US 2011 O259440A1(19) United States(12) Patent Application Publication (10) Pub. No.: US 2011/0259440 A1
Kawashima et al.

(43) Pub. Date:(54) FRICTIONAL RESISTANCE REDUCTION
DEVICE FOR SHIP(76) Inventors:

Hideki Kawashima, Mitaka-shi(JP); Tetsugo Fukuda, Mitaka-shi(JP); Yoshiaki Kodama, Mitaka-shi(JP); Munehiko Hinatsu,
Mitaka-shi (JP); Toshifumi Hori,
Mitaka-shi (JP); Masahiko
Makino, Mitaka-shi (JP);Kazuyoshi Harumi, Mitaka-shi(JP); Masashi Ohnawa, Mitaka-shi(JP); Haruya Takeshi, Mitaka-shi(JP); Tadanori Takimoto,
Mitaka-shi (JP)(21) Appl. No.:

12/935,624(22) PCT Filed:

Mar. 31, 2009(86). PCT No.:

PCT/UP2009/OO1520

S371 (c)(1),(2), (4) Date:(30)

Oct. 27, 2011

Jul. 17, 2008

(JP) ................................. 2008-186588

Mar. 27, 2009

(JP) ................................. 2009-080676

Publication Classification(51) Int. Cl.
B6OS 5/00(2006.01)(52) U.S. Cl. ..................................................... 137/234.6(57)

ABSTRACTA inject gas control device that performs, for example, control reflecting variation in vessel velocity over time without
adversely affecting the main engine is realized. That is, it isprevented that gas is drawn too much and thereby a gas Supply
or charged air rate becomes insufficient, efficiency of themain engine is decreased and exhaust gas is deteriorated, andanalogous events occur because the gas Supply or charged air
rate is too much instead.

Jul. 1, 2011

Foreign Application Priority Data

Apr. 1, 2008 (JP) ................................. 2008-095466
Apr. 8, 2008 (JP) ................................. 2008-100889
Apr. 8, 2008 (JP) ................................. 2008-10O894

There are provided a main engine 4010 acquiring propelling
powerfor a vessel 1, and a turbocharger 4011 that is driven byexhaust gas from the main engine 4010 and blows pressurizedgas to the main engine 4010. A part of the pressurized gas
and/or exhaust gas is drawn from between the turbocharger
4011 and the main engine 4010 (5023, 5024 and 5025). The
drawn pressurized gas and/or exhaust gas are injected in theproximity 9 of the hull on or below the waterline (5040), andthe drawing rate of the pressurized gas and/or the exhaust gas
is controlled on the basis of a physical quantity related to aheat load on the main engine 10 and characteristics of theturbocharger (4200).

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US 2011/0259440 A1FRCTIONAL RESISTANCE REDUCTION
DEVICE FOR SHIPTECHNICAL FIELD

0001. The present invention relates to, for example, a frictional resistance reduction device for a vessel, and more particularly, to a frictional resistance reduction device for a ves
sel that injects bubbles into water, controls inject conditionsof gas and reduces the frictional resistance of a hull.
BACKGROUND ART

0002. As to research on resistance reduction for vessels, a
lot of results on wave-making resistance have been acquired.
However, a distinct result on frictional resistance, which issaid to be responsible for about 80% of the entire resistance ofa large-scaled vessel, has not been acquired up to the present,
because complicated turbulence phenomena are related
thereto. When a vessel is sailing, a turbulent boundary layer isdeveloped on or below the waterline along the surface of thehull. Accordingly, a frictional resistance is exerted on thesurface of the hull, thereby reducing the propulsive perfor
mance of the vessel. In recent years, as to means for reducing
such a frictional resistance on the surface of the hull, a

microbubble system, which reduces the resistance by inject
ing microbubbles into the boundary layer along the Surface,
has received attention as a promising measure for reducing africtional resistance and been researched. It is considered thatthe microbubble system is a promising frictional resistance
reduction device in an era from now on when energy saving isdesired, because the system is remarkable in frictional resis
tance reduction effect, relatively resistant to fouling, has noproblem of environmental contamination of the ocean and thehydrosphere.
0003. However, this microbubble system requires power
because the system generates bubbles with a diameter of aseveral hundred um or less from underwater sides of thevessel and the bottom of the vessel overcoming the waterpressure. Considerations are required that increase a net
reduction effect in consideration of both of a frictional resis

tance reduction effect and power for generating bubbles. Further, there is a problem how the frictional resistance is effec
tively reduced in a vessel sailing on the ocean and rivers,
which receives various disturbances, such as waves andstreams, and receives influences owing to freight conditions
and navigational conditions. In particular, buoyancy acting on
bubbles is small on microbubbles with a diameter of several

hundred um or less. When the microbubbles are injected tothe bottom of the vessel, the micro bubble is susceptive toinfluences of disturbances and easily diffused. Moreover, previous researches have mainly been of a laboratory level andresearches using a model ship, and have not considered the
disturbances and the navigational conditions.
0004 Further, it is required, as a precondition, that con
struction and installation of Such a gas Supply or charged air
device does not cost enormously.
0005. In view of the present states of researches, the inventors of the present application use an actual vessel, equip thehull thereof with a gas inject device capable of injecting
bubbles with a diameter larger or equal to that of micro
bubbles, investigate a relationship between the inject of
bubbles and a frictional resistance reduction effect in situa

tions analogous to actualities, such as vessel conditions, navi
gational conditions, oceanographic conditions, search forOct. 27, 2011

increase in net reduction effect, and acquire a lot of findings.
Further, researches are pursued for optimizing the particle
diameters of bubbles in order not to diffuse the gas injectedfrom the gas inject device in the sea and separate the gas fromthe bottom of the vessel, and also on components, devices andthe shape of the bottom of a vessel. Moreover, the researches
using such an actual vessel have determined that the injectedbubbles are convolved into propeller means, reduce the propeller efficiency and adversely affect a net frictional resis
tance reduction effect.

0006. On the other hand, marine diesel engines as the main
engines of large scale vessels are equipped with turbocharg
ers for compressing and providing air for combusting fuel. In
recent years, the marine diesel engine has realized high powerand high efficiency. This is because, in a large measure, theefficiency of the turbocharger has been increased.
0007 Recently, the efficiency of the turbocharger has
become higher. There appears a turbocharger exerting effi
ciency equal to or higher than that required by the engine.
This means that air required for the engine or exhaust gas
generated by combustion of fuel is more than necessary.
0008 Energy-saving techniques that drive exhaust gas
power turbines using the residual exhaust gas and rotate elec
tric generators have generally become widespread (e.g., turbo
compound system). There also arises a concept utilizing theresidual exhaust gas as a source of generating the bubbles.
0009 For example, as shown in following Patent Documents 1 to 4, concepts that use the exhaust gas from turbo
chargers and generate bubbles have been disclosed.
0010 Patent Document 1 discloses a technical idea that
adjusts fuel adjustment means and gas drawing rate adjust
ment means to reduce fuel consumption while drawing
exhaust gas from a turbocharger and injecting the gas into
water to reduce frictional resistance, and adjusts the flow rateof the exhaust gas So as to minimize the amount of fuel Supply
as a control. However, the idea disclosed in Patent Document

1 only controls the drawing rate So as to reduce the amount offuel Supply to a main engine with respect to a prescribedvessel Velocity. The optimal control is not necessarily real
ized. Further, since only the exhaust gas is used, it is not used
in a case of affecting the environment.
0011 Patent Document 2 discloses a technical idea thatprovides a drawing port at a low pressure spot of a turbo
charger compressing gas for a main engine and releases thedrawn gas into water. Although the idea disclosed in Patent
Document 2 refers to a valve for adjusting the flow rate, theidea discloses no specific control method.
0012 Patent Document 3 discloses a technical idea thatprovides a branch line for a compressed air line of a turbo
charger provided at a main engine, draws scavenged gas froma spot downstream from the intercooler and discharges
bubbles. However, this idea discloses no specific control
method either, and has a possibility of adversely affecting theoperation of the main engine.
0013 Patent Document 4 discloses a technical idea of aturbo compound system (exhaust gas passes through theblower turbine and the blower blows the gas to discharge
bubbles) that branches exhaust gas out of a main engine,
provides a turbine at a branch line, causes the turbine to drivea blower to discharge bubbles from the hull. However, theidea discloses no specific control method, and has a possibil
ity of adversely affecting the operation of the main engine.
0014 Patent Document 5 provides the hull with an air
injection unit injecting air from a nozzle via an air injection

US 2011/0259440 A1

control unit, provides a sensor detecting air bubbles or an air
sheet released therefrom at the bottom of the hull, inputs
signals from the sensor into the hull operation measurement
unit, inputs wave information, relative wave information, displacement, movement Velocity, acceleration, a direction,
detected conditions of bubbles and a wind velocity and a winddirection into the hull operation measurement unit, detects
bubble conditions on the basis of bottom of the vessel pressure information, bubble distribution information, frictional

force information and hull resistance information, and opti
mally controls the released air layer and the bubble condi
tions.

