481
1 INTRODUCTION
There are numerous criteria that can be used for
estimating the safety of navigation in the restricted
sea areas. Yet, most of them are not standardized,
whichcancauseproblemswithdistinguishingthesea
areas difficult for navigation and the restricted sea
areas and classify them as ‘easy’ or ‘difficult
’ for
navigation. It is also hard to present the ‘scale of
difficulty’innavigatinginagivenseaareabymeans
ofnumbersorsymbols,assuchasystemhasnotbeen
establishedsofar[4].
In this article we try to establish, if possible, the
standard, i.e. universal method to classify the sea
areas difficult for navigation with regard to the
conceptofuniformsafety system of tra
nsportin the
seaarearestrictedbyasafetymargin,definedbythe
outlineofathree‐dimensionaldomainofaship[6].
The risk analysishas been prepared for PS Cla
ss
container vessels “Emma Maersk” from AE10 Far
East Asia‐Europe Service in the Deep Container
Terminal(DCT)GdanskPortPolnocny.Navigational
risk for the ships manoeuvring in the restricted sea
areahasbeenestimatedwithrespecttovariedouter
interference (average and extreme condition) on the
approach to Gdańsk Port Północny DCT termi
nal
alongside the currentlyexploited eastern fairway by
meansofathree‐dimensionalmodelofship’sdomain
[6],[7].
2 NAVIGATIONALRISKANALYSESWHEN
PROCEEDINGINRESTRICTEDSEAAREAS
Inthischapterwepresentmethodsthatcanbeused
forestimatingsafetyofnavigation(navigationalrisk)
intherestrictedseaareas by mea
ns of the modelof
the ship’s domain [6], the definition of the
navigational risk [7] and the simple ship’s domain
formulas(from[6])forestimatingtheship’sdomain
parameters (see Fig.1): including the depth of the
ship’s domain (G
D), the height of the ship’s domain
(W
D), the length of the ship’s domain (DD) and the
beamoftheship’sdomain(S
D).Then,usingallabove
informationbymeansofthethree‐dimentionalmodel
oftheship’sdomainandknowingtheparameters,we
aregoingtotrytoestablishthenavigationalriskina
vertical(R
NG,RNW)andhorizontal(RNDdz,RNDr,RNSpand
Safety of Shipping when Navigating on the PS Class
Container Vessel “Emma Maersk” While Approaching
DCT Terminal in Gdańsk Port Północny
G.Rutkowski
GdyniaMaritimeUniversity,Gdynia,Poland
ABSTRACT:Inthispaperauthorpresentsthemethodsthatcanbeusedforestimatingthesafetyofshipping
(navigationalrisk)intherestrictedseaareasoftheGulfofGdanskbymeansofathree‐dimensionalmodelof
ship’s domain specified for the PS Class container vessels “
Emma Maersk”. The essence of the method
suggestedinthethesisisthesystematicapproachtoaseavesseloperationintheaspectofestimatingitssafety
whileapproachingDCTterminalinGdańskPortPółnocnyinthedivergentexteriorconditions.
http://www.transnav.eu
the International Journal
on Marine Navigation
and Safety of Sea Transportation
Volume 10
Number 3
September 2016
DOI:10.12716/1001.10.03.13
482
R
NSl)planeforaPSclassContainervessellike“Emma
Maersk”intheballastand/orloadedconditionwhen
navigatingontheeastfairwaytoDCTTerminalinthe
Gulf of Gdansk (sea area restricted with the overall
dimensions350metersinbreadth,17metersindepth
and253,6‐073,6 direction)
in the divergentexterior
conditions(averageandextreme).
According to the ship’s domain definition [6],
every ship will be safe (in navigational meaning) as
longassheistheexclusiveobjectwhichcangenerate
dangerwithinherdomain.
