71
1 INTRODUCTION
Security and Maritime Safety is a very important
factor to support marine transportion and prevent
accidents where the establishment of shipping lanes
are intended to ensure the security and safety of
navigation by providing a route for ships sailing
through the waters, followed by tagging for
navigational hazards. Implementation shipping
routes which includes the progra
m, structuring,
development,operationandmaintenanceisintended
to be able to provide services and guidance to the
parties in the marine transportation services to
attention to the capacity and capability groove
associatedwiththeweightoftheshipgoingthrough
that route in order to sail safely, smooth and
comfortable.
Risk Analysis on Ship Wreck and Container Cargo to
Ship Navigation
M.B.Zaman,T.Pitana,A.Iswantoro&W.D.Aryawan
SepuluhNopemberInstituteofTechnology,Surabaya,Indonesia
ABSTRACT:Wreckof ashipis anincident thatmust beavoided. Shipaccidents are generallycaused bya
severalcases,suchashumanerror,naturaldisaster,technicalerrors,missedcommunication,poorconditionof
theship,andmanymore.Shipwreckagehavehugeimpactforshipnavigation,environment,economics,and
others.Thoseimpacthavema
nydisadvantagesfortheshipowners,andalsoforenvironment.Forexamples the
fuelspillsthatpollutetheenvironment,makedisturbancetosailingshipbecausethetrackforthosenavigation
isblockedbytheshipwreckandtheircargoespeciallyonshallowlocat
ion(<50m).Theseresearchwilldiscuss
theeffectthecontainerwhenitisfloatsontheseaanditsinterferenceotherships.Themainobjectiveofthis
studyistopresentariskassessmentontheenvironmentalimpactofthewreckandcontainercargo.Wreckson
theseabedislikelytoposearisktopassingships.containerandit
scontentsaswellasthepossibilityofrefloat,
andalsotheirenvironmentalrisksemanatingfromthewreckandcontainercargo,suchasfuels,lubricants,and
chemicalcargo.Variationsscenarioisacollisionbetweenshipsthatpassbyfloatingcontainers.Thefrequency
ofrefloatingcontainer,andtheconsequencesofthepassingshipdependsonseveralfact
ors,whichwillbethe
subjectofresearch.However, because ofthefrequencyofrefloatingcontainersisunlikely,thentheriskislow
anddoesnotposeadangertonavigation.Theseriskassessmentusingriskma
trix5x5whichisthecombined
valueof thefrequencyandconsequences oftheincident.The resultsofthisstudy indicatethelevel ofrisk,
whether the risk is accepted, not accepted or received by considering the costs and benefits (ALARP). To
consequence, thereare twoparameters which energyis absorbed andthe penetra
tion occurs.The absorbed
energyisdividedintotwo,namelytheenergyabsorbedbyshipandtheenergyabsorbedbycontainers.Inthis
studyweretaken5groupsbasedonthesizeofthevessel.Inthiscasesany5sizegroupofvesselsisbasedon
thesizeoftheshipstha
tpassintheshippinglanesatthesiteofthesinking.Assumedthesevesselshavespeed
10knotsatthelocation.Aswellasspeeddriftingcontainershaving0to3knots.
http://www.transnav.eu
the International Journal
on Marine Navigation
and Safety of Sea Transportation
Volume 11
Number 1
March 2017
DOI:10.12716/1001.11.01.07
72
According to H. Landquist research in 2013,
shipwrecksdeteriorateandtheprobabilityofarelease
of oil increases with time on the sea floor. The
potentialleakageisarisktothemarineenvironment
andmayalsohavesocialandeconomicconsequences.
The purpose of this study was to evaluate
existing
methods for risk assessment of shipwrecks and
suggestagenericriskassessment framework.Arisk
assessment is necessary for providing decision
supportonremediationactionsandthusenablingan
efficient use of available resources. Existing risk
assessment methodsaimed for assessingshipwrecks
wereevaluatedbycomparisontorelevantparts
ofan
international standard on risk management. The
comparison showed that existing methods lack
several key components of risk assessment
procedures.Noneoftheevaluatedmethodsprovidea
comprehensive risk assessment for potentially
polluting shipwrecks and few take into account
uncertainty and sensitivity. Furthermore, there is a
needtodeveloprisk
assessmentmethodsconsidering
long‐termeffectsofcontinuousreleaseofoilintothe
marine environment. Finally, a generic
comprehensive framework for risk assessment of
shipwrecksissuggested.
