Guide to Fuel Savings

Guide to

Fuel Savings

A Solutions guide to reducing fuel use

October 2011

Guide to Fuel Savings in association with

OFC_FuelSaving11.indd 1

13/10/2011 14:47:02

Ship Performance Monitoring

Monitoring systems for improved propulsion economy • Kyma Shaft Power Meter

Continuous measurement of shaft power with engine/hull performance monitoring (option).

• Kyma Diesel Analyzer

MIP system for optimizing diesel engine performance using Windows™ based software.

• Kyma Ship Performance

On-line ship performance monitoring system for instant performance information, including CO2 index and SO2 emissions; fuel reporting; trending and sea trial reports, using Windows™ based software.

KYMA Web: www.kyma.no

KYMA.indd 1

Kyma a.s, Aasamyrane 88b, n-5116 Ulset, Bergen, Norway.

Tel.: +47 55530014 Fax.: +47 55530017 Email: mail@kyma.no

13/10/2011 11:52:46

The case for

cutting costs I

Malcolm Latarche EDITOR

October 2011

01_introduction.indd 1

t has been said that if all the claimed savings for various technologies and systems could be achieved on a single ship, then that vessel would actually be producing fuel rather than burning it during the course of a voyage.

Inevitably, the claims made for the fuel-saving potential of any equipment or system tend in the first place to be more optimistic than realistic but when implemented over time the accuracy can be much more easily gauged.

Fuel saving is a no-brainer for ship operators.

They do not need the environmental lobby to preach at them, because they have been practising it for some 40 years or more. The 1970s oil crisis brought the need to reduce soaring fuel costs, but even before then there was a practical benefit to reducing bunker requirements as it meant more space was available for revenue-earning cargo.

Today, cutting fuel consumption remains an economic necessity and now has the added advantage of allowing operators to trumpet the fact that for every tonne of fuel saved they are reducing the amount of CO2 produced by more than 3 tonnes. Over the past decade or so, many equipment-makers and technology innovators have focused on ‘green’ issues as a means of promoting themselves and their products, without realising that for most ship operators it was the fuel-saving aspect that was most interesting.

Coming at the beginning of the 21st century, the changes in coating regulations and the banning of TBT was a definite spur for innovation, and the coatings makers have responded to the challenge with a glut of new products. Each new generation of coatings comes with the promise of efficiency improvements and several operators are prepared to testify to the veracity of some of those claims.

Hydrodynamics and hull design form an area wherein much can be done to improve efficiency. The biggest benefits are usually reserved for newbuildings, but some changes can be made to existing vessels with surprisingly beneficial outcomes. Those changes can include altering the shape of a bulbous bow, adding a hull appendage

or altering the propeller/rudder configurations.

Much attention has been paid to the potential of slow steaming to reduce fuel use and the strategy has been adopted in many sectors. While running slower certainly reduces energy demands, it needs to be recognised that adoption of the strategy has been more a response to overcapacity than a genuine desire to save fuel. If demand for goods matches or exceeds pre-2008 levels, operators will have little option but to return to ‘normal’ service or risk the wrath of shippers tired of disrupted supply chains. The modifications and equipment developed by engine-manufacturers and turbocharger-makers to permit slow steaming can nevertheless be considered as useful means of fuel saving when circumstances permit.

Ancillary machinery, such as pumps, compressors, winches and the like, all consume energy that has to be produced either by the main engine or by auxiliaries. Switching to more efficient technology can produce economies, but, as with major work on the hull, capital outlay needs to be weighed against potential savings. It is a far from easy task given that the future price of fuel is mostly an unknown variable, so a honed instinct or a crystal ball are helpful attributes.

The role of software should not be overlooked. Although a few ship masters and mates might consider that their navigational skills are being called into question, the more astute recognise that software tools can be used to good effect and, so long as the final decision rests with the person in command, there is nothing to be feared and much to be gained.

Software tools come in many guises and can range from weather routeing to advice on optimum trim and engine management.

To help owners consider the merits of some of the many possibilities for saving fuel, Solutions has looked at the savings that have been confirmed by those actually in the business of operating ships. There is, after all, no better endorsement of a product or service than one offered by those who have made use of it and found it to be of merit.

Guide to Fuel Savings 0

13/10/2011 12:19:58

" % %

"

#

! " #

! ! #

!

!

!

, %) %&+ * -- &# , , %

# $ '* ! '' - % # % ) ,#

!

)XHO6DYHU ZLWK WULP DQG EDOODVW VROXWLRQV ,QWHJUDWHG LQ ORDGLQJ FRPSXWHU $XWRPDWHG DQG YDOLGDWHG &KHFNHG IRU VWUHQJWK DQG VWDELOLW\ 6XSSRUWV ÀHHW SHUIRUPDQFHV ,PSURYHV \RXU VKLS¶V FKDUWHU YDOXH

6DYH IXHO EDVHG RQ YDOLGDWHG WULP DQG EDOODVW VROXWLRQV ! ! $ % % $ ' ! $! & ! ! ! ! !' ! ( & ! ! ! $ $ ! ! ' $ ! ! $ ! !

6HW D JUHHQHU IRRWSULQW

ZZZ IXHOVDYHU GN

!

" #) $

0 Guide to Fuel Savings

02_03_FuelSaving11.indd 2

October 2011

13/10/2011 15:33:46

Guide to Fuel Savings October 2011

In association with HEMPEL

Inside your guide...

Cover background: Shutterstock

01 04 08 10 16

Introduction Why fuel saving has become second nature to ship operators

Coatings New choices for operators in the constant battle to keep hulls free from fouling

Interview Hempel’s views on the market for, and development of, fouling protection products

Propulsion Propellers, rudders and recent innovations combine to improve efficiency

Research Projects from around the globe aimed at identifying the potential for fuel savings

18 20 26

Engines Turbocharging options, waste heat recovery and optimum engine choices

Software Trim optimisation and performance monitoring for individual ships and fleets

Hull New bow forms, appendages and air lubrication

Publisher: Jon McGowan Editor: Malcolm Latarche email: malcolm.latarche@ihs.com Sub-editor: Stephen Spark Head of design: Roberto Filistad Designer: Carolina Lorenzo Production: Sarah Treacy Contributors: Steven Valentine David Foxwell David Tinsley Advert sales manager: Julian Bidlake Tel: +44 (0)208 676 2243 email: Julian.Bidlake@ihs.com IHS Fairplay, Sentinel House, 163 Brighton Road, Coulsdon, Surrey CR5 2YH, UK Printed in the UK by

Copyright © IHS Global Limited, 2011. All rights reserved. No part of this publication may be reproduced or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, or be stored in any retrieval system of any nature, without prior written permission of IHS Global Limited. Applications for written permission should be directed to Jon McGowan, jon.mcgowan@ihs.com. Any views or opinions expressed do not necessarily represent the views or opinions of IHS Global Limited or its affiliates.

Disclaimer of liability Whilst every effort has been made to ensure the quality and accuracy of the information contained in this publication at the time of going to press, IHS Global Limited and its affiliates assume no responsibility as to the accuracy or completeness of and, to the extent permitted by law, shall not be liable for any errors or omissions or any loss, damage or expense incurred by reliance on information or any statement contained in this publication. Advertisers are solely responsible for the content of the advertising material which they submit to us and for ensuring that the material complies with applicable laws. IHS Global Limited and its affiliates are not responsible for any error, omission or inaccuracy in any advertisement and will not be liable for any damages arising from any use of products or services or any actions or omissions taken in reliance on information or any statement contained in advertising material. Inclusion of any advertisement is not intended to endorse any views expressed, nor products or services offered, nor the organisations sponsoring the advertisement.

This publication was produced using FSC® certified paper

Warners Midlands plc, The Maltings, Manor Lane, Bourne, Lincolnshire, UK

October 2011

02_03_FuelSaving11.indd 3

Trade marks IHS Fairplay is a trade mark of IHS Global Limited.

Guide to Fuel Savings 03

13/10/2011 16:24:45

Coatings

Reduce cost by

UASC container vessel Umm Sala has been coated with the Hempasil X3 system Photo: Dietmar Hasenpusch

removing friction A

ll owners know that a ship with a freshly cleaned hull performs more efficiently than a heavily fouled vessel. Since TBT was banned, coatings manufacturers have been developing products at a pace not seen before. In such a competitive market, claims of potential fuel savings for the new products have been one of the main tools in trying to grab market share.

Owners may have reservations about some of those claims, but many operators seem happy to back up what manufacturers have been saying. The new breed of coatings employs various technologies, all of which have been described in past issues of Solutions.

The suitability of a particular coating for a ship’s operational method or area can only properly be determined when the owner assesses all the factors involved, but the following case studies do indicate the level of improvement that there is to be had.

Claims for brand-new products may not cut 04 Guide to Fuel Savings

4_6_FuelSaving11.indd 4

much ice for those owners who prefer to rely on a long track record. But athough International Paint’s Intersleek 900, for example, dates from 2007, its pedigree stretches back to 1996.

Intersleek 900 represents a next-generation foul release coating technology, using fluoropolymer chemistry to improve on silicone’s performance. International states that Intersleek 900 is 25% smoother than its previous top product, Intersleek 700. The company promises a 2% fuel saving for the new product over the old, but adds that some of its customers are experiencing even better results.

One significant selling point is that, unlike some products that perform best on fast vessels that are subject to less fouling, Intersleek 900 is suitable for slower-moving ships, such as bulkers and tankers, and even ships sailing at only 10kt.

Grandi Navi Veloci (GNV) began using Intersleek 700 in 2005 on its 32,700gt ferry Majestic.

GNV technical consultant Bruno Dionisi has

gone on record as saying: “On average, this product provides undisputed advantages which, in our case, are represented by a bunker saving of around 6–7%.” GNV went on to choose Intersleek 900 for La Superba.

For some, the greatest imperative has been improving service speed. The first owner to apply Intersleek 900 was Sydney-based Inco Ships, which had its bulk carrier Ikuna coated in March 2006. After the coating was applied in place of a standard, biocidal self-polishing copolymer antifouling, the shipowner reported a 1kt increase over its typical 10.5kt operating speed without any increase in the amount of fuel used.

After 37 months in service coated with Intersleek 900, the 1kt gain was sustained, reported Inco Ships managing director Andrew Dally. The company had three more of its vessels coated with Intersleek 900: cement carrier Goliath, livestock carrier Torrens and bulk carrier Hakula.

October 2011

13/10/2011 15:11:22

Coatings

At the other end of the speed spectrum, shortsea shuttle ferry operator Wightlink opted for Intersleek 900 as the antifouling coating for three of its high-speed catamarans. In addition to registering a speed increase of 2kt after application of Intersleek 900, Wightlink has acknowledged the way the coating has allowed it to maintain schedules while also saving fuel.

The Fastcats now run at reduced rpm and consume less fuel in consequence.

Indian shipping company Mercator Lines first applied Intersleek 900 to the underwater hull of the 109,610dwt Aframax tanker Prem Pride in October 2007. The owner then applied the coating on a larger area on Prem Divya in June 2008.