0015 Since such a configuration is adopted, various
pieces of detected information are limited. The control is not
performed by determination of navigational situations, suchas the relative velocity between the vessel and the water andthe draft conditions, and vessel situations, such as operating
conditions of the vessel and the engine conditions. This can
not appropriately control the air bubbles and the air sheet.
Further, this does not control the number of air injection units
according to various pieces of detection information.
0016 Patent Documents 6 and 7 disclose ideas that control
Supply of pressurized gas and exhaust gas according to presSure and the draft, Supply the gas when the pressure rises to acertain degree and exceeds a pressure determined by a depthof water of protruding (injecting) and stop the gas when thepressure decreases. However, these documents do not dis
close or suggest an idea that Supplies gas at a higher level.
stops even at a higher level or blocks after a backflow occurs.
0017 Patent Document 8 discloses a technical idea thatpertains to a microbubble injecting device, integrally forms a
fluid guide plate, which guides bubble-water mixture fluid aft,at the front end of a fluid nozzle provided at the hull, andconverts a kinetic energy when the bubble-water mixture fluid
is injected into propulsion of the vessel. However, the idea
disclosed in Patent Document 8 is incapable of preliminarily
determining the direction of the fluid to be injected. Further,
there is a possibility that the fluid guide plate itself becomes aresistance preventing the vessel from sailing.
0.018 Patent Document 9 discloses a technical idea that
injects bubbles from an air duct, provides strengthening
devices straitening a drift at an upstream and downstreamsides of the air duct, and secures afriction reduction region by
spreading the bubbles along the drift. However, according to
the idea disclosed in Patent Document 9, the strengthening
device only plays a role that straitens the drift so as tosmoothly flow from the upstream side to the downstream sidewith respect to the air duct. Therefore, when the velocity of
the currents is high, there is a possibility that the bubbles are
diffused on injecting. Further, since the air duct protrudes,
there is a possibility that the air duct becomes a resistancepreventing the vessel from sailing. In a case where the vessel
is carried, when the vessel is mounted on a Supporting stage,
Such as blocks, the air duct becomes an obstacle in security
and working efficiency.
0.019 Patent Document 10 discloses a technical idea thatprovides the bottom of the vessel with a regulating member
for regulating seawater streamed to the side of the bottom of
the vessel by inject stream generation means and air injectedby air injecting means so as not to escape toward the sides of
the hull. However, the idea disclosed in Patent Document 10

provides the regulating member at the sides of the vessel andthe regulating member is fixed Such that a part thereof pro
trudes from the bottom of the vessel. Therefore, when theOct. 27, 2011vessel is carried into a dock because of maintenance of thevessel, if the regulating member hits a Supporting stage Suchas blocks, the vessel cannot only be fixed in a stable manner,
but also the regulating member becomes an obstacle, thereby
reducing working efficiency. Further, the regulating member
itself is provided at a side of the hull. Accordingly, the contact
area with seawater becomes significantly large, and the regu
lating member becomes the resistance adversely affecting the
propulsion of the vessel, thereby reducing the net frictional
resistance reduction effect of the air. Further, since the con

figuration where the air is injected from a centerportion in thelongitudinal direction of the hull is adopted, the frictional
resistance reduction effect is limited.

0020 Patent Document 11 discloses a technical idea
where, in a vessel having a structure of blowing air into thebottom of the vessel, the bottom of the vessel has a substan

tially planar structure with respect to a flow, a lot of grooves
are formed on the bottom of the vessel so as to be structures

for taking air into the grooves and air is introduced, thereby
separating the bottom of the vessel and water from each other.
However, the idea disclosed in Patent Document 11 has astructure where the air is spread at the bottom of the vessel andthe bottom of the vessel is covered with an air layer. The
bottom of the vessel is accompanied by the air, but does nothave a member and the like holding the air. An inclination of
the vessel owing to disturbance of the wave, the flow and thelike diffuses the air toward an area with lower pressure. This
reduces the amount of air accompanying the bottom of thevessel. It is inevitable that the frictional resistance reduction

effect is reduced accordingly.
0021. On the other hand, for example, measures as dis
closed in Patent Documents 12, 13 and 14 have been taken inorder to reduce the frictional resistance of the vessel using
microbubbles.

0022. This Patent Document 12 attaches an air injecting
device communicated with the blower to a board side of thebow of the hull, attaches an air injecting device communi
cated with a compressor to the bottom of the vessel at the bowof the hull, covers areas around the both sides in the board
direction of the bottom of the vessel and the sides of the vessel

with microbubbles generated by the airinjecting device of theblower, covers areas around middle section in the board direc

tion of the bottom of the vessel with microbubbles generated
by the air injecting device of the compressor, and entirely
covers the wet surface of the hull.

0023. Since such a configuration is adopted, only one air
nozzle is provided on each surface of the sides of the vessel orthe bottom of the vessel. It is incapable of controlling themanner of blowing bubbles according to the navigational
condition of the vessel. The reduction infrictional resistanceis limited. Further, in a typical blower, the gas Supply or
charged air rate varies and the air blowing rate varies accord
ing to variation in pressure owing to vertical movement of the
waves. This does not causes stabilized reduction infrictional

resistance. Further, the compressor has a limitation on a rateof air to be blown by the compressor.
0024 Patent Document 13 provides a plurality of open
ings at upper and lower positions with different static presSures of outer plates of the hull, attaches air injecting devices
to the respective openings, provides a gas drawing typeblower device including a blower having a low dischargepressure and blower having a high discharge pressure on thedeck at the bow, communicates the air injecting device on theupper stage and the blower with the low discharge pressure byUS 2011/0259440 A1

the air Supply pipe, and communicates the airinjecting device
on the lower stage and the blower with large discharge presSure by the other air Supply pipe.
0025 Since such a configuration is adopted and, in par
ticular, one motor drives two blowers, it is incapable of controlling the manner of blowing bubbles according to the navi
gational condition of the vessel. The reduction in frictional
resistance is limited. Further, the nozzles are arranged theupper and lower stages of the vessel. Accordingly, in particu
lar at the nozzle on the upper stage, generation of the bubbles
is susceptible to vertical movement of the waves. In theblower, the gas Supply or charged air rate varies and gas
Supply or charged air rate varies according to variation inpressure owing to Vertical movement of waves. Therefore,
this idea is not stabilized and effective measures for reducing
the frictional resistance.

0026 Patent Document 14 provides a plurality of nozzles
in a limited region in the proximity of the bow in an aggre
gated fashion in order to reduce frictional resistance between
the hull and water by injecting gas into water from proximityof the bow during sailing and thereby causing microbubbles
to intervene at the outer shell of the hull. Hydrostatic pressures generated in the proximity of the nozzles diffuse thebubbles over the bottom of the vessel.

