Llyod's Register Container Ship Focus

CONTAINER SHIP FOCUSTECHNICAL NEWS AND INFORMATION ON CONTAINER SHIPS

Welcome to the third

issue of Container Ship

Focus, a technical

publication produced

by Lloyd’s Register

exclusively for the

container ship industry.

IN THIS ISSUE

2 West’s trade imbalancewith China makes and breaks fortunes

4 Preventing shaft bearing damage

7 Lloyd’s Register and Standard P&I Club publish container securing guidance

8 CRC notation – The way forward

10 Mandatory requirementsfor strength of towingand mooring equipmenton new ships

11 New ShipRight procedure for container ships helpsto assess hull stresses

12 News and upcoming conferences

NOVEMBER 2006 Issue 3

2 CONTAINER SHIP FOCUS November 2006

West’s trade imbalance with China makesand breaks fortunes

In Lloyd’s Register’s paper“Design Challenges of LargeContainer Ships”, presented inSingapore at ICHCA 2006,there is mention of the imbalancein the main east-west containertrades.* Cargo leaving Asia isprincipally high value andvoluminous, occupying every sloton container ships trading toEurope and the US West Coast.Conversely, the ‘back haul’, thereturn leg to Asia, tends tocomprise mainly heavy cargoes.Unfortunately, there is ofteninsufficient cargo on the backhaul legs to fill the ships. Theconsequence is an accumulationof empty containers, in Europeand the US, which need tobe returned to Asia.

One side of this story is told by arecent article in the Guardianentitled “The world’s largestcontainer ship Emma Maersk– symbolic of trade imbalancewith China”, which marvels overthe ship’s cargo manifest andcalls the ship “a floating worldof British desires and necessities”on the eve of its first call intothe port of Felixstowe. The articlegoes on to bemoan, however,the significant trade imbalancebetween the UK and China,pointing out that while Chinaexported some £16bn of goodsto the UK last year, only £2.8bnwent the other way.

The back haul trade hastraditionally been bolstered bythe carriage of heavy, low-valuecargoes - any revenue for thisleg is better then carrying loss-making empty containers.Cargoes which have helped tofill some of the otherwise emptycontainers include scrap steel,plastic and waste paper. This washighlighted in a recent article inThe Times bearing the headline"World's wealthiest self-madewoman”, about a self-madebusinesswoman named CheungYan who has amassed a fortuneof £1.8bn.

According to the article, MsCheung is chairwoman of China’sbiggest paper-recycling company,Nine Dragons Paper. She beganbuilding her fortune in 1985when, with less than $4,000, sheset up a wastepaper tradingbusiness in Hong Kong. Within sixyears, on the back of a boomingeconomy, she had accumulated asignificant amount of capital,which she used to set up a scrappaper exporting company calledAmerica Chung Nam in LosAngeles with her husband. Thecompany is now the leadingexporter of scrap paper in theUS. With China establishingitself as a huge manufacturingforce, Ms Cheung spotted anopportunity for paper to packagethe countless products beingexported around the world ormarketed at home.

The east-west imbalance in thecontainer trades is, for many, amajor problem – but clearlynot for Ms Cheung, who hadthe foresight to turn it intoa profitable advantage.

The traditional trade imbalance between the Westand Asia is good news for some and bad news forothers. Either way, container ship operators reapthe benefits.

For further information contact David Tozer, Business Manager – Container Ships, Lloyd’s RegisterE [email protected] T +44 (0)20 7423 1562 F +44 (0)20 7423 2213

November 2006 CONTAINER SHIP FOCUS 3

Cold ironing‘Cold ironing’ is the US Navy’sway of describing the practice ofconnecting a ship to a shore-sidepower supply in port with theship's machinery shut-down,causing the hull to become ‘cold.’This term is now commonly usedto describe a new generation ofdifferent high voltage shoreconnections with fast plugconnections and seamless loadtransfer without blackouts, whichallow the full range of in-portactivities to continue.

The increasing use of sucharrangements has been driven byconcerns for the environment andthe health of residents in portcommunities. There are existinginstallations for visiting containerships in the ports of Los Angelesand Long Beach, for instance. Thefacilities were installed followingin-depth studies carried out bythe state of California whichshowed that measures such ascold ironing could contribute tothe improved health of localresidents.

