Lab. y. Scheepsbouwkunde
Technische Hogescho1
Hydrodynamic
Design and
Development of jh
Speed Cellular Container Ships ¡n MHI
RCHEF
Mitsubishi Heavy Industries, Ltd. have delivered several classes of large sized, high powered and high speed cellular container ships
in these ten years. Those ships are classified into 3 generations in view of their principal dimensions, power, speed and economical aspects. Major problems in the design and construction of ships t'ere encountered in relation to their large size, high powered propul-sion engine, high service speed together with serious demand for improvement of economical aspects of ships.
This paper outlines the hydrodynamic problems raised in the design of those ships and investigations made on propulsive per-formance, propeller, manoeuvrability and seakeeping quality.
Those investigations were consolidated into successful design of the high speed container ships with excellent performance, which have been under service with appreciation of ship owners.
J. Introduction
Development of the large sized, high powered and high speed cellular container ships has been one of the greatest events of the shipping world in these ten years. The cellular
container ships have played an important role in the sea
transportation of general cargoes as a most rationalized sys-tem in the international trading, as well as mass
transporta-tion of mineral and energy resources by the large sized crude oil carriers, ore and bulk carriers.
Many large sized cellular container ships have entered
into service for the expanded sea routes in place of the
conventional types of cargo liners. Even after the oil crisis in 1973, construction of the cellular container ships was continued, keeping place with steady development of the sea container transportation system.
The types of those container ships have been varying
with time from economical point of view and they can be classified into the following three categories according to
their size, power, speed and container carrying capacity.
The first is the single screw container ships called the 1st
generation with length of about 175-200m, main engine output about 28000-34200 PS, service speed about 23 knots and the container carrying capacity less than 1000
TEU.
The second generation ships are characterized by larger size about 245-273 m in length, higher propulsion power about 70000-80000 PS, higher service speed about 26-27 knots and larger container carrying capacity about
1800-2300 TEU. This class of ships is driven by twin or triple screws because very high power is required for propulsion.
The 3rd generation ships are again the handy sized single screw ships with almost the sanie dimensions, power and
speed as those of the first generation, but designed with
more stress on economical aspects, such as larger container
carrying capacity and higher propulsive performance.
Mitsubishi Heavy Industries, Ltd. (Mlii) have successful-ly delivered these container ships of high quality from the
ist to the 3rd generation to the shipping world.
'Nagasaki Technical Institute, Technical Headquarters
/lr$ ¡i8,S 11/
I4't*'y
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/
H3.
Katsuyoshi Takekuma*
Extensive investigations have been made for develop-ment of the ships of each generation from view points of hydrodynamics, structural strength and so on, accompanied
with development of high powered combustion engines.
Fruitful experiences have been accumulated through both
investigations and practical applications in the course of
design and construction, and they have been reflected on
the design of the following ships.
Major problems in the design and construction of the cellular container ships were encountered in relation to
their large size, high powered propulsion engine and high
speed in service which were almost the same as those of
very large transatlantic passenger liners and sonic famous battle ships in the past.
Hydrodynamic aspects of ship's performance, namely, propulsive performance, vibration excitation,
manoeuvra-bility and seakeeping quality were the most important items to be investigated, and efforts have been made to improve the performance by the investigations made in various fields of hydrodynamics by means of theoretical
calculations, model experiments and full scale measure-ments. The ship forms with excellent propulsive perform-ance have been obtained by application of basic studies on wave making and wave breaking phenomena on the water surface, turbulent boundary layer on the hull surface, flow around stern and so on. Lower level of vibration excitation has been pursued through basic studies on the cavitation on the propeller blades operating in non-uniform flow behind
a ship.
In the design of the twin screw container ships of 2nd generation, extensive studies were made for the design of
bossings to carry the propeller shafts, from view points
of propulsive performance, shaft alignment, structural
strength, vibration and maintenance. Steering quality in
passing through the narrow channels such as Panama Canal was also studied to determine the stern and rudder arrange-ment. Prediction of ship motions in waves and various wave loads has been requested for structural design of the cellular container ships operated in higher service speed in rough
sea. Computational means for the pre-diction and the statistical analysis have
been developed together with model
test technique and full scale measure-ments on the transpacific routes.
The cellular container ships built in
MHI have been designed and
con-structed on the basis of the fruitful
experiences accumulated through theinvestigations as above.
This paper outlines first the trend
of the cellular container ships built in MITI and the problems encountered in
the course of their design and
con-struction from hydrodynamic point of view. Next, the investigations made to
cope with those problems are
de-scribed, such as application of
theo-ries, results of model experiments and
full scale measurements made in sea trials and in service.