0027. Since such a configuration is adopted, the bubbles
from the nozzles on a curved surface below the valve in the

bow Section are susceptive to the navigational conditions of
the vessel. Since the idea is a passive bubble diffusion system,
the method is incapable of positively controlling generationof the bubble according to the navigational condition of thevessel and thereby effectively reducing the frictional resis
tance. Further, since the nozzles are arranged on an arc toward
the downstream side in the limited region in the bow section,
the resistance at the bow section cannot effectively be
reduced.
Patent Document 10028 Japanese Patent Laid-Open No. 2001-097276
Patent Document 20029 Japanese Patent Laid-Open No. 2001-48082
Patent Document 30030 Japanese Patent Laid-Open No. 11-348870
Patent Document 40031 Japanese Patent Laid-Open No. 11-348869
Patent Document 5

0032

Japanese Patent Laid-Open No. 2004-188993

Patent Document 6

0033

International Publication No. WO2005122676

Patent Document 7

0034

International Publication No. WO 1999028.180

Patent Document 80035) Japanese Patent Laid-Open No. 8-243368

Oct. 27, 2011

Patent Document 90036) Japanese Patent Laid-Open No. 2003-160091
Patent Document 100037 Japanese Patent Laid-Open No. 5-116672
Patent Document 110038 Japanese Patent Laid-Open No. 6-191396
Patent Document 120039 Japanese Patent Laid-Open No. 10-24891
Patent Document 130040 Japanese Patent Laid-Open No. 10-100983
Patent Document 140041 Japanese Patent Laid-Open No. 2000-296795
DISCLOSURE OF THE INVENTION

Problems to be Solved by the Invention
0042. As described above, the ideas that use the exhaustgas from the main engine directly or indirectly or draw airfrom the turbocharger and use this for reducing the resistanceof the vessel have been disclosed in various manners includ

ing the above Patent Documents. However, any of these isfraught with various problems on actual use, or ignores the
problems to occur in actual use.
0043. For example, gas passing through a turbocharger
turbine is important gas securing performance and reliabilityof the main engine. The gas rate should appropriately be
secured. It is necessary to control gas Supply or charged air
from the turbocharger to the main engine or exhaust gas fromthe main engine, within an appropriate condition, according
to the operating conditions of the main engine. The draw of air
from the turbocharger and the draw of the exhaust gas after
the main engine should be controlled under a strictly con
trolled condition.

0044) The gas can be drawn around the turbocharger
includes 'gas Supply or charged air can be drawn after thecompressor of the turbocharger and before the cooler, “scavenged gas' can be drawn from between the cooler and themain engine, and “exhaust gas can be drawn from between
turbines of the turbocharger after the main engine. The drawof these changes the air to be supplied to the main engine inpressure, flow rate, temperature and the like. This offers aproblem whether the main engine is operable under an appro
priate condition and whether the main engine is operable
under a permissible condition. The next problem is whether
the drawn gas Supply or charged air, Scavenged gas andexhaust gas have conditions allowing the frictional resistanceof the vessel to appropriately be reduced or not. These aredifferent in temperature, flow rate, pressure and further position to be drawn. Accordingly, when the plurality of these are
combined and used, there arises a problem how to acquire theoptimal value of drawing. Further, in a case of the exhaust gas,an environmental problem that the exhaust gas may directly
pollute the ocean is assumed, and it is assumed that there areunusable waters. In the waters where the exhaust gas is unus
able, gas Supply or charged air gas or scavenged gas is to be
used. Situations can occur that cannot discharge the gas frombypass piping according to draft conditions and operatingUS 2011/0259440 A1

situations of the vessel. It is necessary to design so as not todamage the engine owing to immersion of sea water when theoperation is stopped.
0045 That is, various problems exist, in view of the control, function, security, and energy-saving design, to realize
the saving of energy by actually utilizing the bypass gas fromthe turbocharger and reducing the frictional resistance of thevessel. However, the ideas, including the above Patent Documents, only draw and inject the residual gas for the sake ofsaving of energy or only control So as to minimize fuel con
Sumption cannot actually solve the above problems and realize preferable conditions in security and operation. In otherwords, the above Patent Documents do not provide specificmeasures for resolutions.

0046. Further, as described above, the ideas that use theexhaust gas from the main engine directly or indirectly or
draw air from the turbocharger and use this for reducing theresistance of the vessel have been disclosed in various manners including the above Patent Documents. However, any ofthese is fraught with various problems on actual use, or
ignores the problems to occur in actual use.
0047 For example, gas passing though a turbocharger tur
bine is important gas securing performance and reliability ofthe main engine. The amount of the gas should appropriately
be secured. The control only minimizing fuel cost is insuffi
cient to efficiently maintain the main engine without
adversely affecting the main engine. It is necessary to control
air Supply from the turbocharger to the main engine andexhaust gas from the main engine, within an appropriate
condition, according to the operating conditions of the main
engine. The draw of air from the turbocharger and the draw of
the exhaust gas after the main engine should be controlled
under a strictly controlled condition.
0048. Further, the techniques that inject bubbles from thehull in order to reduce the frictional resistance on sailing of
the vessel cannot control the inject conditions such as the
direction of the injected gas and the inject rate, according tonavigational situations of the vessel. Thus, the control for thegas outlet cannot be performed, when the vessel receives
disturbances such as waves and flows, and against an incli
nation caused on turning.
0049 Moreover, in the methods guiding the injected gas
by means of external elements, the external elements themselves cause increase of the frictional resistance and have

fixed structures. Accordingly, in a case of maintenance of thevessel or a case of carrying the vessel into a dock (hereinafter,
collectively referred to as “docking situations'), when thevessel is mounted on a Supporting stage such as blocks, theSupporting stage resides under the external elements, thereby
concentrating the stress and causing breakage.
0050. With certainstructures and dimensions of the external elements, there are problems because operators guide thevessel over the Supporting stage such as the blocks in consid
eration of the external elements under docking situations andthe external elements act as obstacles during maintenance ofthe hull (e.g., including verification of presence or absence of
breakage, repairs of the breakage and coating). Moreover,attachment of the external elements protruding from the bot
tom of the vessel is concerns in operation of the vessel for
officers in charge of operation, in view of security and maneu
verability.
0051. The present invention solves the problems of theconventional techniques. It is an object of the present invention to provide a frictional resistance reduction device for aOct. 27, 2011vessel that is capable of appropriately controlling a inject ofgas according to navigational situations of the vessel andvessel conditions, effectively reducing frictional resistanceby appropriately injecting bubbles even with disturbance, andfurther utilizing an effect of generation of the bubbles.
0052. It is another object of the present invention to pro
vide a frictional resistance reduction device for a vessel thatretains bubbles under the navigational situations of the vessel
and the vessel conditions, such as cases of disturbances

including waves and currents, and a case of an inclination
caused by turning, and avoids formation of a resistanceadversely affecting advance of the vessel.
0053. It is still another object of the present invention toprovide a frictional resistance reduction device for a vesselthat is capable of reducing the frictional resistance without
necessity of further generating energy for generating bubbles
and reducing consumption of energy according thereto.
0054. It is yet another object of the present invention toprovide a frictional resistance reduction device for a vesselthat realizes efficient reduction in frictional resistance byinjecting bubbles in which the navigational conditions of thevessel is accurately reflected.
0055. It is still another object of the present invention toprovide a frictional resistance reduction device for a vesselthat effectively reduces the frictional resistance even withvariation in the navigational situations of the vessel and thevessel conditions, prevents bubbles from being convolved
into propeller means, prevents efficiency of propeller meansfrom being reduced and increases the net frictional force
reduction effect.

0056. It is yet another object of the present invention toprovide a frictional resistance reduction device for a vesselthat is capable of reflecting navigational conditions and/or
vessel conditions of the vessel in adjustment of gas and injecting of gas and thereby realizing saving of energy, preventionof noise, prevention of adverse effects to fishing boats and a
port.

0057. It is still another object of the present application toprovide a frictional resistance reduction device for a vesselthat maintains high efficiency without adversely affecting theoperation of the main engine when generating bubbles using
residual gas from a turbocharger, appropriately controls
drawing according to situations and realizes security andsaving of energy.
0058. It is yet another object of the present invention toprovide frictional resistance reduction device and method fora vessel that is capable of maintaining high efficiency without
adversely affecting the operation of the main engine whendrawing the pressurized gas from the proximity of the turbo
charger and generating bubbles, and thereby preventing thedriving efficiency of the main engine from being reduced.
0059. It is still another object of the present invention toprovide frictional resistance reduction device and method fora vessel that is capable of controlling the inject condition ofgas, for example including the inject rate and the inject direction, when injecting gas.
0060. It is yet another object of the present invention toprovide frictional resistance reduction device and method fora vessel that is capable of Suppressing, to a minimum, that a
resistance against sailing of the vessel is formed and/or an
obstacle is formed under docking situations, and of restricting
the diffusion of gas even when the vessel receives distur
bances such as waves and flows or an inclination occurs
Owing to turning.