(11)
Potentiallypollutingshipwreckscontainingoilor
otherhazardoussubstancesmayposeathreattothe
marine environment. This is a global problem and
many shipwrecks stemfrom the Second World War
and have been deteriorating on the sea floor since
then. Only in Swedish waters there are more than
2,700
wrecksthatwarrantfurtherinvestigationand31
of these are given a very high priority due to the
environmental threat they pose. These wrecks are
together estimated to contain between 1,000 and
15,000tonnesofbunkeroil.Everyshipwreckposesa
uniquethreatdependingon,forexample,thetypeof
vessel,
cause of sinking and environmental
preconditions. Currently, there is no comprehensive
methodforassessingtheenvironmentalriskposedby
shipwrecks and providing necessary support to
decision‐makers. The generic framework for risk
management of shipwrecks clearly shows the
importantsteps thatneed tobe performedand how
theyarelinked.
Italsoemphasizestheneedofproper
assessments to facilitate an efficient resource
allocation for these types of environmental threats.
The tool for probabilistic risk assessment of
shipwrecksenablesuncertaintyanalysisandisafirst
step towards a holistic risk assessment method for
shipwrecks.
(12)
Wreck of a ship is an incident that must be
avoided. Ship accidents are generally caused by a
several cases,such as humanerror, natural disaster,
technical errors, missed communication, poor
conditionoftheship,andmanymore.Shipwreckage
have huge impact for ship navigation, environment,
economics, and others.
Those impact have many
disadvantages for the shipowners, and also for
environment.Forexamplesthefuelspillsthatpollute
the environment, make disturbance to sailing ship
because thetrack for thosenavigation is blocked by
theshipwreckandtheircargoespeciallyonshallow
location(<50m).
(7)
2 ANALYSISOFSHIPWRECK
2.1 RiskAcceptanceCriteria
Risk acceptance criteriain the study are using Semi
QuantitativeAnalysiswithRiskAcceptance Criteria.
This study combines the probability and
consequences of an event based on the Risk
Acceptance Criteria. This protocol uses the Risk
Matrix5 x5to
determinethelevelofriskasshownin
Figure1Figure.Riskcategoriesoccurredareshownin
Table1.Thecriteriaprobabilityofoccurrenceandthe
consequences onthe shipare shown in Table2 and
Table3,respectively.
(9)
PROBABILITY
LEVEL1 1 2 3 4 5
LEVEL2 2 4 6 8 10
LEVEL3 3 6 9 12 15
LEVEL4 4 8 12 16 20
LEVEL5 5 10 15 20 25
LEVEL1 LEVEL2 LEVEL3 LEVEL4 LEVEL5
CONSEQUENCY
Figure1.RiskMatrix
The risk value of 1‐4 can be considered low and
acceptable, without further control mea s ures or
actions.Risk valueof 5‐9 canbe consideredALARP
(aslowasreasonablypossible)ifa ppropriatecontrol
measuresormitigationisimplemented.
Table1.DescriptionoftheRiskMatrix
_______________________________________________
Value Classification Description
_______________________________________________
1‐2SlightNoactionrequired
3‐4MinorNoadditionalcontrolmeasures
arerequired.Monitoringfor
changes
5‐9ModerateActionscanbeperformedunder
thesupervisionofaresponsible
person.
Mitigationisrequiredinorderto
qualifyasALARP
10‐14 HighActionscanbeperformed
afterthe
riskassessment.Mitigationis
requiredinordertoqualifyas
ALARP
15‐25 Intolerable Furthermitigationandrisk
assessmentarerequired
_______________________________________________
Table2.Thecriteriaprobabilityofoccurrence
_____________________
Level Description
_____________________
1Unlikely
2Rare
3Moderate
4Likely
5Mostlikely
_____________________
73
Table3.Theconsequencesontheship
_______________________________________________
LevelDescription
_______________________________________________
1 Nodamageto theshipandstructures
2 Minordamagetotheshipandstructures
3 Damageontheshipandstructures,shiprepair
required
4 Mayordamageontheshipandstructures,ship
repairrequired
5 Thedamageisveryserious,theshipmostly
damaged
_______________________________________________
2.2 FrequencyAnalysis
2.2.1 FrequencyAnalysisofPassing ShipCollidingwith
theWreck
The vessel was sunk on the sea bed in
approximately 70‐80 metres depth of water (sea in
Indonesia) while ships passing to the area
approximately having draught 6.4 metres (biggest
shippassingthe location).Thepossibility
of passing
ships colliding with the wreck is impossible.
Therefore, it is not necessary to conduct a risk
analysis.
