TECHNOLOGY - SHIP EFFICIENCY
April 2015
TANKEROperator
31easily track fuel levels.
Our customer was able to bring down the levels of HFO closer to the company’s policy; showcasing how bringing this high-level of sophisticated data analytics can help to improve overall operations when these problems become visible.
Example 3: Active route management
Routing is a very traditional problem and also very complex with many factors affecting it, such as weather, shallows, distance to the shore, currents and ECA zones.
When analysing routing, quite often the
most effective way to improve this within the fleet is to compare where the vessels are having the most problems and then create best practices for those legs, which seem to be problematic.
In this case, the difference between the best and worst routes is over 12% of the total fuel consumption - a rare case. According to our advanced analytics studies, the overall average potential improvement of actively managing routes of a fleet is typically around 3% of the total fuel consumption.
We understand that every operational issue
is different and every company has different operating parameters. That’s why we customise our solutions, yet use a proven systematic approach.
Data analytics and reporting is an
inexpensive way to find and realise quick wins in operational efficiency. In many cases, customers see a change within a matter of weeks after we detect the problem and help them improve best practices.
Constant follow-up enabled by regular reporting and analytics is a key factor in maintaining the achieved benefits of all improvement actions.
Detailed analysis and modelling enables the separation of environmental effects from operational effects and to understand where the focus of improvement action is needed.
Without data gathering, analyses and constant reporting, it can be very difficult to find the subject and effect from complex on board systems. Eniram offers powerful tools to get at the most minute of details and unravel the mystery, bringing better transparency, efficiency and operational performance to a single vessel or an entire fleet.
*This article was written by Henrik Lano, who is Eniram’s director of analytics and a former management consultant. He has had broad experience gained from various industries in transforming data and analytics into operational insight and improvements. He is responsible for developing Eniram’s analytics services to drive energy efficiency and savings.
Bunkering management.
Active route management.
Eniram’s Henrik Lano.
TECHNOLOGY - SHIP EFFICIENCY
H
e explained that last year, the company had set up this independent department to look at vessel efficiency for both newbuildings and retrofits on existing ships.Some of Great Eastern’s vessels have been fitted with a Becker Marine Mewis Duct. There will be a need to conduct model and tank tests and full scale trials, as a means of validation, but the costs can be spread over a fleet’s sister vessels, he said. Retrofitting takes around four days.
The return on investment in fitting a Mewis Duct is strongly dependant on the number of vessels in the series, the prevailing bunker prices and the operational profile of the vessel, ie sailing days and speed.
He also pointed out that manufacturers including Becker Marine, were building up a database of standard ship types, which could benefit the most from the fitting of ducts. As a result of using the database, the costs involved in the purchase and fitting of the equipment would be less, as the design work had already been conducted.
There are other energy saving devices, such as the Schneekluth WED and spoilers, plus the Mitsui OSK propeller boss cap fin (PBCF), which he said was easy to fit and maintain and validated through CFD. MOL has fitted more than 1,700 PBCFs, the company claimed.
Bose warned that occasionally, the PBCF blades can fall off so it is important to ensure that they are fitted properly.
Others include the Kappel propeller, which is now part of MAN Diesel & Turbo’s portfolio, which Great Eastern fitted to some of its vessels last year with good results and the CLT propellers developed by Sistemar of Spain - the evolution of the tip vortex propeller (TVP).
Propeller efficiency reaches the highest value when thrust generated on a propeller
blade continuously increases from the boss to the tip. In a CLT propeller (contracted and loaded tip propeller) this theoretical principle is realised by fitting an end plate at the blade tips.
This results in a higher efficiency of between 4-8%, fuel savings = reduced emissions, higher top speed = greater operational flexibility, inhibition of cavitation and of the tip vortex, less noise & vibration, lower pressure pulses, lower area ratio, greater thrust, smaller optimum prop diameter and better manoeuvrability, Bose said.
Finally, the TIP propellers are compatible with most of the propulsion improvement devices currently offered, thereby allowing even further efficiency gain.
Also important are hull and propeller maintenance, he stressed.
Hull frictional resistance is governed by the wetted surface (main dimensions and trim) area and the surface roughness of the hull consisting of the steel, coatings, added roughness due to fouling and coating degradation.
Bose explained that the initial roughness is taken as 120 μm, which is the approximate roughness value for a typical newbuilding although some ships are delivered with a very low surface roughness of around 75 μm.
Typically, an average hull roughness (AHR) of ≈5 μ is very good, an AHR of 150 μ is standard and an AHR > 200μ is sub-standard, he explained.
Historical records have shown that even with good maintenance practices, average hull roughness can increase by 10 to 25μm per year, depending on the hull coating system, even when fouling is not included.
As a rule, every 25 μ (25/1,000 mm) of hull roughness increase corresponds to 0.7-1% of increased fuel consumption, due to the additional propulsion power requirement to move a larger volume of water.
The AHR is calculated by dividing the hull into 10 equal sections with10 measurements for each division - five each side of the vessel. This gives 50 readings on each side - 30 on the vertical sides and 20 on the flats.
From the 100 measuring locations, the AHR is calculated and roughness distribution plotted.
Efficiency losses
Several companies have measured the efficiency losses between drydockings, due to bio-fouling and mechanical damage on the underwater hull. For example, Marintek measured the drop in propulsion efficiency as around 15%; Propulsion Dynamics (tankers) of 20% and Jotun (taking an average of over 60 months) of 18%.
When selecting a coating, a checklist should be used to evaluate longevity, suitability, product features, efficacy, maintenance - repainting and repairing, fuel saving, environmental concerns, costs and manufacturer’s guarantees.
Bose also advised that the propeller should be polished every six months and a vessel’s hull blasted and painted every second drydocking- around once every 10 years. For propeller polishing, he advised the use of a service provider active in one of the main shipping centres, rather than an unknown concern based in a smaller port.
Turning to vessel performance management, he described it as measuring, monitoring and managing. He explained that Great Eastern had selected a Marorka power management system, which gathers data related to ship operations, ie, trim, draft, main engine, auxiliary engines, steam plant, voyages, navigation, etc.
The data is categorised the same for differing operating conditions, such as while berthed, manoeuvring, during a sea passage and at anchor/waiting, etc.