388
Semi-Submerged Catamaran *
Masanao Osh ¡ma * *
Abstract
The Semi-Submerged Catamaran (SSC) has been expected as a new type of promising marine vehicle to break the various performance limitations imposed by the conventional
monohull or the conventional catamaran vessel.
This paper introduces the Outline about the characteristics of SSC performance and the
design conceptions on her propulsion system in addition to the outline of the commercial
prototype of SSC ferry for 446 passengers. which had been completed for the first time in the world at the end of August, 1979 at Chiba Yard of Mitsui Engineering & Shipbuilding Co., Ltd.
1. Introduction
The advancement of the means of transportation in the recent years is quite remarkable. On the sea,
demand for such vessels which are not only of high speed, safety, and economy, but also stable
and safe against all meteorological and Oceanogra-phic phenomena is rising higher for the purpose of
using them as passenger boats for ferrying to and from outlying islands, or as ships for performing
research, survey, work, observation, etc. relating to oceanographic development projects.
Mitsui Engineering & Shipbuilding Co., Ltd. (MES), having taken into consideration such a
trend of demand, started research and development
of the
so-called "Semi-Submerged Catamaran" (SSC) in 1970 as a type of vessel to best meet therequirements of the demand, and established its own theoretical calculation formula based on the results of its basic research on various kinds of performance in the initial stage and 0f the actual model experiment. Further, with the cooperation
0f the Japan Marine Machinery Development
Asso-ciation. it built in 1977 a 12-meter long experi-mental SSC model named the "Marine Ace" of which extensive sea trials were conducted to confirm various performances and structural
strength. With chis, all the characteristic features
of SSC have been actually proved as anticipated. Based on these accumulated technical factors, it
Manuscript received Febivary 20, 1980 Translated from Journal of MESJ, Vol. 15, No. 5 Mitsui Engineering & Shipbuilding Co., Ltd. (5-6-4, Tsukiji, Chuo-ku, Tokyo 104, Japan) (80)
finally decided to build, first
in the world, a
commercial prototype of SSC for 446-passenger capacity, the "SSC MESA 80", in 1978 under thesponsorship of the Japan Marine Machinery
Devel-opment Association, and successfully completed
its building in September last year.
Taking this opportunity, the important points calling for special attention with respect to the
general performance features and engine design of SSC as well as the outline of the "SSC MESA 80" are introduced as follows:
2. Outline and Characteristic Features of SSC
2.1 Outline of SSC
lt is said that the concept of SSC already existed
at the end of the 19th century, and although
patents relating thereto were already issued during
the period from the early part to the middle of che
20th century, these had not been put to practical use yet. It was around 1970 that research on SSC
v
c eeps.oiwnz.
Technische HogschooI
Delfi
/ Bulletin of the M.E.S.J., Vol.8, No. 4
/
was really US Navy, displacerne in 1973. lt oceanograp As the e it consists part of its which the connected. small, and completely Fig. 2.2 Chara Because differen t has the fo 2.2.1 M What S compariso motions h perfornian 3 conipa the cc-nyc meter Ion extremely the latter. For the re (i) The lation thus i n orni December Fig. I "SSC MESA 80" on Sea Trialswas really initiated in America sponsored by the US Navy, and an experimental SSC of 190-ton
displacement named the "KAIMALINO" was built
in 1973. lt is playing an active role in the field of
oceanographic experimental research.
As the configuration of SSC is shown by Fig. 2, it consists of the lower hulls which bear the major part of its displacement and the narrow struts with
which the lower hulls and the super structure are connected. The area of waterplane is extremely
small, and the lower hulls are designed to submerge completely under the water surface.
Single Strut Type
Upper Connecting Deck Lower Connecting Deck Strut
Lower Hull Fin
Fig. 2 Configuration of Semi.Subrnerged Catamaran
2.2 Characteristic Features of SSC
Because of the peculiar shape of SSC entirely different from the conventional type of ship. it
has the following characteristics:
2.2.1 Motion Characteristics in Waves
What SSC can demonstrate most remarkablly in comparison 'ith the conventional ship is its motions in waves. This is quite evident from the
performance characteristic curves as shown in Fig.
3 comparing motions in waves between SSC and the conventional type of monohull ship of
30-meter long respectively. The former demonstrated extremely excellent performance as compared with the latter.
