Analysis of the wind influence on the ship turning manoeuvers on

Analysis of the wind influence on the ship turning manoeuvers on

Scientific Journals
Zeszyty Naukowe
Maritime University of Szczecin
Akademia Morska w Szczecinie
2008, 13(85) pp. 40‐44
2008, 13(85) s. 40‐44
Analysis of the wind influence on the ship turning
manoeuvers on port turning basins
Analiza wpływu wiatru na manewr obracania statku
na obrotnicy portowej
Jakub Kornacki
Akademia Morska w Szczecinie, Instytut Inżynierii Ruchu Morskiego
70-500 Szczecin, ul. Wały Chrobrego 1–2, tel. 091 48 09 471, e-mail: [email protected]
Key words: ship manoeuvring, ship motion, ship hydrodynamics, ship aerodynamics, wind
Abstract
The paper presents the problem of the wind influence on a ship during the turning manoeuvre and the influence on this manoeuvre. Attention has been paid to the necessity of attaching larger attention to the influence
of the wind during the turning manoeuvre. The analysis of the wind influence on this manoeuvre has been
conducted.
Słowa kluczowe: manewrowanie statkiem, ruch statku, hydrodynamika statku, aerodynamika statku, wiatr
Abstrakt
W artykule został podjęty problem oddziaływania wiatru na statek podczas manewru obracania i wpływ na
ten manewr. Zwrócono uwagę na konieczność przywiązywania większego znaczenia na oddziaływanie wiatru
podczas manewru obracania. Przeprowadzono analizę wpływu wiatru na ten manewr.
Turning basins and the present state of art
of their planning
or spring. Turning basins are areas appointed and
the reservoirs not appointed on which the turn of
the ship is executed with the considerable value of
the course and they are a part of channels or port
basins. Certainly due to safety, the turning basin as
the hydrotechnical building always has to be larger
in all dimensions than the manoeuvre area to avoid
the collision with bottom or bank [1].
While designing turning basins, two methods of
defining their dimensions can be used. Those are
analytic method and simulating method [2].
Analytic method is very simplified in that turning basins are divided into two groups. The first
group establishes non-current turning basins. The
second group establishes turning basins on current
waters. It is premised that the turn of the ship is
described by the circular area, and in the case of
current waters, the area is described by the shape
similar to figures defined by two semicircle and
two straight lines joining them – a stretched wheel
Turning basins have two different meanings: the
manoeuvring area appointed by the ships and also
the hydro-technical building, artificial or natural,
with suitable horizontal and vertical dimensions,
where the considerable alterations of the course of
the ship are executed. Obviously, the manoeuvre of
the ship turning occurs very often in port manoeuvres. It can be said that the ship turning is executed
during every ship port call. The influence on the
size of turning basin during the manoeuvre has
many factors. Ship turnings are practices “in the
place”. This should be understood as the change of
the course of the ship whose linear speeds, during
the manoeuvre, are close to zero. Turning the ship
over is done on the turning basin as a result of the
planned tactics of manoeuvring and can be done on
itself or in co-operation with tugs or use of anchors
40
Scientific Journals 13(85)
Analysis of the wind influence on the ship turning manoeuvers on port turning basins
Let us consider the case of a chemical tanker
[11]. The ship data is summarised in table 1. Tests
of ship turning are based on this model.
The ship outline is demonstrated in figure 1.
similar to an ellipse. The depth of water in turning
basins is defined in dependence on loading status of
the turned-over ships [2].
The dimension of the turning basin on the noncurrent waters is defined by the equation (1) [3, 4]:
d o = 1.5 LOA
(1)
The dimensions of turning basins on the current
waters are defined by the equations (2), (3) [3, 4]:
lo = 1.5LOA + vcto
(2)
bo = 1.5LOA
(3)
Fig. 1. The ship lateral windage area
Rys. 1. Boczna powierzchnia nawiewu
The simulating method of designing the parameters of turning basins is based on a series of tests
in comparable conditions on a prepared model of
reservoir and the model of the ship destined to use
the turning basin. The results of tests are subject to
the statistical processing. That kind of research
results in delimitation of the area of manoeuvring
on the turning basin according to the various foundations of hydrometeorological conditions, various
parameters of ships and various levels of the trust.
Characteristic feature of the simulating method is
that simulating models of the ship manoeuvring are
designed specially for the solved problem [5, 6, 7, 8].
The wind generalised forces (in terms of force
and moment) are written as follows [9, 10]:
 FxA 
 AF c fxa (γ R ) 
 F  = 0.5 ρ v 2  A c (γ ) 
A R
L fya
R
 yA 