WithreferencetoaverticalplaneOZofthethree
dimensionalco‐
ordinatesXYZestablisheddownfrom
thecentralpointofthelocalship’sreferencesystem,
one can affirm unambiguously that every ship will
remainsafeaslongthevalueofG
Dissmallerthanthe
real value of the sea depth h (see Fig.1). Therefore,
componentR
NGofRNcanbereferredtoasthevertical
component of the navigational risk that concerns
keeping under keel clearance, or risk concerning
under keel clearance. The component mentioned
above can be depicted by means of the following
formulas:
max
max
when1
when10
when0
Th
GhT
Gh
R
D
D
NG
(1)
Formula (1) indicates that the value zero of the
navigational risk [7], deriving from factors (objects)
A
i, signifies total navigational safety with respect to
thesefactors(objects).Consequently,accordingtothe
formula(1),assumption
D
Gh canbedefinedasthe
guarantee of the safe shipping‐navigation with
reference to all underwater objects or obstructions
immersedonthedepthsmallerthanh.Ifseadepthh
is smaller or equal to the ship’s draft T, that is
max
Th ,accordingtotheformula(1)seapassagecan
be unfeasible
13
or highly risky. In that situation the
valueofthenavigationalriskR
NGwillequalone(see
formula (1)), and in all probability it will signify
unquestionable (100%) risk of collision with some
underwaterobjectsimmersedon thedepthlessthan
h.
Furthermore, we can also say that the value of
navigational risk R
NG for the sea depth h limited
between T
max and GD (Tmax<hGD) will be limited
between zero andone (R
NG [0,1]) (seeformula (10)
themiddleline).Generalformula,whichcanbeused
to estimate navigational risk R
NG, depending on h
factor from the range (
D
GhT
max
), is presented
below:
max
TG
hG
R
D
D
NG
(2)
Similarly, risk analyses that refer to all objects
hangingintheairabovethewater(seeFig.1)canbe
carried out just as it was done in case of all
underwater objects i.e. obstructions. Therefore,
componentR
NWofthenavigationalriskRN(let’scallit
the vertical component of navigational risk that

13
Inouranalysesweexcludethesituation,whentheshipcanchangeher
draftduetoforexampledeballastingoperation.
concerns keeping air draft clearance, or shortly risk
concerning air draft clearance) can be depicted by
meansofthefollowingformulas:
No
DoN
ND
oD
Do
NW
HH
WHH
HW
HW
WH
R
when1
when
when0
(3)
where:
H
o ‐distancebetweenwaterlevelandtheheightof
the nearest objects hanging above the water (for
bridgeverticalclearanceaboveHW(highwater),[m];
H
N‐ship’sairdraft,(distancebetweenwaterlineto
thehighestpointontheship’shull),[m].
Similarly, with reference to horizontal plane OX
(see Fig.1) R
NDdz and RNDr components of the
navigational risk R
N (let’s call them horizontal
components of the navigational risk that concern
keeping safe distance from the nearest danger
adequately ahead and astern of the ship, or just the
riskconcerningsafedistanceaheadandastern)canbe
depictedbymeansofthefollowingformulas:
RdNdz
DdzNdzRD
RDDdz
NdzDdz
DdzNdz
NDdz
Ld
DdL
LD
dD
Dd
R
when1
when
when0
(4)
and



RdNr
DrNrRD
RDDr
NrDr
DrNr
NDr
LLd
DdLL
LLD
dD
Dd
R
when1
when
when0
(5)
Interpretation of formulas (4) and (5) will be
carried out similarly to the presentation of
navigational risk R
NG and RNW in case of vertical
navigational reserve. Hence, the assumptions d
Ndz >
D
Ddzfromformula(4)aswellasdNr>DDrfromformula
(5) constitute the guarantee of safety of shipping
(navigation) with reference to all objects
(obstructions) detected adequately ahead d
Ndz and
asternd
Nroftheship.Whenanalysingformula(4)one
can also notice that the value of navigational risk
limited between zero to one (R
NDdz(0,1)) will come
into being only if the value of the distance to the
nearest danger ahead of the ship d
Ndz will be either
lessorequaltothelengthoftheship’sdomainahead
D
Ddz. In all probability, assumption dNdz<LRD will
signify navigational accident or collision with some
objects (obstructions) detected ahead of the ship or
unquestionable (100%) risk of collision with those
objects . A questionable situation concerns those
objects that move with some speed and have their
owndomain,thevalueofwhichnormally decreases
d
Ndzparameter.
SimilarlywithreferencetothehorizontalplaneOY
(see fig. 1) distinguishers R
NSl and RNSp of the
navigational risk R
N (let’s call them horizontal
components of the navigational risk that concern
keeping safe distance to the nearest danger
adequatelyonportandstarboardsideoftheship,or,
in short, risk of keeping safe distance to port and
starboard side) can be depicted by means of the
followingformulas:
483
Figure1.Presentationofnavigationalriskforshippassingalonganarrowfairway(channel)withshallowwaterandbridge.
