281
1 INTRODUCTION
RO‐RO / Passenger vessels have a supplementary
damage stability regulations. There are a number of
publications regarding the damage stability
regulations(VassalosDracos,PapanikolauApostolos,
2002; George Simopoulos Dimitris, Konovessis,
DracosVassalos,2008),whichsettocomeintoforcein
2009.Thesenewregulationsbasedon
awiderangeof
related design parameters, such as the number,
positioningandlocaloptimizationoftransversebulk‐
heads, the presence and position of longitudinal
bulkheadsbelowthemainvehicledeck,thepresence
ofsidecasings,andtheheightofthemaindeckand
double bottom. The effects of water
on deck and of
operational parameters as draught, center of gravity
and trim. The current damage stability standard is
thataRo‐Rovesselshouldbeabletosustaindamage
toanytwoadjacentcompartments.
In northern European countries, an increased
standardofdamagestabilitycalculationsisappliedto
existing Ro
‐Ro vessels, known as the STOCKHOLM
Agreement, which requires either fulfilment of the
deterministic standards of SOLAS’ 90 with an
additional height of water on deck (maximum of 50
cm), or the demonstration, by means of model
experiments, that the RO‐RO vessel can survive the
seastateina
damagedcondition.
The damage stability criteria and provisions laid
down in the SOLAS 2009 Ch. II‐1 Pt. B and
STOCKHOLMAgreementareasfollows:
Safety Management on Ro-Ro Passenger Ships
M.Szymoński
PolishNavalAcademy,Gdynia,Poland
ABSTRACT: To define the safety management on Ro‐Ro passenger ship, the wide spectrum o
f
captain’s
responsibilitiesshouldbetakenintoconsideration.Oneoftheimportantresponsibilitiesistheship’sstability
examination. The other measures as the ship’s condition, wind on ship with large windage area, rolling
characteristics,severeseasetc.,areimportantforensuringthesafeoperatingofship,tominimizetherisktothe
ship,tothepersonnelandpassengersonboard,andtotheenvironment.Theinternationalconventionforthe
SafetyOfLifeAtSea–(SOLAS90)makeintofactthecontinualdevelopmentofsafetystandardsinthe111
yearssincethesinkingoftheTitanic.Importantenhancementstability,operational
requirementsanddamage
stability requirements were made as a consequence of several disasters at sea: “Torrey Canyon” in 1967 ,
“HeraldofFreeEnterprise”in1987(183dead),“ExonValdez”in1989,“Braer”in1993,“Estonia”in1994(892
dead).
InparticularthedramaticlossoftheRo‐Ro/PassengervesselsM/F
“HeraldofFreeEnterprise”in1987,andM/F
“Estonia”in1994,respectively,hasresultedintheinternationalregulationrequiringenhanceddamagestability
requirementsforthistypeofvessels,andinmorestringentdamagestabilitycriteriaadoptedonaregionalbasis
byNorthernEuropeancountries(STOCKHOLMAgreement,1977).
http://www.transnav.eu
the International Journal
on Marine Navigation
and Safety of Sea Transportation
Volume 18
Number 2
June 2024
DOI:10.12716/1001.18.02.02
282
1. RangeofpositivepartoftheGZcurve>10DEG;
2. The area under the righting lever curve ≥ 0.015
MRAD;
3. Maximumheelingangle<12DEG;
4. Metacentricheight>0.05m;
5. MaximumGZ ≥ 0,1m;
6. Maximum GZ ≥ (heeling moment) / (dis‐
placement)
+ 0.04 m , taking into account the
greatestofthefollowingmoments:
Thewindpressureof120N/m²,
The crowding of all passengers to‐wards one
sideofthevessel,
Thelaunchingofafullyloadeddavit‐launched
survivalcraftsononeside.
The presented paper
describes the results of
practicaluseofthestabilitycalculationsanddamage
stability calculationsfor the RO‐RO/Passengervessel
M/F“Polonia”,servinginSouthernBaltic.
ThesaidvesselisshowninFig.1.
Figure1M/F“Polonia”(byUNITYLINE)
2 VESSELCHARACTERISTICS
2.1 General
Twin – screw, roll‐on, roll‐off, rail‐truck‐cars‐
passengervessel, designatedforŚwinoujście– Ystad
route,isarrangedasfollows:
Softnosedandrakedstemwithbulbousbow,
Transomstern,
Two full length cargo decks of 2 670 m total
loading lane length, including lifted car shelves,
with 6 railway tracks of effective loading length
740monthemaindeck,
Machinerylocated aft, with 27.5 m of the engine
roomlength,
Twincontrollablepitchpropellerpropulsion‐plant,
4 x STORK‐WARTSILA medium speed main
engines
of15840KWtotal,
3bowthrustersof1600KWeach,
1sternthrusterof1600KW,
HeelingcompensationINTERINGsystem,
Threeaccommodateddecksabovecargohold,
Access to main deck via stern door and shore
ramp,andviasidedoorsonPort
Sidemid ships,
andPortSideaftthevessel,usingshoreramps,
Liftedcardeck(shelves)oncargodeck,
Framespacingof625mm.
