ITS 2016 Boston - Tugconomy paper

7/25/2019 ITS 2016 Boston - Tugconomy paper

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DayPaper

BOSTONOrganised by The ABR Company Ltd

INTRODUCTIONFloating LNG (FLNG) projects rank among the mostcomplex and prestigious marine greeneld operationsworldwide. Seven FLNG import/export terminals arecurrently approved and under construction globally,with an additional six approved (but not yet under

construction) on the US East coast and Gulf ofMexico. Twenty-two additional export-only terminalsare in various stages of development. LNG is rapidlydeveloping into an energy commodity independent fromoffshore oil. Even if a strong correlation between oiland gas prices persists and only 20 per cent of theseprojects prove to be economically feasible, this wouldmean eight to 10 LNG terminal projects going ahead inthe foreseeable future, in the US and Canada alone.

Hazard and risk assessments on greeneld marineLNG operations demand a structured front-end

development cycle, including assessment of towageservices. Such development cycles should preferablybe conducted in a transparent manner and providestakeholders with multiple options and towagesolutions. Extending the development cycle to includenon-normal operations, as well as studying different tugconcepts in competition, truly provides an as low asreasonable and practicable (ALARP) towage service.

Developing a towage service at an FLNG greeneldsite is usually considered to come within the scopeof such an operations hazard and risk assessment.

Development teams for greeneld operations generallyaim at a pre-dened service level, with ALARP risklevels. Evaluating the required performance space1and bollard pull (as a subset of the performance space)

associated with such risk levels involves multiple parties and just as many disciplines.

The design process is essentially a socialundertaking, where multiple parties, pooling theircumulative knowledge and experience, engage in an

engineering process. For example, port developersgenerally have the means and software capability tooptimise aspects such as bathymetry in port lay-outs,yet developing towage services is often considered atthe back end of such engineering studies. Includingtowage services development at a late stage tends tolimit design solutions to the scope of normal operationsonly, while tug design concepts are over-inuenced bythe past experiences both positive and negative ofinvolved parties.

Including the development of towage services at an

early stage enables synergies between infrastructureand towage service development. Efcient applicationof available knowledge and resources at the earlydevelopment phase, dening the required performancespace, releases resources in the later stage toinclude non-normal operations and create non-biasedcomparative studies between tug concepts to nd theALARP towage solution.

PERFORMANCE MATTERSTugboats are a tool at the pilots disposal. Pilots requirea tug to provide a vector within a reasonable framework

of time or response. How much of a force vector, orwhat is considered a reasonable timeframe, is largely asubjective matter. Industry consensus suggests a fastervector response corresponds with a reduced vector

Tugconomy: A New Approach to Value-Based Towage

SYNOPSISTugconomy is a concept that describes a structured value-for-money framework for determiningperformance space requirements for greeneld marine operations. Tugconomy aims to excludebiases, both positive and negative, in order to provide operators and other stakeholders in

greeneld developments with a transparent development cycle. Studying different tug conceptsin competition during the development cycle, and including non-normal operations in theprocess, will provide all stakeholders with a consensus on the ALARP towage solution for theirprospective projects.

Marinus Jansen (speaker/author), Rotortug BV, the Netherlands

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requirement, but quantifying one or the other mainlyrelates to what technology is available and whether itmeets the functional requirements, rather than the otherway around: what is the functional requirement andwhat technologies are available to meet this?

A tugboats principal purpose is to provide pilotswith additional controllability of the assisted vessel.The extent of the required controllability dependson predetermined operating windows, infrastructure

layouts, typical assisted vessels and risk policy forharbour areas because how safe is safe enough?What does that really mean and safe enough forwhom? What kind of procedures need to be consideredin case of non-normal operations?

Multiple views from various stakeholders can beexpressed within the safety frame of operations: shipowners, regulatory bodies, terminal operators, thoseinvolved in tug (crew) safety. Generating consensusbetween stakeholders involves nding the sweet spotbetween available technology, operating psychology

and economics. Finding this sweet spot is whatTugconomy is all about.