Finally, some description will be given on the design of the advanced
economy class of container ships,
con-struction of which was the greatest
events in the shipping world in recent
years.
2.
Trend of the cellular container
ships built in MHI and the pro-blems encountered in the field of ship hydrodynamics
Major items of the cellular contain-er ships, namely, principal dimensions, fullness coefficients, main engine out-put, service speed, container carrying
capacity and so on are illustrated in
Table 1. Chronological changes of the items as above are illustrated in Figs. I
and 2.
The sea container transportation system started with operation of the
Hakone Maru class (ship lin Table I) of single screw ships with 750 TEU on the transpacific routes between Japan and west coast of USA. At almost the
same time, the Hakozaki Mani class (ship IV in Table 1) of single screw
ships with 1000 TEU entered into
serv-ice for the route between Japan and
south east coast of Australia as shown
in Fig. 3.
Those single screw ship are called
the ist generation type. They were
larger and faster with higher main
engine
output, compared with the
conventional type of cargo liners
which had been operated
in thoseroutes. Some photographs in the sea
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TEChNICAL REVIEW October 1980
trials of the ist generation ships are illustrated in Figs. 4,
S and 6.
Development of ship forms and propellers was made on the basis of the accumulated experiences on the preceding cargo liners together with application of theoretical studies on wave making resistance. Problems of propellers for high powered propulsion in high speeds were studied from
view-Fig. 2 Chrono ogical change of power, speed and TEU
Fig. i Chronological change of principal dimensions of container ships built in MHI
points of cavitation erosion and strength of the blades. The
seakeeping qualities, namely, ship motions, wave loads,
shipping water on deck and so on were extensively investi-gated by theoretical calculations, model experiments and
full scale measurements.
Then followed the 2nd generation ships with much larger size, remarkably higher main engine output and
Delivery 1969 1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 t000 26 24
20
-ist generation ships
2nd 2nd generatIon ships generation ships 3rd generation ships 18 17
.#
p5ist gene ation ships ® i ® \ o 3rd generation 5h 18 ships 2nd generation ships 3rd e generation ships ist generation Dehvc r 1069 1970 1971 1972 1973 1974 1975 1976 t 1977 1978 1979 060
J
Fig. 4 ist generation ships in sea triaI (1)
Fig. 3 Major sea routes around Japan
Fig. 5 Ist generation ships in sea trial (2)
r
-Fig. 6 ist generation ships in sea trial (3)
Mitsubishi heavy industries, Ltd.
higher service speed than those of the previous types of merchant ships, except very large sized and high speed
passenger ships operated in the Atlantic. Photographs in sea trials of the 2nd generation ships are illustrated in Figs. 7, 8
and 9.
In the development of the hull form of the Kamakura
Maru (ship VI in table 1), improvement of economical
aspects, namely, larger container carrying capacity, larger dead weight and easier operational ability of loading
condi-tions were more strongly required. Those requirements
were satisfied by development of new Mill type hull form with a protruding bulbous bow, extremely V shaped frame line, large water plane area, appropriate location of
longi-tudinal center of buoyancy and so on. Hydrodynamic
characteristics of the hossing for twin screw ships, namely, effect of the shape on propulsive performance, flow around
propellers, bearing forces and so on were investigated
together with study on the steering quality of twin screw and single rudder type of container ships.
After the delivery of the Kamakura Maru type of ships,
investigations into twin screw or triple screw container
ships with panamax size and service speed in 30 knots was started taking into account the operation of the SL-7 type of twin screw container ships with main engine output of
120000 PS and 30 knots in service. The results were applied to the design and construction of the Kasuga Maru type
(ship IX in table 1) of twin screw ship with the largest size passing the Panama Canal, but with a little less speed than
SL-7 in view of economics.
Remarkable improvement of various aspects of the ship was introduced in comparison with those of the Kamakura Maru type of ships, for example, larger container carrying capacity, larger dead weight, better propulsive performance due to the improved slender shaped bossings.
Design and construction of the 2nd generation ships was
a commemorating event in the history of Japanese ship-building industry, namely, the complete recovery of the Japanese shipbuilding technology on the large sized and high speed multi-screw ships which was completely lost
through the defeat in the 2nd world war.