 M zA 
 LBP AL cmza (γ R )
The wind forces are a part of [9]:
 Fx = FxH + FxP + FxR + FxA

 Fy = FyH + FyP + FyR + FyA

M Az = M AzH + M AzP + M AzR + M AzA
Character of wind effect during full-scale
trials
d vx

(m + m11 ) d t − (m + m22 )v yω z = Fx

d vy

+ (m + m11 )v xω z = Fy
(m + m22 )
dt

dωz

(J zz + m66 ) d t + (m22 − m11 )v x v y = M Az

Zeszyty Naukowe 13(85)
(6)
Analysis of wind effect during ships turning
trials
The analysis of the wind effect during ship turning on the turning basin is based on the series of the
ship turning tests. The tests have been executed in
the wide port channel in various wind condition.
Those tests apply the model of the ship mentioned
above: chemical-tanker, with no tugboats, with its
own propulsion, standard 35 degrees rudder and
thrusters [11]. Port channel has the width of the
quadruple of the length of the ship and has no influence on the manoeuvring area. The tests have
been carried out in the same places and interrupted
after the ship’s turn-over to final course 270°.
First, just for the comparison, the series of tests
has been conducted on three various models.
Table 1. Full-scale ship data
Tabela 1. Dane statku
TYPE: chemical tanker
103.6 [m]
H
97.4 [m]
HA
16.6 [m]
AF
7.1 [m]
AL
(5)
The ship manoeuvring motion equations are as
follows [9]:
Investigations of the wind effect upon the ship
manoeuvring have a long history. It does not mean
that the previous studies have solved all the problems. It is important to say that all application studies of the wind effect in ship manoeuvring are very
sensitive to the hydrodynamic mathematical model
used. Most works refer to ship wind coefficients
received as a result of scale model tests [9, 10].
The influence of very strong winds on manoeuvring is serious. Of course, it depends on the ship
type and the objectives of manoeuvring. In restricted water areas, ship manoeuvring remains
under a speed of a few knots and the wind is not
able to change the ship track and velocities so
much. The situation can be worse in case of dynamic positioning or low speed manoeuvring like
ship turning.
LOA
LBP
BM
TM
(4)
9.4 [m]
35.2 [m]
350 [m2]
900 [m2]
41
Jakub Kornacki
70
35
traincar
chem
25
40
30
crude
20
10
0
20
crude
15
chem
10
0
50
100
150
–10
200
250
300
5
Course [o]
0
Fig. 2. Ship turning speed according to ships courses on different models
Rys. 2. Prędkość kątowa w funkcji kursu dla różnych modeli
statków
ships type
Fig. 4. Comparison of commands quantity during turning
manoeuvre
Rys. 4. Porównanie ilości wydanych komend podczas manewru obracania
A large crude tanker and a car-ferry have been
taken beside chemical tanker for comparison. All
these ships were in the same environmental condition, that is: shallow water, slow speed, 5B wind,
starboard turning and usage of ruder, main propulsion (ahead/astern) and bow thruster, if available.
Results have been shown in figures 2–5.
The time of manoeuvres is similar, but the quantity of commands is completely different. Because
of the large amount of steering elements on traincar-ferry, the most commands take place there.
The main test was the analysis of the wind effect
during ship turning on the turning basin. The tests
were executed in three different wind conditions,
without wind, with north wind – 5B, and with south
wind – 5B. The results of the tests have been shown
below.
100
crude
50
traincar
200
traincar
Y [m]
–100
0
–50
crude
150
0
–150
traincar
30
50
commands
turning speed [o/min]