Mercator Lines general manager Amit Agarwal said: “In 2008 we achieved up to 6% fuel savings on Prem Pride using Intersleek 900.�

He later confirmed that the fuel and emission savings have been maintained on this vessel,

remarking: “We fully expect an improvement on Prem Divya, as we had increased the areas of the underwater hull coated to include the flat bottom.� Agarwal continued: “Monitoring of the performance of Prem Divya has confirmed a 9% reduction in fuel consumption under comparable conditions.�

Another premium product – Subsea Industries’ glass-flake Ecospeed – has been around a few years longer than some of the others and has had time to substantiate some of the claims made for it. Ecospeed was applied to Peter DÜhle’s 2004-built container ship Baltic Swan during a lengthening of the vessel at Norderwerft shipyard.

Compared with TBT anti-foulings, many of the newer products have much longer lifetimes.

Subsea Industries gives a 10-year warranty for its Ecospeed product, for example, and claims an expected lifespan of 25 years. And this product notably demonstrated its resistance to the effects of winter conditions in the Baltic Sea. At the start of 2010, Baltic Swan came back into drydock at the Damen-Van Brink shipyard in Pernis, Rotterdam. The underwater hull was in virtually the same condition as it was when the vessel undocked two years before. The vessel required only a few touch-ups to bring her back to original condition. A thin layer of slime present on the hull was easily removed with high-pressure jetting.

Baltic Swan was coated with Ecospeed in March 2008 as part of an EU-Life research project. The vessel operated on a fixed route from Rotterdam to Bremerhaven and then on to Saint Petersburg. During the winter, the most northerly parts of this route are almost completely frozen and the vessel’s underwater hull often has to endure the impact of large pieces of floating ice. Despite this, there was no damage from the ice and the captain of the vessel was impressed with the condition of the Ecospeed coating.

At the beginning of 2010, Nippon Paint Marine Coatings launched an organotin-free coating, LF-Sea. It is a copper silyl acrylics hydrolysis anti-fouling coating that makes use of hydrogel technology, in which a waterabsorptive polymer allows a thin film of water

to become trapped within it, reducing friction.

On the 400 vessels now using the coating, friction has been reduced to a level that gives an average 5% fuel saving. The coating costs up to three times more than alternatives, but Nippon Paint claims it is cost-effective compared with silicone coatings because it can be applied directly over anti-fouling paint without blasting.

Working with Mitsui OSK Lines (MOL), Nippon Paint has been able to demonstrate improved fuel efficiency by the use of coatings in a sea trial of the 2010-built 18,716dwt vehicle carrier Neptune Ace. This has been credited to the use of the naturally derived component hydrogel, which apparently minimises friction. It has the added advantage of appearing to be ordinary water to marine organisms, so creatures such as barnacles do not try to attach themselves to the hull.

MOL said in a statement that hydrogel, which has water-containing characteristics, is a ‘macromolecule polymer’ that “allows water to fill in small indentations on the hull to minimise friction drag�.

The partners have set a goal of reducing CO2 emissions by 8–12% compared with conventional anti-fouling paints. Their work is one of several projects subsidised through the Japanese Ministry of Land, Infrastructure, Transport and Tourism’s Support for Technology Development from Marine Vessels for Curtailing CO2 scheme.

Neptune Ace was completed in late October 2010 by Usuki-based Minami-Nippon Zosen Shipbuilding and MOL confirmed the fuel savings less than two weeks later, based on comparisons with sister vessels.

Friction between the hull and the water accounts for the majority of resistance as a vessel moves through the water. Reducing friction drag is a highly effective way to reduce CO2 emissions during vessel operation.

MOL has adopted a new low-friction shipbottom paint, Seaflo Neo, that was developed

by Chugoku Marine Paints. After analysing the results of an onboard test on a newbuilding vessel, the company confirmed that the new paint offers further improvements in fuel efficiency and will also contribute to the reduction of

* # "% %( # # %% # %+%' % # # % # (%

- -

# + % ) * '

#' #$

#' #$ # %% #% %( - - %% # + , # + %'% # ( %% %!

October 2011

4_6_FuelSaving11.indd 5

***!' !

!

Guide to Fuel Savings 05

13/10/2011 15:12:55

Coatings

Prinsendam is one of a pair of Holland America Line ships to benefit from a Hempasil X3 coating Photo: Dietmar Hasenpusch

carbon dioxide emissions from vessels.

The new paint was employed on two 6,233unit car carrier newbuilds, Brilliant Ace and Eternal Ace, which transport standard passenger cars and were completed in March and July 2011 at Minami-Nippon Shipbuilding.

The main characteristic of the Seaflo Neo product is the smoothness of the paint film surface, the result of a newly developed low-viscosity hydrolysed polymer. The finish minimises friction drag between the hull and the water, improving fuel efficiency by 3–5% compared with an identical vessel with a conventional hull coating. Chugoku Marine Paints’ new environment-friendly paint is also low in volatile organic compounds (VOCs), a major source of air pollution.

MOL continues to take a proactive stance in developing and adopting low-friction ship bottom paint as part of its environmental initiatives and believes that these trials will provide a benchmark for future coatings development.

United Arab Shipping Company has joined the many carriers by investing in optimising bunker usage as marine fuel prices continue to increase. The Dubai-based liner is sending nine of its 13,000teu newbuildings to be coated with Hempel’s anti-fouling paint. UASC began with the 145,327dwt container vessel Umm Salal in April 2011, which was constructed at Samsung HI’s Geoje yard in South Korea.

The ships have the Hempasil X3 anti-fouling coating applied at the Samsung shipyard before sailing to a drydock in Shanghai for re-coating, where they are hosed with fresh water in preparation for the Hempel Nexus X-Seal tie coat, which seals the existing anti-fouling coating.

06 Guide to Fuel Savings

4_6_FuelSaving11.indd 6

This coating uses hydrogel silicone that forms a polymeric network over the hull, fooling organisms into perceiving the hull as a liquid.

The application of anti-fouling paint to vessels can substantially reduce their carbon footprint.

The Hempasil X3 system has been shown to offer a fuel saving of at least 2% for ships that use $90,000 of fuel a day, while reducing carbon emissions. Hempel says the payback period on the coating system is well below five years; thereafter it’s money in the bank for the shipowner or operator.

Silicone products are said to be less effective in the cruise industry, which presents a challenge because cruise ships may operate at relatively low activity levels. Hempel reports that its foul release system Hempasil X3 is effective down to 8kt so is ideal for shipowners with varying levels of activity, such as Seattle-based cruise shipowner Holland America Line.

A full coating of Hempasil X3 was applied to two of its vessels, Zaandam and Prinsendam, in April 2007 and December 2007. Holland America Line has reported reductions in fuel consumption, saving the company money and cutting CO2 emissions.

Another operator opting to forsake biocidecontaining products in favour of silicone coatings is Johannesburg-based Sigma Coatings. Its SigmaGlide system protects the hull of Höegh Trapeze, formerly known as Hual Trapeze, a 41,871gt vehicle carrier built by Tsuneishi Shipbuilding in Fukuyama, Japan, in 1983.

Sigma applied the coating to the vessel’s underwater hull while it was in drydock in Chengxi, China, in July 2003. The coating was applied on the Sigma Multiguard system after

full grit-blasting during a very tight drydocking over the course of 10 days.

Owner/operator Höegh Fleet Services of Norway stated the vessel’s operational speed as being 18kt. Sigma reported that the vessel was found to be performing well within expectations for such a coating and service speed 22 months later. An underwater inspection found the hull to be in excellent condition. Perhaps on the back of this success, Sigma notched up one of its biggest contracts in 2007 with the 308,000dwt FPSO Ellen Mærsk.

Norwegian coatings supplier Jotun has even made promises to its customers and issued a challenge to its competitors by offering a cash-back guarantee if its premium anti-fouling system fails to deliver. Jotun’s Hull Performance Solutions (HPS) concept combines its SeaQuantum X200 anti-fouling and monitoring tools to guarantee significant reductions in fuel consumption.

HPS is supported by a Jotun-developed measuring and analysis system. Customers install sensors to measure shaft power, vessel speed, wind and draught. Once the data are collected, Jotun can plot the speed deviation relative to the vessel’s speed performance after drydock. A long-trend analysis of hull performance provides a reliable statistical foundation for a high-performance guarantee for SeaQuantum X200.

Based on the data, Jotun offers customers a guarantee that SeaQuantum X200 will provide a clean hull and less than 1.5% speed loss or a maximum 4.5% increase in fuel consumption over 60 months, using as a baseline the readings immediately after drydock. If the vessel performs worse than this, Jotun will return the additional investment in SeaQuantum X200.

The impact of anti-fouling systems on fuel consumption has long been acknowledged. In a recent study sponsored by Marintek, average vessel speed loss was calculated at 5% for the 60-month lifetime of an anti-fouling paint. If converted to the extra fuel needed to maintain speed, vessels require about 15% more fuel for those 60 months.

In September 2009, the UK Chamber of Shipping said that, in comparison with ships delivered in the 1990s, it expects new technologies and designs to provide energy efficiency savings of up to 40% on today’s vessels. The IMO itself has suggested that “by application of known technology and practices, shipping could be 25–75% more energyefficient, depending on the ship type and the degree of compromise”.

October 2011

13/10/2011 15:21:20

9QTNFYKFG #HVGTUCNGU

Untitled-4 1

27/09/2011 10:13:21

Hempel Interview

Getting the most out of

fouling protection Q A Q Q A A

A & Q Solutions asked Hempel about the future development of coatings and how owners can make sure that they get the most out of this expensive outlay A good antifouling (AF) system is an obvious way to save on fuel costs. Before they were banned, TBT-based products were said to give the best performance in this area. How do the latest coatings perform against their TBT predecessors and what developments can the shipping industry expect in the near future?

The performance of the top products in the market is very good and has reached the levels of the old TBT-based coatings. What may be less widely known is that certain fouling release products have caught up and show levels of performance comparable to biocidal paints (see Chapter 14 in Dßrr and Thomason’s compendium Biofouling). Before long, we expect all suppliers to be providing antifouling products that deliver the same or better performance and that have a better environmental profile with, for example, lower solvent content and optimised biocide packages. Biocide regulations mean that most of the developments are expected on the self-polishing copolymer side rather than involving new biocides. Regarding fouling release, developments will be aimed at improving long-term performance in slow and not very active vessels, and also at continuing to provide economic and environmental advantages in terms of fuel savings.

Q

Ships are often transferred from one type or area of employment to another, or the owner adopts a new operational strategy such as slow-steaming. If the coating on the ship has been not been specifically designed for the new service conditions, would any guarantee still be considered valid?

A

No, it will need to be re-evaluated. The guarantee terms offered are tailor-made and based on careful consideration of the specific vessel. If the scenario changes, then the guarantee terms will need to change too.

08 Guide to Fuel Savings

8_9_FuelSaving11.indd 8

What other advice, if any, could you give to an owner looking to save fuel?