For the reasons, the following points may be cited: (1) The waterplane area is so small that the
oscil-lation natural period becomes very long, and thus it is possible to avoid the resonance with normally encountering waves.
Semi-Submerged Catamaran 4 2 2Q w C lo w n o
s'
I s s SSC Monohull 389 '3f4
2 30 I\
/
w E -no-Twin Strut Type o 50
0 50 100 150 200
Wave length (m) Fig. 3 Comparison of Motions in Waves
(Length 30m, Speed 24knots)
(2) The external force applied by waves to the upper and the lower sections of the torpedo-shaped lower hull offset its force with each other making the vertical wave load smaller and thus reducing both motion displacement and acceleration. Furthermore, as SSC raises
motion characteristics in waves, fin stabilizers arc provided on four sides, fore & aft, inside of each lower hull. But automatic control, manual
control, fixed control or combined control of these three may be applied according to the intended vessel's speed and the presumed sea
conditions.
2.2.2 Speed Performance
In the case of the conventional monohull ship,
in the high speed range above Froude number 0.4,
it is impossible to design an economical ship
because of its increased wave making resistance.
Bin in the case of SSC, as shown by the
compara-tive curves of residual resistance coefficient be-tween SSC and monohull type in Fig. 4, its wave
making resistance becomes small in the high speed
range due to the narrow strut and the lower hull
100 150 200
Wave length (ru)
December 1980 (81) SSC Monohull
I_-.-
'C
50 100 150 200 Wave length (m)'a
SSC - a -- a Monohullid, a
enge r r the )evel-leted OintS the gn of 80" .cisted iough uring the etical a SSC No.40.8 0.6 - 0.4 1.0 0.2 2000 o C. C. 1000 1000 2000 3000 4000 5000
(t)
Fig. 6 Comparison of Deck Areas
types of work-ship which need large spaces.
Furthermore, with an opening provided in the middle part of the deck, it is possible to facilitate via this opening the loading and unloading of equipment, materials or cargoes at a safe location
avoiding ship's rolling and pitching by waves. This
is expected to greatly contribute to the improve-ment of work efficiency in the case of oceanogra-phic research & survey ships or diving support ships.
2.2.4 Maneuverability at Low Speed
Because of the ship's shape of large breadth, SSC
can be steered very efficiently by use of the
differential thrusts on both sides of the ship at alow-speed operation as well as spot turning.
There-fore, operation in narrow water channels, even in_port, etc. can be performed safely without the use of the side thrusters.
3. Main Engine for SSC
3.1 Location of the Main Engine
Because of the peculiar shape of SSC, the
location for the installation of the main engine can be considered either inside the lower hull or
on the connecting deck. In the case of a large-size
SSC of which speed is not required to be so high, its main engine is normally installed inside the
lower hull while in the case of a high-speed,
small-size SSC, it is installed on the connecting deck. From the viewpoint of maintenance and
inspec-tion, it is desirable that the ¡nain engine be installed on the connecting deck. Even in the case of
install-ing the main engine inside the lower hull, it is possible to locate the engine with no actual problem by properly arranging the location of
space and passage for maintenance and inspection, as well as monitoring and operating locations. Even
Bulletin of the M.E.S.J., Vol. 8,No.4
in the case o located insid. noise causes nographic re5 f work-ship consideration connecting d separated as 3.2 Aptitudl In order and speed çJ advantageous the measurei desired to b the main e compact and In the e-located on t make the en the spacious merits of S' other hand, inside the I to be built sufficiently 1 tion inside cl Thus in O the advanta form which of the exce performance necessary t_o the main ç equipments light as post the major p. determined engine, the focused on light-weight case of war passenger b is the key turbine can In respec 4,000 PS cl per horsep 0.25 kg/PS 2.7 kg/PS f for medium low-speed December19. 390 M. Oshinia 01 2 3 4 5 6 7 Sea state
Fig. S Comparison of Speed Down in Waves (30-meter long vessels)
which maintains a proper depth. As previously described, since SSC receives little wave force, speed loss in waves is very small. Fig. 5 shows the
comparison between SSC and the conventional monohull type 0f 30-meter long respectively in respect of their speed down in waves. These per-formance characteristics make it possible for
relatively smaller vessels to maintain high speed in
waves, and are the important advantage for such
smaller and medium size high speed passenger ferry
boats to meet their requirements of maintaining stable and constant operating schedule together with their economical ship operation. Likewise, if used for rescue and patrol mission understormy
weather, SSC is an ideal vessel to surely perform
the role of such mission.
