315
1 INTRODUCTION
The research was carried out for two theoretical
locationsoftherampattheferryterminalintheport
ofGdynia[7]:
inthefirstvariant,fortheramplocatedinthearea
where the wharfs meet: Polish and Finnish,
mooringtheshipalongthePolishQuay,sternto
theramp(bowpointingtowa
rdstheinteriorofthe
pool),asshowninFig.1.
inthesecondvariant,fortheramp locatedatthe
PolishQuay,intheareaofthewesternpartofthe
presentwarehouseNo.2,mooringtheshipalong
thePolishQuay,sterntotheramp(bowpointing
towa
rdstheportexit)‐Fig.2.
Figure1.Ramplocatedintheareawherethewharfsmeet:
PolishandFinnish.
Comparison of the Calculated Wind Loads to the Power
Generated by the Main Propulsion and Thrusters of the
Ship with the Results of Simulation Tests
K.Formela
GdyniaMaritimeUniversity,Gdynia,Poland
ABSTRACT:Oneofthemainfactorsaffectingthesafeportmaneuversbyshipsiswind,whichdirectlya
f
fects
theshipʹsmovement.Thearticlepresents acomparisonofcalculatedwind loadsto thepowergeneratedby
thrustersandthemainpropulsionoftheshipwiththeresultsofsimulationtestsinordertodeterminethesafe
windforcelimitsallowingsafeportmaneuverswithaparticularshipmodel.
http://www.transnav.eu
the International Journal
on Marine Navigation
and Safety of Sea Transportation
Volume 12
Number 2
June 2018
DOI:10.12716/1001.12.02.12
316
Figure2.RamplocatedatthePolishQuay..
The performed research was analyzed for a safe
approach and departure by a simulation model for
both variants. The simulation model was prepared
based on the data of characteristic ferries calling at
passengerterminals[8].
Thetestresultswillalsoallowtoindicateabetter
locationoftherampfromthepointofefficiencyand
safety of navigation during approach and departure
maneuvers.Safetyofnavigationincaseofmaneuvers
ofsuch large vesselsisthe subject of manyresearch
[6] and highlights its importance in the case of
selecting the location of the planned wharf. The
implementation of the full range of tests for the
selectedlocationoftherampwillallowtodetermine
theoperational and hydro meteorological conditions
fortheship.
2 NAVIGATIONALSIMULATOR
The Navi Trainer 5000 Professional navigational
simulator[5], certifiedby theclassification company
DNV (Det Norske Veritas), and the electronic map
simulator and ECDIS Navi‐Sailor 4000 systems as
well as the Model Wizard application (v. 5,0), were
usedinthe research. The simulator islocated in the
laboratory of the Navigation Department of the
Maritime University of Gdynia. The Transas
simulator was used in numerous scientific studies,
researchworkandexpertise[1,2].
For the simulation studies, a model of a
geographical simulation area was built based on
geographicalcoordinates,reflectingtheportbasinin
Gdynia along with the theoretical location of ramps
after performing the possible reconstruction of the
port (Figure 1‐2). In the preparation of the
geographical area of the simulation, maps and
navigational aids were included. A visualization of
theportbasininGdyniaalongwithquaysandnewly
planned ramps was also carried out (Figure 3‐4). In
thesimulationarea,itispossibletocreateanyhydro
meteorological conditions (wind, wave, current)
affectingthemodelmaneuveringinthisarea.
Figure3.Visualizationofthenewsimulationarea‐Portof
Gdynia(VariantI).
Figure4.Visualizationofthenewsimulationarea‐Portof
Gdynia(VariantII).
3 SHIPMODELS
Inordertoselectthemodelforresearch,thedataof
characteristicferriescallingatpassengerterminalsin
theportofGdyniawereused[7,8].Thecontoursof
theferries,alongwithashortcharacteristic(Figure5‐
7) arelistedbelow.
Ferry
Length
overall
[m]
Draft
[m]
Fn‐Surface
areaofthe
above‐water
body[m2]
Fp‐Surface
areaofthe
underwater
part[m2]
k=Fp/Fn
Stena 240,5 6,40 6773,59 1373,26 0,2027
Figure5. Stena ferry‐contour and characteristics of the
surface of the longitudinal section above and underwater
partofthehull.
317
Ferry
Length
overall
[m]
Draft
[m]
Fn‐Surface
areaofthe
above‐water
body[m2]
Fp‐Surface
areaofthe
underwater
part[m2]
k=Fp/Fn
Scandinavia 243,3 6,30 6293,49 1447,25 0,2299
Figure6.Scandinavia ferry‐contourandcharacteristicsof
the surface of the longitudinal section above and
underwaterpartofthehull.