Tugconomy is a concept about value for moneyfor stakeholders in, and related to, towage services.It is about nding towage solutions without a bias,based on previous experiences, both good and bad.Tugconomy believes in always looking for bettersolutions and making efcient and effective use ofresources. It is about taking into account the operationalprole of a tug: intended application and operations,asset lifecycles, contract term expirations and so on.Tugconomy is about transparency and reproducibilityand therefore stands at the very basis of any towagesystems functional requirements.

CASE STUDY: GREENFIELD FLNGBollard pull is any tugs primary performance indicatorand a subset of tugs respective performance space.Determining total bollard pull required to control anLNG carrier or other assisted vessel is often subject todiscussion, with as many opinions as there are experts.Tugconomy discards opinions, instead enabling a multi-tiered, transparent approach, enabling and includingexpert views at every tier.

Tier I static analysis is a static desktopspreadsheet calculation on the basis of the OCIMF (OilCompanies International Marine Forum) and SIGGTO(Society of International Gas Tanker and TerminalOperators) methodology2+20 per cent3. Alternatively,other methods can be applied to determine wind4,current5and wave6forces nding guidance in dynamicpositioning methodology and literature. At this stage,the main focus is a static situation where the assistedvessel is controlled during a berthing manoeuvre.

With a listed serviceability interval of the marineoperation and MET dataset, this enables anyone toestablish a basic tug requirement. At the very basis ofa tugs functional requirement is the static performance

parameter: bollard pull. Tug deployment can beconsidered with equally powerful tugs on a number ofpositions with applicable impinged jet losses7securing acontrolled berthing approach.

Tier II dynamic analysis includes ship dynamics inthe horizontal plane. Whereas tier I provides an outlinerequirement presuming a dead assisted vessel, tier IIincludes an assisted vessels inherent manoeuvrabilityand controllability from propellers, rudders and bow

thrusters. Tier II analysis includes a range of scenarioswith wind elds, variable currents and banking effectsto create an understanding of required tug performancespace during the full harbour approach.

Fast-time simulation tools can run many scenarioswithin the tier II analysis scope. Fast-time simulationprograms MARIN Shipma (version 7.0) and others(Figure 1) enable identication of benchmarkscenarios within a harbour or terminal operatingwindow. Such programs are often considered duringport developments, especially in relation to developing

layouts and bathymetry. Applying these programs todevelop effective performance space and functional tugrequirement is an underappreciated application of fast-time simulation, and enables effective use of Tier III real-time simulation time and resources.

Figure 1: MARIN SHIPMA ow diagram

RISK ANALYSIS AND HAZARD

IDENTIFICATIONAcceptable risk is a key criterion in any professionalhazard identication and risk analysis. A reasonablesub-question would be: Acceptable to whom? Mostrisk analysis includes (maximum) likelihood andconsequence matrices. Within this paper we will focuson operational risks in relation to a greeneld LNGterminal project, yet the principle can be applied to arange of marine operations (Table 1, opposite).

A failure is here dened as a condition of non-serviceability of the operation. Within this scope,

environmental conditions and/or loads can exceedthe towage service capability (Figure 2, opposite),prompting a suspension of marine operations. Threetypes of failures can be identied in this manner, where


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respective consequence ratings are self-evident. Theextent to which a temporary suspension of serviceis acceptable must always be subject to a terminalsoperator risk policy.

Figure 2: Towage service capability

ACCEPTABLE RISK POLICYAcceptable risk is a comparative measure. FMEAC(failure mode, effects and criticality) analysis shouldultimately benet the decision-making process in thedevelopment phase of marine greeneld operations. Howdoes one technology or tug concept compare to the otherand what details in tug design can benet operationalsafety? Creating value, by identifying key areas whereadditional capital investment and operating expensesprovide value for money, appeals to decision-makers.

