International Journal
on Marine Navigation
and Safety of Sea Transportation
Volume 4
Number 4
December 2010
397
1 INTRODUCTION
1.1 The turning basins
Can be understood as a two different meanings. First
as the manoeuvring area appointed by the ships. Se-
cond as the hydro-technical building artificial or
natural with suitable horizontal and vertical dimen-
sions, where the considerable alterations of the
course of the ship are executed.
The manoeuvre of ships turning is one of the often
port manoeuvres. The ships turning is executed eve-
ry time during the ships port call. Simultaneously, it
is comparatively little examined. We know that the
influence on the size of turning basin during the ma-
noeuvre have the large quantity of factors.
The turnings of the ships are practices „in the
place”. This should be understand 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
or spring.
Turning basins are areas appointed and the reser-
voirs 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. Cer-
tainly due to safety, the turning basin as the hydro
technical building always has to be larger in all di-
mensions than the manoeuvre area to avoid the colli-
sion with bottom or bank (Kornacki & Galor 2007).
1.2 Designing of turning basins
Two methods of defining their dimensions can be
use. Those are analytic method and simulating
method (Kornacki, 2007).
Analytic method is the very simplified. Turning ba-
sins are divided on two groups. First group establish
non-currents turning basins. Second group establish
turning basins on currents waters. It is premised that
the turn of the ship is described by the circular area
and in the case of currents waters, the area is de-
scribed by the shape similar to figures definite by
two semicircle and two straight lines joining them -
the stretched wheel similar to ellipse. The depth of
water on the turning basins is defined in dependence
from loading status of turned over ships (Kornacki,
2007; Dz.U.98.101.645).
The dimension of the turning basin on the non-
current waters defines the equation 1 (Gucma &
Jagniszczak, 2006; McCartney, 2005):
OAo
Ld 5.1=
(1)
The dimensions of turning basins on the current
waters define the equations 2, 3 (Gucma &
Jagniszczak, 2006; McCartney, 2005):
ocOAo
tvLl += 5.1
(2)
OAo
Lb 5.1=
(3)
The simulating method of designing the parame-
ters of turning basins are based on series of tests in
comparable conditions on prepared model of reser-
voir and the model of the ship planned to use the
turning basin. The results of tests are subjected the
statistical processing. Effect of that kind of research
is delimitation of the area of manoeuvring on the
Analysis of the Influence of Current on the
Manoeuvres of the Turning of the Ship on the
Ports Turning-Basins
J. Kornacki
Maritime University of Szczecin, Szczecin, Poland
ABSTRACT: The paper presents the problem of the influence of current on ship during the manoeuvre of the
turning and influence on this manoeuvre. The test of the different qualification of the influence of current on
the manoeuvre of the turning of the ship was undertaken. The analysis of the influence of the current was
conducted on this manoeuvre.
398
turning basin according to the various foundations of
hydro meteorological 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 especially de-
signed to the solved problem (Guziewicz & Ślączka,
1997; The unpublished report 1995; The un-
published report 2000).
2 CURRENTS INFLUENCE
A feature of any river manoeuvres is the current. It is
common for a river berth to lie in the same direction
as the prevailing current so that the current can assist
with turning and berthing. In this case, a turning can
be done with a current or opposite a current.
Opposite current give the advantage of relatively
high speed through the water with a reduced speed
over the ground. Consequently, steerage at low
ground speed is improved by the good water flow
over the rudder. The ship will be easier to stop.
Certainly, manoeuvring with a current give com-
pletely different situation. High speed over the
ground may mean low speed through the water. It is
necessary to take care of ground speed all the time.
Below figure show the tendency of the stopped
ship movement.
We should note that currents are usually complex,
with varying rates and directions that can change
hourly. Local knowledge is essential for safe naviga-
tion. A ship making headway into a current, but
stopped over the ground, will have a forward pivot
point.
The influence on manoeuvring is serious for even
weak currents like ½ knots. It depends of the ship
type and the objectives of manoeuvring in a smaller
extent than in case of strong wind. On restricted wa-
ter area everything is fine as long as manoeuvring
ship remains under a speed of a few knots and the
current is not so strong. The situation can be worst in
case of dynamic positioning or low speed manoeu-
vring like ship’s turning.
The ship outline is demonstrated in Figure 2.
Figure 1. The tendency of the stopped ship movement with op-
posite current.
Figure 2. The tendency of the stopped ship movement with cur-
rent.
Figure 3. The lateral and longitudinal ships area with wet sur-
face.
