COMMUNICATION No. 29S
March 1972
(Sgo/ 199)NEDERLANDS SCHEEPSSTUDIECENTRUM TNO
NETHERLANDS SHIP RESEARCH CENTRE TNO
SHIPBUILDING DEPARTMENT
LEEGHWATERSTRAAT 5, DELFT
*
THE EQUILIBRIUM DRIFT AND RUDDER ANGLES OF A
HOPPER DREDGER WITH A SINGLE SUCTION PIPE
(DE EVENWICHTS DRIFT- EN ROERHOEKEN VAN EEN
HOPPERZUIGER UITGERUST MET EEN ENKELE ZUIGBUIS)
by
IR. C. B. VAN DE VOORDE
RIFLO
VOORWOORD
Een aanzienhijk dee! van de inspanningen welke tegenwoordig verricht worden in het kader van het onderzoek naar bet stuur-en manoeuvreergedrag van schepstuur-en, heeft veelal betrekking op vaartuigen, die, ook gezien hun eigen afmetingen in relatie met de beperkingen van het vaarwater, moeiiijkheden ondervinden wat betreft hun stuur- en manoeuvreergedrag. Dit rapport vormt
hierop een uitzondering; het heeft betrekking op een
scheeps-type dat moeilijkheden kan ondervinden a!s gevo!g van zijn on-gebruikelijk operationeel doe!.
Veelal vo!doen de gespecialiseerde vaartuigen, in de
bedrijfs-tak van het natte grondverzet, met ccii eigen voortstuwing en
met name de sleephopperzuigers aan hoge eisen te dien aanzien,
vooral bij vrije vaart. Zuigend, hij !age sneiheid, kunnen zieh
echter problemen voordoen, die ernstiger zijn bu het type zuiger uitgerust met één zuigbuis.
In dit kader werd in samenwerking met het ,,Bureau voor Scheepsbouw ir. P. H. de Groot N.y.", optredend namens een tweeta! grote aannemingsmaatschappijen in het natte
grond-verzet, een onderzoek verricht ter beantwoording van de vraag of een sleephopperzuiger met één zuigbuis in de gewenste vaar-richting kan worden gehouden.
Ten behoeve van dit onderzoek werden door bet Nederlands Scheepsbouwkundig Proefstation te Wageningen modelproeven verricht.
De evenwichts roer- en drifthoeken werden grafisch bepaald.
NEDERLANDS SCHEEPSSTtJDIECENTRUM TNO
PREFACE
The greatest efforts performed to-day in the field of research on
steering- and manoeuvring characteristics generally relate to
vessels which may encounter difficulties because of their large size u relation to the depth or width of fairways. This report may be regarded as an exception; it deals with a vessel that may encounter manoeuvring problems because of its unusual mission. As a rule self-propelled specialized dredging ships meet high demands with regard to manoeuvrabiiity in restricted water and this is certainly true for suction hopper dredgers in free running condition. Dredging at low speed however, may cause problems,
which become more serious for the type of suction dredger
fitted Out with one pipe.
The question was ifa suction dredger having one suction pipe could be kept in the prescribed course.
This problem, subject for the investigation described in this
report, was approached in co-operation with "Bureau voor
Scheepsbouw ir. P. H. de Groot N.V.' (Naval architects), as representative of two prominent Dutch dredging contractors.
For this purpose model tests were carried out by the
Nether-lands Ship Model Basin. The equilibrium values of the
drift-and rudder angles were obtained in a graphical way.
CONTENTS
page
List of symbols
6Summary
7i
Introduction
72
Particulars of ship and model
73
Description of test method
74
Test programme
85
Results and discussion
8LIST OF SYMBOLS
ß
drift angle. positive, when the undisturbed flow comes in at starboard
side.
R
rudder angle; positive to port.
W external force opposite to the direction of advance, representing the
suction pipe loading.
F1
reaction force in the foreward cross-arm: positive to port.
THE EQUILIBRIUM DRIFT AND RUDDER ANGLES OF A
HOPPER DREDGER WITH A SINGLE SUCTION PIPE
by
Ir. C. B. VAN DE VOORDE
Summary
Series of side-force measurements on a model of a hopper dredger with one suction pipe were conducted for three suction pipe loadings (simulated by a weight over a pulley) and for three ship speeds for various drift angles and various rudder angles. The equilibrium values of the drift and rudder angle were determined graphically from the test results.