Table1.Navigationalparametersandhydro‐meteorological factors observed intheGulfofGdansk ondeepwatereaster
fairwayleadingtoterminalDCTGdanskPortPolnocny;theparametersoffairwayare:breadthb=
350m,depthh=17,0
m,directionKR=253,6
‐073,6).Alldatadescribedinthistablehasbeenrecognizedastherepresentativefactors usedforthe
navigationalriskassessmentintheGulfofGdanskfortheaverageandextremenavigationalconditions.Alldatahasbeen
collectedonthebasisofresearchworksandstatisticalinformationprovidedbyHydrographicOfficeof
thePolishNavy
(HOPN), Maritime Office in Gdynia, Baltic Pilot Admiralty Sailing Directions (NP20) and VTS service for the Gulf of
Gdansk.
__________________________________________________________________________________________________
AverageNavigationalConditionsExtremeNavigationalConditions
__________________________________________________________________________________________________
Visibilitygood,calmseahf1m,windmoderate3‐4B, Visibilitymoderatetorestricted,seamoderateinsomeplaces
currentratevp
1,0knanddirection090,verticalagitated(hf3m),wind6‐7B,currentratevp3,0kn
oscillationofseasurfaceestablishedaccordingtoChart anddirection344
(perpendiculartofairwayline),vertical
Datum(MeanSeaLevel)
0,10m(h=16,90m);seawater oscillationofseasurfaceestablishedaccordingtoChart
density
1=1,00525g/cm3,Totaldeviation(drift)ofthevessel Datum(MSL)0,60m(h=16,40m),seawaterdensity2=
lessthan
1,maximumyawing1,list11,00250g/cm3,Totaldeviation(drift)ofthevessel2,
yawing
2,list5
__________________________________________________________________________________________________
0when
when
0,5 2
1when
2
Nl Dl
Dl Nl
NSl Nl Dl
Dl
Nl
dS
Sd
B
R
dS
SB
B
d

(6)
and
0when
when
0,5 2
1when
2
Np Dp
Dp Np
NSp Np Dp
Dp
Np
dS
Sd
B
R
dS
SB
B
d

(7)
Therefore, the risk analyses R
N is going to be
calculated for PS class container vessel ”Emma
Maersk”whennavigating ontheGulfofGdanskon
eastfairwayleadingtoDCTTerminalinGdańskPort
Pólnocny,whichisrestrictedbytheirdraught(h
1=17
m) and breadth (b
1=350) m in divergent exterior
conditionsandotherfactors.
Onthebasisofresearchandlongtermobservation
carriedoutintheGulfofGdansk[1],[3]ithasbeen
established, that all navigational parameters and
hydro‐meteorologicalfactorsdescribedinTable1can
be recognized as the representative factors used for
navigationalriskassessmentintheGulfofGdanskfor
averageandextremenavigationalcondition.
3 NAVIGATIONALRISKASSESSMENTWHEN
NAVIGATINGONTHEPSCLASSCONTAINER
VESSEL„EMMAMAERSK”
The PS Container class vessels such as “Emma
Maersk” have a carrying capacity about15000 TEU.
They have been appointed to the
Far East service
AE10 between Asia and Europe for the world‐wide
MaerskLineoperatorintheDeepContainerTerminal
DCT Gdansk Port Polnocny. PS class vessels are
recognized as the biggest container vessels that can
operateontheBalticSea.
Figure2. PS class container vessel “Emma Maersk”
appointed to the AE10 Far East service between Asia and
Europe in Maersk Line for DCT terminal in Gdańsk Port
Północny.Source:http://www.maerskline.com.
