Historical Trends in Ship Design Efficiency

Against the background of fuel prices, climate change and energy security issues there is growing interest in improving the fuel efficiency of shipping vessels. Amongst other things, this has resulted in a regulation governing the design efficiency of new ships called the Energy Efficiency Design Index, or EEDI for short. As of 2013, new ships are required to have an EEDI that meets or exceeds a certain target, set as a percentage efficiency improvement relative to a baseline constructed from the average design efficiency of ships entering the fleet in the period 1999-2008. The percentage improvement is set to increase from 0% in 2013 (all vessels as efficient as the average of ships built between 1999 and 2008) to 30% from 2025 onwards.

The Marine Environment Protection Committee (MEPC) of the International Maritime Organization (IMO) is currently engaged in a review of the 2020 target. One of the main questions being addressed is whether the stringency of the regulation should be retained or amended. Another issue of general interest is the effectiveness of existing EEDI targets in driving design efficiency improvements.

This study analyses what factor or factors have contributed to changes in the average design efficiency over time and what their relative importance has been.

Key findings of this study:

  • All ship types analysed show a clear pattern of design efficiency changes, in which the average design efficiency of new ships improved considerably during the 1980s, deteriorated after 1990 and improved in recent years.
  • Changes in ship design speeds and in the power required to overcome the main component of resistance, viz. frictional resistance, go only some way to explaining the changes in design efficiency.
  • Other facets of ship design like hull, propeller and rudder design have been more important historically.
  • Historically, fuel price and freight rates have been major drivers of fuel efficiency.
  • The efficiency changes witnessed in recent years appear to be the result of high fuel prices rather than regulation. The impact of the EEDI regulation may become more important in the coming years as a result of lower fuel prices and increased stringency.



John Calleya