The importance of accurate fuel efficiency measurement
1st June 2012 04:24 GMT

Fuel efficiency has been one of the hottest topics in the industry in recent years. Between regulatory pressures to reduce the carbon footprint of ships and historically high fuel prices, the impetus to reduce fuel consumption has never been stronger.

Responding to these pressures has been a raft of new technologies each promising to reduce fuel consumption by leaps and bounds and produce a quick return on investment. Ship operators have been flooded with potential solutions such as slow steaming, hull cleaning, anti-fouling paints and numerous cutting edge technologies that promise to solve all their problems and bring their costs down. In some cases the technology has proven itself effective, however the jury is still out on a number of potential solutions. It is also becoming more challenging to decide which areas fuel saving efforts should be focused on. At a time of low freight rates and rising costs, it is increasingly important that ship operators make well-informed decisions and that the fuel saving initiative that is chosen delivers on its promise.

Fuel oil consumption fluctuates to the extent that savings can be difficult to identify in the short term or even in the long term, especially if they are in the region of 1-2 percent. While this can seem fairly small, it can add up to significant savings on a vessel's fuel bill over time. Verifying the effect of a savings initiative can be challenging, for example, if you do not know the real sea margin or changes in various power consuming factors, even if the vessel is on the same route.

One of Eniram's technologies, the Eniram Vessel Platform (EVP), is a data collection platform that enables ship operators to clearly identify the factors affecting energy consumption. It captures real-time data about a vessel's performance from a number of sources on board, such as the navigation systems, engine automation and Eniram sensors. Data from these systems, and many other readings are measured in the context of the prevailing weather and sea conditions and in particular, against the extensive data store that has been compiled from 500 million signals a day collected during thousands of ocean-going hours on more than 100 different vessels, allowing operators to benchmark their efficiency against the average or peak performance of other vessels in their fleets.

Hull Fouling Analysis is one example of how EVP has been used to identify fuel efficiency improvements. The management team of a large shipping operator noticed increased fuel consumption on one of their vessels and installed EVP to monitor the changes in fuel consumption. Eniram provided a detailed breakdown of the excess consumption and concluded that the main cause of the additional fuel consumption was additional drag caused by fouling. The sides were cleaned annually as advised and a clear drop in fuel oil consumption was identified. The growth of additional drag was followed for a period of time, and another brushing was done; this time the sides and the flat bottom. Being aware that the additional drag was caused by fouling enabled this shipping company to create a schedule for timely brushings. This resulted in a significant reduction in fuel consumption of approximately 3.5% over a long period of time and avoided the financial implications of premature dry-docking.

In times of fast paced regulatory changes and an urgent need to reduce fuel consumption, accurate measurement of a vessel’s fuel efficiency can make all the difference to a ships bottom line. While there may not be a single solution, identifying which areas should be focused on will play a critical role in ensuring well informed decisions are made to establish the combination of technologies that will offer the best results.