The container vessel “Emma Maersk” (IMO
9321483) is characterized by the following data:
lengthover all LOA= 397,60m, breadth B=56,40 m,
C
B=0,598 coefficient factor, height Hc= 76,50 m and
484
maximumdraughtT
max=16,02m(howeverservicein
theDCTterminalinGdanskisexpectedwithreduced
draftT
zr=14,50m),156907DWT,displacement218788
tons,lightvessel61881t,themassesofsegregation
ballast water 60338 t, 170794 GT, 55396 NRT and
carrying container capacity 14770 TEU. “Emma
Maersk” has been equipped with a 80 MW power
plantWartsilaSulzer 14RT‐Flex96c(80080kW,MCR
108877 HP
/ 68 068 kW, CSR 92545 HP), 5 diesel
enginegeneratorsMaK9M32Cwithpower4140kW
eachand8500kWsteam‐gasmainenginepowerunit.
Thevesselhasbeenequippedwithaclockwisefixed
propeller,themassofwhich is135tons.Theshipis
abletoproceed
withmaximumspeedforwardVmax=
27,5 kn (50,9 km/h). However the usual operational
speed is about V
e=24,5 kn (45,3 km/h). Two Rolls
Royce bow thrusters and two Rolls Royce stern
thrusterswithapitchpropellerand25tonspressure,
effectivelyincreasehermanoeuvringability.Thebow
thrusters and the stern thrusters are installed
adequately2,77mabovethekeel.Thebowthrusters
are installed 38,19 m
and 44,44 m from a bow line,
sternthrusters38,50mand44,72mfroma sternline.
Inbadweatherconditionsrollingandpitchingcanbe
reduced by using Litton Sperry Fin Stabilizers. The
Main Engine computer automatically checks 8000
pointsfromthedifferentsensorsandindicators.Due
to
this fact the ship is manned only by 13
crewmembers.“EmmaMaersk”isequippedwithtwo
anchors,29tonseachand2x14shacles(2x385m)
anchorchain.
Figure3.Ship’sparticularsandawheelhouseposterfromthePS classcontainervessel”EmmaMaersk”.All manoeuvres
datacheckedoncalmsea(2°),withnocurrent,windupto10knandseadepthtwotimesbiggerthanthedraftofthevessel.
Source:MaerskLineShipHandling8.02.01andShipManoeuvrability
L203‐L210documentation.
Table2.Ship’sdomainestimatedfor“EmmaMaersk”PSclasscontainervesselproceedingonadeepwatereasternfairway
toDCTterminalinGdanskPort Polnocnydependingonaballastorloadedconditionandtheship’sspeed. 
__________________________________________________________________________________________________
EASTERNMAINFAIRWAY‐DIRECTION253,6‐073,6(fairwayparameters:breadthb=350manddepthh=17,0m;
directionKR=254
)
__________________________________________________________________________________________________
MAIN LOADEDCONDITION(D=156907t)TD=14,50m; BALLASTCONDITION(D=122219t)TD=7,10m;
ENGINE TR=14,50m;Tmax=14,99mfor
1andTR=10,80m;Tmax=11,29mfor1and13,22m
POSITION16,90mfor
5for5
V G
DWD DDdz DDr SDp SDlV GDWD DDdz DDr SDp SDl
[kn] [m] [m] [m] [m] [m] [m] [kn] [m] [m] [m] [m] [m] [m]
__________________________________________________________________________________________________
Average Visibilitygood,calmseahf 1m,windmoderate3‐4B,currentrate vp1,0knanddirection090,vertical
condition oscillationofaseasurfaceestablishedaccordingtotheChartDatum(theMeanSeaLevel)
0,10m(h=16,90m)
seawaterdensity
1=1,00525g/cm
3
,totaldeviation(drift)ofthevessellessthan1,maximumyawing1,
list
1
__________________________________________________________________________________________________
SFH 25,7 22,32 68,18 9037 1171 232 1741 27,5 17,88 71,14 6215 978 170 1170
FH 16,4 19,18 65,04 5644 861 181 1539 18,1 15,09 68,37 3937 744 141 1041
HH 12,4 18,28 64,14 3680 713 156 1148 14,1 14,27 67,53 2650 614 120 795
SH 8,617,68 63,54 1416 458
98 282 9,7 13,63 66,89 1100 427 85 210
DSH 6,017,40 63,26 1061 365 87 197 6,8 13,34 66,60 842 347 77 152
STOP 0,017,15 63,01 272 205 114 114 0,0 13,08 66,34 272 205 114 114