2.2.3 Spacious Effective Deck Area
In the case of SSC, the ship's length/breadth ratio is more or less about 2-fold. As is evident from Fig. 6 which shows the comparison of the deck area on the basis 0f the displacement rate
between SSC and the monohull type, it is possible with SSC to maintain sufficiently spacious effective
deck area. Therefore, it can be said that SSC is of ari ideal shape to meet such requirements as may be demanded of such passenger ships and various (82)
1.0
O 0.5
Froude number ( v/,,rï)
j
in the case of a SSC of which main engine can be located inside the lower hull, where underwater
noise causes problem as in the case of an ocea-nographic research and survey ship or other type of work-ship, it may be necessary to pay special consideration for locating the main engine on the connecting deck so that the source of noisc can be
separated as far as possible from the water surface. 3.2 Aptitude of Main Engine for SSC
In order to upgrade the motion characteristic and speed performance in waves which are the advantageous features of SSC as described above,
the measurements of strut and lower hull are
desired to be made as small as possible. Therefore,
thè main engine is desired to be built small,
compact and light-weight to the possible extent.
In the case where the main engine is to be located on the connecting deck, it is desirable to make the engine room as small as possible so that the spacious deck area, which is one of the major merits of SSC, can be effectively utilized. On the other hand, where the main engine is to be located
inside the lower hull, the main engine is desirous to be built as small as possible in order to secure sufficiently large space for maintenance and inspec-tion inside the limited space area of thelower hull.
Thus in order to make the most effective useof the advantageous features of the ship's shape and form which highly contribute to the enhancement of the excellent motion characteristic and speed
performance in wave of SSC, it naturally becomes necessary to make the size and weight of not only
the main engine, but also any other engines, equipments and machines as small, compact and
light as possible. For this purpose, since weight and
the major part of the space of the machineries are determined depending on the kinds of the main engine, the target of selecting main engine is
focused on a high-speed diesel engine of small-size,
light-weight and large output. Especially, in the
case of warships, naval vessels, or some high-speed
passenger boats for which high-speed performance
is the key requirement, the aircraftderivative gas
turbine can be considered.
In respect of various types of engines of the 4,000 PS class, a comparative example of weight per horsepower gives the following data: About
0.25 kg/PS for aircraft derivative gas turbine, about
2.7 kg/PS for high-speed diesel, about 11.5kg/PS
for medium-speed diesel, and about 20.5 kg/PSfor low-speed diesel. Thus it is well understood that,
December 1980
e
Semi-Submerged Catamaran 391
by use of a high-speed diesel engine, it is possible not only to make the effective utilization of the spacious deck area of SSC, but also to take on
much more dead weight, which is possible tomake
SSC more economic.
Hitherto, mostly gas oil is being used for the fuel of high-speed diesel engines except for a few
special cases where diesel oil is also used. But with
the rising demand for use of lower quality fuel due to the spiralling crude oil price in the recent
years, certain high-speed diesel engine makers have allowed to use the low grade fuel oil by setting up
the rated output of the engine at a sacrifice of
output per cylinder to a certain extent and also by
setting up certain restriction on use of such low grade fuel oil in ship operations, thought it does not yet reach to the level which low-speed or
medium-speed diesel engines are allowed to use it.
And they now are gradually giving satisfactory results on other type of ships. This, indeed, is a good indication of SSC's capability to cope with the needs of today.
4. SSC's Power Transmission System
In the case that the main engine is installed
inside the lower hull, the arrangement of the main engine, reduction gear and the shafting is the same
as in the case of a normal type of ship. However, the space inside the lower hull and the strut where this power transmission system is installed is much
smaller as compared with that of a normal type of
ship. Because of this, a sufficient study is necessary
for securing enough space for maintenance and inspection, and for the location of monitoring and operating. But in this report, description will be given only relating to the power transmission system in the case that the main engine islocated
on the connecting deck which is quite different from the conventional type of ship.
Where the main engine is located on the connect-ing deck, there are considerable two ways of power
transmission from the engine installed on the connecting deck to the propeller shaft located in the lower hull: One is the mechanical method and
the other is the electrical method.