US 2011/0259440 A1

0061. It is still another object of the present invention toprovide frictional resistance reduction device and method fora vessel that is capable of preventing water from entering intoa path for providing gas and stably Supplying gas from gas
Supply or charged air means.
Means for Solving the Problems
0062. In order to solve the problems, a frictional resistance
reduction device for a vessel corresponding to claim 1 of thepresent application includes: a gas outlet injecting bubbles atleast to a bottom of the vessel; gas Supply or charged airmeans for blowing pressurized gas to the gas outlet; naviga
tional condition detection means for detecting a navigational
condition of the vessel; and means for controlling injecting of
the gas according to a detection result from the navigational
condition detection means such that propulsion of the vessel
is not prevented while the injected bubbles efficiently reduces
the frictional resistance of a hull.

0063. The “gas outlet' is a device including a mechanism
for injecting pressurized gas Supplied from the gas Supply or
charged air means as bubbles.
0064. Here, the gas Supply or charged air means has afunction of pressurizing and Supplying air, and includes, forexample, a turbocharger, a compressor, a blower (gas Supply
or charged air device), an electric generation system for driv
ing the blower, and a mechanical system directly drives theblower using (high pressure) gas.
0065. The navigational condition detection means may be
a relative velocity detector detecting a relative velocity
between water and the hull, which is a physical quantity
varying according to navigation of the vessel, a draft detector
detecting the height of the waterline of the vessel, an inclina
tion detector detecting an inclination of the hull, and a shear
force sensor detecting a shear force acting on the hull.
0066. With these configuration, as to injecting of the pres
Surized gas from the gas Supply or charged air means via thegas outlet, the navigational condition detection means detects
the navigational condition of the vessel, and then means forcontrolling the injected bubbles such that the frictional resis
tance of the hull is efficiently reduced while not adversely
affecting propulsion of the vessel controls injecting of air on
the basis of the detection result from the navigational condition detection means. This can realize reduction in frictional

resistance of the vessel in the optimal efficiency adapted tovariations such as those in the relative velocity between waterand the hull, the draft of the vessel, the inclination of the hulland the shear force acting on the hull.
0067. In order to solve the problems, a frictional resistance
reduction device for a vessel corresponding to claim 2 of thepresent application includes: a main engine acquiring propelling power of the vessel; a turbocharger that is driven byexhaust gas of the main engine and blowing pressurized gas tothe main engine; drawing means for drawing the pressurizedgas and/or exhaust gas from between the turbocharger and themain engine; a gas outlet injecting the drawn pressurized gas
and/or exhaust gas at least to a bottom of the vessel on andbelow a waterline via a path; navigational condition detectionmeans for detecting a navigational condition of the vessel;
and a control device controlling a rate of pressurized gas
and/or exhaust gas on the basis of at least any one of a physicalquantity related to a heat load on the main engine and characteristics of the turbocharger and/or the navigational condition detection means.

Oct. 27, 20110068. The “gas supply or charged air bypass” and the"scavenging bypass are compressed a gas in the turbo
charger and a path for drawing the gas, and concepts includ
ing a gas before Supply to a cooler (hereinafter, also referred
to as “intercooler), a gas intermediately cooled by the intercooler, and pipes through which the gases pass.
0069. The “gas supply or charged air bypass rate adjust
ment means' and the "scavenging bypass rate adjustment
means' are devices including functions of controlling a gas
Supply or charged airbypass rate and a scavenging bypass gas
rate, respectively, according to a control device, which will be
described later, and realized by means of for example, anadjustment valve and the like connected to the control device.
(0070. The “control device' is realized by means of amachine, a device, an instrument, a program, a recording
medium on which a program is stored, a computer or the likeincluding functions of varying output values and operations(in the present application, for example, various bypass gas
rates, operation of starting/stopping providing the pressur
ized gas to the gas outlet, operation of starting/stopping Sup
plying the exhaust gas to the gas outlet, etc.) over time, basedon a certain number of variables (in the present application,for example, a physical quantity related to the heat load of themain engine, Scavenging gas pressure, exhaust gas tempera
ture, characteristics of the turbocharger, turbocharger effi
ciency, pressure of the pressurized gas, pressure of theexhaust gas, the draft of the vessel, etc.), on the basis of acontrol principles according to the present application.
0071. The “exhaust gas bypass” is the exhaust gas gener
ated as a result of combustion in the engine or a path throughwhich the exhaust gas is drawn, and a concept including apipe through which the gas passes.
0072 The “exhaust gas bypass rate adjustment means” isa device including a function of controlling an exhaust gas
bypass rate according to a control device, which will be
described later, for example, realized by means of an adjust
ment valve and the like connected to the control device.

0073. Further, the exhaust gas from the turbocharger is
bypassed and reused as bubbles, thereby decreasing the resis
tance on the outside of the hull. This facilitates decrease inresistance without need for separately generating energy for
generating bubbles, allowing consumption of the energy
thereof to be reduced. In this case, the control device isprovided that controls the exhaust gas bypass rate on the basisof the physical quantity related to the heat load of the main
engine and the characteristics of the turbocharger. Accord
ingly, it is secured, as a device, that the optimal value of theenergy efficiency, in which, for example, variation in thevessel Velocity corresponding to the load on the main engine
is reflected over time, is selected. This allows the effect of

reduction in resistance to be reflected over time while appro
priately maintaining the condition of exhausting the exhaustgas generated by increase and decrease of the number of
revolutions of the main engine. This further realizes a device
that maximizes the energy consumption efficiency, on thebasis of calculation and control, using vessel resistance
reduction effect using bubbles generated by reusing theexhaust gas from the turbocharger.
0074. In this case, instead of or together with the exhaustgas from the turbocharger, gas Supply or charged air and/or
Scavenged gas from the turbocharger is bypassed and reusedas bubbles, thereby reducing resistance on the outside of thehull. This facilitates reduction in resistance without sepa
rately generating energy for generating bubbles, and allows

US 2011/0259440 A1

energy consumption to be further reduced. Here, a control
device is provided that controls a gas Supply or charged air
bypass rate and/or a scavenging bypass rate on the basis of aphysical quantity related to the heat load on the main engine
and characteristics of the turbocharger. The optimal value, inwhich, for example, variation in the vessel velocity corre
sponding to the load on the main engine is reflected overtime,
can be acquired. Use of these gases instead of the exhaust gas
facilitates reduction in resistance without causing a possibil
ity that the exhaust gas causes environmental contamination,and effectively facilitates reduction in energy consumption
owing thereto, particularly in a case where there is the possi
bility that the exhaust gas causes environmental contamina
tion.

0075 That is, the control is performed on the basis of thephysical quantity related to the heat load of the main engine
and the characteristics of the turbocharger. This can facilitate
the optimization in all aspects, such as output of the main
engine, fuel consumption efficiency and measures against theexhaust gas, of course in reduction in frictional resistance. In
this case, in view of a fact that a Surplus is generated mostunder 75% load on the main engine, further advantageous
effect is expected, in a case of using what has the character
istics of the turbocharger according to which effective use of
the surplus is applied to the proximity of 75% load on themain engine and gas can be drawn most at a navigational
speed. Any conventional art does not include a concept ofdrawing from gas Supply or charged air of the turbocharger, ora concept of drawing the gas from a high pressure spot
between an intercooler and a compressor. This concept
reduces viscosity of seawater because of high temperature,even without heating by the exhaust gas. Accordingly, anadvantageous effect is expected in further reduction in frictional resistance.

0076. In the configuration in claim 2, the control device
may control starting/stopping Supplying the pressurized gas
and/or the exhaust gas to the gas outlet according to thepressure of the pressurized gas and/or the exhaust gas and thedraft of the vessel.