Moreover, the propeller thrust and power were measured in the equilibrium configuration for the various conditions investigated.
i
Introduction
During operation of the hopper dredger involved the
loading on the single suction pipe, due to its
asymmet-rical position, causes a yawing moment.
To accomplish a straight course of the vessel this
moment has to be counterbalanced by the effects of
drift and rudder deflection.
The purpose of the tests was to ascertain the
equilib-rium values of the drift and rudder angles for various
loadings on the suction pipe and for various ship
speeds.
Finally, the propeller thrust and power have been
measured under equilibrium conditions.
The tests on a model scale of I to 16 were conducted
in the Shallow Water Laboratory of the Netherlands
Ship Model Basin for a water depth corresponding to
17.5 m.
2
Particulars of ship and model
The principal characteristics of the ship are given in
table 2.
A small scale body plan with the outline of the bow
and the stern is shown in figure 1.
The model was ballasted to have a 2 degrees list to
starboard, which was assumed to be representative
for the working condition. During the tests it appeared
that changes of this heel angle were only negligible.
Propellers
Stock propeller models were used for the tests. The
principal particulars of these propellers are also stated
in table 2 (dimensions scaled up to full
size). The
propeller models are shown in the Appendix.
3
Description of test method
The model is fastened to the carriage by means of two
cross-arms, each containing a force transducer for
measuring the side forces indicated by F1 and F0 (see
fig. 2).
Thus the model is restrained in the adjusted position
defined by the drift angle ß, except that it still has the
CQWE OF SECTIONAL AREAS
7
ORO.O0A.P ORD.20 pp
8
freedom to move in the longitudinal direction of the
basin i.e. in the direction of advance.
However, in each condition the RPM of the
pro-pellers have been adjusted such, that equilibrium in
the direction of advance was attained. Care was taken
that the equilibrium position of the model relative to
the carriage was such, that the two cross-arms were
perpendicular to the direction of advance.
To simulate the external force on the suction pipe
(ground resistance) a weight W was attached to a wire
over a pulley.
The point of application of this force W is indicated
in figure 2. This force has always been working
oppo-site to the direction of advance irrespective of the drift
angle.
In view of the low speeds investigated, no skin
friction correction force was applied.
4
Test programme
Measurements of the side forces F1 and F0 were carried
out for various rudder defiections to port for each of
the drift angles ß=0; +5; +10 and +15 degrees,
for speeds of 2, 3 and 4 knots and for W-loadings of
lO, 25 and 40 tons. After the test results had been
analysed and the equilibrium values for the rudder and
drift angles were established in the various conditions
specified by the speed and the W-loading, tests were
o 20 10 o lo -20
carried out on the model completely detached from
the carriage, firstly to check the equilibrium and
second-ly to measure the thrust, RPM and torque of the
propellers under equilibrium conditions.
5
Results and discussion
In figure 2 the forces F1 and F0 were plotted versus
the rudder angle for various ß (drift angle) values.
The points of intersection of the F1- and F0-curves
for equal ß-values were determined graphically. The
curve faired through these points represents the
geo-metrical loci of the points, for which F,. = Fa.
The intersection of this curve with the base yields
Table I. The equilibrium values of the rudder and drift angles________.._k\
iîç
-0lv
rudder angle-j-6.
_..-drigIe +ß
direction of advanceF, F,
-F F,
- o10ts_
00 -R=5° --- -
--
-2-100 l00-
O/
-150 speed w-equilibrium values in degrees total totalin loading ÒR tI thrust power
knots in tons to port rpm in tons DI-IP
2 IO
+ 7.5
+4.0 95.0 13.22 630 3 10+ 5.5
+2.5 102.0 14.11 746 4 10+ 4.0
+ 1.5 111.3 15.66 909 2 25 +10.0 +6.5 140.4 31.24 2124 3 25+ 8.0
+4.1 149.1 33.67 2447 4 25+ 6.1
+2.75 156.2 35.35 2724 2 40 +11.0 +6.0 171.6 47.95 3934 3 40+ 9.0
+5.25 177.3 49.12 4209 4 40+ 7.6
+3.5 182.7 50.46 4490 is 100 50 00 50 loo 150starboard RUDDER ANGLE port
o E o t
5
olo
15
20
5 t5
10
15 20 00 50 10° DRIFT ANGLE 0' 5 100 DRIFT ANGLE 15° i 5 i 00 starboardFig. 3. The equilibrium rudder and drift angle for ship speeds of 2, 3 and 4 knots and a W-Ioading of 10 tons.