4.1 Mechanical Power Transmission System
For the mechanical power transmission system,
there are considerable two methods, one is by bevel gear transmission, and the other by chain
transmission. (83) is the .ditate ig of :atiofl This Drove- logra-pport i, SSC .f the p at a There-even it the I , the gin e uil or e-size high, e the small-deck. ISpec-tailed nst all-it is actual
an of
Ct Ofl, Even No.4392 M. Oshima
(84)
F215 C& .
O ,nrS,,,gr 9Ep tiar ,nr,s,..çr .tA SERS
.'(RT Ihr S.aflr ¿0*66
fl.t* nr
19
Fig. 7 Bevel Gear Power Transmission System Adopted by "SSC MESA 80"
MES adopted the bevel gear transmission system
for power transmission for both the "MARINE ACE" and the "SSC MESA 80", while the US Navy's "KAIMALINO" adopted the chain
trans-mission system. Fig. 7 shows the example of bevel gear transmission adopted by the 'SSC MESA 80"
and Fig. 8 shows the example of power trans-mission adopted by the "KAIMALINO."
In the case of the mechanical power transmission
system, as part 0f the transmission system is installed inside the narrow spaced strut, it is desirable that the dimensions of such portion of power transmission system are ¡nade as small as possible. Moreover, as the strut has low rigidity
toward the vessel's transverse direction, the portion
of the transmission system to be installed inside the Strut must be of such nature as to obediently
follow the deformation of strut, andmust transmit
power accurately without lessening its own func-tion.
4.1.1 Bevel Gear Transmission System
This type 0f power transmission system is called "T-drive" or "Z-drive", and these have been inuse since before for outboard propellers and for the
shafting systems of some hydrofoilcrafts and hovercrafts and have recorded many successful results. Careful comparative studies were
under-I
I ILi
V
UI I,liii
-2 i' 'W I e D,Diu p,eoçcE, KISS n.,, couni,.o'.:.
' 'NN. We 'tfl (*,1U,GFig. S Chain Power Transmission System Adopted by "KAIMALINO"
Bulletin of the M.E.S.J., Vol. 8, No.4
8 ç 6 taken on v tenis in the as the resu was selectei small-size, I reliability, 80" after i' of bevel-ge craft. This called "DS nism is as conception As sho gears are I each of inside the such an horizontal counter b In other installed i each other force so t shaft can driving Po transferre upper bey converged bevel gear advantage Fig. December
-by
). 4
I
December 1980
taken on various kinds 0f power transmission
sys-tems in the building 0f the "SSC MESA $0", and as the results, the bevel-gear transmission system
was selected for its light weightriess, compact and
small-size, high transmission efficiency, and high reliability, and was adopted to the "SSC MESA 80" after it was developed by MES as a new type
of bevel-gear driving system best adaptable to said
craft. This new type of power transfer system is
called "DSD" (Dual Shaft Drive) of which
mnecha-nism is as shown by Fig. 7. Fig. 9 represents the conceptional drawing of this "DSD" system.
As shown by the drawing, two pairs of bevel gears are located on a horizontal floating shaft, each of which is supported by roller bearings inside the upper and lower bevel gear boxes, in such an arrangement as the reaction force in horizontal direction 0f each pair of bevel gear
counter balances that of another pair of bevel gear.
In other words, these two pairs of bevel gears
installed inside the gear boxes are working against each other to counter balance each other's reaction
force so that the thrust bearing on the horizontal shaft can be eliminated. By this mechanism, the
driving power from the main engine is shared and transferred equally by the two output shafts in the
upper bevel gear box, and its driving power is converged into one output shaft by the lower bevel gear system. This system has the following advantages:
Lower gear box
Fig. 9 Conceptional Drawing of DSD System
Semi-Submerged Catamaran
As the transmitted horsepower in a pair of bevel gears become 1/2, it is possible to in-crease the systemn's allowable transmitted
horsepower, and thus it is ideal for a large
capacity bevel gear system.
(2) No thrust bearing is required for the horizontal
bevel gear shaft.
The vertical intermediate shaft diameter can
be made smaller because its transmitted power
is reduced to li-2, and thus it becomes easy to
install it inside the narrow spaced strut.
(4) As flexible joint is provided on the vertical intermediate shafting, it smoothly follows the
deformation of the strut.
As the intermediate shaft is hollow inside and
is of welded shaft, it can be ¡nade light weight.
(6) The reduction ratio 0f the bevel gear is 1:1,
and with the reversing reduction gear provided
immediately in front of the propeller, as it is possible to perform all steps of speed
reduc-tion, each intermediate shaft and the bevel gear can be ¡nade small and light weight because of reducing the transfer torque of them.