2.2.2 FrequencyAnalysisofCollisionbetweenShipwith
Container
Apassing shipwill only collidewith acontainer
from the ship only if the container refloats from its
locationonthe
seabed,oronthewreck.Thecollisions
ilustrationisshowninFigure2.
The likelihood that a container would float free
and up from the wreck of the sunken vessel, is
unlikely(Level1).
All containers within the wreck and within the
location of the wreck site would now be fully
waterlogged (ie filled with water), in the process of
sinking within the seafloor and possibly in the
process ofbreaking upin the process. Thereforewe
canfirmlystate,thatthesunkencontainersfromthe
ship,wouldnotfloatfreeandthuswouldnotbecome
a hazard for shipping, therefore
the frequency
analysis of a collision between ship and container
below,isgenerallyonlyforinformationandguidance
on consequence should a collision had happened at
the time of sinking of the ship with the floating
containersandapassingship.
Figure2. Assumption of a collision between ships with
containers
Basedontheobservationsandsomeshipaccident,
therearesomepartsoftheshipcontainingtrappedair
(bubbles).Theonlylikelywayaircannowbetrapped
inacontainerisifthereisperishablecargowithinthe
container that decomposes, causing carbon dioxide
and other gases to accumulate within
the container.
Theaccumulationofthesegases,whicharelessdense
than seawater, may cause buoyancy if the air is
trappedwithinthecontainer. Itisveryunlikely that
there is any perishable cargo remaining within the
containerstobefurtherdecomposed.
Althoughunlikely,evenifairdidgetreleased
into
a container, it will be released through air vents; it
will not be trapped to the extent that it causes a
containertorefloat. Containersareweathertight,not
watertight, and therefore seawater has already
enteredthecontainersandfloodedthemanditisvery
unlikely that sufficient air can get
trapped within a
containertocauseittofloat.
Furthermore,giventhatthecontainerbindingsare
nickelplated andmuchstrongerthan thecontainers
themselves,itishighlyunlikelythatcorrosionofthe
bindings will be an issue before the containers
themselves corrode. Therefore there is very little
chanceof
thecontaineritselfcorrodingandbreaking
free of its binders and re‐floating. In any event, the
weightofthewaterabovethecontainermakesitvery
unlikelyforitfloatevenifitcorrodedawayfromits
bindings. As the container corrodes, the walls and
sides would collapse before the
container bindings
wouldeffectivelycorrode.Asitcollapses,thereisno
way it would float to the surface, as the container
wouldjustbreakapartandsinkintotheseafloor,ifit
hadnotalreadydoneso.
Thenegligibleriskisdemonstratedbythefactthat
except for containers
that remained afloat
immediately after sinking (and have now been
recovered), there has been no container that has re‐
floatedsincesinkingmorethan10monthsago.
BasedontheregulationofABS(AmericanBureau
of Shipping) and GL (Germanischer Lloyd), a
container must be certified before used to meet the
safety standards. Therefore, to obtain the certificate,
containersshouldperformaseriesoftestsinorderto
match with the classification standard. There are
manytests,buttherearenowatertighttest.However,
there is a weathertight test. Therefore, there are no
watertight containers so that when the container is
submerged in the water, the water will get into the
container.Thereforethecontainercannotfloatdueto
befilledwithseawater.
(1)(4)
In containers the corner post and locking bar,
which are of stronger material than the container
wallsandsides andthuswouldtakea muchlonger
time to corrode. Aluminum corrosion rate is 0.034
mm/year and steel corrosion rate is 0.1 ~ 0.17
mm/year.
So, the frequency of container floats
is unlikely
(Level1)andalmostcertainlythecaseinthisincident.
Therefore, based on the acceptance criteria of the
frequency of container float is currently on Level 1
whichisUnlikely.
74
2.3 ConsequencyAnalysis
2.3.1 ConsequencyAnalysisofCollision
Thecategoriesofaccidenti.e.acollisionbetweena
passingshipwiththewrecksorcargocontainers.This
couldcauseapassingshipbedamagedorleakageof
thehull.
2.3.2 ImpactEnergy
Impact energy that occurs when the collision
between ships
that pass with containers are as
follows.Thecollisionmarkedbyseveralparameters.
Thefollowingarethemainparametersthatinfluence
thelevelofdamage.
(5)
Structuralcharacteristicsofshipthatbumped.
Structuralcharacteristicsofcontainer.
Massofshipthatbumped.
Massofcontainerthatwashit.
Thespeedoftheshipthatbumped.
Speedofcontainersthatwashit.
Thedistancebetweenthewreckandthecontainer.
Locationofcollisionontheship.