The requirement to use coldironing is soon to have astatutory footing, following theapproval by the California AirResources Board (ARB) of a newregulation to reduce emissionsfrom auxiliary diesel enginesoperated on ocean-going vesselswithin state waters.

According to an advisory issuedby the ARB, the regulation willrequire ship operators visitingCalifornia ports to reduce the airpollution from their auxiliarydiesel engines through the use ofcleaner marine distillate fuels orequivalent emission controls.One way that shipowners andoperators can comply with theemission limit is through the useof shore-side electrical power.To do so, however, owners andoperators must submit anapplication demonstrating thatsuch alternative strategies willresult in emissions that are nogreater than would result fromcompliance through the use ofthe cleaner fuels stipulated in theregulation.

The regulations are not yet inforce, but are expected tobecome legally effective by theend of 2006.

It is important, however, that shipsafety and environmentalbenefits are given equal weight.The technical difficulties, hazardsand potential for serious injuryand damage are not to beunderstated. To address thepotential hazards Lloyd’s Registerhas developed draft Rules foron-shore power supplies inconsultation with a wide varietyof stakeholders. We have alsobeen invited to contribute to theongoing industry discussions andworking groups tasked withdevising uniform standards forthese arrangements. The aim is toharness best practice to mitigatethe risks posed by the significantchange to port operations thatcold ironing represents.

Panama votes "Sí" to PanamaCanal expansionOn the October 22, 2006Panamanians voted ‘Sí’ (‘Yes’ inSpanish) in a national referendumon Panama Canal expansion.The voting began on a quietSunday morning at 7:00 am.The enthusiasm and energy wasapparent as each voter played hisor her part in determining thedirection and future of the canal.By law, expansion must be put toa vote in a popular referendum.The Panama Canal Authority(ACP) presented its formalproposal to the Panamaniangovernment in April, and on theday of the vote 78% voted forexpansion as of 9:30 pm EDT.

According to the ACP’s report“Proposal for the Expansion ofthe Panama Canal - Third Set ofLocks Project”, the containerisedcargo trade between NortheastAsia and the US East Coastreflects the highest canal transitgrowth rate. This route currentlyrepresents more than 50% of thePCUMS – Panama Canal UniversalMeasurement System – volume ofall containerised cargo transitingthe canal and is anticipated tobecome a key growth driver forthe canal.

* A copy of the paper can be obtained

from www.lr.org

Panamanians voted ‘yes’ to the

expansion of the Panama Canal

by an overwhelming majority.

The expansion will see the

construction of a third set of

locks to accommodate

increasing traffic from Asia,

through the Canal, to the US

and back.

Today’s vast order

book for container

ships, and especially

post-panamax

container ships,

continues to cause

nervousness in

the market. Photo

courtesy of AP Møller -

Mærsk A/S.

Preventing shaft bearing damage


A good shaft alignment is onein which all the supportingbearings are well loaded inthe static condition and thesystem is flexible enough towithstand hull deflections andimposed forces so that thebearings remain well loaded inall operating conditions. Forcontainer ships, this requirementhas historically been easier tofulfil than for other commercialvessel types such as oil tankersand bulk carriers. This has beendue to the inherent flexibilityof the shafting systems oncontainer vessels as a result ofthe mid-position of the mainengine and the subsequentlylong shaftlines.

It is somewhat counterintuitivethat long shaftlines with manybearings are in fact easier toalign than short shaftlines withfew bearings. However, theoryand practical experiencedemonstrate that the short, stiffsystems found on vessels withhigh-powered machinery placedas far aft as practicable are themost problematic.

With the advent of ever largerand more powerful containervessels, propeller andintermediate shaft diametersare increasing, with somesingle-screw ULCS designs nowincorporating a propeller shaftdiameter in excess of 1 metre.In conjunction with the largerdrive shafts, main engine designsare also incorporating shortercylinder spacings and largercrankshaft diameters.

