Development of an Energy Efficient Stern Flap for Improved EEDI of a Typical High speed Displacement Vessel

  • Y. Hemanth Kumar Indian Institute of Technology Madras, Chennai - 600 036, India
  • R. Vijaya Kumar Indian Institute of Technology Madras, Chennai - 600 036, India
Keywords: Energy efficiency design index, Energy saving device, Exhaust emissions, Stern flap


The surge in maritime trade is leading to large scale deployment of high-speed displacement ships by all nations. Cargo vessels are designed for a voyage in pre-determined routes at consistent speeds. On the other hand, high-speed displacement vessel engines designed with a capability to cater for top speeds are under-utilised during their normal course of operation. This sub-optimal utilisation impacts efficiency and increases emissions. In this study, a most favourable stern flap is designed for reducing the energy efficiency design index of a typical high-speed displacement vessel with a slender hull. CFD simulations and experimental model testing were conducted for 12 different stern flap configurations for determining most favourable flap design in the Froude no of 0.17-0.48. Performance of the most favourable stern flap was established by calculating, energy efficiency design index (EEDI) and fuel consumption based on typical operating profile. NOx, VOC and PM emissions were estimated in with and without flap condition. Studies demonstrated that the stern flap reduced effective power demand, average fuel consumption and emissions by about 8 per cent, which when considered for the ship’s operating life cycle, are significant. The most favourable stern flap reduced EEDI by 3.74 units and 1.98 units as compared to the bare hull condition and the required EEDI respectively, thereby demonstrating that EEDI could be used as an index to indicate stern flap efficiency.


Michalchuk, B.W. & Bucknall R.W.G. CO2 reduction design strategies for naval ships. In 12th International Naval Engineering Conference. Amsterdam, Netherlands, 2014.

Stapersma, D. Some thoughts on an energy efficiency design index for naval ships. In 13th International Naval Engineering Conference. Bristol, U.K, 2016.

Karafiath, G.; Cusanelli, D.S. & Lin, C.W. Stern wedges and stern flaps for improved powering–US Navy experience. Trans. Soc. Nav. Archit. Mar. Eng., 1999, 107, 67-99.

GEF-UNDP-IMO GloMEEP Project and IMarEST, Ship Emissions Toolkit, Guide No.1, Rapid assessment of ship emissions in the national context, 2018.

Global maritime energy efficiency partnerships and DNV GL. Energy Efficiency Technologies Information Portal. (Accessed on 10 October 2019).

Hemanth, K. & Vijayakumar, R. Review of hydrodynamic performance of stern flap. In International Conference MARHY 2018: Computational and Experimental Marine Hydrodynamics, IIT Madras, Chennai, India, 2018

Hemanth, K. & Vijayakumar, R. Stern flaps : A cost-effective technological option for the Indian shipping industry. Maritime Affairs: J. National Maritime Foundation, India, 2018, 14(2), 26-37.

ITTC-Recommended procedures and guidelines. Practical Guidelines for Ship CFD: Rev.01, 7.5-03-02-03, 2011.

ITTC-Recommended procedures and guidelines. Ship Models: Rev.04,7.5-01-01-01, 2017.

Joseph, L.; Rakesh, N.V.N. & Subramanian V.A. Computer-aided CAD. Energy conservation method combining anti-spray rail and wedge flap for high-speed displacement hulls. Def. Sci. J., 2019, 69(4), 409-414.

ITTC-Recommended Procedures and guidelines. Testing and Extrapolation Methods Ice Testing, General Guidelines: Rev.01, 7.5.02-04.01, 1999.

Fraser, W. Opportunities for improved warship energy efficiency : A Canadian patrol frigate’s operational energy use patterns. Harvard University, Cambridge, USA, 2016. (Masters Thesis).

Paul, Schulten; Rinze, Geertsma & Klaas, Visser. Energy as a weapon part II. In International Conference EAAW VII, Glasgow, UK, 2017.

Trozzi, C. Emission estimate methodology for maritime navigation. In 19th Annual International Emission Inventory Conference: Emissions Inventory - Informing Emerg Issues, 2010.

How to Cite
KumarY. H., & KumarR. V. (2020). Development of an Energy Efficient Stern Flap for Improved EEDI of a Typical High speed Displacement Vessel. Defence Science Journal, 70(1), 95-102.
Naval Systems