Ferry
Length
overall
[m]
Draft
[m]
Fn‐Surfacearea
oftheabove‐
waterbody[m2]
Fp‐Surface
areaofthe
underwater
part[m2]
k=Fp/Fn
Germanica 240,1 6,15 5814,48 1328,50 0,2285
Figure7. Germanica ferry‐contour and characteristics of
the surface of the longitudinal section above and
underwaterpartofthehull.
Inordertocarryouttheanalysisofsafeapproach
anddepartureofshipsinbothvariantsofthelocation
of the ramp at the ferry terminal in the port of
Gdynia, the simulation model PCS1 (Fig. 8) was
selected. The characteristics and contours of the
simulationmodelareshownin
Figure8.
Ferry
Length
overall[m]
Draft
[m]
Fn‐Surfacearea
oftheabove‐
waterbody[m2]
Fp‐Surfaceareaof
theunderwaterpart
[m2]
PCS1 290,00 8,00 6172,00 1417
Figure8.SimulationmodelPCS1‐contour and
characteristics of the surface of the longitudinal section
aboveandunderwaterpartofthehull.
4 WINDLOADS
The main component of the resistance when
maneuveringtheferryatlowspeedsistheforceofair
pressure on the above‐water part of the shipʹs hull
(waveresistanceandfrictioncanbeneglected).Itcan
becalculatedbytheformula[3,4]:
Rpow.=0,5*Cpow.*
ρpow.*V2pow.*Fn
where:
Rpow.‐ airresistance(kG)
Cpow.‐ coefficientofairresistance(forthehull1.0,
forsimplesuperstructures1.0to1.2)
ρpow.‐ airdensity1,226kg/m3attemperaturę20C
andnormalatmosphericpressure1013hPa;
Vpow.‐relativeairvelocity(m/s);
Fn‐surfaceofthelongitudinalshipʹssection
(m2)
After entering the averaged values Cpow. = 1,1,
andρpow. = 1,226 kg/m3, the above can be
simplifiedtotheform[3,4]:
Rpow.=0,069*V2pow.*Fn[kG]
Thisformula wasusedtocalculatewindpressure
forcesonthesurfaceofthelongitudinalshipʹssection.
In case of mooring and unmooring maneuvers
without the assistance of tugs, in the most
unfavorable directions and wind force, the power
generatedbythethrustersandmainenginesmustbe
greaterthanthecalculatedwindpressureforcesofthe
characteristic vessels and the simulation model
considered. A summary of the
calculated wind
pressureforcesisshowninTable1.
Table1.Listofwindpressureforces
_______________________________________________
FerryWind WindWind
Force speedpressure
[
o
B] [m/s]force[KG]
_______________________________________________
Scandinavia 4
o
 5,5‐7,9 27101,6
5
o
 8,0‐10,7 49717,4
6
o
 10,8‐13,882698,7
7
o
 13,9‐15,0 97766,4
Stena4
o
 5,5‐7,9 29169,0
5
o
 8,0‐10,7 53510,1
6
o

10,8‐13,889007,4
7
o
 13,9‐15,0 105160,0
Germanica 4
o
 5,5‐7,9 25038,5
5
o
 8,0‐10,7 45933,3
6
o
 10,8‐13,876404,4
7
o
 13,9‐15,0 90269,8
ModelPCS1 4
o
 7,926578,4
5
o
 10,748757,6
6
o
 13,881102,3
7
o
 15,095820,3
_______________________________________________
Comparison of the longitudinal sectional area of
theunderwaterpartoftheFphulltothelongitudinal
sectionoftheabovewatersectionoftheFndetermine
(k = Fp / Fn) that the adopted simulation model
differsinanon‐significantwayfrommodelswiththe
characteristicparameterspresentedin
Table1(onlyin
thecaseoftheStenaferry,about12%).Theresultsfor
the model adopted for simulation and maneuvers
reliably correspond to a ferry with the characteristic
parameterspresentedinTable1.
The selected model corresponds to the
characteristicferries (similardimensions,theratio of
thesurface
areaofthewaterbodytothesurfacearea
of the underwater part and characteristics of
maneuveringdevices).Theshortageofpowerof the
bow thruster on the bow in the selected model in
relation to the set of characteristic ferries is
compensated by the application in which the
simulatoris
equipped.Similarly,thepowershortage
ontheboltshasbeensupplemented. The simulation
318
modelusedisanextensivemathematicalmodelofthe
real unit. Both the simulation area and the models
usedforsimulationarehighlyrealistic.
5 SIMULATIONTEST
Theresearchhasbeendividedintotwoparts.Inthe
firstpart,theapproachanddeparturemaneuverwas
performedwith the PCS1simulation
modelforboth
theoretical variantsoftherampposition. Part II is a
continuationandsupplementtotheresearchinPartI.
Theresultsofthetestsfromthesecondpartallowed
to determine the operational and hydro
meteorologicalconditionsfortheparticularship.
Thewindstrengthanddirectionhave
asignificant
impacton theexecution of the safeport maneuvers,
especially for units with a large wind area section.