__________________________________________________________________________________________________
Extreme Visibilitymoderatetorestricted,seamoderate,insomeplacesagitated(hf 3m),wind6‐7B,currentrate
condition v
p3,0knanddirection344(perpendiculartothefairwayline),verticaloscillationofseasurfaceestablished
accordingtotheChartDatum(MSL)
0,60m(h=16,40m),seawaterdensity2=1,00250g/cm
3
,totaldeviation
(drift)ofthevessel
2,yawing2,list5
__________________________________________________________________________________________________
SFH 25,7 26,39 67,11 8453 587 2017 3526 27,5 22,05 70,13 5851 615 1330 2330
FH 16,4 22,86 63,58 5226 444 1507 2865 18,1 18,84 66,92 3662 470 1057 1957
HH 12,4 21,85 62,57 3348 382 1245 2237 14,1 17,90 65,98 2445 408 848 1523
SH 8,621,17 61,89 1282 323
645 829 9,717,16 65,24 1014 340 491 616
DSH 6,020,85 61,57 980 283 500 610 6,8 16,82 64,90 790 296 400 475
STOP 0,020,57 61,29 257 191 271 271 0,0 16,52 64,60 257 191 271 271
__________________________________________________________________________________________________
REMARKS:Inthispapertheauthorestablishedthefactorsandparametersasfollows:n=1,1;m=1,0;k=1,0;sD=1,0;sS=
1,0;r
D=1,0;rS=1,0;L=976,60m;L=25m;B=56,40m;B=25m;LRD=232m;tr=0,5‘;Hc=76,5m;p=1,0forthevesselina
loadedandballastcondition(cargo,notdangerous).TheMainEnginepower=80080kW(108877HP),blockcoefficient
factorCB=
=0,598.
__________________________________________________________________________________________________
485
Table3.”Crash Stop”/FSAH‐FAStest estimated for”EmmaMaersk”in a calmsea,withno current and SW3°Bwind.
Source:MaerskLineShipHandling8.02.01andShipManoeuvrabilityL203‐L210documentation.
__________________________________________________________________________________________________
MAINLOADEDCONDITION BALLASTCONDITION
ENGINE TD=16,0m;TR=16,0m,DWT=156907TD=7,12m;TR=10,82m(D≈122219t)
POSITION V[kn] TStop[min] PC[m] PB[m]V[kn] TStop[min] PC[m] PB[m]
RPM
__________________________________________________________________________________________________
SFH 10425,7 20,17’7800 150927,5 12,75’5170 1000
FH 65 16,4 14,58’4716 135818,1 9,75’3126 900
HH 50 12,4 11,67’2900 99214,1 7,42’1970 675
SH 35 8,6 5,03’8921849,7 3,42’607125
DSH 25 6,0 3,25’6301106,8 2,25’42875
__________________________________________________________________________________________________
Figure4.Thegraphicalrelationbetweentheship’sspeedV,thedepthofaship’sdomainGDandthenavigationalriskRNG
estimatedforthePSClassContainervessel“EmmaMaersk”inaloadedconditionwhileapproachingtheDCTterminalin
GdanskPortPolnocny.WorkedoutinMay2011.
The ship’s domain parameters, estimated by the
means of formulae described in paper [6] forthePS
classcontainervessel“EmmaMaersk” arepresented
intable2.Ship’sdomainisestimatedfortheaverage
andextremeweathercondition,shiploaded&shipin
a ballast condition and ship proceeding with a
differentspeed.ThenavigationalriskassessmentR
Nis
estimatedonthebasisofformulas1to7andtable2.
The results presented as the factors from the range
between 0 and 1 can be used to estimate the
navigationalriskandconsequentlyestimatethesafety
of navigation in this area. According to the
navigational risk definition [7], we
know that the
valuezeroofthenavigationalrisk,derivingfromthe
factors (i.e. objects), signifies a total navigational
safetywithrespecttothesefactors(objects).Similarly,
the bigger the risk (when the factor is approaching
value1)thesmallerthesafetyofnavigation.Byusing
this factor, a navigational
riskcan be presented ina
graphicalmanner.