The ship manoeuvring motion equations are as
follows (Artyszuk 2002):
( ) ( )
( )
( )
( )
( )
=−++
=+++
=+−+
Azyx
z
zz
yzx
y
xzy
x
Mvvmm
dt
d
mJ
Fvmm
dt
dv
mm
Fvmm
dt
dv
mm
112266
1122
2211
ω
ω
ω
(4)
direction of current
direction of current
tendency of
movement
tendency of
movement
direction of current
direction of current
PP
tendency of
movement
tendency of
movement
399
The influence of current is a part of hull forces, which are
a part of:
+++=
+++=
+++=
AzAAzRAzPAzHAz
yAyRyPyHy
xAxRxPxHx
MMMMM
FFFFF
FFFFF
(5)
Hull forces can be shown:
=
B
b
T
h
cLTvF
zfhxyH
,,,5.0
2
ωβρ
(6)
3 ANALYSIS OF CURRENT EFFECT DURING
SHIPS TURNING TRIALS
Tests of ships turning are based on chemical tanker
model. The ship data is summarised in Tab. 1
(Artyszuk 2005).
Table 1. Ships model data.
TYPE: chemical tanker
OA
L
103.6 [m]
BP
L
97.4 [m]
M
B
16.6 [m]
M
T
7.1 [m]
H
9.4 [m]
A
H
35.2 [m]
The analysis of the current effect during ships
turning on the turning basin is based on the series of
turning-tests. The tests were executed in the wide
port channel in various current conditions. Tests
were executed apply the model of the ship men-
tioned above chemical-tanker, without the use of
tugboats, with own propulsion, standard 35 degrees
rudder and thrusters (Artyszuk 2005). Port channel
had the width of the quadruple of the length of the
ship and had not the influence on the area of
manoeuvring. The tests were begun from the same
places and interrupt after turn over ship to final
course 270°.
3.1 Turning manoeuvres without current
First, for the comparison, the series of tests was con-
ducted without current. All tests were in same envi-
ronmental condition. It means: shallow water, slow
speed, no wind, starboard and port turning and usage
of ruder, main propulsion (ahead/astern) and bow
thruster if necessary. Results are introduced below.
Figure 4. The turning manoeuvre without current – ship shapes
in time of commands.
Figure 5. The turning manoeuvre without current – ship shapes
in every 30s.
Figure 4 and 5 present typical turning manoeuvre
with starboard turn without current. Below are pre-
sent manoeuvring areas on turning basin (Fig. 6) and
comparison with analytic method (Fig. 7).
Figure 6. The manoeuvring areas on turning basin without cur-
rent.
Figure 7. The manoeuvring areas on turning basin without cur-
rent compared with analytic method.
Results base on series of 30 tests.
ships turning basin
-100
-80
-60
-40
-20
0
20
40
60
80
100
-250 -200 -150 -100 -50 0 50 100 150
m
m
max
min
95%
ships turning basin
-100
-50
0
50
100
-250 -200 -150 -100 -50 0 50 100 150
m
m
turning basin 95%
non current
400
3.2 Turning manoeuvres with opposite current
All tests were in same environmental condition as
without current (shallow water, slow speed, no wind,
starboard and port turning and usage of ruder, main
propulsion and bow thruster). Similar as before 30
tests were conducted. Current had 2 knots and direc-
tion 270º. Results are introduced below.
Figure 8. The manoeuvring areas on turning basin with oppo-
site current.
Figure 9. The manoeuvring areas on turning basin with oppo-
site current compared with analytic method.
Figure 8 presents manoeuvring areas on turning
basin with opposite current. In all cases tests were
conducted as much as possible around beginning of
co-ordinates. Figure 9 presents comparison results of
analytic method and simulating method.
3.3 Turning manoeuvres with current
During tests of turning manoeuvres with current,
similar like before, all environmental conditions stay
the same. Current had 2 knots and direction 090º.
First, the shapes of typical tests are presented.
Figure 10. The turning manoeuvre, starboard turn, with current
090º and 2 knots – ship shapes in time of commands.
Figure 11. The turning manoeuvre, starboard turn, with current
090º and 2 knots – ship shapes in every 30s.
Figure 12. The turning manoeuvre, portside turn, with current
090º and 2 knots – ship shapes in time of commands.
Figure 13. The turning manoeuvre, portside turn, with current
090º and 2 knots – ship shapes in every 30s.
Next, manoeuvring areas on turning basin with
current are presents (Fig.14).
ships turning basin
-150
-100
-50
0
50
100
150
-250 -200 -150 -100 -50 0 50 100
m
m
max
min
95%
ships turning basin
-150
-100
-50
0
50
100
150
-250 -200 -150 -100 -50 0 50 100 150 200 250 300
m
m
turning basin 95%
current
401
Figure 14. The manoeuvring areas on turning basin with cur-
rent.