0077. Here, in order to grasp and sense the draft, a method
can be adopted that grasps the waterline from a proportional
relationship between pressure and depth using, for example,
a sensor measuring and detecting a pressure at the bottom of
the vessel or at a surface of a side of the vessellower than thewaterline. A method may be adopted that images situations
around a water Surface by a camera from a side of the vessel,
applies an image processing on the image and thereby estimates the draft. A pressure sensor may be used for sensing thepressure of the exhaust gas.
0078. With such a configuration, the pressure of the pres
Surized gas and/or the exhaust gas is detected, the operation ofstarting/stopping Supplying the pressurized gas and/or theexhaust gas, which is bypassed from between the turbo
charger and the main engine, via the gas outlet is controlled on
the basis of the detected pressure of the exhaust gas and thedraft of the vessel. Accordingly, an event that seawater flows
into the vessel, which occurs when the pressure is equal to orless than that at the gas discharge port, can be prevented.
Further, Supply of the pressurized gas and/or the exhaust gas
is started when the pressure condition becomes a condition
capable of injecting, and stopped when the condition
becomes that incapable of injecting. This guarantees, as adevice, more secure reduction in resistance of the vessel using
bubbles. Separately therefrom, the pressure of the pressurized

Oct. 27, 2011

gas and/or the exhaust gas can be shared for managing theconditions of the turbocharger and the main engine, and thedraft of the vessel can be shared for managing the amount offreight.
0079. In this case, basically, when pressure of the pressur
ized gas and/or the exhaust gas is equal to or more than thepressure at the draft, injecting of gas is available. When thepressure of the pressurized gas and/or the exhaust gas is equal
to or less than the pressure at the draft, injecting of gas is
stopped. In actual cases, control is performed on the basis ofa value therearound including a certain extent of error. This
control holds effective control, even in cases where condi

tions vary, Such as a case where injecting of gas and seawaterflow to the opposite directions, thereby allowing a vessel
resistance reduction effect using bubbles to be strongly
attained.

0080 Further, with respect to the above description, aconfiguration may be adopted that further comprises gas Sup
ply or charged air means provided at an exhaust gas bypass
drawing the exhaust gas, wherein the drawing means controls
a drawing rate of the exhaust gas, and the gas outlet, which isprovided via the path from the gas Supply or charged airmeans, injects bubbles.
I0081. Here, the gas supply or charged air means represents
what has a function of generating gas, and includes a blower(gas Supply or charged air device), an electric generation
system for driving the blower, and a mechanical system that
directly drives the blower by means of (high pressure) gas.
I0082. According to such a configuration, the exhaust gas
from the turbocharger is bypassed and used as an exhaust gas
bypass. The gas Supply or charged air means is driven by theexhaust gas bypass. This generates bubbles to be generated by
the gas Supply or charged air means. The bubbles reduce theresistance of the vessel. Here, a control device is provided that
controls the exhaust gas bypass rate on the basis of the physi
cal quantity related to the heat load on the main engine and thecharacteristics of the turbocharger. The exhaust gas bypass
rate, in which, for example, variation in the vessel Velocity
corresponding to the load on the main engine is reflected overtime, is selected. This allows the optimal value to be selectedeach time with respect to generation of bubbles from the gas
Supply or charged air means, thereby securing, as a device,
optimization in energy efficiency. As a result, the advanta
geous effect of reducing the resistance can be reflected overtime, while appropriately maintaining the condition of
exhausting the exhaust gas generated owing to increase anddecrease in the number of revolutions of the main engine.
This attains reduction in resistance of the vessel using bubbles
generated by reuse of the exhaust gas of the own device, andallowing the energy consumption efficiency using the reduction to be optimized, as a device, on the basis of calculationand control. In other words, it is different, in that control is

performed on the basis of the navigational condition detectionmeans, the physical quantity related to the heat load of themain engine, and the characteristics of the turbocharger, fromthe conventional turbo compound system (i.e., a system ofdischarging bubbles from the exhaust gas by means of theblower via a blower turbine). Therefore, the exhaust gas canbe drawn, while an appropriate value is maintained also inview of restriction on exhaust gas. For example, in a casewhere the exhaust gas cannot be discarded directly into theseawater and a case where it is necessary to raise the tempera
ture of the exhaust gas and reduces NOx, a preferable control
can be performed.

US 2011/0259440 A1

0083. Further, with respect to the above description, aconfiguration may be adopted that further comprises a variable nozzle improving gas Supply or charged air characteristics of the turbocharger, wherein the variable nozzle is con
trolled according to a drawing rate of the pressurized gas
and/or the exhaust gas, the physical quantity related to theheat load on the main engine, and the characteristics of theturbocharger.
0084. The “main engine' of the vessel represents anengine driven by liquid fuel orgas fuel, or a gas turbine driveby gas fuel.
0085. The “turbocharger supplying pressurized gas to themain engine may, for example, cause the exhaust gas to passtherethrough, rotate an exhaust gas turbine, drive a compres
Sorand the like, and thereby Supply the pressurized gas to themain engine. The exhaust gas rate passing through theexhaust gas turbine of the turbocharger is an important physi
cal quantity for the main engine to secure performance andreliability. It is necessary that the value thereof is appropri
ately be secured. Further, it is necessary that the gas Supply or
charged air rate from the turbocharger to the main engine iscontrolled under an appropriate condition according to theoperating condition of the main engine. Drawing of gas fromthe turbocharger and drawing of the exhaust gas after the main
engine should be controlled under strictly controlled condi
tions.

I0086. The “variable nozzle improving gas supply or
charged air characteristics of the turbocharger indicateswhat can adjust the direction and angle of vanes at the nozzle
Such that gas including air and exhaust gas preferably flows
into the turbocharger, when the gas including air and exhaustgas is Supplied to the turbocharger. More specifically, thevariable nozzle reduces the area of the path and controls the
direction of flow so as not to reduce the efficiency in driving
the turbocharger. That is, the variable nozzle is arranged at a
position capable of controlling the inflow condition of
exhaust gas before the exhaust gas flows into the exhaust gas
turbine pertaining to the turbocharger and/or a position
capable of controlling the inflow condition of air before airflows from the atmosphere into the compressor pertaining to
the turbocharger, and cause the inflow air to act on the exhaustgas turbine and the compressor even if the inflow gas varies.
0087. The “physical quantity related to the heat load on themain engine' is a physical property value measured anddetected in relation to the heat load on the main engine. For
example, Scavenging gas pressure, exhaust gas temperature(or temperature of an exhaust gas pipe, or ambient tempera
ture that is capable of being treated alike or has a relationshiptherewith on a one-to-one correspondence), flow rate, thenumber of revolutions (peripheral speed) of the turbocharger
and the like, may be adopted. The efficiency of the turbo
charger, and property and characteristic values of a degree ofmatching between the turbocharger and the engine can be
adopted as the characteristics of the turbocharger. As acquisition of physical quantities, sensors detectable respective
physical property values can be adopted.
0088. With such a configuration, the degree of open or
close and aperture setting of the Vane pertaining to the variable nozzle are controlled according to a certain variable. Thiscan optimize the inflow condition of the exhaust gas Supplied
to the turbocharger. Accordingly, the variable nozzle is con
trolled according to the pressurized gas bypass and/or theexhaust gas bypass, the drawing rate of pressurized gas and/or
exhaust gas, the physical quantity related to the heat load ofOct. 27, 2011

the main engine, and characteristics of the turbocharger.
Accordingly, the gas Supply or charged air characteristics ofthe turbocharger are improved. That is, the pressurized gas ispreferably supplied to the main engine, without reducing theturbocharger efficiency. The variable nozzle may be controlled so as to follow the optimal turbocharger efficiency on
the basis of a certain variable pertaining to the characteristicsof the turbocharger.
I0089. The variable nozzle is further provided. Accord
ingly, adaptive adjustment of the variable nozzle can acquiregas to be injected even under low load or high road, thereby
allowing reduction in frictional resistance by injected gas tobe realized.

0090. In order to solve the problems, africtional resistance
reduction device for a vessel corresponding to claim 6 of thepresent application comprises: a vessel; a plurality of gas
outlets injecting bubbles at least to a bottom of the vessel; gas
Supply or charged air means for blowing pressurized gas tothe plurality of gas outlets via a path; a drive device driving
the gas Supply or charged air means; gas adjustment meansfor controlling injecting of gas from the gas outlets; naviga
tional condition detection means for detecting a navigational
condition of the vessel; and a control device that controls thegas adjustment means according to a detection result from thenavigational condition detection means and changes a injectcondition of the pressurized gas from the gas outlets.
0091. Here, gas adjustment means represents an inverteror rotation adjustment device of a motor for controlling driveof the drive device, a valve or a damperfor adjusting starting/stopping Supplying air and adjusting an air rate, and generally,
hydraulic and pneumatic drive devices including a motor anda Solenoid for driving these elements.
0092. Here, the gas supply or charged air means represents
a blower or a turbine-driven compressor securing an gas
Supply or charged air rate effective for generating bubbles, apneumatic source preliminarily mounted on the vessel, or
exhaust gas that is derived from the engine and pressurized. In
particular, it is preferable that variation in gas Supply or
charged air rate be small even if the pressure at a dischargeside varies.