Therefore, the navigational risk assessment when
navigating on the PS class container vessel on the
eastern fairway leading to the DCT terminal in
GdańskPortPółnocnyrestrictedbythedepthh=17,0
m±0,10minanaverageconditionand±
0,60minan
extreme condition can be estimated in the following
way:
The navigational risk R
NG for “Emma Maersk”
concerning her under keel clearance in a loaded
condition with the draft T= 14,5 m, which can be
increased due to a ship’s list = 1º in an average
condition from the wind and the sea waves to T
max
=14,99misgoingtovarybetweenthevalue0,12fora
driftingconditionto0,74foravesselproceedingwith
speedSFH(SeaFullAhead)=25,7kn.
InthatcasethevesselproceedingwithspeedDSH
(DeathSlowAhead)=6,0knisgoingtogeneratethe
navigational risk R
NG on level 0,21. In order to
simplify that method the factor R
NG = 0,21 can be
interpreted similarly as 21 % of probability that we
touchtheseabottomand/ordestroytheship’shullon
the shallow water or because of the underwater
obstructions.Theseapassageof“EmmaMaersk”ina
loaded condition and the extreme passage
circumstances(seeTable1
and2andFig.4)isgoing
to generate the risk on the level 1 regardless of the
ship’sspeed.Inthisexampleoneshouldalsotakeinto
consideration: the maximum fluctuation of the sea
water level observed in Gdańsk Port Północny h=
0,60mestimatedwith
thereferencetoachartdatum
relatedtoMSL(MeanSeaLevel),changesinthe sea
water density from value
1= 1,00525
g
/cm
3
to 2=
1,00250
g
/cm
3
andchangesintheship’sdraftT=2,40
m due to ship’s list = 5º caused by the wind, sea
wavesandcurrentincaseoftheproblemwiththeFin
Stabilizers. Therefore, the sea passage of “Emma
Maersk”inthatconditionisimpossibleorextremely
risky(R
NG=1).Inseapracticetherearethesituations
in which due to the extremely bad hydro‐
meteorologicalconditions,e.g. a strong storm, wind,
loweringofthesealevelorarestrictedvisibility,the
vessels, which have a submersion T
max too big with
referencetothedepthoftheseaareah,aresenttothe
buffer zone in the anchoring place. The ships are
expected to wait there until the severe conditions
improve,whichcanenabletheshiptocoverthegiven
distance.
486
Figure5.Thegraphicalrelationbetweentheship’sspeedV,thedepthoftheship’sdomainGDandanavigationalriskRNG
estimatedforthePSClassContainervessel“EmmaMaersk”inaballastconditionwhileapproachingtheDCTterminalin
GdanskPortPolnocny.WorkedoutinMay2011.
Figure6.Thegraphicalrelationbetweentheship’sspeedV,thewidthoftheship’sdomainSDlandSDpandanavigational
riskofkeepingasafedistancetoaportRNSLandtoastarboardsideRNSpestimatedforthePSClass Containervessel
“EmmaMaersk”inaloadedconditionwhile
approachingtheDCTterminalinGdanskPortPolnocnyintheaverageand
extremeexternalconditions.WorkedoutinMay2011.
Thesea passageofthevesselclass“EmmaMaersk”
in a ballast condition (Fig. 5) proceeding in the
average sea conditions specified in table 1 with the
speedlessthan18kngenerates thenavigationalrisk
R
NGonthelevel0(GD<15,09m;hmin=16,90m,Tmax=
11,29 m, R
NG=0). In extreme external conditions her
entrancetotheportwithspeedDSH=6,8kngenerates
navigationalriskR
NGonlevel12%(GD=16,82m;hmin=
16,40 m, T
max= 13,22 m,RNG=0,12). Increasing the
speed of the ship to SH = 9,6 kn can increase a
generatedriskR
NGto value 0,12. Furthermore,if we
increasethespeedtoSFH=27,5kn,thenavigational
riskR
NGcanincreaseto64%(GD=22,06m;hmin=16,40
m,T
max=13,22m,RNG=0,64).Inthatcasethepassage
of“EmmaMaersk”ispossibleinallconditionswith
referencetotheunderkeelclearance,howevermuch
riskywithahigherspeed.
ThankstotheanalysisofthenavigationalriskR
NW
forthecontainervessel“EmmaMaersk”withrespect
to the objects located on the route, one draws the
logicalconclusionthatthepassageisdefinitelygoing
tobesafeandconstitutesnothreatastherearenoon‐
water objects on thearrival fairway to DCT Gdansk
PortPółnocny.