60
50
100
150
100
–50
drift [o]
chem
x
Fig. 3. Ships trajectories for starboard turning manoeuvre with
different models
Rys. 3. Trajektorie statków dla manewru obracania różnych
modeli
50
0
0
50
100
150
200
250
300
–50
–100
chem
–150
The drift is defined as an angle between ship
heading and direction of speed over ground vector.
One can see in conducted tests that the ferry
turned the most quickly, with the biggest turn rate
in all range of courses and draught the smallest
trajectory. Obviously, the reason for it was that the
the ship was equipped with the best propulsion. The
final position has been shifted in relation to the
initial one above the width of the ship (around
25 m).
The slowest turning was made by the crude
tanker because of the largest dimensions and only
one main propulsion without thrusters. Of course,
that kind of ships have a tug assistant in natural
situation. It is interesting that the final position
of the ship in relation to initial position has
been shifted more or less the same (around 25 m).
Obviously, the wind force according to displacement is much weaker.
–200
course [o]
Fig. 5. Drift direction according to ships courses for different
models
Rys. 5. Wartość kąta dryfu w zależności od kursu statków dla
różnych modeli
Figures 6–8 present manoeuvring areas, turning
speed according to ships course and average time of
manoeuvres divided in three groups. Very interesting is that all the three test groups have shown similar final position offset compatible with wind direction. It is possible to see similar turn rate offset as
well.
Of course, the wind conditions are more difficult
for manoeuvring thus it takes longer. Obviously,
turning to starboard is easier and therefore trials
with southern wind are shorter than trials with
northern wind.
42
Scientific Journals 13(85)
Analysis of the wind influence on the ship turning manoeuvers on port turning basins
150
460
wind_O
wind_5N
wind_5S
Pianc
50
y [m]
time [s]
100
0
-250
-200
-150
-100
wind_5N
470
0
-50
50
100
150
200
450
wind_5S
440
430
wind_O
420
410
250
400
-50
390
trials
-100
-150
Fig. 8. Average time of manoeuvres in different wind conditions
Rys. 8. Średni czas trwania manewru w różnych warunkach
wiatrowych
x [m]
Fig. 6. Manoeuvring area for ships turning – chemical vessel,
series of 30 trials in different wind conditions
Rys. 6. Obszar manewrowy podczas obracania statku – chemikaliowiec, seria 30 prób w różnych warunkach wiatrowych
Final remarks
Based on the above examinations, some general
points can be formulated.
It is harder to execute the manoeuvre of the turning at small speeds. What the time of the manoeuvre lengthens, the growth of the wind influence
causes. It is much better to approach faster than
rapidly stop the ship and start fast turning into direction of wind impact.
While being in line of wind impact, it is necessary to remember about rapid acceleration in direction of wind impact.
Obviously, the wind has influence on the position of manoeuvring area making offset, but it has
no great influence on the size of the manoeuvring
area. It is similar to the case of current influence but
the effects are less significant. It suggests using
offset parameter to define turning basin dimensions
during windy conditions. The offset formula needs
future tests.
Lateral manoeuvring areas offsets are around
25 m to each side. Accepting the steady working of
the wind in the steady direction, it can be:
 FA = 0.5 ρ AvR2 A c fa