A thorough analysis of the fleet when it comes to maintenance of the underwater hull should be carried out and should include the condition of the anti-corrosive system, years since the last full blasting, development of hull roughness caused by touch-up etc. We also advise the owner to follow the IMO guidelines set out in SEEMP. In addition, we advise the owner to select a fouling control system whose performance is well documented.

Even the best product performs well only if it is the most suitable for the ship type and area of operation and if it has been properly applied. Since many owners rely on the yards (whether newbuilding or regular drydockings) to carry out the job of coating or recoating, how can they best ensure that they choose the right product and that it is applied correctly?

Owners and ship managers take the decisions when it comes to the choice of coating for maintenance, while in the newbuilding situation it is normally the yard that is the decision-maker. We have two main tools to ensure that our products will deliver their full potential. We have performed a great many yard audits worldwide to evaluate their degree of preparation for carrying out high-quality jobs, thereby helping owners/managers to select the most suitable yard for their purpose. The second, and most efficient, tool that we possess is our technical service team, which helps superintendents make the right decision and maximise the outcome of the docking irrespective of which yard has been chosen. If the owner/manager chooses the highest level of technical service offered by Hempel, they can be sure that the final result will be satisfactory.

Q A

What, if anything, can an owner intending to lay up a vessel do to ensure the coating remains in the best possible condition? Are there any measures that should be avoided?

The intensity and aggression of fouling organisms varies. The fouling risk is highest in tropical and nutrition-rich water. After extended layup periods, underwater cleaning may be necessary.

October 2011

13/10/2011 12:27:05

Hempel Interview

Q

Q A

A

Q A

Q

Given that guarantees might be in place, what can a coatingsmaker offer an owner that ensures the product performs as advertised and delivers the fuel savings that attracted the owner to that product?

Our guarantees take into consideration the geometry and the sailing pattern of the vessel – so as long as they are maintained, the fuel savings will be delivered. If the owner/manager wants exceed the guaranteed savings, we can advise on underwater hull surveys and cleaning. Should the vessel’s operational parameters change, we can advise the customer what will be best from the hull performance point of view, taking into consideration the constraints that their trade imposes.

What advice could you or any other coatings-maker give to an owner to ensure that their ships’ performance remains optimal? For example, would you tell a slow-steamer that occasional bursts of a higher operating speed would be beneficial?

Ship inactivity is perhaps more damaging to coatings performance than slow-steaming. A self-polishing paint designed for a fast-moving vessel that suddenly changes to slow-steaming will experience a lower polishing rate and an increase in the leached layer thickness (ie a decrease in the protection level). The location and duration of the idle period can become critical when the vessel stays in port, since the biocide release rate may fall below the threshold level for guaranteeing full protection. Occasional bursts of speed can be positive, but their efficacy depends on many variables – most importantly, the type of coating. For fouling release coatings, an increase in speed would be recommended right after the idle period to remove as much of the accumulated fouling as possible. Release of accumulated fouling will be less efficient when slow-steaming.

That is why it is beneficial to use fouling release coatings that are designed to prevent fouling (eg Hempasil X3), rather than those simply designed to release accumulated fouling (previous generations).

Q A

Many of the new products carry premium prices, but do such products warrant the extra outlay? For example, can a coating that costs 50% more than a basic product be expected to last at least 50% longer?

“Lasting” is probably not the right benchmark. We prefer to use quantitative, relative variables such as fuel savings. In this respect, coatings 50% more expensive can provide fuel savings many times higher than the differential in paint cost. This has been emphasised by independent third parties such as the US Navy (see www.paintsquare.com/news/?fuseaction=view&id=5685)

October 2011

8_9_FuelSaving11.indd 9

Over the past 10 years or so there has been a trend for coatingsmakers to claim extended lifespans for their products – five years is now quite common. What do you think the future will bring in this regard and what is your best guess as to when an antifouling or fouling release coating offering a 10-year lifespan might come on to the market?

In recent years classification societies have been approving extended (90-month) drydocking schemes for container vessels and general cargo vessels. Best-in-class self-polishing copolymer paints are already capable of reaching very long-term (90-month) active lifetimes and it is basically a matter of applying higher dry film thickness. For fouling release, silicone coatings based on hydrogel can be specified for 90 months. At present, a 10-year lifespan is merely theoretical, because it implies that the condition of the paint system is the sole or decisive factor for docking intervals, whereas in fact maintenance of the shaft, bearings etc has to occur more frequently.

Several coatings-makers, including Hempel, now offer ‘guarantees’ for performance standards, but many owners view these sceptically, believing that there are too many strings attached. What can you say to these owners and have you – or any other coatings-maker to your knowledge – ever had to pay out on such a guarantee?

A

Performance guarantees have been offered for a long time and they do include a number of reservations that are well understood and accepted by the industry. Fuel-saving guarantees are basically the same, with the only difference that they include an extra element, which necessitates quantifying hull performance in an objective and comparable way. Monitoring and normalising hull performance is complex and ship sailing patterns are varied, so it is far from easy to offer a simple guarantee. Perhaps the main obstacle is that most owners/managers are not monitoring the hull performance of their vessels right now, so they cannot benchmark on what to expect from the new coating.

In this respect, we have two options for fouling release coatings (Hempasil X3).

We benchmark against the vessel’s performance before entering dock. The savings guaranteed here include those related both to the docking itself and to the shift to fouling release performance. The savings related to the docking itself depend upon the surface treatment, on the skills of the yard and on the condition of the vessel, among others.

If we eliminate this benchmark and the owner cannot provide a reliable alternative (eg eliminating the influence of draught, trim, wind, waves, currents), we suggest that they then use the study performed

by Marintek, which claims that on average a conventional AF coating is responsible for an increase in fuel consumption of about 15% over a 60-month service interval (depending on the type of vessel).

Hempel has not had to pay out on any fuel-saving guarantee so far.

Guide to Fuel Savings 0

13/10/2011 12:32:03

Propulsion

Wärtsilä’s Energopac is an example of new thinking in propulsion arrangements Photo: Wärtsilä

Screwing down costs I

nterest has been growing lately in the fuel savings potential of the external propulsion system. Opportunities range from minor modifications to a change of propeller. The latter is an expensive option but one that can pay dividends quickly if the original propeller has proved to be less than optimal, and sale of the replaced propeller can bring in extra income too.

New propeller technology, especially when applied to blade design, can result in substan-

10 Guide to Fuel Savings

10_15_FuelSaving11.indd 10

tial fuel savings, as can a switch to a different size or type if the service profile of the ship has changed. Savings well into double figures have been achieved on some ships.

In March 2010, Solutions reported on some proven fuel savings that were made through changing the propeller. At the higher end was Rolls-Royce’s reblading of a series of Stena Line ferries from 2005. Since reblading Stena Germanica in that year, Rolls-Royce has carried

out similar work on at least four more of the Swedish operator’s vessels. After the changes, fuel consumption on all of the ships was reduced by around 10%; Stena Nordica, however, returned a 17% cut in fuel burn.

Royal Caribbean’s Empress of the Seas provided another example of double-figure savings when it was fitted with a newer design of controllable-pitch propeller. The ship had its propeller blades replaced in late 2006 and a year later was burning 13% less fuel. As a multi-engined dieselelectric ship, requiring less power to maintain the same operating speed meant that the number of on-line engines could be reduced, producing major savings in maintenance. MAN Diesel achieved a 12% saving when it fitted a new design of blade to propellers on the Scandlines passenger ferry Sassnitz.

Other options involving the propeller and rudder interactions include Wärtsilä’s Energopac or the Rolls-Royce PROMAS. In the latter system, the rudder is fitted with a bulb located immediately behind the propeller, optimising interaction between the two main components of the propulsion/steering systems. Both systems can offer savings around 5% and as much as 8% in some ship types.

Wärtsilä’s system is produced in conjunction with German rudder manufacturer Becker, whereas the Rolls-Royce system is entirely in-house. Although intended primarily for newbuildings, RR does offer a simplified version of its system in which the existing rudder is modified by the addition of the bulb and the propeller is fitted with a special hub cap and new blades.

One well-known solution that can be used to reduce fuel costs is the contra-rotating propeller (CRP) first used by Japanese builder Mitsubishi in the late 1980s. More recently, IHI Marin United in Japan has taken the concept a step October 2011

13/10/2011 15:25:33

Propulsion

further. It has been working on CRP technology for a long time and to improve their efficiency further has developed advanced CRPs with tipraked fins.

Initially, the company investigated the hydrodynamic characteristics of tip-raked fin propellers (TRP) using theoretical calculations.

When these proved to be promising, the higher efficiency of the TRP was verified using open water tests.

In general, the efficiency of TRP can be improved by modifying the lift distribution over the blade and reducing drag. The most

successful example of this is the now wellknown Kappel Propeller developed by Andersen and Kappel. The Kappel Propeller has been fitted to a number of vessels and improvements of 4–5% have been reported.

In the work carried out by IHI Marine United special attention was paid to blade tip geometries that realise larger aft propeller diameters when the TRP concept is applied to a contrarotating propeller. Tests carried out in HSVA’s high-speed cavitation tunnel in Germany indicated that combining a CRP with TRP produced a design that was 1.5 times more efficient than

a conventional CRP without curved rake.

The company said it has found that negative pressure on the suction side is moderated by backward tip rake; the slipstream moves according to the shift of the blade tip position. By applying backward tip rake to the forward propeller, the diameter of the aft propeller can be increased, which improves efficiency. The model test demonstrated that the viscous effect for the TRP is larger than that for the conventional propeller. IHI Marine United said it believed that further improvements to the efficiency of CRPs with tip rake may be possible.

Backward step could be big advance Research into propeller improvement involves a number of areas, but one concept that seems to hold particular promise, at least in the long term, is moving the propeller aft so that it is behind the hull rather than under it.

Doing so allows the diameter of the propeller to be increased without the risk of pressure pulses being transferred to the hull. An increase in efficiency can then be achieved, reducing fuel consumption and emissions.

The concept of a large-area propeller (LAP) has been studied recently at Chalmers University of Technology in Gothenburg in Sweden. Its researchers used computational fluid dynamics software to investigate the effectiveness of LAPs. It has been known for a long time that increasing propeller diameter improves propulsive efficiency.

The work is a part of a larger project, the aim of which is to identify hull types that are suitable for the application of the LAP concept. The starting point for the study was to study the effectiveness of different types of propeller and propellers with differing diameters and longitudinal positions.

Having used different propellers and propeller diameters on a single type of vessel the researchers next intend to apply them to other hull types that might be suitable for LAP and look for general trends (if any). From these results they expect to be able to identify the most promising hull for further improvement. The hulls and propellers used throughout the project were carefully chosen with guidance from SSPA and Rolls-Royce.