Comparison of results of analytic method and
simulating method is presented below.
Figure 15. The manoeuvring areas on turning basin with cur-
rent compared with analytic method.
3.4 Comparison of turning manoeuvres in different
current conditions
It was interesting what differences are between the
various tests groups of the manoeuvres of the turn-
ing of the ship. One can observe differences in
manoeuvring areas appointed for various current
conditions. But, if the influence of the current on dif-
ferent elements for this hides.
The comparison of the profile of yow velocity was
introduced in dependence from the course of the
ship for three typical current situations below.
It is easily to notice that there are no considerable
differences in the course between individual situa-
tions. One can qualify the phase of the growth of the
yow velocity, then the period of changing course in
dependence from the tactics of the manoeuvre with
the possible to the qualification maximum, and final-
ly the phase of slowing down the yow velocity in the
aim of the position of the ship on the new course.
Figure 16. Turning rate [deg/min] on different tests groups.
You can not also see the considerable difference
of period of executing manoeuvres.
Figure 17. Average time of manoeuvres on different tests
groups.
The differences what can be observe they are the
result of hurry during the executing of the manoeu-
vre rather, in the aim his of the safe realization.
3.5 Work of current
Looking on the manoeuvring areas of individual
groups, you can see that current has the influence
not only on the growth of the dimension in the axis
of the working of the current but he also influences
growth of width of such area. We observe the differ-
ences in width of manoeuvring areas of grade ten
percent of the width of the manoeuvring area with-
out current. Accepting the steady working of the current,
it can be:
=
=
CHC
zfhxyMBPH
sFW
B
b
T
h
cvTLF ,,,5.0
2
ωβρ
(7)
Working of the current can be understood as the kinetic
energy causing position offset.
ships turning basin
-100
-50
0
50
100
150
-250 -200 -150 -100 -50 0 50 100 150 200 250
m
m
max
min
95%
ships turning basin
-100
-50
0
50
100
150
-250 -200 -150 -100 -50 0 50 100 150 200 250 300
m
m
turning basin 95%
current
-20
-10
0
10
20
30
40
50
60
70
80
60 90 120 150 180 210 240 270 300
course [deg]
turn rate [deg/min]
cu 0
cu 90
cu 270
0
50
100
150
200
250
300
350
400
450
1
average time of maneuvers
no current
current 270
current 090
402
4 CONCLUSIONS
According to the above examinations some general
points could be formulated.
The manoeuvring area is not complaint with this
appointed by the analytic method.
It was observed, larger from foreseen, the exten-
sion of the size of the turning basin upon the width.
It was observed, smaller from foreseen, the exten-
sion of the size of the turning basin upon the length.
The current does not have the significant influence
on stepping out yow velocity and the time of the
manoeuvre. However certain influence has on accel-
erations, what joins with the occurrence of addition-
al strengths on the hull and different moving the ship
causes.
The ship on the current behaves like the wing and
not as the inert object moving oneself together with
the surrounding her environment. It joins with the
use of ships drive propulsions obviously, and occur-
rence on the hull of the suction side and the pressure
side.
One can apply the work of the current on the hulk
to the qualification of the sizes of the turning basin
while manoeuvring on the current.
5 SYMBOLS AND UNITS
o
b
- width of the turning basin [m],
M
B
- moulded breadth [m],
β
- drift angel [º],
fxC
c
,
fyC
c
,
mzC
c
- hall coefficients [-], [-], [-],
o
d
- diameter of the turning basin [m],
x
F
,
y
F
,
Az
M
- external total surge, sway forces and
yaw moment [N], [N], [Nm],
h
- depth [m],
A
H
- air draught from the keel [m],
BP
L
- length between perpendiculars [m],
OA
L
- length over all [m],
o
l
- length of the turning basin [m],
m
,
zz
J
- mass and inertia moment [kg], [kg m
2
],
11
m
,
22
m
,
66
m
- virtual masses [kg], [kg], [kg m
2
],
C
s
- length ship track to final position offset [m],
M
T
- draught [m],
o
t
- time of the turning [s],
c
v
- speed of the current [m/s],
d
v
- drifting speed [m/s],
x
v
,
y
v
,
z
ω
- surge, sway and yaw velocity [m/s],
[m/s], [1/s],
ρ
- water density [kg/m
3
],
C
W
- work of wind [J],
H, P, R, A - subscripts indicating respectively: hull,
propeller, rudder or wind
ACKNOWLEDGEMENTS
I would like to thank Jarosław Artyszuk for the facil-
ity of the application of the simulation of manoeu-
vring the ship to scientific of aims.
Some part of tests was executed using the Ship-
handling Simulator.
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