4.1.2 Chain Transmission System
The nominal transmitted horsepower of the chain transmission system adopted by the above
mentioned the "KAIMALINO" is said to be 2,000
PS. This is the largest of all the silent chains presently available in the market. The distance between chain sprocket axes was limited to an
appropriate length in view of the problems arising
from the adjustment of chain's tension, etc.
Because 0f this, if this system is installed, as in the
case of SSC, inside the strut of which length is
relatively long, it becomes necessary to provide additionally, as shown in Fig. 8,
2 or 3 more
sprockets in between. In the case of a silent chain,a strict alignments between each sproket shaft is required so that the driving force will be equally
shared b each constituting element of the chain. if failed to ensure this strict alignments, there
would arise unbalanced contact between sprockets and chain causing irregular friction and wear. Also
in the case 0f chain transfer, forced lubrication is required by providing oil feeding nozzles on the engaging sides of the chain with the sprockets.
Thus, where the chain transmission system is used by SSC, it is necessary to make sufficient study on the arrangement of chain and shafts of the sprocket so that the parallel alignment of sprocket axes will
not be spoiled by the sophisticated deformation
of the
strut during ship's navigation, or by a (1)(3)
(5)
393
unexpected large counter-moment to the sprocket shafts caused by the reaction force of chain to the
sprocket shafts.
Table I shows an example of comparison be-tween the bevel gear transmission system and the
chain transmission system.
4.2 Electrical Propulsion System
Considering a propulsion system to be adopted to SSC, the electrical propulsion system of the present technology is inferior to the existing
mechanical power transmission system when com-pared its power transfer efficiency, weight, external dimensions, and so forth, and has no higher merits. However, in the case 0f SSC to be used as survey,
observation and/or work-ship which require large consumption of electric power during working, it may be effective to use an electrical propulsion system.
These types of ship are mostly requested tise
navigation at low-speed, and if diesel main engines are used, the engines may have to operate at under minimum load limit of them. But in the case of an electrical propulsion system, it is possible to solve
this problem easily by installing plural number of main electric generators so that actual operating number of main generators can be properly re-(86)
duced while the vessel is in a low speed navigation.
Likewise, in the case of SSC requiring a large capacity of output exceeding the allowable trans-mitted horsepower of the earlier mentioned me-chanical power transmission system, and if the main engines can not be located inside the lower
hull, an electrical propulsion system can be adopted
too. According to the presently progressing US Navy's SWATH (Small Water-Plane-Area Twin
Hull) project, it is said that the final required PS per each side propeller is 40,000 PS. For this
purpose, a super-conducting electric driving system
is currently under development, and a 3,000 PS prototype system is scheduled to be completed
in 1980.
Fig. 10 shows the conceptional drawing of stern
section of the lower hull of SSC as projected by the SWATH plan. Table 2 represents the major outhne of this project. It consists of one unit of cruising turbine of 5,000 PS, and two units of boost turbine of 20,000 PS each totaling three
units of prime movers, and with a super-conducting electric motor of 40,000 PS, 200 rpm, it is planned
to directly drive the propeller system. Table 3
shows the efficiency
of the
super-conductingelectrical drive propulsion system. According to
the table's data, this system, even ii compared with
Bulletin of the ME.S.J., Vol. 8, No. 4
Cruising tu Boost turb Propeller Dimension Weight of Motor out Generator efficiency Power of compresso Elements Generator Motor Cable Sub-total Exciting generator Cooling and keeping coo Total of the whole syste Table the total not only f propulsion the media 5. The "S Passeng 5.1 Basic In buil December 1 Item of comparison
Bevel gear drive Chain dnve
Items (unit)
Efficiency (%) 98--97
9897
Limit of transmitted PS (PS) I 10,000 3,700
Elements having limit of life Shaft bearing Shaft bearing Diameter of casing
(in the case of 2,000 PS) (mm)
4800 41 200
Reversing, gear change Not possible Not possible
Noise Bevel gear drive better
Vibration Same as above
Merits
(1) Possible to transfer large power (2) High efficiency (3) Small-size & light
weight
(1) High efficiency (2) Flexibility
(3) Adoptable where axial distance is large Demerits (1) Restriction on arrangement (1) Restriction on arrangement (2) Large counter-moment occurs on intermediate shaft bearing (3) Oil packing volume is
large
394 M. Oshirna
ion. large ans-ni e-the ;wer Dted US win PS this :em PS ted em by jor of of -ee rig 'ed 3 ng 4
i
I Semi-Submerged Catamaran 395swAtHPrOpUII0fl Motor Initoltatton
The40tO-trppropslond'we soers or the4D-tori eesgn require that the machinery package it itla0ea Cyindrical space about13Cet rl nameteranS 15set ong
Ft
?-tn-; F-i-1
Table 2 Major outline of SWATH Project
Table 3 Efficiency of Super-conducting Electric Driving System
the total system including the cooling system, is
not oniy far better than the conventional electrical
propulsion system, but also equally comparableto the mechanical system.