These design trends make thecoupled propulsion shaft andengine system more sensitiveto changes in bearing position.In order to prevent bearingfailures, it has become necessaryto pay greater attention toshaft alignment design andpropulsion shafting installationon container ships.

Sensitivity of shaft systemsThe design stage is crucial inestablishing a suitably flexibleshafting system. It is importantfor the designer to minimisethe value of the bearinginfluence numbers (the measureof shaft stiffness). It is alsoimportant to keep the staticbearing loads high enough toprevent them from unloadingduring operation. In simpleterms, this means that thesterntube forward bearing and

With the advent of ever larger and more powerfulcontainer vessels, it has become necessary to paygreater attention to shaft alignment design andpropulsion shafting installation.

Wiping damage at aft section of sterntube aft bearing

on a 4,500 teu container ship.


plummer bearings need to bespaced sufficiently far apart.As a rule of thumb, thelength/diameter ratios of thebearing spans should be keptabove 10:1. To achieve thisit may be necessary to omit thesterntube forward bearing inplace of an aft plummer bearinglocated on the propeller shaft,immediately inboard of theengine room aft bulkhead seal.

Table 1 compares the parametersof several selected containership and oil tanker designs andshows the theoretical influencenumbers. As a measure ofsensitivity, the downward offsetfrom the design positionrequired to unload the sterntubeforward bearing or, where noforward bearing is fitted, theaft-most plummer bearing isshown.

Of the container ship designsstudied, the 4,500 teu vessel hasthe most sensitive system,comparable to that of the oiltankers. An important aspect ofthe particular 4,500 teu designstudied is that the shaft spanbetween the forward and aftsterntube bearing supports isonly 6.5 metres. This produces anL/D ratio of only 8.2:1 with asubsequently high influencenumber of 13.6 tonne/mm.

When combined with a designbearing load of 12 tonnes,it only takes 0.88 mm ofdownward displacement forthe sterntube forward bearingto unload.

A better design is the 6,000 teuvessel, which has a span of11.0 metres between sterntubebearings, producing an L/D ratioof 11.3:1. Despite the largershaft diameter, the sterntubeforward bearing’s influencenumber is kept down to6.7 tonne/mm.

The 6,000 teu design also has theadvantage of a longer shaftlinewith more plummer bearings(six, compared to only three inthe 4,500 teu design), whichhelps to reduce the influencenumber at the sterntubeforward bearing.

Bearing failure investigationsThe need to achieve a goodstatic load on the sterntubeforward or aft plummer bearinghas been highlighted in recentinvestigations undertaken byLloyd’s Register’s TechnicalInvestigations. Measurementsconducted on container vesselsdemonstrated how the bendingmoments imposed uponthe propeller shaft changesignificantly during manoeuvringturns, causing the sterntube

forward bearing to unload andthe propeller shaft to runcross-axis in the aft bearing. Thistypically occurs during turns tostarboard. The measurementsadditionally confirmed thatsuccessful sterntube aft bearingperformance is dependent onachieving a static slope mismatchbetween the journal and bearingsurfaces to within Lloyd’sRegister’s limit of 0.0003 radians(0.30 mm/m).

These results are in line withthe findings of numeroussterntube aft bearing failureinvestigations conducted byour Technical Investigations.The most common forms ofpropulsion shaft bearing damageare wiping or overheating atthe aft end of the sterntube aftbearing. In a number of cases,such damage has occurred

during starboard turns whenincreased bearing load andslope mismatch between thejournal and bearing surfaceshas adversely affected thedevelopment and maintenanceof a satisfactory oil film.

Although the shaft alignmentdesign calculations normallyconsider the hydrodynamicforces and moments generatedby the propeller, we have foundthat overly simplistic assumptions

Table 1: Sensitivity of selected shaft systems to bearing displacementsSterntube forward bearing or aft plummer bearing

(2nd bearing from aft)Prop. shaft Bearing Influence Downward offset todiameter static load number unload bearing

Vessel type (mm) (tonne) (tonne/mm) (mm)

2,000 teu container 640 11 3.9 2.82

4,500 teu container 792 12 13.6 0.88

6,000 teu container 975 31 6.7 4.63

8,000 teu container 971 30 12.5 2.40

150,000 dwt oil tanker 706 8 16.1 0.50

310,000 dwt oil tanker 801 18 27.4 0.66


are often made which have ledto poor alignment designs beingsubmitted for class approval.