In an initial series of tests the original propeller used and a larger one

were systematically moved aft and the delivered power, as well as the propulsive coefficients, computed. The results were compared with experimental data from SSPA. The results of the work undertaken at Chalmers University indicate that big benefits could accrue from moving the propeller aft and increasing its diameter and that there was a large gain in total efficiency, mainly as a result of increased hull and propeller efficiencies, even though no modifications of the hull or propellers were carried out. “By optimising these, it could be possible to improve the concept even further,” said the researchers.

The tests were carried out on a small single-screw tanker designed by Rolls-Royce in Norway. Two propellers were used: the original one and a larger propeller called the LAP. The propellers were carefully chosen to match the design conditions of the tanker. Both propellers were moved back systematically in seven steps from their original location to a position far behind the transom stern.

“Moving the propeller aft and increasing its area indicated a great potential for power reduction. Interesting trends in propulsive factors were revealed in the simulations and verified in experiments,” the researchers responsible for the work said. “Since the investigation was carried out without a rudder and without optimising the hull or propellers, there is room for further improvement that would reduce the power required even further.”

Cap fits for Teekay

A

fter an extensive series of tests, Teekay Corporation has decided to fit a modified propeller boss cap, known as a propeller boss cap fin, to its Aframax and Suezmax tankers.

In 2006, Teekay Corporation started a technology development programme to enhance the efficiency of existing and newbuild vessels.

The company undertook a comprehensive October 2011

10_15_FuelSaving11.indd 11

investigation and evaluation of fuel-saving devices that had the potential to be retrofitted or fitted on new vessels. The most promising

4%

Fuel saving made with PBCF under loaded operation

were then tested at model scale. Among them was the propeller boss cap fin (PBCF).

The results showed that propulsive gains were to be expected and that the investment payback period would be short, so full-scale trials were conducted on an Aframax tanker.

As representatives of Teekay Corporation, BMT Defence Services and MOL Techno-Trade explained at a recent conference, the vessel used in the full-scale trials, Kilimanjaro Spirit, underwent a carefully controlled sea trial immediately before the PBCF was fitted afloat.

The sea trials were then repeated after it was fitted. Both trials were performed within a Guide to Fuel Savings 11

13/10/2011 15:26:21

Propulsion

period of about four days in the southern Adriatic in deep water, good weather conditions and little traffic.

The vessel was some four years out of dock, so the hull had some degree of fouling, but in view of the exceptionally good test conditions and the care taken during the trials, the quality of the measurements are regarded as being unusually good. The results conformed closely to the predictions from the model tests.

The PBCF was developed by MOL and two Japanese engineering consulatant organisations, West Japan Fluid Engineering Laboratory and Mikado, as long ago as 1986. By 2006, 1,000 ships had been fitted with a PBCF and in the five years since then the number of vessels equipped with the device has doubled to around 2,000. A relatively simple device, the PBCF consists - as its name suggests - of a modified propeller boss cap (or hub cone) with fins. The number of fins matches the number of propeller blades and it rotates together with the propeller.

Installation of a PBCF device is straightforward. The device is simply bolted on to the propeller boss using the existing bolt holes for the propeller bonnet, the bonnet being replaced by the PBCF device. No other modification to vessel or propeller is required, so the PBCF is an effective and inexpensive fuel-saving device that can be applied to existing vessels.

The PBCF device works by improving the flow around the boss. Looking into the flow around the propeller boss, the water flow is accelerated and twisted when it passes through the propeller disc. Close to the hub blade root vortices are also present. These coalesce with the general twist in the flow induced by the blade downwash to produce a very strong vortex aft of the boss.

t 4 4

$ + * "" $ $ $ )$ -# t * )$$ ' ,'$ ' $ $ $ $ $%# -" ""$ * - #

t % $ '$) ')$ % %% %# t ' $ % " %% %# t * $ ' %% %# t % $ $* %% %# t $ %' ' % $ $'% %' ' ' %#

t * "$ $ " $ * %% % % $ %'$) ')$ %# t * ' %)$ '% + ' $ * " $'% % ' # t $ $ ' $ # t !. (. . ' $ $ # t ) - $ $ + ' $ %"$ -#

($)

$ ( 0 " /4 %. . ) ( $(1 3 ' * ++ # * 44 2 ' * ++ #4 % *4 ! $ ! ($)&"$ ) - ! ($)&"$

12 Guide to Fuel Savings

10_15_FuelSaving11.indd 12

When the PBCF device is installed, the strong downflows from propeller blade trailing edge are rectified by the PBCF fins and the hub vortex is reduced. The fins produce a force that reduces the propeller shaft torque and increases the thrust. As a result of this hydrodynamic mechanism, the propeller boss cap fin improves propeller efficiency.

The model tests mentioned above were carried out under the supervi-

“With approximate 3.5% savings predicted, the payback time for Aframax and Suezmax tankers was estimated to be about six months�

sion of BMT at the SSPA model test tank in Sweden, using a model of an Aframax tanker that was available from previous work undertaken by BMT for Teekay. “The suppliers of many similar devices to the PBCF claim that not only do they have better efficiency at full scale, but also that they have a greater scale effect between the model and the ship propeller than is the case for conventional propellers. They therefore claim that their devices are more efficient at full size than is determined from model size tests,� the authors of the paper explained.

The model test programme was undertaken to establish the model size efficiency of the propeller by itself (propeller open water tests) and when driving the model (propulsion tests). So that these results could be benchmarked, these same tests were performed without the PBCF device fitted to the propeller.

The other aim of the tests was to investigate whether the propeller boss cap fin was subject to a greater scale effect than a conventional propeller. This was researched by performing the open water tests both for the baseline propeller and the baseline propeller fitted with the PBCF over as large a range of Reynolds number as possible.

In the full-scale test, over the speed range a reduction in power demand of about 3.7% was achieved. This is close to about 3.8% at 14.5kt and is about 3.5% at 15.5kt, which compares well with the model test results, where an efficiency gain of about 3.5% was found in the range 8–16kt for the ballast condition. The model tests predicted a reduction in shaft power required of about 4% at 14kt for the load condition.

According to Teekay, the fact that the full scale results are close to the model test results indicates that no scale effect is present. Full details of all the previous trials conducted on these devices are not known. Teekay may not have found much evidence of the scale effect, but it was in no doubt that using the PCBF reduces fuel consumption, noting that it amounts to a like-for-like cut in fuel use of 3.5% in ballast and 4% when loaded.

After the tests were completed, the effectiveness of the PBCF was considered to be sufficiently understood to make a decision on the implementation of the PBCF in Teekay’s tanker fleet. With approximate 3.5 % savings predicted, the payback time for fitting the device to the company’s Aframax and Suezmax tankers was estimated to be about six months.

Rollout of PBCF in the company’s fleet started in 2010 with eight installations planned. In fact, although three installations were carried out, five others had to be postponed to 2011 to suit the vessels’ operational programme. Further installations are expected when these are completed and the in-service follow up of the performance of the vessels has confirmed the savings predicted by the model and full-scale tests. October 2011

13/10/2011 16:19:12

Propulsion

Swirl way to save S peaking at June’s Second International Symposium on Marine Propulsors in Hamburg, Germany, representatives of Maritime Research Institute Netherlands (MARIN) and Delft University of Technology (TNO) described the advantages to be gained from fitting a pre-swirl stator device to single- and twin-screw ships.Doing so, they explained, can reduce the rotational losses incurred by the propeller.

They explained the general mechanism by which pre-swirl stators reduce fuel consumption and the tools used to analyse and design different configurations for ships fitted with propellers and pre-swirl stators, with particular attention to viscous effects. They also worked out a solution for a single-screw container ship with a pre-swirl stator.

The combination of a pre-swirl stator and a main propeller has sometimes been called the “poor man’s contra-rotating propellers�, as it is a comparatively inexpensive solution that is relatively easy to apply in ship propulsion. “Fitting a pre-swirl stator ahead of a propeller can provide a fuel saving in the order of 4.5% without the high costs and other adverse effects associated with the far more complex contra-rotating propellers driven by concentric shafts,� they said. A pre-swirl stator “is only part of a total potential gain� and upstream ducts – sometimes used on high block, singlescrew ships – can add 2–5 % to fuel savings.

A pre-swirl stator can be combined with an upstream duct such as the Mewis Duct.

Alternatively, a large pre-swirl stator can be combined with an upstream duct of the ‘L-J’ shape proposed by Stierman. “The purpose of a pre-swirl stator ahead of a propeller is to generate a ‘swirling flow’,� they explained, noting that the propeller blades experience this rotating flow “as an additional blade loading, through which the delivered thrust per unit of power is raised.� (The increase in propeller thrust should, of course, be greater than the resistance experienced by the pre-swirl stator.) “The pre-swirl stator induces rotation of the flow downstream, which is absorbed and diminished to a great extent by the opposite rotation induced by propeller, thus leaving less rotation in the final slipstream,� they explained. “This is because, in comparison to a single propeller, less rotational energy is carried away by the flow passing through the propeller disc.�

Although debate surrounds the energy-saving mechanisms of upstream ducts, experience based on model tests indicates that they affect

October 2011

10_15_FuelSaving11.indd 13

both the resistance of the hull with driving propeller and the efficiency of the propulsion. “Both the concentration of viscous hull wake in the propeller disc and the generation of a small

amount of thrust are factors to be considered,â€? the MARIN and TNO representatives explained. “Pre-swirl stators mounted in front of the propellers can provide substantial energy savings of up to 5% for single- and twin-screw ships. For high-block ships, an additional saving in the order of 2–5% can be attained using an upstream nozzle.â€?Â

0VS QSPWFO SVEEFS TZTUFNT BSF UIF QFSGFDU DIPJDF GPS BMM UZQFT PG TIJQT " UPVHI XPSLJOH FOWJSPONFOU SFRVJSFT B TUVSEZ JOEJWJEVBM EFTJHO DPN CJOFE XJUI TVQFSC NBOPFVWSBCJMJUZ 4FBTPOFE DBQUBJOT SFMZ PO #FDLFS SVEEFST GPS UIFJS SFMJBCJMJUZ TBGFUZ BOE FYDFQUJPOBM NBOPFVWSBCJMJUZ 8 8 8 # & $ , & 3 . " 3 * / & 4 : 4 5 & . 4 $ 0 .

7JTJU VT BU UIF ,03."3*/& *OUFSOBUJPOBM .BSJUJNF &YIJCJUJPO BU #FYDP JO #VTBO ,PSFB (FSNBO 1BWJMJPO 4UBOE 0

"MTP WJTJU VT BU UIF ."3*/5&$ *OUFSOBUJPOBM .BSJUJNF &YIJCJUJPO JO 4IBOHIBJ $IJOB (FSNBO 1BWJMJPO )BMM 8 4UBOE $

Guide to Fuel Savings 13

13/10/2011 16:20:27

Propulsion

The Mewis Duct saves power and reduces vibration Photo: Becker Marine Systems

Duct proves its worth O

ne of the most effective energy-saving devices (ESDs) developed in recent times is the Mewis Duct marketed

by Becker Marine Systems. The device was launched at the 2008 SMM in Hamburg and is designed to improve water flow to the propellers of full-bodied ship types, such as bulkers, tankers

14 Guide to Fuel Savings

10_15_FuelSaving11.indd 14

and some container ship designs. More than 20 examples have been installed on vessels.