Some failure modes can be mitigated by proceduralmeans. That is why you want to deal with expert

operators in their eld, and why there is an increasingfocus on operator QHSE (quality, health, safety,environment) qualications, and risk awareness andassociated skill-levels among crews. Some hazardsand risks cannot be fully excluded because they are,by their very nature, beyond our control, but we canprocure t-for-purpose tugs designed to provide crewswith the tools to mitigate the consequences of this typeof failure.

ALARP is a term often used in the towage industry,

underlying the comparative nature of technologiesand procedures deployed in the eld. Within thisframework, Tugconomy appeals to the reasonablenessand practicability of towage solutions. But perhaps theprincipal underlying questions are: acceptable risk towhom, and what are my options?

PsychologyTechnology

Economics

Figure 3: Technology, economics and psychology

Decision-making involves combining the above

disciplines (Figure 3)into acceptable towage solutions

ie, those providing the most effective vectors andleverage to assisted vessels in a practicable manner.Maximising berth availability, minimising operationaldelays, securing safe work conditions and providing

KEYVery Low:Acceptable level of risk.

Further analyses not needed.

Low: Acceptable level of risk

Medium:Represents a manageable

level of risk. Controls required,

implemented and veried.

High:Extensive risk controls must be

immediately implemented.

Very High:Stop activities unless risk

controls have been implemented and

the risk is reduced to a lower level.

Table 1: Example likelihood and consequence matrix

T

T

T

Reversible, excess windage

Non-reversible, allision with

terminal

Reversible, after repairs:

towline failure


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a cost-effective towage service capability, includingmarketable assets (tugs) should be an integralpart of infrastructure developments considering atowage service.

TUGCONOMYWithin the framework of Tugconomy, the question iswhether better solutions are available and, if so, to whatextent are they practicable? The Tugconomy conceptapplies both to individual technologies and sub-systemdesigns, and includes tug concepts and designs, aswell as procedures designed to successfully deploytugs and react to unexpected events.

But Tugconomy is also about economics, with costbreakdowns where crew expenses are a substantialpart of an operators cost base. Such a cost base, andhigh-powered engines, inevitably create a drive forfewer, but more powerful, tugs consequently alteringthe towage operation/tug deployment and the towageservice failure modes.

Creating public support for terminal and/or portinfrastructure developments requires a structured andtransparent approach to how we go about managingnavigational risks in marine operations. The psychologyof a marine operation involves all stakeholders, rangingfrom the not-in-my-back-yard neighbours to crews and associated unions operating in front of a ULCCat 8 knots, and US EPA-required additional emissionscontrols for engines >2,000kW. In towage terms, thatmeans any tug of more than 60 tonnes BP. Exploringand comparing multiple tug concepts appears to bea sensible and transparent approach to covering

these liabilities.

In particular, greeneld LNG developments favour thisunbiased approach to determining towage requirementsand dene both the functional requirements andtechnology meeting those requirements. Tugs oftenprovide myriad functional requirements within thewider QHSE scope, with a differentiation between theprimary navigation risks and, for example, re-ghting,stand-by or oil pollution prevention. Within the scope

of Tugconomy, all such functional requirements areaddressed and weighted providing competitive andeffective support services.

TIER III A TOUCH OF ELEGANCEIdentifying performance space requirements andbenchmark scenarios in tier II fast-time simulations8enables effective use of tier III real-time resources.Real-time simulations can take 2hrs/run involvinga team of marine pilots and tug masters, often in aconsultancy capacity. Considering one weeks testingamounts to 16-20 runs to test a range of scenarios,resources are limited indeed. Running tier I desktopand tier II fast-time simulation prior to such simulationsensures key benchmark performance scenarios areidentied beforehand, and non-normal operations canbe considered.

Real-time simulations are where the human elementcomes into the equation. Anticipating manoeuvres,there is a lot to say in favour of including human skill-levels in that equation. Real-time simulations also

enable you to include non-normal operations as anadditional layer of complexity, and to compare suitabilityof tug concepts for your operation.

Tugconomy is about zeroing in on your towagesolution, increasingly dening and rening theboundaries of a tugs performance space for ship and/or tug-handling concepts. Marine pilots require vectors,but act with caution in case of vector tugs. Vectorresponse and jet-impinged thrust phenomena aretricky to grasp at best. Jet-impinged thrust losses, frompropeller wash impinging on the assisted vessels, can

range from 23-62 per cent9

.