It must be remembered that thepropeller hydrodynamic forcesand moments are predictedfor the zero rudder conditiononly and often at one vesseldraught condition. When thevessel turns or operates indifferent ballast conditions, thepropeller hydrodynamic forcesand moments can changesignificantly due to wake fieldvariations. This causes the centreof propeller thrust to move fromits predicted position, therebyinvalidating the values assumedin the calculations.

We have recently amended ourshaft alignment Rules (Part 5,Chapter 8, Section 5) to requirea sufficient static load onthe sterntube forward bearingto prevent it from unloadingin all operating conditions,including the transientconditions experiencedduring manoeuvring turns.

The amended Rules alsointroduce formal requirementsfor bearing load measurementsto be performed at theverification stage of thealignment process.

When applied to containervessels, this will mean thatshipyards will need to conductjack-up load tests on thesterntube forward bearing, allthe plummer bearings and theaft three main engine bearingsat acceptance sea trials.

Final adjustments to theplummer bearing height willbe made, where necessary, tooptimise the alignment. Thefinal bearing load measurementsrequired by Lloyd’s Register areto be conducted in a sailingdraught condition, with theengine warmed through in orderto minimise the uncertaintiesof hull deflections, machinerythermal rise and propellerbuoyancy effects.

For further information contact Daniel Legg, Senior Surveyor, Engineering Systems, London Design Support Services, Lloyd’s Register EMEAE [email protected] T +44 (0)20 7423 1757 F +44 (0)20 7423 1824

Overheating damage at aft end of sterntube aft bearing on

a 2,000 teu container ship.



Lloyd’s Register and the StandardP&I Club have published A Master’sGuide to Container Securing. Thebook is the fifth in the Master'sGuide series by Standard P&I andthe second produced in associationwith Lloyd's Register.

As the guide says, “In the earlydays of containerised transport,ships carried containers stowed onhatch covers, three or four high. Avariety of lashing systems were inuse. However, the most reliablesystem consisted of stacking cones,twistlocks, lashing bars, bridgefittings and turnbuckles (bottlescrews). These systems wereeffective in lashing containerscarried on deck to the third tier.

“Today, ships are bigger and apost-panamax container ship willcarry containers on deck stackedup to six, seven or eight tiers high.However, while the ships are ableto carry containers stacked higher,the lashing systems are still onlycapable of lashing to the bottomof the third tier containers or thebottom of the fourth or fifthcontainer tiers when a lashingbridge is fitted. Ship design hasdeveloped but container lashingsystems have not.”

The book is intended to helpmasters and seafarers tounderstand the principles ofcontainer securing, to describethe various securing methods andthe fixtures and fittings whichare used, to describe commoncauses of lashing failure and tooffer advice on how losses can beminimised. The guide is designedto be as readable as possible.

The intention is that a copy will beavailable on-board every containership which is classed with Lloyd'sRegister. Similarly, Standard P&Iwill be distributing the guide totheir members.

The previous four publications inthe Master’s Guide series are:

� A Master’s Guide to Ships' Piping

� A Master’s Guide to Berthing � A Master’s Guide to Hatch

Cover Maintenance (in collaboration with Lloyd's Register)

� A Master’s Guide to Accident Response.

A Master’s Guide to ContainerSecuring may be viewed on theLloyd’s Register website atwww.lr.org. To obtain a copy,please contact your local Lloyd’sRegister Group office.

Lloyd’s Register and Standard P&I Clubpublish container securing guidance

A Master’s Guide to Container Securing aims toprovide masters and seafarers with best practiceguidance on how to safely stow and lash containersinto place to help prevent injury and loss.

Container ship design has

advanced, but container lashing

systems have not necessarily

kept pace.

A Master’s Guide to Container

Securing provides masters and

seafarers with guidance and

advice on container lashing.