Theschemebellowisbasedonkeydirectionsthatcan
be important at critical moments during the entire
maneuver, ie: set in or under the wind line during
entryandexit
toandfrombasinIV(directions:045°
and237°‐Fig.9),andwindactingperpendicularto
the shipʹs side (290 ° and 135 °‐Fig. 10) at the
momentof approach and departuretoand from the
Polishberth.
Figure9.Windfrom045°and237°
Figure10.Windfromdirections 290°and135°
Fortheconsideredramplocation(variantsIandII)
at the Polish Quay, two series of simulation tests
(mooring and unmooring maneuvers) of the PCS1
simulationmodelhavebeenplanned.Inthefirststage
of the tests, simulations were carried out at a wind
speedof10m/s.Such
astudywillallowtoassessthe
difficulty,duration, neededwaterareaandsafetyof
maneuvers for both variants of the proposed ramp
locations.
Table 2 shows the duration of simulation of
mooring maneuvers and unmooring the PCS1
simulationmodelinbothvariantsofthelocation.
Table2.Durationofmaneuvers
_______________________________________________
Wind Durationofmaneuvers[hh:mm:ss]
BerthingUnberthing
[direction/ LocationI LocationII LocationI LocationII
speed]
_______________________________________________
290°10m/s00:12:53 00:12:17 00:18:15 00:06:47
045°10m/s00:20:24 00:14:14 00:10:07 00:06:44
135°10m/s00:27:40 00:18:43 00:18:46 00:05:56
237°10m/s00:11:56 00:10:12 00:11:05 00:11:07
_______________________________________________
Average 00:18:13 00:13:51 00:14:33 00:07:38
durationof
maneuvers
_______________________________________________
The comparison shows that both the duration of
mooring maneuvers asand unmooring is longer for
thefirstvariant.
Example of a trajectory of the shipʹs movement
duringthetestisshowninFig.11.
Figure11. Mooring maneuver of the PCS1 simulation
model.VariantII.Wind:045°‐10m/s.
Inordertodeterminethepermissiblewindforce,a
comparisonoftheoreticalcalculations(theratioofthe
wind pressure force at given speeds to the power
generated by the bow thrusters and the shipʹs main
propulsion that canreduce thewind pressure force)
wascomparedwiththeresultsofsimulation
tests.As
theoretical calculations showed that the permissible
windforceforboththecharacteristicandsimulation
ferries iswithin the wind speed range of 13.3 m/s‐
14.1 m/s, four series of simulation tests were
performed (mooring and unmooring maneuvers for
windspeed13m/sand14m/s).
Duringmooringand
unmooringmaneuversofthe
PCS1 simulation model with wind blowing at the
speed of 13 m/s throughout the maneuvers, the
control of the shipʹs movement was maintained.
Usingthethrustersandruddermaneuversandmain
propulsion,theshipsafelymooredandunmooratthe
selectedlocation.
Afterincreasing the wind
speed to 14m/s,at the
least favorable wind directions (blowing
perpendicularly to the shipʹs side at the time of
parallel approach / departure to the wharf) power
generatedbythemaindriveandsteermaneuversand
jet thrusters were not enough to counterbalance the
wind pressure, which resulted
in the loss of control
overtheshipʹsmovement.
319
6 SUMMARY
The reliability of the obtained test results from the
compliance of the results of tests performed on the
simulator,theoreticalcalculationsandconfirmingthe
opinionofmasterswithknowledgeandexperience in
thestudiedarea.
Theresearchshows that the durationof mooring
and unmooring maneuvers, the width
of the
navigation channel needed to perform them, the
complexity of the maneuvers themselves and the
maneuverability of a twin‐screw ship are more
advantageousformooringtotheramplocatedatthe
Polish Quay in the western part of the current
warehouseNo. 2,mooringtheship along the
Polish
Quay, stern to the ramp (bow towards the sea)
(optionII).
It is also important that this variant ensures
greater safety of the ferry during its stoppage and
during exit maneuvers dueto less difficultyin their
performance. In this case, the ferry rotates on the
turntable and approaches the
ramp with the stern.
The place of maneuvers (the supply of navigable
water needed to perform the maneuver) is virtually
unlimited. This also applies to unmooring and
departuremaneuvers,whentheferrymayfollowthe
exitimmediatelyafterunmooring.
Theresearch does not excludethe locationof the
ramp located
in the area where the wharfs meet:
Polish and Finnish. However, they show that
maneuversrelatedtomooringandunmooringwillbe
more difficult and more complicated, their duration
will be longer, and thus they will be less safe,
especiallyinthewindsfromthedirectionsofWand
NW‐prevailing
in the port of Gdynia. The time of
both berthing and unberthing maneuvers will be
significantlylonger(asconfirmedbysimulationtests
‐Table2).
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