil consumption, therefore the operational cost. At the same time, considering the reduced fuel oil consumption, the CO2 emissions will be less, which helps both on the EEXI and more significantly at the CII rating of the vessel.

Regarding EEXI compliance, most ship managers are exploring the Engine Power Limitation option or the Shaft Power Limitation, which are considered less expensive than the ESDs and have a high impact on the attained EEXI.

The immediate effect of an EEXI non-compliance is that the Flag Administration or any other Recognized Organizations duly authorized by it (i.e., class of the vessel) will not be able to issue the International Energy Efficiency Certificate (IEEC).

The IEEC is a statutory mandatory certificate for new buildings upon the initial survey before the ship is put into service and for existing ships of 400 gross tonnages and above during intermediate or renewal survey.

The IEEC ensures compliance with MARPOL convention Annex VI.

Basically, not having the IEEC can be encountered as a MARPOL violation.

In such a case, the vessel may be detained, and the ship might be out of trade.

If a vessel is not compliant with EEXI in 2023, the immediate impact is that the IEEC cannot be issued/re-issued according to the relevant regulations, that is obviously not good for the ship.