The first was retrofitted in early 2009 at China’s Chengxi shipyard to Grieg Shipping’s 46,000dwt multi-purpose ship Star Istind. In tank tests on models, the Mewis Duct achieved a 5–6% fuel saving and soon after the first full

scale version was installed, Becker confirmed the outcome of the first sea trials had shown those predictions and others from CFD calculations to be accurate.

Grieg is clearly satisfied with the results as it has since ordered similar retrofits on other vessels. Swedish owner Laurin Maritime is also trialling the Mewis Duct on its 2004-built 46,764dwt chemical tanker Tambourin.

Speaking at the Second International Symposium on Marine Propulsors in Hamburg in June, Friedrich Mewis of Mewis Ship Hydrodynamics in Dresden, Germany (the inventor of the device) and Thomas Guiard of Maritime Innovationsgesellschaft in Rostock, Germany, described the results of some of the most recent tests carried out on the device.

In general, the results have been very October 2011

13/10/2011 16:34:59

Propulsion

successful, and Mewis Duct has been shown not only to reduce the power required by up to 8% with a mean saving averaged over 35 tests of 6.5%, but has also significantly reduced vibration excitation, reducing pressure pulses by up to 80%. At the same time, the cavitation behaviour of the propeller is positively affected, and the Mewis Duct tends to improve course stability of otherwise unstable vessels.

Mewis and Guiard explained in their presentation that new full-scale trial measurements without and with the Mewis Duct were undertaken in October 2010 on a newbuild 57,000dwt bulk carrier, AS Vincentia.

The results of the trials were compared at the ship’s contractual speed of 14.4kt. At full scale, with the Mewis Duct fitted, there was a 6.5% power need reduction, or 0.25kt higher speed at constant power, with propeller speed increased by 0.8%. This compared with a 7.1% power demand reduction (or 0.27kt higher speed at constant power, with the propeller speed reduced by 0.9 %) at model scale. The power savings measured are, to all intents and purposes, identical, because the difference

between them lies within the overall measurement accuracy range.

On the first vessel to be fitted with a Mewis Duct, Star Istind, a window was installed above the propeller and Mewis Duct to allow cavitation behaviour to be observed. Mewis explained that there was no cavitation on the Mewis Duct and no cavitation at the blade roots of the propeller.

6%

Fuel saving on Star Island with a Mewis Duct

No measurement data for vibration behaviour are available, unfortunately, but Mewis said that crews of nearly all the ships retrofitted with Mewis Ducts reported vibration to be greatly reduced, particularly at ballast draught.

Another important benefit of the concept is that propeller revolutions in heavy seas seem to stabilise with the Mewis Duct fitted.

By the end of January 2011 self-propulsion

tests designed to estimate the power savings achieved with the Mewis Duct had been carried out on 18 projects in six model tanks with virtually no differences in the results from one test tank to the other. The ship types ranged from a 12,000dwt bulk carrier to a 320,000dwt VLCC to a 20kt ro-ro. “Based on a 6% average power saving and 220 days a year operating time, the return of investment is about one year,� Mewis told delegates at the conference (assuming a bunker price of $600 per tonne).

Furthermore, he explained, the Mewis Duct is suitable for use on ships whose propeller load is typically greater than 1.0kt and speed less than 20kt. Generally speaking, this encompasses small container vessels, small vessels with a high block coefficient, multipurpose carriers and all varieties of tanker and bulk carrier. “Future developments of the Mewis Duct involve extending the design and optimisation process to include vessels faster than 20kt, for example very large container vessels,â€? Mewis and Guiard concluded.Â

) & & ) $' '# ' $ & $ & # # # '&'# #' $ #' $" &# ' ' $ $ # ) ( $ $ &* !' $ $ ' # &

& &# &

#

$ # ) ' $*$& $ & '

$

#

& # &# ' ' $ # #

& & $ $ ( #&' * &

# # ( # & #' $ #

# $ $ ( # &$ ) & ' $ & $ # # ( & $'# ++ # ' $

$ ( $ & & '& # '& & * &$ '$ &# '

' $ & #

October 2011

++ # '

10_15_FuelSaving11.indd 15

$'# $ ) *

$&$

Guide to Fuel Savings 15

13/10/2011 16:35:29

Research

Setting fuel-saving scenarios

for bulkship owners F

uel typically represent 60–70% of the operating costs of a bulk carrier and, against a backcloth of intensified competition and persisting or recurrent rate weakness in key segments of the market, it has assumed added importance.

Reflecting each organisation’s substantial vested interest as a technical services provider to the bulk shipping industry, Shanghai Merchant Ship Design & Research Institute (SDARI) and classification society Det Norske Veritas (DNV) have together reviewed methods of improving bulker propulsion efficiency, resulting in an advisory document for owners, yards and designers.

The joint initiative is founded on the conviction that newbuild bulk carriers offer scope for cutting fuel costs by some 5–10% through the adoption of various design and engineering measures. Applicable to vessels to be constructed in China, the outcome is a guideline covering 14 fuel-saving devices and solutions, and a companion return-on-investment tool for analysing the cost-effectiveness of each method.

The approach demonstrates a pragmatic understanding of the sector’s requirements and acknowledges the fact that owners in the still highly fragmented bulk shipping industry do not always have the in-house resources to investigate the various technical options and their potential

worth with the necessary thoroughness. The ensuing guideline sets out how various devices, appendages and systems work, and examines compatibility between devices, manufacturing complexity and classification requirements. It also validates fuel savings for each measure and provides an indication of price.

“An example with a relatively simple device shows that a $47,000 investment has a net present value after three years of more than $250,000 and that the investment is profitable after five months,” said Michael Aasland, DNV’s director for bulk carriers. “Through the new guideline and RoI [return on investment] calculator, we hope to make it easier for owners who order bulk carriers to include investments in fuel-saving devices in order to improve environmental performance, save cost and gain competitiveness in a very tough market,” he added.

The project has been shaped by the particular challenges of implementing fuel-saving measures in bulk carriers, the traditional workhorses of sea transportation, which have been subject to continual design optimisation yet are regarded generally as of relatively low technical sophistication. Bulker owners’ characteristic scrutiny of every element of cost also gives rise to a tendency to seek comparatively short payback times on any extra expenditure on added

technical features to promote improved efficiency, although market uncertainties and fuel price volatility drive a renewed bid for further energy savings.

The growing uptake of certain types of hull appendage and propeller efficiency improvement device demonstrates a propensity for measures with proven effectiveness. SDARI and DNV have sought to build on this interest by delivering clear assessments of available technology, the worth and cost of the increasing array of options available, and of the practical steps entailed in implementing the respective solutions. DNV’s specific contributions have included development of the RoI calculator.

The 14 measures detailed in the guideline include the Mewis Duct, the propeller boss cap fin (PBCF) and the pre-swirl rotor, as well as the propeller nozzle, contra-rotating propeller, pre-duct and propeller rudder transition bulb concepts, plus aspects of hull, rudder, propeller and engine design and technology.

Each of the measures is described and evaluated with respect to compatibility, classification requirements, manufacturing complexity, anticipated fuel savings, expected maintenance needs and price indications.

Taking, as an example, the PBCF, the guideline covers the functioning of the device, class criteria and production and installation issues. It is said to be simple in concept, relatively widely used, effective and comparatively easy to incorporate in a newbuild. The guideline then describes the device’s maintenance needs and the range of fuel savings to be expected with the PCF fitted, plus price indications from a range of sources.

Various scenarios for fuel prices, interest rates, payback times, estimated fuel savings and costs can be entered in the return on investment tool to calculate cost/benefit and also environmental impact arising from reduced fuel consumption.

The guideline and calculator are available upon request from SDARI and DNV.

Weighing up the savings

A

n obvious way to save fuel is to reduce the weight the engine has to move through the water. Naturally, this saving has to be in the ship rather than the cargo, which would be self-defeating in most cases – although lightweight containers would make a considerable difference to ships engaged in that sector.

A standard ISO shipping container weighs around 2–3 tonnes, depending on whether it is a 20ft or 40ft unit. The typical Southeast Asia– Europe container ship now carries as many as 14,000teu, which may

16 Guide to Fuel Savings

16_17_FuelSaving11.indd 16

equate to 28,000 tonnes of effective deadweight. A composite container now being tested for possible ISO acceptance could reduce that weight by 25%, or 7,000 tonnes. As well as being lighter, the new containers are also collapsible and fitted with rolling rather than side-opening doors.

Saving weight in the construction of the ship is something that has been practised for many years although not always with great success.

Scrimping on scantlings has in the past resulted in ships that were not fit for purpose and hence were subject to early structural failure. It was

October 2011

13/10/2011 13:43:48

Research

Identifying practical options

for cutting fuel costs

A

n energy efficiency review service, known as ECO-Practices, has been developed by the Germanischer Lloyd (GL) consultancy company FutureShip to help owners identify practical options for reducing fuel costs. This latest initiative augments a growing range of ECO brand solutions for raising ship efficiency, previously boosted by the ECO-Patterns tool, which exposes weaknesses in energy management.

The concept behind ECO-Practices is to draw together ship’s systems data, IMO’s Energy Efficiency Operational Indicator (EEOI) data, voyage information, and crew and management input, so as to identify measures with the greatest or most pragmatic fuel-saving potential. Subsequent analysis leads to suggestions for changes or improvements in crew procedures that can be implemented straightaway, as well as for technical enhancements that may require additional investment.

ECO-Practices entails three core stages. It starts with data analysis to determine immediate and potential areas for fuel savings, and associated benchmarking, followed by a workshop presentation and discussion, and subsequent refinement and implementation of selected measures.

The workshop is held at the customer’s premises for key crew members and management. Over the course of two days, the data analysis results are discussed and a systematic review is presented of the ship’s systems and related operational activities. From this interac-

tion with the client, FutureShip’s experts determine where operational and technical changes might best yield savings. The most promising areas and measures for improving fuel efficiency are then highlighted and subjected to more intense qualitative analysis and reviewed with the customer.

Estimated fuel savings and related investment costs are presented for each improvement measure identified. These are evaluated and compared in various fuel price scenarios, which enables the client to prioritise fuel-efficiency improvement options quickly and easily.

Benefits claimed for ECO-Practices include: Suggestions for improved crew working practices, to yield immediate savings Suggestions for changes to onboard systems, that can bring about improvements in operational energy efficiency Cost/benefit comparisons that assist in prioritising options requiring financial investment Suggestions for improvement of control and automation processes and systems that can be applied to other, existing ships Information on options that can be implemented in future newbuild vessels and designs.

ECO-Practices is essentially a failure mode and effects analysis, whereby each energyrelevant system undergoes an error and risk assessment. “To give an example,” explained FutureShip managing director Volker Hoppner, “a situation we encounter frequently, the cooling water system often wastes a lot of energy.