2.2 Mainparticulars
Maindimensions:
LengthOA169.90m
Depthto1stsuperstructuredeck19.95m
LengthBP159.00m
Depthtoupperdeck14.15m
Breadthmoulded28,00m
Depthtomaindeck8,65m
Draughtdesigned/scantling5,90m/6,20m
Lightshipweight10886T
Table1.Draught&Deadweight
________________________________________________
ItemDraught Displacement Deadweight
________________________________________________
Summer 6.20m 18107T 6855T
(1.025T/m³)
________________________________________________
3 CALCULATIONOFREQUIREDRIGHTING
LEVER
With respect to the criterion 6. described in
INTRODUCTION, the following heeling moments
hasbeencalculatedfordifferentvesseldraughts‐5,00
m,5,50,and6,20m:
3.1 Momentduetothewindpressureof120N/m².
Theresults of calculationsabovemoment
duetothe
windpressure,ispresentedinTable2.
Figure2 The distribution of windage areas for draught of
5.00meters
Table2.Momentduetothewindpressure
________________________________________________
Draught:5.00m
________________________________________________
Item Area Windpr. W.forceVCG V.Moment
m2 N/m2Tons m Ton.m
________________________________________________
Area1 1486.80 120.00 8.19 8.08 146.95
Area2 1533.30 120.00 18.76 18.15 340.42
Area3 148.80 120.00 1.82 28.20 51.33
Area4 286.50 120.00 3.50 26.06 91.33
Area5 50.50 120.00 0.62 26.60 16.43
Area6 194.50 120.00 2.38 3.10 7.38
________________________________________________
SumArea 3700.00 45.27 14.44 653.00
Displacementatdraught5.00m:13667.00T
RequiredGZ=0.088m
________________________________________________
Draught:5.50m
________________________________________________
Area1 1486.80 120.00 18.19 7.83 142.41
Area2 1533.30 120.00 18.76 17.90 335.73
Area3 148.80 120.00 1.82 27.95 50.87
Area4 286.50 120.00 3.50 25.81 90.45
Area5 50.50 120.00 0.62 26.35 16.28
Area6 112.60 120.00 1.38 3.10 4.27
________________________________________________
SumArea 3618.50 44,27 14.46 640.01
Displacementatdraught5.50m:15434.00T
RequiredGZ=0.081m
________________________________________________
283
Draught6.20m
________________________________________________
Area1 1486.80 120.00 18.19 7.48 136.04
Area2 1533.30 120.00 18.76 17.55 329.17
Area3 148.80 120.00 1.82 27.60 50.24
Area4 286.50 120.00 3.50 25.46 89.23
Area5 50.50 120.00 0.62 26.00 16.06
________________________________________________
SumArea 3505.90 42.89 14.47 620.73
Displacementatdraught6.20m:18107.00T
RequiredGZ=0.074m
________________________________________________
3.2 Momentduetocrowdingofallpassengersto‐wards
onesideofthevesselispresentedinTable3
Table3.Momentduetocrowdingofpassengers
________________________________________________
Item AreaNo. Weight Tot.Weight T.Mom
m2 Kg Kg Ton.m
________________________________________________
Area1 140.04.0 75.0 42000.0 483.0
Area2 80.04.0 75.0 24000.0 240.0
Area3 30.04.0 75.0 9000.0 67.5
________________________________________________
SumArea250.0790.5
________________________________________________
Draught=5.00mDispl.13667.0TRequiredGZ=0.098m
Draught=5.50mDispl.15434.0TRequiredGZ=0.091m
Draught=6.20mDispl.18107.0TRequiredGZ=0.084m
________________________________________________
Theabovecalculationsweremadeforthecase of
launchingofsurvivalcraftsinonesideofthevessel.
Itshouldbenotedthatthevesselissuppliedwith
two Marine Evacuation Systems (RDF Ltd) for both,
PortandStarboardside,eachconsistingofdualtrack
evacuationslide,embarkation(landing)platform
and
14liferafts(RDFLtd),for50personseach.
Taking into account the greater of the above
heeling moments, the results of calculation of the
rightingarmsarepresentedinTable4.
Table4.Summaryofadditionalheelinglevers
________________________________________________
Leverduetothewindpressureatdraught=5.0m0.088m
Leverduetothewindpressureatdraught=5.5m0.081m
Leverduetothewindpressureatdraught=6.2m0.074m
Leverduetocrowdingofpassengersatdraught=5.0m0.098
m
Leverduetocrowdingofpassengersatdraught=5.5m0.091m
Leverduetocrowdingofpassengersatdraught=6.2m0.084m
Leverduetolaunchingofsurvivalcraftsatdraught=5.0m0.049m
Leverduetolaunchingofsurvivalcraftsatdraught=
5.5m0.048m
Leverduetolaunchingofsurvivalcraftsatdraught=6.2m0.046m
________________________________________________
4 STABILITYCALCULATIONS
In order to improve the ship safety during the sea
voyage, the stability calculations are computerized,
getting loading dependent issues, such as results of
intact stability, longitudinal strength, and damage
stability.Somestabilitycalculationsforthepresented
vesselaredescribedbelow.
