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Maersk’s latest container ship design, the Triple-E, was designed using a range of operational profiles that would maximise its fuel efficiency.

16-20), and it is certain that there will be disagreements, one element of this month’s story which does strike a chord and should set some alarm bells tinkling, at least, is the company’s view on the Energy Efficiency Design Index (EEDI). In Jotun’s view EEDI is, “A good


example of a typical time zero (initial/ perfect condition and not representa- tive to actual long term performance) perspective that offers little or no advantages for the existing fleet of vessels.” In other words while EEDI will tell us

how efficient a particular ship was when it was delivered new, but it cannot tell us how efficient that ship is aſter five years of punishing operational service. Nor will it tell us how well maintained that vessel has been. And that could mean that the industry will not know the extent of the pollution that ships are emitting as the ships age. Tis means that unless there is a constant monitoring of the vessels all emissions statistics based on EEDI will necessarily be inaccurate. Maersk has rightly made great play of

the fact that it has altered its focus and now, when it is designing and building its new vessels, it no longer designs them for a single speed or operational profile, but rather takes into account the range of operational profiles that a ship may encounter during its operational life.

The Naval Architect July/August 2011

hatever one might think about


By taking this approach Maersk views on paint technology (see pages

has significantly improved the design of its vessels and believes that it can substantially reduce the greenhouse gas emissions that its fleet produces as a result. Efforts by the International Maritime

Organization (IMO) to promote the EEDI are also commendable, but the niggling worry expressed by Jotun is that the index will only address a ship’s performance at a single point in time and that the Maersk approach, looking at the operational life of the vessel, would be a far more accurate way to measure the greenhouse gas emissions as the efficiency of engines and hulls deteriorate with wear and tear. If a vessel, pristine out of the ship

yard operates at a level that is 20% more fuel efficient than a comparable ship designed 15 years ago will it still be at that level in four years time? In developing the EEDI the IMO produced a formula that will tell us at what level emissions from a new vessel are, but the formula for the continuing measure- ment of the efficiency of ships and thereby the actual emissions over a given period are lacking. Is there a solution to this difficulty?

Well one solution might be to develop Jotun’s method which monitors the torque and rpm of the propeller shaft along with the ship speed through the water using data from the Doppler log. The system by-passes the need to measure other variables such as wind

speed and current say Jotun and it has the added advantage that most ships have already got

the necessary

equipment for collecting the data installed on the ship. Norwegian class society Det Norske

Veritas (DNV) is set to evaluate the system this summer, but while the company was interested in the method- ology and the idea in general terms DNV insisted that it would not endorse the system. There may be other difficulties with

using this system to analyse a ship’s performance in the way that would be necessary to understand how a vessel’s performance deteriorates over time. For example it may be necessary to measure NOx, SOx and particulate emissions from the funnel. It may be that the Jotun method

is totally useless in dealing with the problem. However, industry is

if the maritime serious about reducing

greenhouse gas emissions it will need to accurately measure the levels of pollution in the first place. It could be that the IMO will need to

develop an EEDI Plus that will target a vessel’s actual emissions rather than just the theoretical pollution from a new ship. Will the costs for such an exercise be prohibitive? At this stage we cannot tell, but with the world’s population growing and the need for shipping set to increase the need to make certain that the planet’s atmosphere is clean is pressing and the alarm bells should be getting louder. NA


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