So we take a close look at its operation and try

this practice that provided much of the motivation for IMO adopting the concept of goal-based standards and it was also behind the IACS’s common structural rules.

Alternatives to steel in shipbuilding have had limited success so far, save for the use of aluminium in fast ferry construction and more recently the use of sandwich plate for ship repair. While most shipowners would reject the idea of using anything other than steel for hull construction, they may be more open to the idea of employing aluminium or composites for superstructures and in areas in the ship where structural strength is not a function of the material used. A project known as LASS, (Lightweight Construction Applications at Sea), led by a Swedish consortium, has been running for some time and has investi-

October 2011

16_17_FuelSaving11.indd 17

to come up with the best way to improve efficiency.” Another area that warrants scrutiny is the onboard power generating equipment.

Hoppner believes it is essential to work closely with the ship’s officers, who can provide valuable insights into the subtle ways in which the vessel’s systems interact: “The amazing thing is, knowledge [as to] how to achieve efficient ship operation does exist on board. But in many cases, nobody ever asks. We try to bring it out into the open.”

The first step towards optimising the fuel consumption of a vessel is to analyse its current operation. FutureShip’s ECO-Patterns tool is used to gather relevant information over a period of time long enough to be representative.

It provides fuel usage insights through analysis of voyage-related variations in fuel consumption patterns, and compares the subject vessel’s efficiency against that of sister ships and the market average for similar vessels. ECO-Patterns enables an owner to evaluate the influence of speed, distance sailed, and transport capacity utilisation on the overall EEOI for the vessel.

gated the potential of using various Norwegia n lightweight alternatives to steel. project ex Gem is a baseline fo ploring us e of comp r a LASS’s overall goal is to Photo: Die osites tmar Hasen pusch improve the efficiency of ships by reducing their weight by 30% while keeping performance unchanged and providing a total cost reduction of 25% over the lifecycle. The initial project, which concluded in 2009, explored the potential for application of the concept to a number of ship types. Now, with the co-operation of German builder Meyer Werft, it has been extended to cover cruise ships. LASS will compare a ship of the Norwegian Gem type built conventionally against one using composite materials of various sorts.

Guide to Fuel Savings 17

13/10/2011 13:44:30

Engines

Breathing exercises

save fuel A

s the place where the fuel is burned, the engine would seem to be the place to start when attempting to save fuel.

Good maintenance plays a major role here, because fuel consumption increases as components within the engine begin to wear. A modern engine, festooned with sensors of all kinds and monitoring units capable of recording even the tiniest change in engine running parameters may be not every engineer’s cup of tea, but true professionals recognise and appreciate assistance even if it is non-human.

Electronically controlled camshaftless engines have become commonplace over the last decade, but they are not yet dominant, even in newbuildings. Engine-makers testify to their ability to reduce fuel use, but some users dispute those claims and support their own views with anecdotal evidence. It is of course impossible to make direct comparisons between a new ship with an electronic engine and an older vessel with a more conventional powerplant without taking into account every other possible difference between the two ship types. However, those who believe in the savings potential of electronic engines do have the option of upgrading some types of existing mechanical engines.

The single aspect of the engine that has a proven effect on fuel use is the turbocharger.

Without one, the power output of the engine would drop by as much as 60–70% and fuel use needed to maintain the same speed (were that possible) would increase by a like amount. In essence, the turbocharger increases air intake to the combustion chamber, allowing as much fuel as possible to be fully burned and its potential energy released.

Turbocharger technology is advancing almost as rapidly as other engine developments and improvements such as variable turbocharger geometry and two-stage turbocharging allow the device to perform at optimum efficiency across a much wider load range. The mere act of replacing an ageing turbocharger with a newer 18 Guide to Fuel Savings

18_19_FuelSaving11.indd 18

MAN Diesel & Turbo’s Turbo cutout can make fuel savings of 5% possible Photo: MAN Diesel & Turbo

version can boost performance or allow a similar operating profile while burning less fuel.

Most deepsea ship types make use of a single low-speed diesel engine directly linked to a propeller and operating at loads greater than 60% of MCR. When adopting a slow-steaming strategy to save fuel, the load can often fall below the optimum level. This applies more to container ships than to tankers or bulk carriers because the former are designed for higher operating speeds.

Under such conditions, the turbocharging can become excessive and the fuel-saving effect of slow steaming much reduced. A quick fix would be to disconnect one turbocharger on a multi-unit engine, but the operation is not easily reversed (as might be necessary in an emergency). Both major engine-makers, Wärtsilä and MAN Diesel & Turbo, have developed and marketed solutions that allow some of the turbocharging capacity that has been cut out to be restored relatively easily.

Wärtsilä’s Upgrade Kit Slow Steaming for its RTA and RT-Flex engine ranges has been available for around two years although many of the container ship operators that could have

benefited from it may have avoided installing one in the belief that slow steaming would be just a short-term phenomenon.

In the worsening economic situation that appears to be developing, however, that view may need to be revisited. The kit allows Wärtsilä low-speed marine engines to be operated continuously at any power in the range of 10–100% of the contracted maximum continuous rated (CMCR) power without additional operating restrictions. The modified engine is not permanently derated but can operate at any time up to its full installed power for full sea speed.

The achievable specific fuel consumption figures are strongly dependent on the final NOx emission balances over the whole load range.

For ships that must comply with the IMO NOx emissions regulations, the restrictions imposed by the emissions limits will be evaluated in each case and a customised turnkey package may be offered.

Installing the kit involves fitting shutoff valves in the exhaust duct before the turbocharger turbine and in the scavenge air duct after the compressor. The valves are remotely controlled, so the kit includes the fitting of a control system to operate the valves. Installation and commissioning of the upgrade kit can be completed during normal commercial operation of the ship and during normal port calls for the majority of engine types.

Potential savings are quite high, but in practice will depend upon the time spent slow steaming. Based on a 12RTA96C engine capable of producing 68,640kW running at 100% of MCR and 102rpm for an annual 7,000 running October 2011

13/10/2011 14:20:34

Engines

hours the annual fuel saving with the kit fitted and running at 45% load could be as much as 1,903 tonnes.

MAN Diesel and Turbo was a slightly later entrant into the turbocharger cutout upgrade arena than its main rival, bringing its offering to market in early 2010. By the time of the SMM exhibition in Hamburg in 2010 enough of them had been sold and fitted to allow the company to say that tests have proved that a large container vessel, powered by a 12K98MC in slowsteaming mode at 40% MCR, can save 8g HFO per kWh when one out of three turbochargers is disconnected. This corresponds to a reduction of around 5%. When power needs to be increased to full load, the turbocharger cutout with swing gate can easily and safely be opened without manual work. Fitting the turbo cutout swing gate valve takes around 48 hours and can be arranged at a number of the company’s PrimeServ service depots.

For tankers and bulk carrier newbuildings for which the operator is contemplating a permanently lower operating speed, several options are possible. The one most likely to accord with IMO’s Energy Efficiency Design Index (EEDI) rules would be a smaller or derated engine. An alternative would be to install one of the new breed of super-long-stroke engines such as the recently announced MAN G Type. These engines run at a lower speed than other types and allow a largerdiameter, more efficient propeller to be fitted.

Athens-based Almi Tankers will be the first to equip VLCCs with the new 7G80ME-C9.2 engine. The two vessels, which will run at 13kt rather than the more usual 15kt, will be built at DSME in South Korea, with delivery scheduled for May and December 2013. Earlier this year, Thenamaris placed an order for four 6G80MEC9.2 engines to power four 5,000teu container vessels, to be built by Hyundai Samho. It has been estimated that the new designs offer potential fuel-consumption savings of 4–7%.

As already mentioned, the most heavily promoted means of complying with the draft EEDI is to install a smaller engine that will have to run at almost 100% MCR to propel a vessel at a realistic service speed. One owner takes an opposing view, however, and believes fuel savings – and an improved safety margin – can best be achieved by fitting a larger engine and running it at just 75% MCR. Atlantic Bulk Carriers Management did just that in a new series of 57,800dwt bulkers. In making its engine choice the company compared the maker’s consumption figures for six- and seven-cylinder versions of the same MAN S50MC-C7 engine type. Based on a required speed of 14.5kt, an assumed sea state October 2011

18_19_FuelSaving11.indd 19

Electronically controlled engines such as this MAN S70MEC improve fuel efficiency Photo: MAN Diesel & Turbo

of Beaufort 4 and allowing for some element of hull fouling, the results of the calculation were that the six-cylinder engine would burn 35.65 tonnes of MDO a day while the seven-cylinder version needed just 32.5 tonnes. As the engines can also run on cheaper IFO, the MDO consumption figures took account of IFO’s lower calorific value compared with MDO. The results indicate that the smaller engine would consume 38.3 tonnes/day and the larger unit just 34.9 tonnes/day. The owner also believes that the small engine simply does not have sufficient power to go 14.5kt at the ship’s maximum draught in Beaufort 4. In reality, therefore, the top speed would be 14.2kt, a speed at which the larger engine’s consumption could be a further 1t/day lower.

There are futther savings obtainable from the main power system of most ships. An engine produces much of its energy as heat rather than as motive power. While most vessels recover some of this energy for water heating, the majority is wasted and disappears up the funnel.

For most types of ship a waste heat recovery system is a possibility, and although it requires a high capital outlay, payback is relatively quick.

One of the most notable recently built ships to be fitted with such a sytsem is the Emma Maersk.

The vessel’s owner has also fitted several more of its newbuildings with similar systems.

Current ships generally employ the waste heat to power a turbine for producing electricity, which does away with the need to run a

Two-s ta help c ge turboch ontrib ute to arging syste Photo: fuel sa ms ca Wärts n vings ilä

genset, so the fuel saving is not from the main engine but from the auxiliary. A more complex system might make use of the energy recovered to run a power take-in device, thereby either increasing the main engine’s power output or reducing the need to burn as much fuel.

However, it should be noted that ships which are fitted with very low speed engines will not gain as much benefit as vessels with higher revving engines because the heat generated by the engine will be much reduced.

Guide to Fuel Savings 19

13/10/2011 14:21:40

Software

S

oftware on board ships can help with fuel management and provide many ways of making savings particularly when electronically controlled engines are installed and the quantity of fuel delivered can be precisely controlled. Various trim optimisation software programs have been developed recently, all of which promise large fuel savings and in many cases have sufficient ‘in-service’ performance data to back up the claims.

Keeping a ship on an even trim is a fundamental element of seamanship, but the growing market for software that monitors and advises on this topic suggests that, for whatever reason, some ships are sailing in less than ideal conditions. It is perhaps no coincidence that product tanker operator Torm has christened its

corporate strategy to put profits on an even keel ‘Changing Trim’.

Helsinki-based Eniram was an early proponent of trim optimisation software and it remains a leader in the field. In April it announced that Hamburg Süd had ordered a dozen more installations of its Dynamic Trimming Assistant (DTA) and will deploy this fuel-saving, emission-reducing technology on all of its post-Panamax container vessels. Proven savings from vessels already equipped with the Eniram system encouraged Hamburg Süd to place this follow-on order.