With the advancement of the sea container
transporta-Fig. 10 3rd generation ships in sca trial (1)
TECHNICAL REVIEW October ¡980
Fig. II 3rd generation ships in sea trial (2)
253
tion system in the major sea routes of the world,
replen-ishment by newly built ships or replacement of the original first generation ships have been promoted. The single screw
ships with almost the same handy size as those of the Ist generation ships were considered to be suitable for the
purpose, but economical aspects such as higher propulsive performance, larger container carrying capacity and so ori
were more demanding. Further, more economical ships with better propulsive performance have been strongly
requested to cope with remarkable rise of bunker oil price. Such single screw ships with improved economical
as-pects are called the 3rd generation ships. The ship forms
and propellers of the 3rd generation ships have been
desig-ned to get as high propulsive performance as possible within the design constraints, such as larger container carrying capacity, lower level of vibration excitation and so on.
Photographs in sea trials of some 3rd generation ships are illustrated in Figs. 10, 11 and 12.
Improvement in economical aspects as above is shown by trend of TEU versus ship length and TEU/LBD versus Codm illustrated in Figs. 13 and 14.
Those ships have a largely protruding bulbous bow, a
stern profile with large clearance between hull and propel-ler, and appropriate size of stern bulb designed to achieve better propulsive performance and lower level of vibration excitation. Frame lines of fore and after body are
extreme-ly V shaped to satisfy the requirement of stability and
larger container carrying capacity. Much attention was paid in the design of after body to improve the flow around the
propeller.
The propellers have been designed by use of NIH! stand-ard propeller series as the best compromise of the various requirements such as higher propulsive efficiency, less ero-sion, lower level of vibration and less weight within proper consideration of fatigue strength.
The cellular container ships designed and constructed by MHI have been successfully operated in service with ap-preciation of ship owners on high propulsive performance, low level of vibration, easy operational ability of loading, proper hull strength and so on.
150 200 250
(m)
300
3. Major items of investigations made for development of the container ships
As mentioned in the previous sections, various problems were encountered in relation to hydrodynamic characteri-stics of the ships and extensive investigations as shown in
Table 2 were made for development of each type of con-tainer ships.
The investigations are classified into 5 categories as
fol-lows.
Development of hull form by application of hydro-dynamic theory and experimental study on the flow
around a hull.
Study on the hydrodynamic characteristics of bossings
for twin screw ships.
Investigations on hydrodynamic characteristics of
pro-1, 1.5 L4 13 1.2 1.1 10 0.9 IOU 450 XV 500 23.V) Cd,,= Xii 550 11
pellers, such as open-water characteristics, cavitation, vibratory forces and strength of tite blades.
Experimental study on the steering quality of twin screw ships with single rudder.
Investigations on seakeeping quality, such as applica-tion of theory, model experiments and full scale
meas-urements.
In the following, major items of the investigations made in hydrodynamic aspects are described.
3.1 Development of hull form
3.1.1 Application of wave resistance theory
Application of the linearized wave making resistance
theory to hull form design had already been attempted ori the conventional type of cargo liners before the appearance of container ships. Numerical calculation and experimental verification had been made on some methods of hull form
Mitsubishi Heavy Industries, Ltd. Item
Ship
Propulsive performance
Propeller Manoeuvrability Seakeeping quality
Hull form Appendage
ist
genera-tion shi
Application of wave
resistance theory Study on flow around a propeller by wake
survey
Application of propeller
theory
Study on propeller with higher pitch ratio and expanded area ratio Study on strength of
blade
Application of strip theory and wave
statistics
Advancement of model
test technique
Full scale tests in service 2nd genera Application of wave resistance theory Development of new hull form Study on hydrodynamic characteristics of large sired bossings Development of slender shaped bussing Development of
pro-pellers for twin screw ships
Study on propellers for
very high powered ship
Comparative study
on rudder and
pro-peller
configura-iO S the same as above
3rd genera-tion ships
Development of new hull form with high economical
perform-ance
Improvement of flow around propeller
Study on propellers
with lower level of
vibration excitation
Design of propeller compromising effi-ciency, erosion and
vibration excitation Confirmation of proper manoeu-vrability Contribution to ration-alization of structural design Improvement of soft
ware system for cal-culation
Fig. 13 Advancement of economical aspects (1) Fig. 14 Advancement of economical aspects (2)
'n 20 30 x10
Result of wave analysis
F,.= 0.250
Onginar hull form
Modified hull form
'i
Result of wave analysis
F=0 258
Originar huf form
9 (deg)
Result of wave analysis
Fn = O 258
TECHNICAL REVIEW October 1980
Fig. 16 Effcct of large sized bulbous bow
design and improvement based on the theory of minimum
wave resistance, theory of waveless hull form and wave pattern analysis.