0093. The drive device is an eclectically driven motor, anengine driven by liquid fuel or gas fuel. In addition thereto,the drive device is a turbine gaining rotational force using theexhaust gas from the engine of the vessel, a hydraulic motor
or a pneumatic motor driven by hydraulically or pneumati
cally.
0094. The navigational condition detection means repre
sents a relative velocity detector detecting a relative velocity
between water and the hull, which is a physical quantity
varying according to navigation of the vessel, a draft detector
detecting the height of waterline of the vessel, an inclination
detector detecting an inclination of the vessel, and a shear
force sensor detecting a shear force acting on the hull.
0.095 Typically, the control device is electrically con
trolled. The control device represents concepts including a
program for attaining a control object, an algorithm, an elec
tronic medium storing them, and a computer for executing the
program and algorithm, in addition to an electric control
circuit. The control device includes, in addition to electric

control systems, what is controlled pneumatically or hydrau
lically, and any combination thereof.
0096. The control of the gas adjustment means according
to the detection result of the navigational condition detectionmeans represents control of the inverter of the motor, theUS 2011/0259440 A1

rotation adjustment device, the valve and damper for adjust
ing starting/stopping Supplying air and adjusting the air rate,
the motor and the Solenoids, and the hydraulic and pneumatic
drive devices for driving these elements on the basis of therelative velocity between water and the hull detected by the
relative velocity detector, the waterline of the vessel detectedby the draft detector, the inclination detected by the inclina
tion detector, and the shear force acting on the hull detectedby the shear force sensor. The control varies injecting of air
responsive to the conditions.
0097. With such a configuration, the navigational condition detection means detects the navigational condition of thevessel. The control device performs controls that adjusts thegas adjustment means to change the number of injecting at theplurality of working gas outlets injecting bubbles to the bot
tom of the vessel and/of the inject rate of gas under control of
the control device according to the detection result and effec
tively injects bubbles to the bottom of the vessel according to
the navigational condition of the vessel. Accordingly, controlof the bubble inject condition in which the navigational con
dition of the vessel is accurately reflected realizes more effi
cient reduction in frictional resistance.

0098. In the configuration in claim 6, the gas supply or
charged air means may plurally be provided, and Supplied toa plurality of gas outlets via a plurality of paths.
0099. With the above configuration, the navigational con
dition detection means detects the navigational condition of
the vessel. The control device controls the drive device

according to the detection result. The number of working
nozzles injecting bubbles to the bottom of the vessel and/or
the inject rate of gas is changed. The control is performed
such that the bubbles are effectively injected to the bottom of
the vessel according to the navigational condition of the ves
sel. In view of alleviating adverse effects owing to inclination
and waves, it is preferable that the gas outlets be plurally
provided. This plural provision exerts a novel effect capableof controlling injecting so as to inject bubbles only from the
middle one or fully inject bubbles according to the relative
velocity and the draft. Further, this plural provision enables
the individual gas Supply or charged air means to be mini
mized, thereby allowing the center of gravity of the vessel tobe lowered.

0100. In the configuration in claim 6, the plurality of gas
outlets may be arranged along a fore shape of the bottom of
the vessel.

0101. With Such a configuration, gas can be injected along
the bottom of the vessel of the hull from the gas outlets
arranged along the fore shape of the vessel formed in a socalled boat shape. That is, arrangement of the gas outlets
along the fore shape of the bottom of the vessel enables a large
area to be covered with the injected gas. This enables a sepa
rate control Such that airis selectively injected on a spot where
resistance is acting most and selectively facilitates reduction
in resistance.

0102. In the configuration in claim 6, the gas outlets may
include a configuration that does not protrude from a Surfaceof the bottom of the vessel.

0103) The configuration that does not protrude from theSurface of the bottom of the vessel is, for example, a configu
ration that does not protrude from the keel line. The configu
ration may be a configuration where a part equipped with thegas outlets is concave from the surface of the bottom of thevessel, or a configuration where the gas outlets are arranged
on a surface substantially flush with the surface of the bottom

Oct. 27, 2011of the vessel. The shape and the dimensions of the configu
ration are not subjected to any limitation.
0104. This configuration can prevent the gas outlet frombeing a resistance when the vessel is sailing. Since the gas
outlet does not protrude, the configuration does not become aload on operation under docking situations. More specifi
cally, when the vessel is mounted on the Supporting stage Suchas blocks for fixing the hull, there is no need to consider aprotrusion owing to the gas outlet. Since the gas outlets form
the same plane with substantially identical height to the bot
tom of the vessel, no consideration is necessary. Further, since
the gas outlets can be treated as with another element even in
repair of the bottom of the vessel, the working efficiency is not
impaired.
0105. In the configuration in claim 6, the plurality of gas
outlets may control a inject direction of the pressurized gas
and/or a inject rate of the pressurized gas.
0106 The navigational condition of the vessel varies
according to the relative velocity between water and the hull,
the height of waterline of the vessel, the inclination of thehull, the shear force acting on the hull, the depth of water in anavigational region and the like, which are physical quantities
varying according to navigation of the vessel.
0107 The navigational condition can vary owing to varia
tion in any one of prescribed situations of the vessel (total
amount of freight including passengers and cargoes, at thetime unnecessary to injecting gas, at the time of energy saving
operation, etc.), a navigational location immediately after
departure from a port or on cruising, the weather and currents.
Accordingly, it is necessary to adjust the inject condition ofgas in various situations along with the navigational condi
tions. It is necessary to adjust the inject rate and the inject
direction of gas to acquire a desired frictional resistance
reduction effect.

0108. The inject rate of gas can be adjusted by means of
the drive control by the gas Supply or charged air means,generation rate of gas and the like. Further, the inject rate ofgas can also be adjusted by means of changing the aperture of
the nozzle immediately before injecting. On the other hand,
the inject direction of gas can be adjusted by means of pro
viding a straightening plate on the nozzle to adjust the angles,changing the directions of a nozzle configuration itself of thenozzle, and utilizing a fluid element.
0109 Such a configuration is effective, in a case incapableof acquiring a desired frictional resistance reduction effectowing to the navigational condition of the vessel, even if thegas Supply or charged air means for generating gas appropri
ately controls the Supply rate. For example, there is a tendency
that the bubbles are diffused by buoyancy responsive to thenavigational conditions varying according to influences dueto the relative velocity between water and the hull, the heightof waterline of the vessel, the inclination of the hull, the shear

force acting on the hull, the depth of water in a navigational
region and the like. In these cases, if the inject direction of gas
can preliminarily be adjusted, the loss of the frictional resis
tance reduction effect can be prevented. The above configu
ration realizes that. Further, this allows a control of effectively
spreading bubbles around the bottom of the vessel (e.g., control of injecting bubbles slightly inward, because a slow
Velocity easily causes diffusion) in cases of inclination of thehull and small inject rate of bubbles, thereby allowing thefrictional resistance to be effectively reduced even under ves
sel conditions different from usual conditions.