Hamburg Süd was the first container line to install the DTA, which helps crews optimise trim. Since late 2008, the line has been reporting reductions averaging 3% in bunker

consumption of the DTA-equipped vessels compared with those without the system. As these sister vessels were operating on the same route, they provided an accurate benchmark for fuel consumption.

Japan’s MOL has also recognised the benefits of trim optimisation and joined with Akishima Laboratories (Mitsui Zosen) to develop its own system. A pilot test, using a 6,400-unit car carrier, showed an increase in fuel efficiency of up to 4%. The system is one of the technologies MOL is promoting in its Sempaku ISHIN project to develop concepts for next-generation vessels and will, the company said, be adopted on other types of ship as well.

Class societies have become enthusiastic supporters of trim optimisation and some offer

Trimming fuel

costs Images: Shutterstock

20 Guide to Fuel Savings

20_24_FuelSaving11.indd 20

October 2011

13/10/2011 14:30:31

l

s

Software

services that enable crew to determine the optimal trim for most conceivable permutations of cargo, fuel and operational conditions.

Germanischer Lloyd has its Eco-Assistant service from its FutureShip operation and Lloyd’s Register has advised its members that up to 5% savings can be made by optimising trim using its software calculations.

An example of how GL’s FutureShip software helped cut fuel use is included on page 26 of this supplement, but it was also used in a widerranging project.

That optimisation exercise, carried out on a 7,000teu ship, identified no fewer than six areas where savings could be made. Particular attention was paid to energy production and consumption and also the hydrodynamic efficiency of the vessel. A rearrangement of the reefer stack vent ducts, to allow better flow and reduce consumption, provided an efficiency saving of 0.6% at a cost of €25,000 and a payback time of less than five months based on a fuel price of just $250 per tonne.

Assuming the same fuel price of $250 per tonne, installing frequency control to major electrical consumers would cut auxiliary use at sea by 37% and would pay back the €108,000 cost within a year. A full decision support system to allow better power management would cost €200,000, and again the investment could be recovered in a year if the crew were to use it to cut energy use. Adjusting the main engine to the true operational profile of the ship rather than the maker’s default parameters would cost €160,000, with a payback time of 1.1 years. Major work such as replacing the bulb at a cost of €250,000 or spending €750,000 to change the old rudder to a twisted flow design would achieve payback in 1.2 and 2.9 years respectively.

Taken together, an outlay of less than €1.5M could be recouped in less than 18 months and

October 2011

20_24_FuelSaving11.indd 21

Screen shot from FORCE Technology’s SeaTrim software Photo: Force Technology

thereafter the operator might expect annual savings of around $1M in operating costs.

Naturally, changes in fuel prices can alter the viability or attractiveness of such alterations dramatically. In this case, payback could have been achieved in around six months and the annual savings increased to $2.5M–3.0M The system can also be employed to compare the performance of similar vessels within a fleet. In one project, four 4,000teu container ships were compared. Although originally identical, each ship had been slightly modified, making it slightly different from its sisters. It became clear that one vessel operated at 10% higher efficiency than its three sisters, which were noticeably worse than the market average. Identifying minor improvements such as shutting down half of the main engine-room ventilation fans during low-speed long-distance voyages and painting the deckhouse white to reduce air conditioning requirements allowed an annual saving of 98 tonnes of fuel per ship.

The quantity may not have been huge, but at today’s fuel prices the savings were roughly

equivalent to the wages of one AB. Collaboration between Norwegian class society Det Norske Veritas and Fugro Seastar has seen the latter’s Marinestar Manoeuvring system take on an added dimension with a dynamic trim measurement tool. Marinestar Manoeuvring uses twin GNSS systems mounted fore and aft on a ship to aid precise manoeuvring. Since these systems can also measure vertical movement to an accuracy of 1cm, they are ideal for determining changes in trim.

Any ship equipped with Marinestar can have a display added to show trim information. The display gives a graphic view of the ship’s attitude along with a numeric value for positive or negative trim at the bow. Graphs of trim and speed allow crew to see the effect of alterations to trim in real time. An optimum trim can be overlaid on the graphs as a target. The information is logged continually, permitting later examination if required.

FORCE Technology, formerly the Danish Maritime Institute, has performed trim tests for more than 50 vessels including tankers, container vessels, LNG carriers and ro-ro vessels. The tests indicate that it is possible to reduce fuel consumption by up to 15% in specific

Guide to Fuel Savings 21

13/10/2011 14:31:25

Software

conditions. In overall fleet operations, typical savings can reach 3–4%.

Until now, it has been the general belief in the maritime business that such savings were applicable only for large vessels with pronounced bulbous bows and high service speeds.

But in a recent study for Clipper Project, FORCE Technology documented that, by sailing with optimum trim, fuel consumption of the Clipper Confidence-class could be reduced by the same order of magnitude as for larger vessels. In specific conditions, up to 10% reduction is possible. Because smaller vessels have a larger degree of speed dependency on optimum trim than do larger vessels, selection of the correct trim is therefore of great importance.

Christian Schack, head of department, Hydro- & Aerodynamics, explained: “FORCE Technology has 50 years of experience within hydrodynamics and we continue to support our clients with expertise in ship performance. We utilise the most modern approach and combine CFD, route simulations and model tests when we work with our clients. The combined approach ensures that the client gets the best

performance for the fleet. Many owners have been very focused on the speed and often forget that and increase in speed of 1% can result in a power increase of 3–5%, depending on type and speed range.

There are many ways of obtaining and using data to gain the optimum trim. At FORCE Technology both scaled model testing and computational fluid dynamics (CFD) are used to determine the optimum trim at different speeds and loads. Christian Schack explained: “The best results in regards to trim are obtained through self-propulsion tests with a scale model. With self-propulsion tests, not only the change in hull resistance is investigated, but also the propulsion coefficients are measured and the gain and loss from change in these coefficients are a part of the trim guidance. With a simpler resistance test the change in propulsion coefficients will not be caught. With today’s accuracy, trim guidance based on RANS CFD calculations can be compared to resistance model tests. However, RANS CFD calculations can also be done with a ‘volume disc’ as propulsion in order to

calculate the propulsion coefficients, but this approach is quite time consuming.”

An important part of operating at the optimum trim is usability of the test data. FORCE Technology’s guidance tool, SeaTrim, calculates the optimum trim within seconds for a given combination of speed and displacement. The software is said to be easy to use and evaluating optimum trim for a vessel requires the input of just three parameters: draught forward and aft (typically taken from the ship’s loading computer) and the planned vessel speed (from vessel route planning). The program advises the user about the trim situation and, by simple colour codes and reduction/increase in power, states if current trim is optimal. If it is not, the tool gives guidance about where the optimum trim can be found. The user can then use the cargo or ballast water to obtain the best possible trim before leaving the port.

SeaTrim has been validated through the Danish joint industry project Green Ship of the Future and is delivered together with any trim test performed by FORCE Technology free of charge.

Saving fuel by using less 20%

Royston’s enginei system can also transmit data ashore Photo: Royston

T

here are numerous technical solutions that can reduce a ship’s fuel consumption, but for diesel specialist Royston Ltd the most effective fuel control system is 22 Guide to Fuel Savings

20_24_FuelSaving11.indd 22

the man with his hand on the ship’s throttle.

Engines at sea are much the same as vehicle engines in that the more you ask them to do, the more fuel they will burn. This means that if

Fuel saving per tug fitted with enginei system

you slow down and accelerate more gently you will still get where you are going but you will use less fuel.

This will not be news to anyone, but the trick to achieving it lies in knowing when and by how much to slow down, which is where the Royston enginei system comes into its own. It can be fitted to any diesel-powered vessel and works by accurately measuring fuel flow and matching the data with its GPS location. This makes it possible to calculate a vessel’s ‘miles per litre’ continuously, correlating this information in real time with its speed and activity.

There are many situations when a ship must operate at full power, but just as many when the engines can run more gently. By providing a simple, easy-to-read display on the bridge, enginei enable the master to remain aware of October 2011

13/10/2011 14:33:18

EVERY DROP ACCOUNTED FOR

Jotun’s revolutionary Hull Performance Solutions could form the basis for a new industry standard Jotun has combined SeaQuantum X200, the cutting edge Silyl Methacrylate antifouling, with a transparent and long-term hull performance monitoring system. With the confidence in our technology leadership and our ability to measure hull performance, we can now offer an attractive fuel saving guarantee that is valid for the full period between dry-dockings.

Jotun’s HPS essentially means – Every drop accounted for jotun.com/hps

Untitled-3 1

12/10/2011 15:13:14

Software

their fuel consumption and to decide on the most appropriate balance of speed and fuel consumed. Enginei does not impose itself upon the vessel’s control systems or override a master’s judgement, Royston insists; it simply provides the information needed to operate a ship’s engines efficiently.

The enginei system has been adopted on increasing numbers of vessels, but Svitzer Tugs is one company that has been particularly keen to seize the opportunity to make cost savings.

A system trial involving 15 installations proved so successful that the company is expanding the fuel efficiencies throughout the company’s fleet. Throughout the year-long trial Svitzer kept careful records of fuel consumed and concluded that, on average, tugs fitted with enginei had been achieving fuel savings of 20%. With the installation costs repaid after just months, simple

mathematics removed any doubts about extending enginei throughout the Svitzer fleet. Royston is now fitting its systems to 14 more Svitzer tugs.

Sensors monitor fuel flow and this data is converted for graphical presentation, so masters can quickly become thrifty in the way they operate their vessels. Yet the benefits of the enginei system are also available to operations managers ashore, who can have a display that makes it easier to deploy vessels more efficiently. Vessel data is incorporated on a satellite map that provides a real-time presentation of each tug’s location and its fuel consumption.

Through internet access to the Royston server, easy-to-follow charts of fuel used on a journey can help operators guide crews on fuel savings.

Managers can then deploy their vessels more efficiently and avoid issuing instructions that might lead to unnecessary fuel consumption.

Fuel fl o the wa w and cons umpti tchful o using the en eye of the m n under g aster in ei disp Photo: Roysto lay n

Keeping an eye

on consumption

Screen shot of KSP system Photo: Kyma

T

here are many software systems that have been designed to provide constant monitoring of a ship’s performance and, as some form of Energy Efficiency Operational Index (EEOI) may well be imposed before long, that number is likely to grow further. Norwegian company Kyma has been active in the field 24 Guide to Fuel Savings

20_24_FuelSaving11.indd 24

for longer than most and claims an impressive client list for its Kyma Ship Performance (KSP) products, which have recently been upgraded.