With the coming of the container ship age, the study was accelerated because of stronger requirement for speeds, and extensive investigations were made into design and modifi-cation of sectional area curve, protruding bulbous bow and bulbous stern. Some results are shown in Figs. 15 and 16.
t
020
Modification of sectional area curves
0.16 0.18 0.20 0.22 0.24 026
Fig. 17 Effect of large sized stern bulb
Result of resistance test
F,,
F,, =
r'
t'
0.25
Result of resistance test
028 0.30
tu
030
-And hull fornis with remarkably less resistance were
ob-tained as exemplifiled in Fig. 17.
Further to the above investigations, development of higher order theory was studied, taking into account the
results of experiments on the separation of resistance com-ponents, on the wave breaking phenomenon particular to
bow near field, as shown in Fig. 18. The higher order
theory thus developed was proved to give better explana-Fig. 15 Effect of modification of sectional area curves
(
Result of resistance test20 40
8 (deg)
60 80
Original hut form Bulbous bow
0,25 0.30 0.20 F,, 30 40 10 20 9 (deg)
0.010
0035
n
Fig. 18 Wave breaking phenomenon around bow
0.10 0.12 014 0.16
C = O. 78 C = 0.74
° C56
0.18 0.20 0.22 0.24 026 0,28 0.30 0.32 0.34 F
Fig. 19 Comparison of measured and calculated wave making resistance coefficient
tiori of wave-making characteristics of various hull forms
and to yield numerical values with practicable accuracy. Some results are illustrated in Fig. 19.
3.1 .2 Study on viscous resistance and flow around a propeller
Irs the design of after body, efforts have been made to
decrease viscous resistance of the hull and to obtain a
favorable flow pattern around the propeller. Since the ship
boundary layer theory had not yet been at the stage of
quantitative estimation of the viscous resistance and wake distributions, the theory was utilized as guidance for vary-ing hull forms and the study on the after body design was made mostly on experimental basis. An example of wake pattern thus obtained in the plane of propeller is illustrated in Fig. 20. With fairly equalized velocity distribution, low wake peak and little turbulence, this wake pattern turned out to be satisfactory from viewpoint of vibration excita-tion and cavitaexcita-tion erosion of propeller.
3.1.3 Development with a view to more economical
hull form
Hull forms of the first generation ships succeeded the properties of the preceding cargo liners, though many
improvements had been introduced as stated above, retain-ing slightly V shaped frame lines, a relatively small bulbous
bow and clear water stern.
In the design of second generation ships, an extremely V shaped fore body with largely protruding bulbous bow was examined to cope with the economical requirements.
Val-uable informations obtained by theory were applied
to-gether with experiences accumulated on both the conven-tional cargo liners and the first generation container ships, and thus the new hull form for the second generation ship
was successfully designed.
In the design of the third generation ships with almost the same handy size as the first generation ships but with much more economy, extensive investigations were made
into hydrodynamic characteristics of principal factors of
hull form, namely, water plane curve, frame line of fore and
0.80
075
Fig. 20 Wake contour curves of a single
screw container ship 085 Ill 0.70 V N 2.0 2.5 3.0 JI h E 52 51 ro
O ist Generation sups o 2nd generaton ships
3rd generatan ships
(IC)
30
Fig. 21 Trends of hull form of container ships built in MHI
after body, sectional area curve, longitudinal location of
center of buoyancy, bow and stern bulb, stern profile and propeller tip hull clearance. In Fig. 21 are shown the water plane area and longitudinal center of buoyancy. The model experiments and theoretical studies were carried out with
a view to better propulsive performance, lower level of
vibration, more cargo carrying capacity and more efficient operation.
Experiences of the second generation ships were also
reflected to the design. The third generation ships contrast with the first generation ships in extremely V shaped frame
lines, largely protruding bulbous bow, properly shaped
stern bulb and larger propeller tip hull clearance. Compara-tive figures of ist and 3rd generation ships are illustrated in Fig. 22. Experience gained on each of the 3rd generation ships has been included in the design of the next ship, thus
improvement of hull form has been steadily continued to Mitsub ish i Heavy Industries, Ltd.
Calculated by newly devetoped theory
cao
o Obtaned by wave analysis
BL
construct a more economical ship.