50
starboard
50 00
RUDDER ANGLE port
50
RUDDER ANGLE
50
100 port Fig. 4. The equilibrium drift and rudder angle for ship speeds of 2, 3 and 4 knots and a W-loading of 25 tons.
loo 15° 9 hit1.:
p,1
-"do
f-4, Il IIrii.. -a"'7
-\\1-'.f.
'I'o
5 o 1015
20
diameter of propellers pitch (uniform) pitch ratioexpanded blade area ratio Boss-diameter ratio number of blades
direction of rotation
the equilibrium value of the rudder angle (for which
F = F0 = O). To find the corresponding equilibrium
drift angle, the points for which Ff = F0 have been
Table 2. Particulars of ship and propellers of a twin screw
hopper dredger
plotted on a base, of the drift angle. The intersection
of the curve faired through these points with the base,
yields the equilibrium value of the drift angle. The
results of the measurements are shown in table i and
in the figures 3 through 5.
The equilibrium values as found above were checked
while the model was completely detached from the
carriage. They were found to be correct. It has to be
remarked, however, that the equilibrium is statically
unstable; i.e. at a deviation from the equilibrium drift
angle the occurring static moment to be derived from
the measured static reaction forces on the ship is
such that it will rotate the ship farther away from the
equilibrium position.
The values of RPM, tota! thrust and total DHP as
measured under equilibrium conditions are given in
table i as well.
6 Conclusions
The equilibrium rudder and drift angles decrease
with increasing speed for a constant W-loading
and increase with increasing W-loading for a
constant ship speed.
The equilibrium is statically unstable.
L..
./i/,2
L
\\
0° 5° 10° 15° Q0 50 100 150
DRIFT ANGLE starboard RUDDER ANGLE port
Fig. 5. The equilibrium drift and rudder angle for ship speeds for 2, 3 and 4 knots and a W-loading of 40 tons.
designation symbol unit
length between perpendiculars Lpp m 85 .953
length on waterline LWL m 91.108
breadth moulded B m 16.612
draught moulded (on even keel) T m 7.01
with all appendages
displacement volume moulded V m3 7881
displacement weight moulded metric 8078
(in salt water) tons
without appendages
longitudinal centre of buoyancy
aft of FP FB m 44.34
block coefficient CB 0.788
midship section coefficient CM 0.994
prismatic coefficient Cp 0.793 D min 3200 P mm 2259 P/D 0.706 AE/A0 0.465 dID 0.185
z
4 outward turningPI2 DETAIL ANTI-SINGING 80ff 05 - ro Ñ _;,...
--r
';, :'-TJI
0
____________
TIPIII
II1..
I1U
-I
No._
radius 2350 _ia -particulars xl propeller noses furl size modeli RIGHT HAND PROPELLER I LEFT
HAND PROPELLER 2 RINGS diameter D = 3200 mm pitch at root P = 2259 mro pitch at 0.7 P = 2259 mm
pitch at blade tip
= 2259 mm
disc area
A0 = 8038 mms
exp blade area
A0 = 3 737 m5
proj. blade area
Ar = 3.369 mtm number of blades Z 4 material d1D = 0185 PemJD 0706 A5IA5 = 0.465 AA0 = 0,419 diameter = 200.00 mmmii
material pitch at root
141.18 men,
pitch at 07G
=
141.18 mm
pitch as blade tip
= 141.18 mismo
-propeller mmmodel no 3538 A d= boss diameteruhrp nudel no. 3791A
drawin9 no. 11 3791-13
scale latro C = i
'
PUBLICATIONS OF THE NETHERLANDS SHIP RESEARCH CENTRE TNO
PUBLISHED AFTER 1963 (LIST OF EARLIER PUBLICATIONS AVAILABLE ON REQUEST)
PRICE PER COPY DFL. lo.- (POSTAGE NOT INCLUDED)
M = engineering department S = shipbuilding department C = corrosion and antifouling department
Reports
57 M Determination of the dynamic properties and propeller excited vibrations of a special ship stern arrangement. R. Wereldsma,
I 964.