CRC notation – The way forward


Owners and operators are beingpushed by charterers to carry everincreasing numbers of standardintegral refrigerated containersonboard their ships. The inability tocarry these refrigerated containersas hold cargo has been one of themain stumbling blocks to the idealsituation of total containerflexibility. Historically, the holdcarriage of refrigerated containerswas limited to specialist thermallyinsulated ‘port-hole’ containers orthose fitted with a non-standardwater-cooled condenser in additionto the normal air-cooled condenser.

As a result, devising a means ofcarrying refrigerated containersbelow deck, with their self-contained refrigeration systems inoperation, became a priority.Towards this end, Lloyd’s Registerdeveloped our Rules for theCarriage of Refrigerated Containersin Holds (CRCH Rules) in 2000.They were published as ‘Notice No.2’ of the July 2000 edition of theRules and Regulations for theClassification of Ships and werethen included as Part 7, Chapter 10of the July 2001 edition of theRules for ships.

The feedback obtained from bothshipyards and owners was that theLloyd’s Register CRCH Rules did notadequately cover the following:

1. hold ventilation systems other than a ducted exhaust type

2. refrigerated container plug-in sockets and their associated electrical supply system

3. refrigerated containers with water-cooled condensers

4. deck-stowed refrigerated containers and the effects of waste heat dissipation.

In response to these comments,we have developed Rules for thecarriage of refrigerated containers(CRC Rules).

CRC notationIt was proposed that the originalCRCH Rules be completely revisedto embrace the above issuesand also be revised to take intoconsideration knowledge gainedduring subsequent discussionswith owners, operators, charterersand shipyards.

It was also proposed that theCRC Rules needed to allow anappropriate notation to be appliedto any ship which has the facilityto carry refrigerated containers.

The notation additionallydifferentiates between hold-stowed refrigerated containersand those stowed on deck. Furtherdescriptive notations cover itemssuch as cargo storage regimes(such as chilled and frozen) andthe amount of electrical powerdedicated to container plug-inpoints.

Assigning the CRC notationindicates that the design,installation and testing of thehold ventilation system achievesa satisfactory standard to allowthe carriage of a specifiednumber of integral refrigeratedcontainers below deck. The Rulesare based on the philosophythat it is advantageous to allowthe shipyard’s ventilation systemdesigner to submit a proposalwithout having to comply withprescriptive regulations, specifictemperature limitations or airflowrequirements. However, guidanceair flow values are provided.

Thus, the type of ventilation systemproposed and its design, includingaspects such as ductwork sizing, fansizing, maximum air velocity, holdspace temperature limitations andair sealing arrangements, are theprerogative of the system designer.

Previous to the development of our CRC Rules, refrigerated containers

carried on deck could not be assigned a dedicated notation.

Lloyd’s Register has developed a new set of Rules forrefrigerated containers which enables owners andoperators to carry refrigerated containers below andon deck – and to give charterers confidence that thiscan be done without risk to their cargoes.


Lloyd’s Register’s heat flowmodelDuring operation, a container’sintegral refrigeration unit removesthe total container heat load made up of the following: heatgenerated by the respiration ofthe cargo, heat transferred acrossthe container’s boundary, heatcarried in infiltration and air-refreshing air and heat generatedby internal electrical equipmentsuch as evaporator fan motors.This heat is transferred by therefrigerant and rejected throughthe container’s condenser to theatmosphere. When a number ofcontainers are located in the samehold, the temperature inside thehold can increase significantly,adversely affecting the efficiencyof the refrigeration units and theirability to maintain the containers’internal temperatures. If sufficientfresh air is circulated through thehold, the temperature of the airin the hold can be maintainedwithin acceptable limits.

To adequately assess all these heatloads and the interaction betweenthe various refrigerated containersin a cargo hold for the purposes ofwriting the new CRC Rules, Lloyd'sRegister created a macro-volumemodel (MVM), which focuses onthe bulk movement of heat. Thisbulk movement is referred to asthe ‘reefer heat flow’. As thecontainer refrigeration units areoperational before loading, andtheir operation is quasi-steady overthe duration of a voyage, the heatflow is assessed under steady-stateconditions.