3.1.4 Shafting supports for twin screw ships
Shafting apparatus is the essential item to be investigated in the design of multi-screw ships, because of its influence
on propulsive performance of ships, namely, increase of
resistance, effect on self-propulsion factors and flow around a propeller. Shaft-bracket type installed usually to the small sized twin screw slups is not always applicable to the large sized and high powered ships, because of difficulty in fabri-cation and in maintenance of shafts.
In the case of the 2nd generation ships, easier
mainte-nance of shafts and avoidance of shafting problem were
strongly requested. Thus, a bossing type with large diameter
was adopted in spite of larger resistance.
Effect of fillet angle of bossings on the resistance, self-propulsion factors and flow around a propeller was studied in connection with effect of frame line form of after body.
The shape of bossings was refined as much as possible within the design constraints, namely, shafting
arrange-ment, structural strength, maintenance and so on.
Outward rotation of propeller was chosen with suitable fillet angle because of better propulsive performance, less unsymmetrical bearing forces and smoother flow around a propeller than those in the case of inward rotation.
Experi-ences of seamen on the steering in low speed operation
were also taken into consideration. Some model test results
are illustrated in Fig. 23. Good performance as expected
was demonstrated in sea trials and in services without such
problems as experienced by some other type of ship on
which inward rotation of propeller was adopted.
After development of Kamakura Maru (ship VI in Table 1), refinement of shape of bossings was extensively studied
from viewpoints of hydrodynamics, structural strength,
maintenance, fabrication and so on, taking into account the experiences obtained by the Kamakura Maru type of ships.
As a result, the bossing with smaller diameter and more
refined shape was developed and was installed successfully to Kasuga Maru (ship IX in Table I), the twin screw con-tainer ship with panamax size as shown in Fig. 24.
3.2 Propeller
On the design of a propeller, the following requirements
are usually imposed.
(I)
Avoidance of resonance of vibration(2) Higher propulsive performance
TECHNICAL REVIEW October 1980
Fig. 22 Comparison of the ist and 3rd generation ships
Outward turning
A AC
A8C
Bonsing Bossing
Fig. 24 Effect of size of bossings on propulsive performance of a twin screw container ship
Less erosion on the blades Lower level of vibration excitation
Less propeller weight within the proper consideration of fatigue strength.
Which of these requirements is important and what is to be
done have been changing with each generation as follows.
3.2.1 Propellers for the first generation ships
In this generation, efforts were made chiefly to extend design data such as open-water and cavitation
characteri-sties of propellers to the range of higher pitch ratio and
larger expanded area ratio. The work was done not only by experiments, but also by application of theory. Compara-tive studies on the wake-adapted propellers have been made
B
'j
Trial loadn
n
'II
AB
BL Fillet angle B Larger angle C Srsaller angleFig. 23 Effect of fillet angle and turning direction of propellers on propulsive performance of a twin screw container ship
3rd generation sFap L 1
N:N
V\
h---
¿./
f-
/
/
-
I I t/
/
TT-::5t
generasse ship I \\\
\\
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f
t
AJ
1\
Fillet angle A Standard
C A A 8 C A Bossing Bossing
Fut load mal load ic 95 Q-= o-9O
258 3 2
(7
N 60 120 180 240 300 360 O (deg)Fig. 26 Comparison of measured and calculated blade stress of a propeller
and effect of propeller particulars, for example, number of
blades, expanded area ratio and so on was examined as
shown in Fig. 25. As the results, the original MHI type of five-hiaded propellers was adopted for the first generation ships, since it was found to be equal to theoretically opti-mum propellers in respect of performance and more reliable
in view of service experience.
Strength of blades was also a matter of concern, since a number of blade failures was then reported on high speed single screw merchant ships in many countries.
Along with extensive investigations on model propellers, full scale measurement was undertaken on Hakone Marsa, which provided with valuable data for the strength design (cf. Fig. 26). Further, a quasi-steady method of estimating
propeller shaft forces was developed in the course of the
investigations and was applied successfully to the study on
structure of bossings of the twin screw 2nd generation ships.
3.2.2 Propellers for the second generation ships
For the 2nd generation ships featured by high speed and high powered twin screw propulsion, investigations were
P 1451 P=Iou A, A4 06426 Z=5 P, 1450 P 1.05 A...44O75 Z=5 P 1452 P.LO5 A,fA=O 5425 l 1453 P= LOS A,/A4= 075 z4
Fig. 25 Cavitation patterns
(Effect of expanded area and No. of blade)
- Measured on Hakone Maru
Calculated by quassteady
method
::6,p:O.89 z:7.p:O.88
AeIAdl.l
AeIAd:I.20Fig. 27 Cavitation patterns on 4, 5, 6 and 7 bladed propellers with large expanded area
made mainly into the cavitation characteristics, and as a
result the MHI type five-bladed propellers were adopted
with some modification to the leading edge.