Noël Jelsma,
1st June 2012 04:24 GMT

Comments on this Blog
Caroline Clarke
1st June 2012
Salutations Noel,
An excellent innovation on the measurement tool - yes as to initiatives to apply plural not singular - a one size fits all is not possible hence the reliance on industry to look at initiatives which support informed verified driven decision making. Thank you for the details.
Kind regards
Daniel Kane - Propulsion Dynamics Inc.
1st June 2012
Good comments on hull performance. A few years ago, hull performance sounded like some esoteric concept. These days, there is widespread data from many aspects on the effect of: 1) basic 'roughness', 2) hull fouling, and 3) propeller friction on performance losses. The CASPER Service, in use now on over 300 ocean going vessels, has shed light on these 3 aspects of hull performance in relation to the clean smooth hull (physical model). By calculating speed through water, and full correction for wind, waves, sea current, draft/trim, fuel oil quality, etc; what we find is that the basic roughness made up of old paint systems can cause a significant performance loss on all ship types but esp. containerships with their long vertical sides and relatively small flat bottoms. Ships entering their second or third 5-year docking, can significantly improve fuel efficiency by white-metal blasting of the hull. Also, the effects of slime and onset of fouling appear as a continuous increase of the ship's resistance over a time function. Furthermore, the propeller fouling appears somewhat dependent on propeller composition and time in port, vessel speed etc. Therefore, as an example if a VLCC is consuming 15 more tons per day (than at design speed and draft in relation to the clean smooth hull and propeller performance) 5 tons per day could be the basic roughness (all hull coating systems experience some roughening over time, even if no hull cleaning) another 7 tons per day could be the fouling of hull and 3 tons per day could be the propeller friction. For another VLCC, it could be different proportions of hull roughness, hull fouling and propeller friction. Shipowners using the CASPER Service on a fleetwide basis typically conduct ‘super polishing’ of the propellers more often, and hull cleaning at an EARLY enough time to gently remove slime and marine growth but not scratch the hull coating as well as evaluate the effect of different hull cleaning devices. We see good results with the hull cleaning robots. [We also see the super polish of the propeller saves an additional 1-2% over normal polishing]. The drop in ship resistance after docking or husbandry immediately tells the speed and fuel gains. The development of resistance after cleaning indicates if the hull was cleaned at the right time. Lastly is the blasting of the hulls in dock – many shipowners now square off large portions of the hull for blasting which is more effective to reduce basic hull roughness (compared to lots of small blasted areas). Shipowners using a hull performance monitoring system are also able to easily see the short term and long term differences in real fuel efficiency between hull coating systems and also the apparent fuel savings of various energy saving devices. You can find published data about use of CASPER in the Carbon Disclosure Project of Teekay Shipping and Norden A/S as well as technical presentations by APL and Teekay on fleetwide basis. Like was previously mentioned it is now possible to establish a performance monitoring system for assessing the condition of the fleet, and benchmark as well as point out a summary of recommendations for each ship. The next step in this is the ‘target resistance’ for each ship. Working closely with shipowners – knowing age of ship, time out of dock and operational patterns, it is possible to set a target FOC for each ship type and improve year over year. However, this is usually not possible from analyzing noon data. The speed log error and changing conditions over 24 hour reports usually show too much scatter to utilize for serious decision making.
Heinz Otto
2nd June 2012
Hi Noel,
1) The cleaner the hull-the less of GHG are emitted from the burned HFO of the ships engines, That’s all, we know this since years. Is it really necessary to make this sure by data collection platform?
2) Hi Pierre C. Sames, your (GL-MAN) - study about the payback time of Scrubbers or LNG is maybe helpful for some ship owner decisions, but not for all and really not for short time decreasing of GHG from ships to protect SECA.
I am not a friend of scrubbers, but scrubbers are a step for short time results, if you burn HFO. You for your own know the problem of peakoil/peakgas and so do you know, that other systems for ship propulsion must come. Others, than Measurements and scrubbers and LNG. All this takes time and money and both is limited - like oil and fresh air.
So my conclusion is: Noel and Pierre and all the responsible Persons in the maritime industry: you have to check asap the wind systems of our oceans and compare this study with the most needed Bulker routes across the seas.
Pierre, you have the key, as you told me in Rostock, in your files. Open them. Please.
The german promise of CO2-reduction needs it.

All the best from , Heinz Otto
Daniel Kane - Propulsion Dynamics Inc.
12th June 2012
Hello Heinz I am aware your reply was addressed to Noel. Since we are also experts in hull performance, I think I can provide a reply that is meaningful. Common data collection platforms do not give accurate assessment of performance losses due to hull and propeller condition, ergo, the need for the hull coating suppliers themselves to join forces with makers of hull performance monitoring systems. Being able to determine performance losses due to basic hull roughness versus propeller friction versus hull fouling are a valuable tool for the shipowner who is serious about energy efficiency. But to simply imply 'we already know this' is oversimplification. What often seperates profitability between shipowners is how they use information.... hull performance monitoring assists a shipowner in profitability and competitiveness.
Same could be said about weather routing, how long has it been know that heavy weather resistance burns more fuel? centuries perhaps? yet there are shipowners not engaged in weather routing. Not for lack of technology. When I attend these green ship technology conferences many suppliers can be overheard at the coffee bar - not talking about whether a technology works but which shipowners have the resources to take on projects that bring profit.
Caroline Clarke
9th August 2012
Salutations Heinz,
Absolutely - it shipped carbon neutral - the product system. The observations recognised - amplify those who are attending to - help you suppliers in asking the right questions.

Avoid double counting frees up capital to invest in initiatives to improve efficiencies.

The emphasis on initiatives trials undertaking independent verification paramount conclusion - forged from
Kindest regards to be catching up with you Heinz.
Caroline Clarke
9th August 2012
The initiatives within reported guidelines exciting to read here - to be party - I thank you most kindly - Caroline
Vernon Harris
9th October 2012
Dr. Vis gave many examples fuel consumption calculations before and above are some technical ideas to reduce lag and increase efficiency.

If the vessel was carrying 5 tons less would it affect fuel consumption s
enough to be measurable over a period?

Thank you!

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