The system takes information from a variety of sources, beginning with a sensor on the propeller shaft to measure power output, and then records other information such as fuel

viscosity, temperature and flow from engineroom systems and ship’s speed, wind direction and other navigational data from the bridge instruments. The software includes sea trial or model tank propulsion baselines, which can be displayed graphically, together with the actual condition in real-time mode. Depending on the version of KSP used, some or all of the following features are available: noon-noon, voyage and trial reports; short- and long-term trending; instant and accumulated data; deviation from baseline conditions (trending); hull roughness and heavy propeller indication; diagnostic of vessel performance; trim optimisation; EEOI and emission calculations; export of trend and reports to onshore office.

As well as giving vital information to onboard personnel, the system can be useful to shore-based staff. Users ashore can group vessels into classes and compare the performance trend between different vessels within the same class. The analysis could be a valuable tool to identify performance deterioration and speed loss for a particular vessel and to allow the cause to be identified and rectified.

October 2011

13/10/2011 14:35:13

¨ £ Ó¨¨£½½½

ö¨æÏ £nô e ÓÝ £[Ý ón ¨¨ |¨Ï 0 A Ï· Aö AÏ Ý n ·æQ [AÝ ¨£Ó $ónÏ Ý n £nõÝ |nô ¨£Ý Ób A Ï· Aöb 0A|nÝö AÝ 0nA £ÝnÏ£AÝ ¨£A b 0¨ æÝ ¨£Ó A£e Ïne £ I -¨ÏÝ ¨£ÓÝÏæ[Ý ¨£ ô Qn£n}Ý |Ϩ A £nô ¨¨ A£e |nn

-Ïnó nô Ý n £¨ô AÝ Ó½[¨ Ù|A Ï· Aö £nô ¨¨

Ý n ÓA n ÄæA Ýö ne Ý¨Ï A Ý n ÓA n £ en·Ý Ïn·¨ÏÝ £ Ý n ÓA n £Ó Ý A£e £Ýn n£[n æÓÝ A ÏnAÝ £nô ¨¨

ßsäØëü¤¯¯ ë - /nQÏA£e

Untitled-1 1

30/09/2011 14:29:47

Illustrations: Shutterstock

Hull

D

Shapin to save fuel

rastic changes to the hull of a ship are not an option for many owners and the older a ship gets the less attractive such an option becomes. But operational changes and altered economic circumstances may make hull modification an option that merits careful consideration. Some modifications are actually relatively inexpensive and promise a very short payback period – usually those involving the welding of appendages on to the hull so as to better direct the flow of water to the propeller.

When any major alteration is in prospect, the cost of the work is a major factor in determining its merit. Much consideration needs to be given to current and predicted future bunker costs.

Today, bunker prices for 180 and 380 fuels are about double what they were two years ago, and while modification costs may also have changed, the increase has been negligible in comparison.

Embarking on costly projects based on future projections involves an element of chance, so while some owners that undertook work in 2009 may have achieved a payback in half the time, the possibility of a fall in fuel prices and more time being needed to offset original costs always has to be considered.

Germanischer Lloyd’s new FutureShip service was the subject of a Solutions report in July 2009. It uses advanced software to compare numerous variants of a basic design so as to determine potential efficiency savings.

While worthwhile savings can accrue from operational and low-level technical changes, 26 Guide to Fuel Savings

26_27_FuelSaving11.indd 26

GL says that the greatest savings generally arise from engineering optimisations. Some may involve radical changes, such as the replacement of the bulbous bow with a variant more suited to the new operating mode.

For example, a ship with a design speed of 25kt might be operated at 18kt under a slow-steaming strategy. Since its bulbous bow is not optimised for this speed, the generated wave patterns create greater water resistance. In consequence, any savings anticipated through slow steaming may be much reduced or even wiped out altogether. One German owner approached FutureShip back in 2009 with a view to exploring potential savings from a bulbous bow change. The owner was not anticipating a permanent change to slow steaming and wanted a bulb design that would be optimised for slow steaming while not adversely affecting resistance at the full design speed. The vessel in question was an 8,000teu container ship with a normal service speed of 25.2kt that was operating at 18kt and running at 50% MCR. Having carried out a computer analysis of the ship’s existing bulb, FutureShip was able to produce a new shape to suit the owner’s requirements. Model tests showed that this would give a 2.5% reduction in resistance, fuel consumption and emissions when slow-steaming and a 1% reduction at the design speed.

It was estimated that the ship’s operating profile meant that fuel consumption would fall by 1,000 tonnes a year. The next task was to evaluate the cost-effectiveness of changing the bulb on the actual vessel. Calculations at the time when the Rotterdam bunker price was $350 per tonne indicated that payback of the requisite

outlay of $450,000 could be achieved over 18 months; however, the higher fuel price over the following two years would have reduced that time to about 12 months.

Considerable attention has been paid to bow configurations over the past decade or so and many designers have either dropped the bulbous bow altogether or incorporated some of its characteristics into a new bow shape. This has been particularly noticeable in the offshore sector and bulk carriers and tankers produced

by Japanese yards.

The first offshore design to move away from the conventional hullform was the inverted XBow shape developed by the Norwegian Ulstein Verft. Later, STX Offshore and Rolls-Royce also adopted new bow shapes with much less emphasis on the bulb.

Substantial fuel savings have been claimed

Rolls-Royce’s Enviroship bow design with integral bulb Photo: Rolls Royce

October 2011

13/10/2011 13:24:04

Hull

ing up l for the new offshore designs, although the operational profile of ships in this sector makes it difficult to determine the exact level of fuel savings. It is a different story in the bulk carrier and tanker sector, where the pattern of trading allows much more detailed comparisons between ships and their efficiency levels. As major builders and operators of both types of ship, Japanese yards and owners have experimented with bow shapes for many years and each yard has its own patented variants.

Among the first to do this was NKK (now part of Universal Shipbuilding) when in 2001 it built the Capesize bulker Kohyohsan with its distinctive Ax-bow. The ship retained a bulbous bow, but the upper bow form differed markedly from conventional designs by having a definite hard-edged vertical drop from the uppermost part to form a notched shape overall. More than 90 vessels have been built with this bowform and results from the Kohyohsan indicate that required power is reduced by 3–4% As successor to NKK, Universal Shipbuilding developed the shape into what it calls the Leadge-Bow (a contraction of leading edge). In this design, hull performance in waves has been improved by straightening and

October 2011

26_27_FuelSaving11.indd 27

sharpening the bow edge between the AxBow above the waterline and the bulbous bow below. Viewed from the side, the bow is completely vertical, but the bulb has been partially retained within this structure.

Model tests showed the new shape to give the same wave-making resistance in still water as the conventional hull with a bulbous bow. In waves, on the other hand, the Leadge-Bow reduced the required horsepower by 4–5% compared with conventional ships.

Around 20 ships have been built with this hullform, including the Shin Koho delivered in May this year. The ship was also distinguished by being the first to employ another fuel-saving device – the hybrid turbocharger.

Another ship of unique appearance, the City of St Petersburg, built by Kyokuyo Shipyard, won the 2010 Ship of the Year award from the Japan Society of Naval Architects and Ocean Engineers. It is a car carrier in which reduction of wind resistance has received a huge amount of attention. The hemispherical stem shape has been achieved without sacrificing the cargo space. The bulbous panel, formed by press-bending, constitutes a part of a relatively distortion-free smooth hull shape. According to the society, “although a streamlined hull had been drawn for conceptual ships, its first realisation has been highly appreciated”. The efforts to reduce wind resistance are also evident in the streamlined funnel and the round shape of the upper part of the hull. Two other ships were honoured at the same awards – the twin sister heavy load carriers Yamatai and Yamato, which are among the first ships to feature an air lubrication system. The system delivers air to the bottom of the vessel using a blower and

NKK were pioneers of new bow forms with Kohyohsan Photo: Dietmar Hasenpusch

is claimed to reduce the frictional resistance of the hull surface against seawater, thus achieving about 10% energy saving even after taking into account the power used by the blower.

Energy-saving bowforms are not confined to Japanese and Norwegian builders and designers, as was highlighted in the October Solutions article on the ships built for Atlantic Bulk Carriers Management by South Korea’s Hyundai Mipo. Their bow design was actually achieved in consultation with Atlantic Bulk’s naval architects.

Initially the yard had been asked to increase the deadweight of the yard’s standard 56,000dwt ship by 2,000 tonnes. The first attempt, a 57,500dwt design, was considered to have an adverse effect on the ship’s consumption, so it was rejected and the yard asked to refine the ship’s lines forward.

The final selected version was a 57,400dwt ship which, despite being heavier and having a larger engine than the yard’s standard design on which it was based, managed a fuel saving of 3 tonnes of fuel a day. More pertinently, the cargo volume was equivalent to the larger version, with the ‘lost’ space being achieved by reducing ballast volume.

Guide to Fuel Savings 27

13/10/2011 13:25:13

¯s~ë¯ü¯¯ ë nÓ·¨ n 0AÝn Ýn

2 n nAe £ ·Ï¨ó enÏ ¨| [¨ Q £ne ÓAÝn Ýn A£e ÝnÏÏnÓÝÏ A 0 Ó · ¨ón n£ÝÓ½

| ö¨æ £nne æ£ £ÝnÏÏæ·Ýne ón A£e ÓÝ¨Ï [ [¨ónÏA n ¨| Ó · ·¨Ó Ý ¨£Ó A£e ¨ón n£ÝÓ A ¨£ Ý n ô¨Ï eÌÓ [Ï Ý [A AÏ Ý n ÝÏAen ϨæÝnÓb £[ æe £ enn· ¨[nA£b |¨Ï AÓÓnÝ ÝÏA[ £ ¨Ï Ï Ó AÓÓnÓÓ n£Ýb ÝæÏ£ ݨ 0 A Ï· Aö v Ý n nAe £ Ó¨æÏ[n |¨Ï Ý Ó [¨ Q £ne £|¨Ï AÝ ¨£½ 2 Ó [¨ Q £ne ÓAÝn Ýn A£e ÝnÏÏnÓÝÏ A 0 ·¨Ó Ý ¨£ A£e ¨ón n£Ý £|¨Ï AÝ ¨£ [A£ Qn Óæ·· ne £ A |¨Ï AÝ ¨| ö¨æÏ [ ¨ [nb AÝ A |ÏnÄæn£[ö ¨| ö¨æÏ [ ¨ [nb ݨ £Ýn ÏAÝn £Ý¨ ö¨æÏ ¨ô£ ÓöÓÝn ¨Ï |¨Ï ö¨æÏ ¨ô£ A£A öÓ Ó½

¨£ÌÝ ÝÏAen AÝ A e ÓAeóA£ÝA n½

¨£ÝA[Ý æÓ Ý¨eAö |¨Ï ¨Ïn enÝA Ó½ A Ï· Aö½ AÏ nÝ £ O Ó½[¨

Untitled-1 1

13/10/2011 17:12:17

Untitled-1 1

04/10/2011 12:15:29

Save Now. Save Later.

The revolutionary new HEMPASIL Nexus X-Seal tiecoat is the fastest, most cost-effective way to upgrade from your conventional antifouling to HEMPASIL X3. For more information see www.hempel.com or contact your local sales ofÀce.

Untitled-2 1

27/09/2011 14:48:55