The studies were made further on the propellers with expanded area ratio larger than 0.9. Effect of number of
blades, Z = 4, 5, 6 and 7, outline shape of propeller blade, blade section and so on were examined by model testsas
shown in Fig. 27. Those results were not applied to the
design of the propellers for the Kasuga Mari.i, but theywere
employed as useful material in the development of
pro-peller for the 3rd generation ships.
3.2.3 Propellers for the 3rd generation ships
With the recently increasing requirements for lower level
of vibration, studies in various fieldstheory, model tests
and full scale testswere made on excitation forces induced
by cavitating propeller.
Influence of various features of propellers, namely, pitch distribution, skew, outline shape of blade, expanded area ratio and number of blades on the cavitation phenomena on propeller blades were extensively investigated together with studies on the flow around a propeller. Some examples of them are illustrated in Fig. 28.
Some sophisticated design with high skew, remarkable
unloading at tip and hollow face section was found to be
effective for decreasing the vibration excitation, but with deteriorated propulsive performance and larger risk of
ero-sion. As the
best compromise of vibration, propulsiveperformance and erosion, the five-bladed propeller of the
MHI type was adopted to the 3rd generation ships with
some modifications of outline and blade section shape.
Excellent performance of the propellers designed as
above have been demonstrated in sea trials and in services.
The MHI built container ships have experienced no
pro-blems arising from improper design of propeller in contrast
Mitsu bis/ii Heavy Industries. Ltd.
¿2
CT
:4,p :0.91 2:S,p:0.90
Sliew & ootne
Pitch dmtnbution
t t
0.5 0.6 0 7 0.8 0.9 LO
nR
Fig. 28 Some examples of pitch distributions skews of propellers
with some reports on severe erosion and vibration problems which occurred on the other type of container ships.
3.3 Manoeuvrability of twin screw container ships
In the course of development of twin screw container ships, investigations were made into rudder and stern
ar-rangement from viewpoint of the course-keeping quality of ships passing through the narrow channels, such as Gailard Cut in Panama Canal, as well as propulsive performance.
Twin rudder type was excluded from the viewpoint of
propulsive performance though better course-keeping
quali-ty was expected.
Then comparative model experiments on 3 types of sin-gle rudder and stern arrangement of twin screw container ships of the Kamakura Mani type were made as shown in Fig. 29. As a result, a single mariner type rudder with large area was adopted together with propellers arranged close to
each other so that the rudder may enter the slipstream of
the propellers with small rudder angles. A center line skeg was fitted to the hull above rudder to increase course
sta-bility. Good manoeuvrability expected as above was
de-monstrated in sea trials and in services, as illustrated in Fig. 30. In the case of single screw container ships, appropriate manoeuvrability was obtained by the stern arrangement as mentioned in Chapter 3.1.
3.4 Study on the seakeeping quality
Prediction of ship motions and wave-induced loads encountered in rough seas is one of the most important
items in the design of container ships with large openings on the deck. Prevention of shipping water on the weather
deck is also important to avoid the accidental damage of containers loaded on the weather deck. And at the same
time, prediction of torsional moment and stress induced in
the rough sea has been also a serious concern.
In order to make the predictions, methods of calculation of ship motions, resistance increase and wave-induced loads in regular wave was developed and has been improved
con-stantly incorporating model experiment data and results
TECHNICAL REVIEW October 1980
r
Fig. 31 Full scale measurement in service (I)
I
1.2 1.0 0.8 0.6 04 0.2 10 0.2 04 06 0.8 1.0 O (deg) 20 30 40Fig. 30 Reverse spiral test results on Kamakura Maru
from theoretical investigations. Statistical prediction of
various items of seakeeping quality in irregular waves was
made on the basis of the data in regular waves by using
wave spectrum. Some kinds of extreme values statistically predicted have been examined in the course of design and
they were confirmed by full scale tests made on some of
the ist and 2nd generation ships as shown in Figs. 31, 32
and 33.
Since the completion of the seakpeeing and manoeuvring
basin in MI-11, extensive investigations have been conducted
to make clear various aspects of seakeeping quality together with advancement of experimental techniques. As a result,
a software system for prediction has been improved and
applied for various aspects of the ship design as shown in Fig. 34. By virtue of this, remarkable improvements in the
structural design of Kasuga Maru, Thames Mani and the
259
Hanging rudder Spade rudder Seru-banced
(small tip to Sp rudder
clearance
Fig. 29 Typical stern arrangement of twin screw container ships
I
(a -a o 4 (a AIL olliw (a )
cs2
a ca IP D H oO3 aa.