The MVM was created in aspreadsheet to assess the heatbalance for a container ship’s hold,to enable us to appraise proposedventilation systems. The modelcan simulate any ISO arrangementof reefers, at a variety of cargotemperatures (see Table 1), andreturns a value of ambient airflow required to maintain atarget temperature in the hold.

Modelling has been undertakenon existing ships to verify theprogram, and this has shown thatthe guidance air flow values givenin the CRC Rules are conservative.The model considers each holdseparately, and the hold input dataincludes number of rows, numberof tiers, refrigerated containerslots, non-refrigerated slots andvoid areas such as fuel tanks.For each slot, the model can showthe effect of carrying, not onlycontainers having differenttemperatures, but also differentcargoes. Other aspects such asthe effects of carrying emptycontainers can also be modelled.

Giving confidenceThe development of the CRC Rulesnow allows owners whose shipshave the ability to carry refrigeratedcontainers to demonstrate thatthe facilities provided achievecertain design criteria. This willallow charterers to have confidencein the ship’s ability to carry theirvaluable refrigerated cargo in asatisfactory and safe manner. Thehistoric view that it is not possibleto transport refrigerated containersin enclosed holds has now beendiscredited. We now have theability to verify the amount ofventilation required to ensure theeffective carriage of refrigeratedcargoes. We believe that our reeferheat flow model has the ability tonot only determine air flowrequirements but also the resultinghold space temperatures.

For further information contact Robbie Sillars, Senior Surveyor, Engineering Systems,London Design Support ServicesE [email protected] +44 (0)20 7423 1921F +44 (0)20 7423 1824

Is this the ‘new’ reefer ship?

Name Temperature ºC‘Banana’ 13.0‘Chill’ 2.0‘Frozen’ -18.0‘Deep Frozen’ -29.0

Table 1 – Cargo containerset temperatures



Mandatory requirements for strength oftowing and mooring equipment on new ships

“A new regulation on towing and

mooring equipment has been added

to SOLAS.”

The new regulation 3-8, “Towingand mooring equipment”, has beenadded to SOLAS Chapter II-1, PartA-1. The regulation reads:

1. This regulation applies to ships constructed on or after 1st January, 2007, but does not apply to emergency towing arrangements provided in accordance with regulation 3-4.

2. Ships shall be provided with arrangements, equipment and fittings of sufficient safe working load to enable thesafe conduct of all towing and mooring operations associated with the normal operation of the ship.

3. Arrangements, equipment and fittings provided in accordance with paragraph 2 shall meetthe appropriate requirementsof the Administration or an organization recognized bythe Administration under regulation I/6.*

4. Each fitting or item ofequipment provided under thisregulation shall be clearly markedwith any restrictions associatedwith its safe operation, takinginto account the strength of itsattachment to the ship’s structure.

In addition to this amendmentto SOLAS, the InternationalAssociation of ClassificationSocieties (IACS) has developed andissued a second revision to UnifiedRequirement (UR) A2 and a newUnified Interpretation (UI) SC212.Copies of UR A2 and UI SC212 maybe downloaded from the IACSwebsite (www.iacs.org.uk).

The requirements specify thestrength of the towing andmooring equipment to be suppliedand give criteria for the designand approval of associated supportstructure. These new requirementsare applicable to new ships ofall types and sizes which areconstructed on or after January 1,2007. They apply to continuationsof existing series, even if the leadship was built before this date.

Currently, for ships under 90 metresLloyd’s Register’s Rules specify theminimum number, length andstrength of mooring lines. Towlinesare not required for classification,but details are given in the Rulesfor guidance.

Ships greater than 90 metres inlength do not require towlines andmooring lines as a classificationitem; however, guidance is given inthe Rules.

Container shipsOf particular note with regard tocontainer ships is the EquipmentNumeral used for establishing thestrength of towing and mooringequipment. This numeral must takeinto account the profile area of anycargo carried on deck. This is achange from the current method,which excludes deck cargo from thecalculation. It is anticipated that thiswill have the effect of increasingthe equipment numeral by onestep, irrespective of ship size. Therewill be exceptions where a greateror zero increase in the numeral willresult, but for most new containerships, there will be an increase inthe required strength, length andnumber of mooring lines over andabove the minimum basic standardcurrently recommended by class.