58 S Numerical calculation of vertical hull vibrations of ships by
discretizing the vibration system, J. de Vries, 1964.
59 M Controllable pitch propellers, their suitability and economy for large sea-going ships propelled by conventional, directly coupled engines. C. Kapsenberg. 1964.
60 S Natural frequencies of free vertical ship vibrations. C. B. Vreug-denhil, 1964.
61 S The distribution of the hydrodynamic forces on a heaving and
pitching shipmodel in still water. J. Gerritsma and W. Beukel-man, 1964.
62 C The mode of action of anti-fouling paints : Interaction between anti-fouling paints and sea water. A. M. van Londen, 1964.
63 M Corrosion in exhaust driven turbochargers on marine diesel
engines using heavy fuels. R. W. Stuart Mitchell and V. A. Ogale, 1965.
64 C Barnacle foul ing on aged anti-fouling paints ; a survey of pertinent literature and some recent observations. P. dc Wolf. 1964. 65 S The lateral damping and added mass of a horizontally oscillating
shipmodeL G. van Leeuwen, 1964.
66 S Investigations into the strength of ships' derricks. Part I. F. X. P. Soejadi, 1965.
67 5 Heat-transfer in cargotanks of a 50,000 DWT tanker. D. J. van der Heeden and L. L. Mulder, 1965.
68 M Guide to the application of method for calculation of cylinder liner temperatures in diesel engines. H. W. van Tijen, 1965. 69 M Stress measurements on a propeller model for a 42,000 DWT
tanker. R. Wereldsma, 1965.
70 M Experiments on vibrating propeller models. R. Wereldsma, 1965.
71 S Research on bulbous bow ships. Part Il. A. Still water
perfor-mance of a 24,000 DWT bulkcarrier with a large bulbous bow. W. P. A van Lammeren and J. J. Muntjewerf, 1965.
72 S Research on bulbous bow ships. Part II. B. Behaviour of a 24,000 DWT hulkcarrier with a large bulbous bow in a seaway. W. P. A. van Lammeren and F. V. A. Pangalila, 1965.
73 S Stress and strain distribution in a vertically corrugated bulkhead. H. E. Jaeger and P. A. van Katwijk, 1965.
74 S Research on bulbous bow ships. Part 1. A. Still water investiga-tions into bulbous bow forms for a fast cargo liner. W. P. A. van Lammeren and R. Wahab, 1965.
75 S Hull vibrations of the cargo-passenger motor ship "Oranje
Nassau", W. van Horssen, 1965.
76 S Research on bulbous bow ships. Part I. B. The behaviour of a fast cargo liner with a conventional and with a bulbous bow in a sea-way. R. Wahab, 1965.
77 M Comparative shipboard measurements of surface temperatures
and surface corrosion in air cooled and water cooled turbine outlet casings of exhaust driven marine diesel engine
turbo-chargers. R. W. Stuart Mitchell and V. A. Ogale, 1965.
78 M Stern tube vibration measurements of a cargo ship with special afterbody. R. Wereldsma, 1965.
79 C The pre-treatment of ship plates: A comparative investigation on some pre-treatment methods in use in the shipbuilding
industry. A. M. van Londen, 1965.
80 C The pre-treatment of ship plates: A practical investigation into
the influence of different working procedures in over-coating
zinc rich epoxy-resin based pre-construction primers. A. M. van Londen and W. Mulder, 1965.
81 S The performance of U-tanks as a passive anti-rolling device.
C. Stigter, 1966.
82 S Low-cycle fatigue of steel structures. J. J. W. Nibbering and J. van Lint. 1966.
83 S Roll damping by free surface tanks. J. J. van den Bosch and
J. H. Vugts, 1966.
84 S Behaviour of a ship in a seaway. J. Gerritsma, 1966.
85 S Brittle fracture of full scale structures damaged by fatigue.
J. J. W. Nibbering, J. van Lint and R. T. van Leeuwen, 1966. 86 M Theoretical evaluation of heat transfer in dry cargo ship's tanks
using thermal oil as a heat transfer medium. D. J. van der
Heeden, 1966.