US 2011/0259440 A1

0110. In order to solve the problems, a frictional resistance
reduction device for a vessel corresponding to claim 11 of thepresent application comprises: a vessel; a gas outlet that isprovided at a bottom of the vessel and injects bubbles via apath to the bottom of the vessel; gas Supply or charged airmeans blowing compressed gas to the gas outlet; a drive
device driving the gas Supply or charged air means; andbubble condition control means that is provided at least after
the gas outlet and for controlling the injected bubbles.
0111. The bubble condition control means has a functionof controlling the injected bubbles so as to effectively exert
the frictional resistance reduction effect, and includes an end

plate, and a bubble convolvement prevention structure.
0112 The end plate is a plate-like material made of materials, such as metallic material including iron and steel, lum
ber including cedar and cypress, and FRP. It is preferable thatthe materials be rigid and resistant to rust owing to adverse
effect of moisture and the like. It is further preferable to coatthe surface of the materials so as not to cause rust. Methods ofarranging the end plate include a method of connecting theconnecting portion material to the bottom of the vessel andarranging the material thereon by means of a connecting
method including screws, nails and adhesives. However, it ispreferable to adopt methods where the vessel main bodypertaining to the bottom of the vessel and the end plate are
fitted to each other by their shapes and/or both are dovetailed
together, or connected by welding. In arrangement, thearranging strength may be improved using the connecting
portion material for reinforcement.
0113. With such a configuration, the gas supply or charged
air means driven by the drive device causes the gas outlet to
inject gas. A plurality of end plates may be arranged, in theastern direction with reference to the gas outlet, around an end
portion of the bottom of the vessel in the longitudinal direc
tion thereof. Accordingly, the injected bubbles can flow while
being retained at the bottom of the vessel in the water.
0114. In a case of adopting the end plate as the bubble
condition control means, according to this configuration, theend plate is arranged after the gas outlet of the bottom of thevessel. Accordingly, Small amount of the contact area withwater is sufficient in comparison with the case of arranging
the end plate on the side of the vessel (e.g., comparison withthe above Patent Document 11), and increase in frictional
resistance owing to the end plate is significantly Small. Further, it is advantageous to provide the end plate on the bottomof the vessel, in view of stability of the vessel. More specifi
cally, accumulation of air on the vessel side disturbs thebalance, which further means that the bubbles have generated
in vain. This configuration with arrangement on the bottom of
the vessel can avoid Such an event.

0115. In a case of adopting a bubble convolvement prevention structure as the bubble condition control means, thebubble convolvement prevention structure can prevent the
bubbles from being convolved into the propeller means andthe like and becoming obstruction of maneuvering, without
receiving any effect owing to waves or currents.
0116. The configuration in claim 11 may further include
retractable diffusion limiting means for limiting bubble dif
fusion, which is provided as the bubble condition control
CaS.

0117. Here, the diffusion limiting means, for example,
suppresses bubble diffusion around the bottom of the vessel
caused by normal sailing (including sailing in a straight line
and turning) and a sudden inclination of the vessel owing toOct. 27, 2011

waves and wind force. The diffusion limiting means may be
the end plate, a rib structure (e.g., a rib structure with atriangular profile), a mound structure, a fin structure and thelike.

0118 More specifically, the diffusion limiting means ismade of materials, such as metallic material including ironand steel, and FRP and the like, and may be a plate-like orstreamlined structure where the whole or a part thereof pro
truding from the hull. It is preferable that the materials be
rigid and resistant to rust owing to adverse effect of moistureand the like. It is further preferable to coat the surface of thematerials so as not to cause rust. The shape and the dimensions of the diffusion limiting means are not subjected to any
limitation.

0119. Accordingly, “retractable diffusion limiting means’represents what is capable of causing the diffusion limiting
means to be a state of protruding from the main body of thevessel, such as the bottom of the vessel or a bow section, or astate of retracting.
I0120 Here, the state of protruding the diffusion limiting
means represents a state where diffusion limiting means canprevent bubble diffusion around the bottom of the vessel
caused by a Sudden inclination of the hull owing to influences,
Such as rolling by normal sailing (including sailing in astraight line and turning) with the diffusion limiting means,

waves, wind force and the like, and a state where diffusion

limiting means can exert an effect on a prescribed operation
under docking situations, and also includes a state where apart of the end plate (a distal end, etc.) protrudes.
I0121 On the other hand, a state of retracting the diffusion
limiting means represents, for example, a state where a Sur
plus space arranged in the main body of the vessel. Such as thebottom of the vessel or the bow section stores the entire partsof the diffusion limiting means and no part protrude or a partof the diffusion limiting means is retracted and the other part
protrudes, or a state where the diffusion limiting means isfolded at a boundary plane between the diffusion limiting
means and the main body of the vessel. The above limiting
means can also function as the diffusion limiting means. The
retraction is performed when air is not injected, when the ship
is carried into a dock, and when cooperation with injecting ofgas is performed as control.
0.122 The configuration realizing the protrusion and theretraction of the diffusion limiting means includes means forreversibly driving the diffusion limiting means by a drive
mechanism. The drive mechanism is a power source, such asa hydraulic, water-pressurized or pneumatic actuator, or a
motor, capable of linking to the diffusion limiting means, andpreferably arranged in the Surplus space provided in the main
body of the vessel, such as the bottom of the vessel or the bow
section. In this case, the drive mechanism is capable of driv
ing the diffusion limiting means so as to protrude and be
retracted. The drive mechanism may be operated manually or
automatically on sailing according to control on the basis of apredetermined condition.
I0123. The drive mechanism may be a link mechanism
configured by combination with a joint and the like. This
allows the linear movement of the drive mechanism to beconverted into rotational movement by means of the linkmechanism and the like.

0.124. On the other hand, the diffusion limiting means can
protrude by the self weight according to receiving gravity
and/or by urging by an elastic member Such as a spring
attached thereto, and be retracted by receiving compressingUS 2011/0259440 A1

load from underneath. In other words, the state where thediffusion limiting means protrudes is maintained unlessreceiving compressing load from underneath greater than theself weight of the diffusion limiting means or the elastic forceof the elastic member. On the contrary, the state of retracting
the diffusion limiting means is maintained during receiving
the compressing load. In particular, in order to bend the dif
fusion limiting means, it is preferable that a prescribed incli
nation be provided for easily bending the diffusion limiting
means and the compressing load be received without contact
ing with the diffusion limiting means or the like. A configu
ration may be adopted where variable movement by a drive
mechanism or a link mechanism and movement by the self
weight of the diffusion limiting means or the elastic member
attached to the diffusion limiting means are combined andthereby realizes protrusion and retraction. More specifically,
the self weight may be used when the diffusion limiting
means protrudes, and retraction may be performed by thedrive mechanism or the like at an arbitrary timing.
0.125 With such a configuration, the diffusion limiting
means can limit diffusion of the gas blown from the gas
Supply or charged air means and injected from the gas outlet
during sailing, and the gas can flow while being maintained in
the proximity of the bottom of the vessel. With the retractableconfiguration, when the vessel entering a port or sailing inshallow water, if reduction in frictional resistance by bubbles
is unnecessary, the diffusion limiting means is retracted.
Accordingly, the diffusion limiting means does not act as a
resistance or an obstruction, and does not become a load on
operation under docking situations. That is, in comparison
with the case where the end plate is not retractable as in theabove Patent Document 16, retraction can be performed whenthe vessel is sailing and the diffusion limiting means is unnec
essary, thereby reducing the frictional resistance. Further,when stability of the vessel is required, protrusion thereofalso serves as stabilization means (i.e., in addition to resis
tance, an effect of lowering the center of gravity is exerted).
Moreover, when bubbles are injected, the diffusion limiting
effect is acquired together with the stabilization effect.
0126 The configuration in claim 11 may further include
diffusion limiting means that is transformable according to aninternal/external force limiting bubble diffusion and provided
as the bubble condition control means.

0127 Here, as in the above the “diffusion limiting means’can prevent bubble diffusion around the bottom of the vessel
caused by a Sudden inclination of the vessel owing to influ
ences by normal sailing (including sailing in a straight line
and turning), waves and wind force, and configured with aflexible material.

0128 More specifically, the diffusion limiting means may
be, for example, a hollow object (hereinafter, also referred toas “hollow structure') made of material having a certain
extent of elasticity, rigidity, flexibility or resiliency and/or
strength including vinyl, rubber or various textile (e.g., materials used for a flak jacket and the bottom of the vessel of an
air-cushion vehicle), or an object in which a flexible material
Such as Sponge is filled. In this case, the shape (e.g., a round,an oval, a triangle, a rectangle, another polygon, etc.) is not
subjected to any limitation. However, the shape is preferably
adopted to which an internal force is applied by filling or
encapsulating fluid (gas such as air, or liquid Such as water oroil) or fine particles such as powder or dirt therein, thereby
allowing a desired shape to be maintained even in sailing. In
particular, with flexibility, under docking situations, when theOct. 27, 2011vessel is mounted on the Supporting stage such as blocks, it ispreferable that the diffusion limiting means be capable ofbeing compressed (crushed) by an external force owing to thepressure. Further, the injected or encapsulated fluid of fineparticles may be drawn or taken out. The inside and theoutside of the object may be configured only with an elastic
material, which may be anything capable of maintaining an
expanded State without being compressed owing to the waterpressure when the vessel is sailing, preventing bubbles frombeing diffused when the vessel is sailing and maintaining the
bubbles to be retained at the bottom of the vessel and flow.