WA = FA s
(7)
Working of the wind can be understood as the
kinetic energy causing position offset. Knowing
above-water average area, the air density, the wind
velocity, aerodynamic coefficients and work we can
accept:
s=
mvd2
ρ Av A2 A c fa
(8)
where s means final position offset and m means
total mass of the ship and non-current water.
Of course it needs future examination.
Symbols
A
AF
AL
bo
BM
cfxa, cfya, cmza
do
Fx, Fy, MAz
60
turning speed [o/min]
40
wind_5S
20
wind_O
H
HA
LBP
LOA
lo
m, Jzz
m11, m22, m66
S
TM
to
vc
vd
vR
wind_5N
0
0
50
100
150
200
250
300
350
400
-20
-40
-60
course [o]
Fig. 7. Turning speed acc. to ships course – port and starboard
turning
Rys. 7. Prędkość kątowa w funkcji kursu – obrót na lewą
i prawą burtę
Zeszyty Naukowe 13(85)
43
– above-water average area [m2],
– above-water frontal area [m2],
– above-water lateral area [m2],
– width of the turning basin [m],
– moulded breadth [m],
– aerodynamic coefficients [–], [–], [–],
– diameter of the turning basin [m],
– external total surge, sway forces and yaw moment [N], [N], [Nm],
– depth [m],
– air draught from the keel [m],
– length between perpendiculars [m],
– length over all [m],
– length of the turning basin [m],
– mass and inertia moment [kg], [kg m2],
– virtual masses [kg], [kg], [kg m2],
– final position offset [m],
– draught [m],
– time of the turning [s],
– speed of the current [m/s],
– drifting speed [m/s],
– relative wind velocity [m/s],
Jakub Kornacki
vx, vy, ωz
γR
ρA
WA
H, P, R, A
8. The unpublished report. Analiza nawigacyjna dla przebudowanego Nabrzeża Górników w porcie handlowym Świnoujście. Maritime University of Szczecin, 2000.
9. ARTYSZUK J.: Wind Effect in Ship Manoeuvring Motion
MM – a Review Analysis. International ScientificTechnical Conference Explo-Ship 2002, Maritime University of Szczecin, 2002.
10. ARTYSZUK J.: Sensitivity of Ship Manoeuvring Trials upon
Wind and Irregular Wave Action. Szczecin/Kopenhagen,
Scientific Bulletin, Maritime University of Szczecin, 2004,
65.
11. ARTYSZUK J.: Methodical guide of the ships manoeuvring
simulation with application. Maritime University of
Szczecin, 2005.
– surge, sway and yaw velocity [m/s], [m/s], [1/s],
– relative wind direction [deg],
– air density [kg/m3],
– work of wind [J],
– subscripts indicating respectively: hull, propeller, rudder or wind.
References
1. KORNACKI J., GALOR W.: Analysis of ships turn manoeuvres in port water area. TransNav’07, Gdynia 2007.
2. KORNACKI J.: The analysis of the methods of ship’s turning-basins designing. XII International Scientific and
Technical Conference on Marin Traffic Engineering, Maritime University of Szczecin, 2007.
3. GUCMA S., JAGNISZCZAK I.: Nawigacja dla kapitanów.
Fundacja Promocji Przemysłu Okrętowego i Gospodarki
Morskiej, Gdańsk 2006.
4. MCCARTNEY B.: Ship Channel Design and Operation.
American Society of Civil Engineers, 2005, 107.
5. The unpublished report. Badania symulacyjne ruchu statków w bazie paliw płynnych w Świnoujściu. Maritime
University of Szczecin, 1995.
6. The unpublished report. Określenie optymalnego wariantu
przebudowy wejścia do portu Kołobrzeg w oparciu o badania symulacyjnego ruchu statków. Maritime University of
Szczecin, 1995.
7. The unpublished report. Badanie możliwości optymalnej
lokalizacji przeładowni kwasu fosforowego w Porcie Police. Maritime University of Szczecin, 1998.
Recommended literature
1. BRIX J.: Manoeuvring Technical Manual. Seehafen Verlag,
Hamburg 1993.
2. GUZIEWICZ J., ŚLĄCZKA W.: The methods of assigning
ship's manoeuvring area applied in simulation research. International Scientific and Technical Conference on Sea
Traffic Engineering, Szczecin 1997.
Recenzent:
dr hab. inż. Lucjan Gucma, prof. AM
Akademia Morska w Szczecinie
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Scientific Journals 13(85)