87 S Model experiments on sound transmission from engineroom to accommodation in motorships. J. H. Janssen, 1966.
88 S Pitch and heave with fixed and controlled bow fins. J. H. Vugts, 1966.
89 S Estimation of the natural frequencies of a ship's double bottom by means of a sandwich theory. S. Hylarides, 1967.
90 S Computation ofpitch and heave motions for arbitrary ship forms. W. E. Smith, 1967.
91 M Corrosion in exhaust driven turbochargers on marine diesel
engines using heavy fuels. R. W. Stuart Mitchell, A. J. M. S. van Montfoort and V. A. Ogale, 1967.
92 M Residual fuel treatment on board ship. Part II. Comparative
cylinder wear measurements on a laboratory diesel engine using filtered or centrifuged residual fuel. A. de Mooy, M. Verwoest and G. G. van der Meulen, 1967.
93 C Cost relations of the treatments of ship hulls and the fuel
con-sumption of ships. H. J. Lageveen-van Kuiik, 1967.
94 C Optimum conditions for blast cleaning of steel plate. J.
Rem-melts, 1967.
95 M Residual fuel treatment on board ship. Part I. The effect of cen-trifuging, filtering and homogenizing on the unsolubles in residual fuel. M. Verwoest and F. J. Colon, 1967.
96 S Analysis of the modified strip theory for the calculation of ship motions and wave bending momcnts. J. Gerritsma and W. Beu-kelman, 1967.
97 S On the efficacy of two different roll-damping tanks. J. Bootsma and J. J. van den Bosch, 1967.
98 S Equation of motion coefficients for a pitching and heaving des-troyer model. W. E. Smith, 1967.
99 S The manoeuvrabilíty of ships on a straight course. J. P. Hooft,
1967.
100 S Amidships forces and moments on a CB = 0.8(1 "Series 60" model in waves from various directions. R. Wahab, 1967. 101 C Optimum conditions for blast cleaning of steel plate. Conclusion.
J. Remmelts, 1967.
102 M The axial stiffness of marine diesel engine crankshafts. Part I. Comparison between the results of full scale measurements and
those of calculations according to published formulae. N. J.
Visser, 1967.
103 M The axial stiffness of marine diesel engine crankshafts. Part li. Theory and results of scale model measurements and comparison with published formulae. C. A. M. van der Linden, 1967. 104 M Marine dieselengine exhaust noise. Part I. A mathematical model.
J. H. Janssen, 1967.
105 M Marine diesel engine exhaust noise. Part II. Scale models of
exhaust systems. J. Buiten and J. H. Janssen, 1968.
106 M Marine diesel engine exhaust noise. Part III. Exhaust sound
criteria for bridge wings. J. H. Janssen en J. Buiten, 1967.
107 S Ship vibration analysis by finite element technique. Part I.
General review and application to simple structures, statically loaded. S. Hylarides, 1967.
108 M Marine refrigeration engineering. Part I. Testing of a decentraI-ised refrigerating installation. J. A. Knobbout and R. W. J.
Kouffeld, 1967.
109 S A comparative study on four different passive roll damping tanks. Part I. J. H. Vugts, 1968.
IIOS Strain, stress and flexure of two corrugated and one plane
bulk-head subjected to a lateral, distributed load. H. E. Jaeger and
P. A. van Katwijk, 1968.
Ill M Experimental evaluation of heat transfer in a dry-cargo ships'
tank, using thermal oil as a heat transfer medium. D. J. van der Heeden, 1968.
112 S The hydrodynamic coefficients for swaying. heaving and rolling cylinders in a free surface. J. H. Vugts, 1968.
113 M Marine refrigeration engineering. Part li. Some results of testing a decentralised marine refrigerating unit with R 502. J. A. Knob-bout and C. B. Colenbrander, 1968.
114 S The steering of a ship during the stopping manoeuvre. J. P.
Hooft, 1969.