Auditing the simulation centres beforehand to ensurethat such physics phenomena are included appearsto be a sensible approach. Auditing subcontractorsand suppliers is becoming an increasingly commonphenomenon among global operators. Includingsimulation requirements to provide and include newtug concepts in their portfolio is a straightforward policywhich any simulation software provider can endorse.

Tier 1 SIGGTO/OCIMF

Tier 2 Fast-time simulations

Tier 3 Real-time simulations, human factors

Non-normal operations

Towage solution

Assisted vessel, Basic MET conditions,

Basic Bathymetry, Serviceability level

Scenario-driven

Figure 4: Towage in port development


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NON-NORMAL OPERATIONSLimited resources, or more specically available runs,restrict the number of non-normal operations andassociated procedural actions to be explored. Non-normal operations can be distinguished between generalfailures, such as towline failures, and total blackouts.Both can be mitigated by either split/double drums, orturning around, using another winch (Rotortug) or using24V back-up systems. There really is no differential withregard to tug concepts in these circumstances, or it is adifferential that can be successfully simulated.

The other types of failure consider the tugs orassisted vessels propulsion and steering system.Considering two tug concepts to create a comparativeanalysis further reduces the available runs to about fouror ve per tug concept. The following list of scenariosshould be considered as a minimum: Loss of steering assisted vessel. Loss of propulsion assisted vessel. Temporary (5 mins) loss of propulsion unit on centre-

lead fore tug.

Temporary (5 mins) loss of propulsion unit on centre-lead aft tug.

Pursuing ALARP risk levels should by all means

include an analysis of different tug concepts. RotortugBV, the technical marketing company dedicated to thedevelopment of the Rotortug concept, has suppliedtug design and trial data to a range of simulatorsoftware suppliers as a policy for a number of years10.Within this scope, the key issue is whether you canafford not to review alternative tug concepts, and howthese might mitigate hazards in a marine operation.

Note: Tugconomy is not just about incorporating thetriple Z-drive Rotortug in the aforementioned analysis.Other concepts, such as SDMs, are out there andavailable and these successfully meet their intendeddesign criteria. However, some of these concepts maylack versatility with regard to their intended applicationand long-term operation after contract expiration.

CONCLUSIONDeveloping towage service functional requirementsincludes many different stakeholders with as many

interests. Acknowledging that port developmentincludes social engineering (and design, by its verynature, is a social process) and requires a transparentand unbiased approach to stakeholders. Such bias canbe mitigated only by having multiple technologies andtug concepts acting in competition, within the scope of amarine operations development.

Within this framework, Tugconomy involvesa transparent design cycle, establishing a rmperformance space requirement and including non-normal operations during the front-end developmentphase thereby providing greeneld marine operations

with a cost-effective and ALARP towage solution.Expert opinions alone are not sufcient to alignstakeholder interests and mitigate an operators liability.Tugconomy provides a framework model to establish

secure greeneld developments and quantify expertviews while excluding human operator bias.

FOOTNOTES1All tugs have a fully-developed theoretical performance

space, indicating their respective towing capability,

Performance Matters A Case Study, Marinus Jansen,

Tugnology 15, London

2Mooring Equipment Guidelines, 3rd edition, OCIMF, 2013

3Tug Use in Port a practical guide, Hensen, NauticalInstitute, 1997

4DNV-RP-C205: Environmental conditions and

environmental loads, October 2010

5Modifed strip-theory

6Sea Loads on Ships and Offshore Structures, Faltinsen, OM,

Cambridge University Press, 1990

7,9SafeTug Offshore berthing operability methodology,

MARIN, January 2008

8eg, MARIN SHIPMA programme

10Force Technology: Tackling the Rotortug challenge, Jesper

Nielsen, International Harbour Masters Congress 2012


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ITS 2016 Boston - Tugconomy paper