4.1 Loadingconditionsforstabilitycalculations
The selected loading condition for stability
calculationsareshowninTable5.
Table5.Loadingconditions
284
4.2 Theresultsofstabilitycalculations
Fi 5 10 20 30 40 50 60 70
GZ 0.3180.6371.2641.8441.9261.3780.491‐0.598
Figure3.Therightingleverscurve.
________________________________________________
StabilityCriteria Actual Required
________________________________________________
GZmaxvalueGZmax=1.97m 0.20m
GZmaxangleFi=36.25° 30.00°
Metacentricheightcorr. GMc=3.51m 2.98m
AreaunderGZupto30° A30°=0.493mrad 0.055mrad
AreaunderGZupto40° A40°=0.835mrad 0.090mrad
Areabetween30°‐40° A30°‐40°=0.342mrad
0.030mrad
Angleofheeldueto Ap=0.93° 10.00°
crowdingofpassengers
Angleofheeldueto At=3.17° 10.00°
turning
IMOWeatherCriterion K=2.198 1.00
HeelingleveroflateralLw1=0.148m
windforce
Angleofrolltowindward F1=24.74°
duetowind
action
Angleofdownflooding FiD=44.6°
ListFi=0.1°
________________________________________________
5 DAMAGESTABILITYCALCULATIONS
Fortheloadingconditionsdescribedinsection4,two
damage situations has been simulated. First of them
concernsthefloodingofdryspacesandwaterballast
tank in fore part of the double bottom and section
belowthemaindeckofthevessel:dryspace(SP01)
in
double bottom, deep tank (WB02) and dry space
(SP03).
Thedoublebottomcompartmentslayoutisshown
in Fig. 3. The water ballast tanks are marked green
colour,dryspacesarewhite,fuelandoiltanksarered
andgrey,andfreshwatertanksareblue.
Theresultsofcalculationsthe
hypotheticalcasesof
damage some of double bottom compartments are
presentedinthispaper.
Theresultshasbeenobtainedbyuseofthevessel’s
stabilitycalculationsoftware.
5.1 Caseofdamageinforepartofthevessel
In this case only 3 compartments in fore part of the
vesselhas
beendamaged.Thevesselinthisstatehasa
good stability and will float in equilibrium position.
The damage stability complies with criteria of
SOLAS’90andSTOCKHOLMAgreement.
Figure4.Theshipcompartmentslayout[7]
The ship’s compartments to be damaged as per
case5.1,arepresentedinFig.5.
The results of stability calculations for damage
case5.1,arepresentedinTable5.Whenthewaterwill
be on the train deck, the stability results correspond
also
with criteria of SOLAS ’90 and STOCKHOLM
Agreement.
Figure5.HorizontalsectionoffloodedcompartmentsCase
5.1
The results of stability calculations for damage
case5.1,arepresentedinTable5.
MetacentricheighGMc=2.9m.
GZmax=0.54mwithnowateronthetraindeck,but
withwateronthetraindeck
GZmax=0.53m.
TheFreeboard=1.19m.
285
Table5.Stabilitydataforcase5.1
5.2 Caseofdamageinthemiddlesectionsofthevessel
This case corresponds the flooding of dry spaces in
themidship’spartofthedoublebottomofthevessel:
SP13,SP14,SP15andSP11‐12.
Case of vessel’s damage, presented in point 5.2
corresponds
thesituationofthestabilitylosswhenthe
waterisaccumulatedonRo–Rodeck.Thedamaged
volumesofthevesselarelocatedinthedoublebottom
and below of the main deck of the midships are
showninFig.6.
WithnowaterontheRo–Rodeck
thevesselhasa
small stability margin, but she will float in
equilibrium position. The stability is however not
sufficienttocomplywithcriteriaofSOLAS’90.
Figure6. Horizontal section of flooded
compartmentsCase5.2
Table6.Stabilitydataforcase5.2
6 CONCLUSIONS
Resultsofstabilityanddamagestabilitycalculations,
presented in this paper are getting knowledge of
practice in simplified stability information for the
master. It’s a very important element of safety
managementontheRo‐RoVessel.
Author of the paper, having the practice as the
master of M/F
”Polonia”, is also experienced that
absolute safety doesn’t exist, and a large number of
safetymeasuresaredifficulttoexecute.
The results of the above calculations are giving
proof of the significance of simplified stability
information for the master and tools for fast
verification:ifavesselsinksorstayingafloat.
The case 5.1, regarding to the damage of the
forespacesofthevessel,istestifyingthatthevesselis
stayingafloat,evenif40tonsofseawaterisflooding
themaindeck.
The case 5.2 corresponds to the sinking of the
vessel due to the damage of four spaces
in the
midship.The190tonsof the sea water is coming to
floodthemain,openun‐subdivideddeck.
The results presented in this paper were
performedbyusingthecertifiedvessel’ssoftwarefor
loadingandstabilitycalculationsaccordingtoSOLAS
2009andSTOCKHOLMAgreement(1997).
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