5. The "SSC MESA 80" in Actual Serviceas
Passenger Ship
5.1 Basic Plan
In building this type of ship, the accumulated December 1980
20 Ft Access
Fig. 10 Conceptional Drawing of Siens Section of Lower Hull of SWATH Project
technology from the past relating to SSC was effectively utilized, and carefully considering the inherent problems of steering, operating, and maintenance of this type of ship in actual service,
the initial design conditions were elaborately
studied and selected as follows:
Considering severe sea conditions for its
navi-gation route even though its operating sphere is within relatively short radius, it can operate
sufficiently up to 3.5ni of significant wave height.
Although it has the restricted coastal service
area as the service limitation in the light of the
specifications of its provided life saving appa-ratus, but its structure and engines are to
follow the coastal service specifications. Set its sea speed at higher than 22 knots, while its cruising time is set to about 10-hours. Set its draft to less than 4 m considering in-port water depth.
From the viewpoint of weight reduction and
fuel saving, its hall structures are entirely made of anti-corrosive aluminum alloy and to install high-speed diesel engine for its main engine.
From the viewpoint of raising speed perform-ance and maintenperform-ance service efficiency, the main engine is to be installed on the lower connecting deck, and use the DSD system
(refer to Paragraph 4.1.1) for driving the
propeller.
The passenger room be made a mono-class type for all the passengers seated in one room. The passenger capacity is more than 400 persons.
As the results 0f the repetition of elaborate studies to make it an optimized passenger ship, the following principal particulars were finally
determined:
(87) Items Major specifications
I-lull (LxB) 3SOftxISOft(170mx46m)
5,000 PS (GTP 990)X 2 units Cruising turbine
Boost turbine 20,000 PS (LM 2.500)X4 units Propeller 40,000 PS/200 rpmX2 sets
E
-Dimensions ofmotor l0ftx L12ft( 3mx L3.7m)
Weight of motor 61 ton
Motor output/rpm 40,000 PS/200 rpm GeneratorXmotor efficiency 95.4% Power of helium compressor 90kw x 2 units Elements Efficiency (%) Loss (%) Required power (%) Generator 98-99
2.01.0
-Motor 97.5 98.5 2.5 1.5 -Cable 99.599.8 0.5-0,2 -Sub-total 95-97.3 5.0-2.7 Exciting generator-
0.3-0.2 Cooling and keeping cool-
-
0.8 0.6 Total of the whole system 939-.-965 6.1-3.5 Deck 1.05er5.2 Principal Particulars and Arrangements Main structural material:
Anti-corrosive aluminum alloy
Ship classification:
JG (Restricted coastal service) Length (between perpendiculars): 31.50
Displacement (by designed draft): 343 tonS Gross tonnage: 692.84 tons
Passenger capacity: 446 seats
Crew: 7
Total 453 persons
Main engine: Fuji-S.E.M.T.-Piclstick
"18PA4V-200DS"/ 2 Units Max. continuous output:
4,O5OPS/1,47 5rpm/unit
Service output:
3,600PS/ 1,425rpm/unit Reversing reduction gear:
Niigata converter MGN4100Z (Special)/2 units
Reduction ratio: About 3:1
Auxiliary engine: GM "8V-71(N)"/2 units Rated output: 244PS/ 1,800rpm/unit Generator (dynamo): Drived by auxiliary engines, self-ventilation, and drip proof: 206.25kVA. AC45OV, 3ç, 6OHz/2 units Propeller (4-blade, solid, fixed pitch type! 2 sets)
Max. speed: 27.1 knots
Service speed: 23.6 knots
As shown by the general arrangement drawing represented by Fig. 11,
the major part of the
(88)
f1 u
.'