Heave RailA
---
A 0.5 1.0 1.5 2.0 0 (a o A Jo 34 10-20 - 10 O 40 30 20 A O 2 10 Regular wave S.S.1/2 Pdship s.S.g ru ru n ru.rD 1.0 1.5 Q 0.2 -o oit
1.5 20 O 04 03 0.2 --01 A 10_-
---5 lO 0.5 1.0 1.5 20 0ll,a> (m) full scale
AIL
Fig. 34 Comparison of scakeeping quality
5
10 o
Midship
s s.g
Hit,)) (m) fall scale
20 15
Speed drop Regular wave
lo still waler
11/4
500
Irregular wave
f!it,i (m) full scale
03 02 0.1 o Irregular wave S.Sl/2 A o o A 1,5 1.0 0.5 2.0
-o----Calculated A o p = 180 p = 90 Regular wave Irregular wave o Pitch o 5 A A3rd generation ships were achieved.
The experiences obtained through investigations on both
models and ships as above to the hull form design were
applied to the 3rd generation ships, for example, design of frameline of fore part of the ship, appropriate combination of sectional area and water plane curves.
4. Design of the advanced economy class of single screw container ships
The ships belonging to the last three columns in Table 1
are featured by advanced economy in the 3rd generation
ships. In this section, some explanations are given on the design of the typical one of those ships. lt was intended for world-wide service with the performance to cope with the urgent need for lowering the operating cost. After careful evaluation on various types of ships, a class of handy sized
diesel driven single screw ships was chosen as the most suitable one, and construction of a fleet of 12 ships was decided.
MHI took part in the owner's construction program as
the design agent, and constructed 7 of 12 ships. In the course of design, emphasis was laid on achievement of
economical performance, namely, larger container carrying
capacity, higher propulsive performance and at the same
130 120
z
C
Measured
S Corrected to no wind and Sde
- - - - Estimated from model test result
18 19 20 21 22 23 24
V, (kn)
Fig. 35 Speed trial results
TECHNICAL REVIEW. October 1980
Fig. 36 Flow visualization around a propeller
time lower level of vibration and noise was required.
Seakeeping quality, namely, avoidance of structural failureof the hull due to wave impact load and damage of
con-tainers on the weather deck by shipping water was
investi-gated, because relatively small depth of the hull was
a-dopted in order to save steel hull weight.
Hull form and propeller were designed to meet the design requirements as above on the basis of the
experi-ences and the investigations mentioned in the previous sec-tions. The hull form followed the features of the 3rd gen-eration ships described in 3.1, such as extremely V shaped
0.04
0 03
0.02
0.01
0=40° 0=80°
Fig. 37 Cavitation test result
Ship de, Ship o Aa. Model 'Ode -.---I i i i I i 1.1 1.2 1.3 1.4 5 1.6 1.7 18 1.9 = - Pr2D
Fig. 38 Pressure fluctuations above a propeller
o= 0° o = 60°
U= 20° O= 70°
20000
Fig. 39 Turning test result
Fig. 40 Locus of the center of gravity
Beaufort scale 9 o
Meajred j Culculated
frame line of fore and after body with largely protruding
bulbous bow. Location of center of buoyancy was carefully
chosen to maintain little trim with least water ballast.
Afterbody was designed considering both propulsive per-formance and vibration excitation, and a Hogner type stern
was adopted with large propeller hull clearance and ap-propriate water line endings. The bulwark and the
break-vater on the forecastle were designed on the basis of model
tests in heavy seas. Frame line shape of forebody above water was also carefully determined to avoid excessive wave
impact load.
In the course of propeller design, extensive study was
made on various kinds of propellers in view of propulsive performance, erosion, vibration excitation and so on.
Num-ber of propeller blade, skew, pitch distribution and
ex-panded area ratio were changed systematically. As a result, a five-bladed wake-adapted propeller with slightly increing pitch was chosen as a best compromise of various as-pects of the propeller performance.
At present total of 12 ships have already been delivered,
and all the ship are under service with high economical
performance. Some results of model and full scale trials are illustrated in Figs. 35-42.
Fig. 41 Seakeeping test results (Significant values of ship motions)
Fig. 42 Seakeepirig test
S. Concluding remarks
Summarizing the hydrodynamic design and the devel-opment of high speed container ships in MHI, the
follow-ings are regarded as main features.