The new regulations also definerequirements for the design andstrength of shipboard fittings(including bollards and bitts,fairleads, stand rollers and chocks)and supporting hull structure.

Our Rules and Regulations for theClassification of Ships are currentlybeing amended to incorporate theabove amendments.

*Refers to MSC/Circ 1175, Guidance

on shipboard towing and mooring

equipment (available as a download

from www.imo.org).

A new regulation, “Towing and mooringequipment”, has been added to SOLAS.


For further information contact Sue Rutherford, Technology Manager,Research and Development, Lloyd's RegisterE [email protected] T +44 (0)20 7423 2538 F +44 (0)20 7423 2061

Lloyd’s Register’s Structural DesignAssessment (SDA) and ConstructionMonitoring (CM) procedures aremandatory for container shipswith a beam of panamax size orgreater and for other containerships of abnormal hull form, or ofunusual structural configurationor complexity.

In May 2006 a new version of theSDA procedure was released toprovide guidance on the directcalculation methods to be appliedto a number of new features whichare being used in the design andbuild of the latest container ships,principally the positioning of fueloil tanks within the cargo holds,driven by the introduction ofMARPOL Annex 1, Regulation 12A.

Positioning the fuel oil tanks withinthe cargo holds can have asignificant effect on the distributionof stress within the hull of acontainer ship, particularly whenthe ship is subjected to torsionalloads such as those produced byuneven distributions of cargo,ballast water and fuel and by thetwisting of the hull in oblique seas.For a ‘conventional’ container ship,the cargo hold region is generallyU-shaped in section and the centreof twist – which is close to the shearcentre – is about D/2 below thebaseline. For a closed section, suchas the engine room and at theforward end, the centre of twist iswithin the ship, at about D/2 abovethe baseline.

When a ship twists, warping (foreand aft) stresses are generated andthese are resisted partly by shearforces in the transverse bulkheadtopside structure – principally atupper deck level. This effect isquite small because the bulkheadsare slender.

However, the introduction oftanks within the cargo holds hasa big effect – they increase theenclosed area of the hull cross-section and therefore increasethe St Venant torsional stiffness.The centre of twist of the hullmoves up sharply into the hull inthe region of the tanks, and theentire stress distribution withinthe hull is changed.

In addition, the ‘hard spots’ createdat the ends of the fuel tanks, atthe top of the tanks, must beexamined carefully to ensure thatthe design will perform effectively– leakage due to cracks at thispoint could lead to fuel oil ingressinto the cargo holds.

All of these aspects, and the localstrength issues associated withsuch arrangements, are addressedin the new procedure. The newprocedure also includes a revised,simplified method of fatigueassessment for hatch corners,which recognises the benefit ofhigh-tensile steel on the fatigueperformance of unwelded material.This has been introduced as a resultof Lloyd's Register's on-goingprogrammes of fatigue assessmentand testing.

The new ShipRight SDA procedurecan be accessed from ClassDirectLive (www.cdlive.lr.org).

New ShipRight procedure for containerships helps to assess hull stresses

Lloyd’s Register’s has published a newShipRight procedure for the StructuralDesign Assessment of container ships.

A new SDA procedure for container

ships is supported by software.

ShipRight SDA software provides support

Lloyd’s Register ShipRight SDA software has been developed to support

the application of the SDA procedure. The software is designed to

interface with shipbuilders’ own systems and provides load generation

and post-processing of stress and buckling results which are

automatically assessed against the SDA criteria.

Key features include:� ship modelling – users can create a ship model using the software or

work with models imported from CAD systems or in NASTRAN format� automatic generation of many of the SDA load components – for

example, to identify a tank within the finite-element model, all that is

required is a single reference point anywhere within the tank. The

software identifies the tank boundaries and automatically applies

pressure loading as appropriate� automatic wave balancing – when assessing the structural strength of

a large container ship it is necessary to model the entire ship and

balance it on a wave profile. Our ShipRight SDA software can

automatically adjust draught and trim to achieve equilibrium.

Additionally, the wave height can be adjusted to achieve the required

bending moment value at midships.� automatic loading of fine mesh models and transfer of boundary

deflections obtained from the full ship model� automatic stress assessment against the SDA or user-defined criteria� automatic panel buckling calculations and assessment� automatic report generation in Word format.