Fig. Il General alTangernent of "SSC MESA SO"
Bulletin of the M.E.S.J., Vol. 8, No. 4 engine room area installed with the main engine,
auxiliary engines, etc. is located in between the connecting decks so that the upper connecting deck area can be fully and effectively utilized for passenger seating space, and together with the
consideration to make the passenger room floor
above the engine room a floating structure, on the
side in the midship area facing the main engine, there are located toilet rooms, lobby, etc. as a measure to prevent as much as possible the noise of engine from reaching the passenger room, and at the same time, to make passengers to enjoy comfortable voyage helped by the sperb motion
performance of the ship itself.
5.3 Outline of Machinery Part
For its main engines, the "SSC MESA 80" has
two high-speed diesel engines installed on the lower
connecting deck, one on each side in an arrange-ment of two engines and two shafts. The power from the main engine is transmitted by the DSD type power transmission system to the reversing reduction gear located inside the lower hull. This reversing reduction gear reduces the revolution speed down to about 1/3 to drive the propeller.
Flexible joints are provided at all necessary sections
of the shafting in order to absorb the effect of
deformation of the hull. Auxiliary machineries for
propulsion except the cooling seawater pump and
fuel transfer pump are incorporated into the engine to reduce weight.
In planning and designing the machinery part, due consideration was given to lessening of the noise and vibration level in the passenger cabin
since tIsis sh main engines with resilieni main engine yooms, etc. absorption The main independenti-house. All
ki-performed fr stop by push. off in the re control leven m ecli anical Iv For the two 2-cycle i connected t, rpm. One of driving an
this air corn start and st compressor. The puni, thc lower h which is u pump, and', The oily bu the builge deck. The vent formed by each comp auxiliary CI
and the sha 5.4 Install 5.4.1 Fin Fin stab as fore, aft fin stabiliz automatic com forta bi automatic such instr eromccer, obtained b to the mier and orders the results The autorn (1) Level 5m December 1 Breadth (mould): 17.10 m Depth (mould): 5.84 5 Designed draft: 3.15 Strength draft: 3.80
LOWER CONNECTING DECK (UPPER DECK) UPPER CONNECTING DECK
ginc, the cting d for the floor n the gine, as a noise and enjoy otion Jo. 4
since this ship is for passenger service. Both the main engines and auxiliary engines were applied with resilient mounts. All the compartments for main engine rooms, auxiliary engine rooms, gear rooms, etc. are provided with glass wool sound
absorption and sound proof material.
The main engines are made remote controlable independently for each engine from the wheel
house. All kinds of operation for main engines arc
performed from the wheel house such as, start & stop by push-button, speed control and clutch on-off in the reversing reduction gear by pneumatic control lever. The above described control is also
mechanically possible in the engine room.
For the auxiliary engines, there are installed
two 2-cycle diesel engines, each of which is directly
connected to one AC generator of 165 kW/1,800
rpm. One 0f these two auxiliary engines is used for
driving an air compressor via clutch. Other than
this air compressor, there is provided one automatic
start and stop controled electric motor driven air compressor.
The pump room located in the bow section of
tise lower hull is equipped with huilge-bahiast pump
which is usable also for fire-pump, oily builge
pump, and various types of cooling seawater pump. The oily builge is discharged from tIse ship through
the builge separator installed on the connecting deck.
The ventilation of the machinery room is
per-formed by each independent axial fan provided in
each compartment of the main engine room, auxiliar)' engine room, pump room, gear room, and the shaft room.
5.4 Installation of Special Devices 5.4.1 Fin Stabilizer
Fin stabilizers are provided at such four locations
as fore, aft, inside of each lower hull. These four fin stabilizers are controlled independently either automatically or manually to enhance the, sailing comfortability 0f the passengers. In the case of automatic control, there are provided as sensors such instruments as radio altitude meter, accel-erometer, and vertical gyro. Information and data obtained by these measuring instruments are sent
to the micro-computer installed in the wheel house, and orders and instructions are issued according to
the results of the processing of these data. The automatic control modes are as follows:
(1) Level flight mode: Where waves are relatively small, keep level
December 1980
Semi-Submerged Catamaran 397
Following wave mode: Sail along the wave
sur-face of the height of heavy waves of long cycle
Bank turn mode: Sail inward banked while
turning
These three modes are prepared and stored for
automatic ship control.