Major problems in the design of container ships were encountered in relation to their large size, high powered
propulsion engine and high speed in service.
Hydrodynamic aspects of the problems, namely, pro-pulsive performance, vibration excitation,
manoeuvra-biity and seakeeping quality were the most serious
concerns and needed extensive investigations on the basis of basic researches on ship hydrodynamics.
Takekuma K., Some Problems on the Applications of Line-arized Wave Making Resistance Theory to Hull Form Design, International Seminar on Wave Resistance (1976)
Baba E., Ship Form Improvement by Use of Wave Pattern Analysis, Mitsubishi Technical Bulletin, No. 85
Baba E., Study on Separation of Ship Resistance
Compo-nents, Mitsubishi Technical Bulletin, No. 59
Baba E. & Takekuma K., A Study on Free Surface Flow around Bow of Slowly Moving Full Forms. Journal of the
Society of Naval Architects of Japan, No. 137
Takekuma K., Study on the Non-linear Free Surface Problem
around Bow, Journal of the Society of Naval Architects in
Japan, Vol. 132
Baba E., Wave Breaking Resistance of Ships, International
Seminar on Wave Resistance (1976)
Baba E. & Hara M., Numerical Evaluation of a Wave-Resist-ance Theory for Slow Ships, Mitsubishi Technical Bulletin,
No. 125
Fujita T., On the Flow Measurement in High Wake Region at the Propeller Plane, Journal of the Society of Naval Architects in Japan, Vol. 145
Nagamatsu T., A Method for Predicting Ship Wake from
Model Wake, Journal of the Society of Naval Architects in Japan, Vol. 146
Nagamatsu T., Calculation of Viscous Pressure Resistance of
Ships Based on a Higher Order Boundary Layer Theory,
Journal of the Society of Naval Architects in Japan, Vol. 147 Chiba N. & Hoshino T., Effect of Unsteady Cavity on Pro-peller-Induced Hydrodynamic Pressure, Journal of the Society of Naval Architects in Japan, Vol. 139
Chiba N. & Nakamura N., Highly Skewed Propeller, Journal of the Marine Engineering Society in Japan, Vol. 15, No. 3 (1980)
Sasajima T. et al., Propeller Stress Measurements on the Con-tainer Ship Hakone Maru, ISME Tokyo 73
TECHNICAL REVIEW October 1980
References
263
Improvement of economical aspects, namely, larger
container carrying capacity, higher propulsive perform-ance has been demanded all the time. Successful design of ships to meet the demand has been made on the basis of the results of investigations and developments above together with the accumulated experience.
High speed container ships designed and constructed in MHI have been successfully operated in service with
appreciation of ship owners.
Results of investigations and developments of the
con-tainer ships above have been further extended to other
classes of sophisticated ships, for example, the world largest
class of high speed roll on/roll off ships, a class of high speed reefers, passenger and car ferries and so on.
Sasajima T., Usefulness of Quasi-steady Approach for Estima-tion of Propeller Bearing Forces, Propeller Symposium 78.
(S NAME)
Tanibayashi H. & Nakanishi M., On the Method of Cavitation Tests for Prediction of Tip Erosion of Propeller, Journal of the Society of Naval Architects in Japan, No. 133
Tanibayashi H., Practical Approach to Unsteady Problems on Propellers, 2nd Lips Propeller Symposium (1973)
Fujii H. & Ogawara Y., Calculation of Heaving and Pitching Motions of a Ship by the Strip Method, Mitsubishi Technical Bulletin, No. 34
Takahashi T. & Fujii H., Experimental Study on the Ship
Motions and Hydrodynamic Pressure in Regular Oblique
Waves, Transactions of tise West Japan Society of Naval
Architects, No.49(1975)
Takahashi T. & Takekuma K., On the Evaluation of Sea
Spectra Based on the Measured Ship Motions, Transactions of the West Japan Society of Naval Architects, No.45 (1973)
Fujii H., Forced Oscillation Tests on Manoeuvrabiity in
Nagasaki Experimental Tank, Mitsubishi Technical Bulletin,
No. 63
Taniguchi K., On the New Seakeeping and Manoeuvring Basin of Nagasaki Technical Institute MHI, Transactions of the West Japan Society of Naval Architects, No. 45 (1973)
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Umezaki K. et al., Evaluation of Hull Girder Stress on the Open Ship (ist report) - Calculation of Total Hull Girder
Stress, Journal of the Society of Naval Architects of Japan,
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