Theillustrationwhenthecollisionoccurasshown
inFigure3.
Figure3.Theillustrationwhenthecollisionoccur
From the collision scenario above then we
obtainedanequationasfollowst:
2
12
1sin
22 1
MM M
Ek V
MM M
(1)
where:
ΔEk =absorbenergy
M1 =massofshipthatbumped.
M2 =massofcontainerorwrecksthatwashit.
V1 =Thespeedoftheshipthatbumped.
ΔM = additional mass coefficient of container or
wrecksthatwashit.
Basedonequation(1),the
absorbedenergybyship
and the absorbed energy by container are given in
Table6uptoTable9.
Table6.Theabsorbedenergybyship(containerspeedis0.5
knots)
_______________________________________________
Container AbsorbedEnergy(ton.knot
2
)
ShipA ShipB ShipC ShipD
_______________________________________________
C204.992 4.827 4.985 4.994
C403.496 3.415 3.493 3.497
CR202.248 2.215 2.247 2.249
CR403.122 3.057 3.119 3.123
_______________________________________________
Table7.Theabsorbedenergybyship(containerspeedis1
knot)
_______________________________________________
Container AbsorbedEnergy(ton.knot
2
)
ShipA ShipB ShipC ShipD
_______________________________________________
C2019.968 19.308 19.942 19.976
C4013.984 13.660 13.971 13.988
CR208.994 8.861 8.989 8.995
CR4012.488 12.230 12.478 12.491
_______________________________________________
Table8.Theabsorbedenergybyship(containerspeedis1.5
knots)
_______________________________________________
Container AbsorbedEnergy(ton.knot
2
)
ShipA ShipB ShipC ShipD
_______________________________________________
C2044.928 43.442 44.869 44.946
C4031.464 30.735 31.436 31.473
CR2020.236 19.937 20.224 20.239
CR4028.097 27.516 28.075 28.104
_______________________________________________
Table9. The absorbed energy by container (ship speed 10
knots)
_______________________________________________
Container AbsorbedEnergy(ton.knot
2
)
ShipA ShipB ShipC ShipD
_______________________________________________
ShipA4058.353 2871.671 1879.380 2574.377
ShipB3557.403 2612.493 1765.652 2364.456
ShipC4036.363 2860.691 1874.708 2565.565
ShipD4064.997 2874.981 1880.786 2577.033
_______________________________________________
Note:
Assumedtheangleformedbytheshipandthecontaineris
90.
Assumedadditionalmasscoefficient(Ch/ΔM)is0.85when
sway.
Table4.ShipGroup
__________________________________________________________________________________________________
Shipgroup L(m) B(m) H(m) D(m) Cb Displacement(m3) Displacement(ton) Vs(knot)
__________________________________________________________________________________________________
A126.50 19.80 8.40 6.40 0.75 12022.5612323.1210.00
B44.30 9.00 3.60 2.30 0.58 531.87545.1610.00
C98.00 16.50 7.80 5.40 0.75 6548.856712.5710.00
D134.00 26.40 11.00 5.40 0.84 16046.5516447.7210.00
__________________________________________________________________________________________________
A:Mediumshipsize;B: Smallestsizeoftheshipthatpassintheshippinglanesatthesiteofsinking;C:Sizeoftheship
between44m‐134mthatpassintheshippinglanesatthesiteofsinking;D:Largestsizeoftheship
thatpassintheshipping
lanesatthesiteofsinking
75
Table5.ContainerGroup
__________________________________________________________________________________________________
ContainerGroupL(m) B(m) H(m)Weight(ton) DriftingSpeed
0.5knot 1knot 1.5knot
__________________________________________________________________________________________________
C206.10 2.44 2.5940.000.501.00 1.50
C4012.20 2.44 2.5928.000.501.00 1.50
CR206.10 2.44 2.5918.000.501.00 1.50
CR4012.20 2.44 2.5925.000.501.00 1.50
__________________________________________________________________________________________________
C20:Container20‐feet(lightweight2930kg)C40:Container40‐feet(lightweight3764kg)
CR20:Reefercontainer20‐feet(lightweight3400kg)CR40:Reefercontainer40‐feet(lightweight4900kg)
2.3.3 DepthofPenetration
The absorbed energy of an object due to the
collisioncanresultindeformationorpenetration.The
followingisadeformationorpenetrationthatoccurs
based on the number of energy absorbed in the
calculation of the energy absorbed in the previous
discussion.Thepenetrationonthe
shipandcontainer
canbeseeninTable10uptoTable13.Besidesusing
equation(2)and(3),alsocanbeusedFigure4.