5.4.2 Control System for Ship's Condition
In order to control the ship's abnormal list or heel during passengers leaving the ship, there is provided a heel automatic control device to make gravity flooding of seawater into the ballast tank by automatically sensing the ship's heel, and this device is controlable from the wheel house.
Furthermore, the wheel house is equipped with the
display panel of the pneumatic gauges for ship's drafts and ballast water capacities, as well as a remote control system for actuation of valves for each ballast line so that the ship can maintain an
optimum operating condition by control of ballast water.
6. Postscript
As SSC has excellent performance character-istics, its future potential is high for its effective utilization not only for general purpose maritime transportation, but also in a broader field of oceanographic projects including ocean
develop-ment.
This type of SSC craft with its well stabilized and spacious deck, which can be effectively
uti-lized as a platform, when used as an oceanographic survey ship or an ocean development support ship,
to carry and drop into water such equipment and
supplies as necessary for underwater work, and to
lift them up and taken them aboard the ship's
platform, will play an important role in these particular fields, too. Likewise, it will offer spa-cious deck area for a helicopter hanger as well as helicopter deck, and the opening provided in the center of its deck will serve for many and varied
useful purposes to facilitate on-the-sea and
under-water work. Under these favorable conditions, there are many other attractive points such as high
workability, better movability, improved
habita-bility of crew members, high safety, etc.
By the same token, in the field of off-shore oil
development, SSC's applicable area is quite exten-sive. It can be used as an effective supply boat for
transport of rig, drilling equipment, etc., and personnel and workers on shift to and from the (89) has lower ange-iower DSD rsing This ut ion cher. tionS et of s for ) and ngine part, f the :abin I
off-shore production platform. Thus its future
progress is expected with great hope.
Lastly, the author of this paper wishes to
ex-press, taking this opportunity, to the Japan Marine
Machinery Development Association and other
concerned gentlemen for their assistance and co-operation provided in respect of the research and
development of the "MARINE ACE" and the
Society News
The 28th annual meeting was held on October 22 and 23, 1980 at Kobe University of Mercantile Marine.
;n the technical session, were given the general presenta-tion covered 23 papers and a special lecture on "Notes on Marine Machineries" by Mr. R. Nihei, Executive Vice
Sixteen Research Committees of the Society are carrying out researches and investigations, and the following twenty research results were reported in 1979.
1) Machinery Plant Committee Group I
Countermeasure on Machinery Part for Cold District Condition in Ice-Class Ships
Installation Standard of Incinerator Plant on Board
2) Machinery Plant Committee Group Il
Cost Minimum Design of Generating System Cost Minimum Design of Cooling Water System (51 Cost Minimum Design of Fuel Oil System
Cost Minimum Design of Lubricating Oil System Cost Minimum Design of Bilge Water System
3) Machinery Plant Committee Group Ill
On the Sterilizing Unit for Potable Water Procedure of Outfitting for Funnel (Diesel Ship) Countermeasures to Solidification in High Viscosity
Fuel Oil Piping System
Guidance of Piping for Instrumentation
(90)
"SSC MESA 80". Referential Literature
T.G. LANG, et a)., an ASME publication, Paper No. 73, WA/OCT. 2. (1973-12)
GAS TURBINE WORLD, (1975-3), 12
1980 Autumn Annual Meeting
President of Kawasaki Heavy Industries, Ltd.
Besides, 6 papers were presented and discussed at the
symposium on "Machinery Outfitting on Merchant Ships
for Resources Saving and/or Energy Saving".
The Activities of Research Committees in 1979
(121 Standard Machinery Arrangement of Engine Room for 27 KLT Bulk Carrier
4) Electrotechnical Committee
Problems on AC Marine Motor Starter
Study on Co-ordinative Protection of Emergency
Distribution Circuits Supplied from Storage Batteries
5) Propeller and Shafting Committee Alignment of Aft Side Shafting
New Shafting System (Aft Support of Propeller) 6) Machinery Maintenance Standard Committee
(17) Maintenance Standard of Auxiliary Boiler and
Exhaust Gas Economizer 7) Automation System Committee
(181 Recent Condition-check Systems for NK-M0
Un-manned Engine Rooms
8) Boiler Committee
-Design Practice of Recent Marine Boilers
Failures Analysis of the Turbine Ships (Lanched
about 1972, 1973)
Bulletin of the ME.S.J., Vol. 8, No. 4
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