TheonlybridgeOster‐Renden which
islocatedintheGreatBeltontheroutefromtheBaltic
SeatotheNorthSeahasthewatergapwhichequals
65meters(H
o=65mwithrespecttoMSL).Itenables
thesafepassageofthesevesselsthedomainsofwhich
aredescribedas:W
D65m.
Furthermore, if we assume that “Emma Maersk”
proceeds in the axis of the fairway with the speed
DSH≈6 ÷6,8 kn, when the separated gaps between
thevesselsremainnotsmallerthand
N=0,5Nm(dN=
926 m), the navigational risk R
NDdz defined in the
horizontalplaneinfrontofthebowalongthepassage
reachesthevaluefrom0,13intheaverageconditions
(D
Ddz max= 1061m)to 0,06 for the extreme external
conditions (D
Ddz max= 980 m) and to value 0 for all
conditionsinaballastpassage(D
Ddzmax=842m<dN=
926 m). Paradoxically, in the extreme external
conditions, due to the higher resistance from wind,
current and sea waves, the vessel needs a shorter
distance to reduce the speed using e.g. “the Crash
Stop” method; thus the navigational risk R
NDdz is
smaller.However,iftheship’sspeedincreasesinall
conditions the navigational risk R
NDdz automatically
increases.
487
Figure6.Thegraphicalrelationbetweentheship’sspeedV,thewidthoftheship’sdomainSDlandSDpandanavigational
riskofkeepingasafedistancetoaportRNSLandtoastarboardsideRNSpestimatedforthePSClass Containervessel
“EmmaMaersk”inaloadedconditionwhile
approachingtheDCTterminalinGdanskPortPolnocnyintheaverageand
extremeexternalconditions.WorkedoutinMay2011.
Inpractice,thenavigationalriskanalysisfromthe
starboardR
NSpandthe port side RNSlof the ship (see
Fig.6and7)isreducedtothecomparativeanalysisof
the ship’s domain parameters S
Dp and SDl with the
fairwaybreadthb
t,thewaterlanebreadthba,andthe
distance to the nearest hazard d
N, detected
respectively at the starboard and the port of the
vessel.
Hence, if we assume that the ship is going to
proceed within the eastern fairway with the speed
DSH,intheaxisofthefairwaythebreadthofwhich
equals 350 m (b
t=350 m), the navigational risk RNSp
defined in the horizontal plane on the starboard is
going to range: from 0 for the average external
conditions regardless of the loaded or ballast ship’s
condition(Fig.6andFig.7)andfromthevalue0,68for
speed V=6,8 kn in a ballast condition (Fig.7, S
Dp=
400m,d
Np=(350m‐56,4m)/2=146,8m,RNSp=0,68)to0,75
for the loaded ship proceeding with speed V= 6 kn
(Fig.6, S
Dp= 500m, dNp= 146,8 m, RNSp=0,75) in the
extremeexternalconditions(e.g.astrongwind,orthe
currenttransversetothefairwayaxis).
ThenavigationalriskR
NSl,definedinthesectoron
the port side in the eastern fairway for the ship’s
speedDSH,isgoingtorangefrom:0.04fortheballast
condition (Fig.7) in case of the normal passage
circumstances (S
Dl= 152 m) to 0.80 for the loaded
conditionandtheextremepassagecircumstances(S
Dl
= 610 m). For the loaded condition (Fig.6) and the
average passage circumstances the navigational risk
R
NSloscillatesinrangeof0,30(SDl=197m).
4 CONCLUSION
Thus, the analysis of the navigational risk R
NSp and
R
NSlprovesthatthePSclasscontainervessel“Emma
Maersk”proceedingintheaxisoftheeasternfairway
would be able to carry out properly neither the
circulationmanoeuvrenortheemergencymanoeuvre
of stopping bythe engine operation full asternwith
the fishtailing, as those two manoeuvres would
involvecrossing
theboundariesofthegivenfairway.