For further information on our marine services relating to thecontainer ship sector, please contact

David Tozer, Business Manager– Container Ships: T +44 (0)20 7423 1562F +44 (0)20 7423 2213E [email protected]

Container Ship Focus is produced by Marine Business Development.Lay-out by theclubb design consultants.Care is taken to ensure that the information in Container Ship Focus isaccurate and up to date. However, Lloyd’s Register accepts no responsibilityfor inaccuracies in, or changes to such information.

Managing Editor: Dolly RobinsonMarine Media ManagerT +44 (0)20 7423 1682E [email protected]


Lloyd’s Register EMEAT + 44 (0)20 7709 9166F + 44 (0)20 7423 2057E [email protected]

71 Fenchurch StreetLondon EC3M 4BS, UK

Lloyd’s Register AsiaT + 852 2287 9333F + 852 2526 2921E [email protected]

Suite 3501 China Merchants TowerShun Tak Centre 168–200 Connaught Road CentralHong Kong, SAR of PRC

Lloyd’s Register Americas, Inc.T +1 (1)281 675 3100F +1 (1)281 675 3139E [email protected]

1401 Enclave Parkway, Suite 200Houston, Texas, 77077, USA

www.lr.org

November 2006

Services are provided by members of the Lloyd’s Register Group. Lloyd’s Register, Lloyd’s Register EMEA and Lloyd’s Register Asia are exempt charities under the UK Charities Act 1993.

CONTAINER SHIP FOCUS

Horizons

Horizons is our quarterly

technical publication for

the marine industry. Topics

recently covered include:

• revisions to MARPOL Annex I• improving Port State Control

performance• a profile of leading ship

operator Teekay Shipping.

Horizons includes regularfeatures on:

• legislative developments• the latest in ship technology• recent deliveries to Lloyd's

Register class• forthcoming exhibitions and

technical papers.

Horizons can be downloadedfrom our web sites (www.lr.organd www.cdlive.lr.org). If youwould like to receive a hard copy,please contact:

Adele WilliamsLloyd’s Register71 Fenchurch StreetLondon EC3M 4BS, UKT +44 (0)20 7423 2309F +44 (0)20 7423 2213E [email protected]

UpcomingconferencesLloyd’s Register will be

presenting at the following

container ship conferences

in the upcoming months:

RINA Design & Operation ofContainer Ships, November22-23, 2006, London, UK

“Development ofrequirements to safeguard large container ships from the effects of bow flare slamming”, Ling Zhu, Lloyd’s

Register

“Energy prices andcontainer shipping”,Andrew Penfold, Director,Ocean Shipping ConsultantsLtd and David Tozer,Business Manager – Container Ships, Lloyd’s Register

“Design of container shipsfor safer securing andaccess”, Brian SherwoodJones and Roland Ives,Lloyd’s Reigster and RoySmith, Hutchinson Ports

Boxship 2006, December 5-6, 2006, Shanghai, PRC

“Impact of bunker prices oncontainer ship design”,David Tozer, BusinessManager – Container Ships,Lloyd’s Register and AndrewPenfold, Director, OceanShipping Consultants Ltd

“Container ship propulsionefficiency enhancement”,John Carlton, Head ofTechnology andInvestigations, Lloyd’sRegister

• Changes to the Rules andRegulations for the Classificationof Ships, 2006 – Part 1: TheRegulations (Applicable to allLloyd’s Register-classed ships)

• Changes to the Rules andRegulations for the Classificationof Ships, 2006 - Part 1: TheRegulations (Applicable toESP ships)

• Removal of redundant, expiredor replaced certificates fromships' files

• EU Sulphur Regulationsapplicable to passenger ships onregular services in EU waters

• Daniamant Rescue Dan Mand Rescue Dan W lifejacketlights replacement

• Canada introduces newmandatory ballast waterregulations.

Classification News is availablefree of charge. These issues,together with the archiveof alerts, may be viewedelectronically at www.cdlive.lr.org

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Llyod's Register Container Ship Focus

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