1 0≤ΔEk≤218ton.knot
2
:
Rt=ΔEk/145 (2)
2 218≤ΔEk≤744ton.knot
2
:
Figure4.MinorskyCurve
3 ΔEk≥744ton.knot
2
:
Rt=(ΔEk–121.9)/0.4145 (3)
Table10.Penetrationontheship(containerspeed0.5knots)
_______________________________________________
Container DepthofPenetration(ft
2
.in)
ShipA ShipB ShipC ShipD
_______________________________________________
C200.0344 0.0333 0.0344 0.0344
C400.0241 0.0236 0.0241 0.0241
CR200.0155 0.0153 0.0155 0.0155
CR400.0215 0.0211 0.0215 0.0215
_______________________________________________
Table11.Penetrationontheship(containerspeed1knot)
_______________________________________________
Container DepthofPenetration(ft
2
.in)
ShipA ShipB ShipC ShipD
_______________________________________________
C200.138 0.133 0.138 0.138
C400.096 0.094 0.096 0.096
CR200.062 0.061 0.062 0.062
CR400.086 0.084 0.086 0.086
_______________________________________________
Table12.Penetrationontheship(containerspeed1.5knots)
_______________________________________________
Container DepthofPenetration(ft
2
.in)
ShipA ShipB ShipC ShipD
_______________________________________________
C200.310 0.300 0.309 0.310
C400.217 0.212 0.217 0.217
CR200.140 0.137 0.139 0.140
CR400.194 0.190 0.194 0.194
_______________________________________________
Table13.Penetrationonthecontainer(shipspeed10knots)
_______________________________________________
Container DepthofPenetration(ft
2
.in)
ShipA ShipB ShipC ShipD
_______________________________________________
ShipA9496.871 6633.946 4240.000 5916.712
ShipB8288.307 6008.668 3965.625 5410.267
ShipC9443.819 6607.457 4228.730 5895.452
ShipD9512.901 6641.933 4243.393 5923.119
_______________________________________________
2.3.4 RiskMatrixand AcceptanceCriteria
Risk acceptance criteria in the study are using
Semi Quantitative Analysis with Risk Acceptance
Criteria. This study combines the probability and
consequences of an event based on the Risk
Acceptance Criteria. This protocol uses the Risk
Matrix5 x5todetermine thelevel
of risk.For each
case(shiphitintocontainerandcontainerhitintothe
shipbecausedrifting) attheshipA untilshipDare
showninFigure5uptoFigure32.
Figure5. Container hit into midship of ship A‐B‐C‐D
(drifting0.5knots)
76
Figure6. Container hit into midship of ship A‐B‐C‐D
(drifting1knots)
Figure7. Container hit into midship of ship A‐B‐C‐D
(drifting1.5knots)
Figure8. Ship A‐B‐C‐D hit into container 0 knot (vessel
speed10knots)
Figure9. Ship A ‐B‐C‐D hit into container 0.5 knot (vessel
speed10knots)
Figure10. Ship A‐B‐C‐D hit into container 1 knot (vessel
speed10knots)
Figure11. Ship A‐B‐C‐D hit into container 1.5 knot (vessel
speed10knots)
3 CONCLUSIONSANDFUTUREWORKS
Based on the results of risk assessment of the ship
wreckandcontainercargotoshipnavigationcanbe
summarizedasfollows:
1 Riskofwreckinterferencetoshipsnavigationand
damage to environment is non‐existent and not
requiredtobeassessedfurther.
77
2 Thecontainerre‐floatingisunlikelyandtherisks
tosafenavigation/shippingintheareaarelowand
acceptable.
Based on the risk matrix, for the scenario of
container hit into the ship at the speed 0.5
knots,1knot,and1.5knots,theshipeitherA,
B,
CandD,doesnotcausedthedeformationon
theshipstructures.Sotheriskmatrixshowsthe
acceptable area (low risk) for all types of
containers.
Basedontheriskmatrix,forthescenarioofthe
shiphitintothecontaineratspeed10knots,the
shipeither
A,B,CandD,forcontainer0knot,
does not caused the deformation on the ship
structures. So the risk matrix shows the
acceptable area (low risk) for all types of
containers.
Basedontheriskmatrix,forthescenarioofthe
shiphitintothecontaineratspeed
10knots,the
ship either A, B, C and D, for container 0.5
knot,1knot,and1.5knots,doesnotcausedthe
deformationontheshipstructures.Sotherisk
matrixshows theacceptablearea(lowrisk)for
alltypesofcontainers.
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