Furthermore, the arrival fairway to DCT Gdansk
Port Północny for “Emma Maersk” ought to be
treatedastherestrictedseaareabothwithrespectto
its breadth (narrow passage) and its depth (shallow
area). Generally speaking, this particular sea area is
treated as the
area difficult for navigation for the
vessels similar to “Emma Maersk”. It seems to be
reasonableorevenindispensabletomaintainaspecial
navigational supervision such as the VTS service as
well as the obligatory pilotage for this sea area
including the tug assistance with minimum one tug
forewardand
onetugaft.Theoptimalspeed,which
can assure the adequate manoeuvreabilities of the
vessel with the acceptable level of risk R
N ranges
between3,5knto6,0kn.Thefurtherspeedreduction
withouttheassistanceofthetugboatscanincreasethe
drift, especially in case of the strong wind and the
currentactinginatransversedirectiontothefairway
axis.
The approaching speed on the eastern fairway
should range between
3 and 6 kn. The minimum
steeringspeedforthePSclasscontainervesselsimilar
to “Emma Maersk” in a loaded and/or ballast
conditionisestablishedonthelevelofabout3kn(5,6
km/h). The passage speed in case of the towing
operation with a towing line should also range
between 3 to 6 kn. The navigational passage for all
inboundandalloutboundPSclasscontainer vessels
in the loaded conditions are recommended in good
and/or in average weather conditions within the
visibilityupto1Nmandawindforceupto7ºB.All
manouevresonaturnover
areainportofGdanskare
recommended with the wind force less than 6ºB. It
thatconditionsa navigationalriskR
Ncanbeaccepted.
Similarly, a navigational passage in bad and/or
extremeweathercondition(seetable1)isimpossible
or extremely risky due to the high value of the
navigationalriskR
N.
Thehighriskoperatione.g.dueto the extremely
badweatherconditionssuchasthewindforce7ºBor
more should be done with a tug assistance. The
recommendedtowingconfigurationistohaveatleast
twotugsaftandtwotugsforward,twotugsfastand
twotugsin
assistance.Ifthewindforceincreasesto
488
8°B and more from NE and SE direction the vessel
shouldberemovedfromtheportinadvanceandsent
to the buffer zone in the anchoring place. The ships
areexpectedtowaitthereuntilthesevereconditions
improve, which can enable the cargo and/or
manouevresoperations.Thefinal
decisionismadeby
thecaptainofthevesselwhoconsultstheCaptainof
Port of Gdansk and the top management from the
DCTterminalinGdansk.
Taking into consideration “Emma Maersk”
dimensions,themainengineforceandthelocationof
all bow and stern thrusters, the entire mooring and
unmooring operation needs to be done with the
special precaution and a tug assistance to avoid
washingawaythesandfromthejettyandthesea bed
inside the port. This kind of problem can be
eliminatedintheDCTterminal when thesea bed is
secured by some tarpaulin. Having
analysed the
navigational risk of the PS class container vessel
„EmmaMaersk”duringherpassagetoDCTGdańsk
Port Północny, one can unanimously state that the
three‐dimensional model the ship’s domain can
constitutetheappropriatecriterionforestimatingthe
safety structures of the sea transport as well
as the
structuresthatclassifytheseaareas.
REFERENCES
[1]Admiralty Sailing Directions, Baltic Pilot, Volume I,
NP18,edycja15/2009.
[2]AdmiraltyListofRadioSignals,Volume6(2),NP286(2),
edycja2009/2010.
[3]Research works from Maritime Office in Gdynia
established in February 2005 for VLCC service In
GdanskPortPolnocny.
[4]Holec M., Rutkowski G. Próba zdefiniowania akwenu
trudnego
pod względem nawigacyjnym ,ZeszytyNaukowe
WSMNr32,Gdynia1997.
[5]Nowicki A.: Wiedza o manewrowaniu statkami
morskimi,WydawnictwoTrademar‐Gdynia1999.
[6]Rutkowski G. Modelowanie domeny statku w procesie
manewrowania w ograniczonych akwenach,Politechnika
WarszawskaWydział Transportu,PraceNaukowe„T”,
Warszawa2001.
[7]Rutkowski G. Zastosowanie modelu
domeny do oceny
bezpieczeństwa nawigacyjnego statków poruszających się w
akwenach ograniczonych, Politechnika Warszawska
Wydział Transportu, Prace Naukowe „T”, Warszawa
2001.
[8]Website: http://www.ships‐info.info/mer‐emma‐
maersk.htm
[9]Maersk Line internal documentation including “Ship
Handling (8.02.01)” and “Ship Manoeuvrability (L203‐
L210)” for PS class container vessel „Emma Maersk”,
2011.