I0129. Accordingly, the “transformable diffusion limiting
means’ includes that the diffusion limiting means is capableof being in a state of protruding from the bottom of the vessel
or a state of being contacted, and represents what is transformable into various shapes and states desired.
0.130 Here, the state where the diffusion limiting means
protrudes represents that fluid Such as air or water, fine particles or the like is injected or encapsulated into the hollow
diffusion limiting means to apply an internal force, thereby
maintaining a desired shape without being compressed by thewater pressure even when the vessel is sailing. Further, thediffusion limiting means may be anything that is not hollow,
and likewise includes anything capable of maintaining adesired shape without being compressed by the water presSure even when the vessel is sailing.
I0131 On the other hand, the state of contracting the dif
fusion limiting means represents a state where there is no or
substantially no internal force pertaining to the diffusion lim
iting means, or a state of maintaining a state of contracting
where the diffusion limiting means is crushed during receiv
ing the compressing load greater than the internal force
despite of presence or absence of the internal force. Further,
the contraction is performed when gas is not injected, whenthe vessel is carried into a dock and when cooperation with
injecting of gas is performed as control.
0.132. With such a configuration, the diffusion limiting
means is expanded by applying a prescribed internal force.
This can prevent bubbles from being diffused around thebottom of the vessel caused by a sudden inclination of the hull
owing to influences of rolling by normal sailing (including
sailing in a straight line and turning), waves, wind force andthe like. Further, the diffusion limiting means is contracted
without application of the internal force thereto, or contracted
during receiving a load greater than the internal force,
because the diffusion limiting means is crushed. Accordingly,
in a state of contraction, when gas is notinjected, the diffusion
limiting means does not become a resistance. Further, underdocking situations, the diffusion limiting means is crushed byreceiving the compressing load from the Supporting stage
Such as blocks. Accordingly, the diffusion limiting means
does not become an obstacle, the vessel can be fixed, and no

influence exerted on operation Such as a repair of the bottomof the vessel.

I0133) On the other words, in comparison with the case of
the end plate not retractable as in the above Patent Document
16, and with the end plate that is not transformable according
to the internal/external force, in this configuration, retraction
by reducing the internal force when it is unnecessary in Sailing reduces the frictional resistance, while also serving asstabilization means by increasing the internal force and pro
truding when stability of the vessel is required. When the
bubbles are injected, the effects of diffusion limitation and of
the Stabilization means can be acquired at the same time.

US 2011/0259440 A1

Further, transformation is automatic according to pressure. A
deep waterline causes contraction (Small amount of bubbles),and an inclination causes expansion at the risen side, thereby
preventing air from escaping.
0134. The configuration in claim 11 may further includes
limiting flow generation means for generating a flow limiting
diffusion of bubbles injected from the gas outlet. The limiting
flow generation means is provided as the bubble condition
control means.

0135 The bubbles generated by the injected gas receive an
influence owing to buoyancy by a starboard and port inclina
tions of the hull. Accordingly, diffusion can be suppressed byblocking the moving direction of bubbles by the diffusion
limiting means. On the other hand, as described above, thediffusion limiting means may be a solid plate-like object oran
object expanded using elastic material. Without limitation
thereto, the object may be a pseudo wall formed by injecting
liquid at a prescribed flow velocity. More specifically, thelimiting flow generation means capable of generating thepseudo wall by the flow of liquid is arranged in the hull in theproximity of the bottom of the vessel, thereby allowing thistechnical idea to be realized.

0136. With such a configuration, the limiting flow genera
tion means generates the flow of liquid having a prescribed
extent and a thickness dimension. This forms a so-called

pseudo wall (end plate), blocks the bubble diffusion path, andsuppresses the bubble diffusion generated by the inclinationof the vessel, thereby allowing the bubbles to flow while being
retained in the proximity of the hull. Further, the limiting flow
generation means is arranged in the bottom of the vessel so as
not to protrude. This prevents the limiting flow generationmeans itself from becoming a resistance, and negates the needfor considering the positions of blocks in consideration of thelimiting flow generation means under docking situations,
thereby negating the operational obstruction.
0.137 For example, a pump is used in order to generatesuch a limiting flow. It is preferable that the direction of thelimiting flow be, for example, a direction Substantiallyorthogonal to the bottom of the vessel. For example, if theflow rate of the limiting flow is proportional to the inject rateof bubbles, limiting flow is generated more efficiently. Further, for example, when the vessel is inclined, a control may
be performed such that the limiting flow is generated more ata shallow area. Together therewith/alternatively thereto, theflow rate of the limiting flow may be controlled according to
the vessel velocity. This can effectively prevent the bubbles
from being diffused, and prevent the limiting flow generationmeans itself from being a resistance.
0.138. The configuration in claim 11 may further include a
convolvement prevention structure that prevents bubbles
from being convolved into the propelling device of the vessel
and is provided on a stern side after the gas outlet at least on
the bottom of the vessel as the bubble condition control
CaS.

0.139. The convolvement prevention structure represents
structural measures for preventing bubbles from being con
volved into the propeller means, indicates all structures effec
tively preventing bubbles from being convolved into the propeller means, such as a protuberance having an after
mentioned curved Surface, including a V-shaped mound, a fin
structure, a bubble protection and a porous, and preferably isa structure where increase in resistance is Small as the vessel

is propelled.

Oct. 27, 20110140. With the above configuration, the convolvement
prevention structure arranged at least on the bottom of thevessel after the gas outlet causes the bubbles blown by the gas
Supply or charged air means and injected from the gas outlet
to escape so as not to be convolved into the propeller means.
More specifically, the bubble convolvement prevention structure can prevent the bubbles from being convolved into thepropeller means and the like and becoming an obstruction
against maneuvering, without receiving influences owing towaves and currents. In particular, according to the mound andfin structures, the shape can prevent convolvement. Accord
ingly, an event that the function is impaired owing to a failure
and the like is not required to be considered. The preventionof bubble convolvement can always be realized.
0.141. The configuration in claim 11 may further include
bubble drawing means for drawing at least bubbles provided
after the gas outlet and before a propelling device of thevessel, as the bubble condition control means, wherein thedrawn bubbles are discharged to the outside.
0.142 Here, the bubble drawing means represents what is
operated using a dedicated power, such as a blower drawing
the bubbles, a compressor, a pump drawing water in whichbubbles are mixed, and an ejector or the like and what uses
existing facilities of the vessel.
0.143 With the above configuration, the bubbles injectedfrom the gas outlet are drawn by the bubble drawing means
arranged before the propeller means such that the bubbles are
not convolved into the propeller means. The drawn bubbles
are discharged to the outside where there is no influenceowing to the propeller means. According to this, although, ina case of the configuration that recirculates the drawn bubbles
as disclosed in National Publication of International Patent

Application No. 2001-524421, recirculation causes decreasein temperature and reduction in Viscosity is not expected, thisconfiguration discharges the bubbles to the outside andthereby does not decrease the temperature and reduction in
Viscosity can be expected, in contrast to that.
0144. The configuration in claim 11 may further include
bubble convolvement detection means for detecting con
volvement of bubbles into a propelling device of the vessel, as
the bubble condition control means, wherein a inject condition of the gas outlet and/or an operating condition of thepropelling device is changed when the bubble convolvement
detection means detects convolvement of bubbles.

(0145 Here, the bubble convolvement detection means
generally represents a sensor that detects variation in driving
force of the propeller owing to convolvement of bubbles into
the propeller means as variation in thrust force or torque of thepropeller drive shaft, a vibration sensor that detects vibration
generated at the propeller means by convolvement of bubbles,
an acoustic sensor that detects sounds generated by convolve
ment of the bubbles and variation thereof, and imaging meansthat detects convolvement of the bubbles as images by a video
camera and the like.

0146 With the above configuration, when the bubbles
injected from the gas outlet are convolved into the propellermeans, the inject condition of the gas outlet and/or the oper
ating condition of the gas Supply or charged air means arechanged, thereby reducing the convolvement of the bubbles
into the propeller means.
0147 Previously, there is no idea that detects convolve
ment of bubbles and performs control based thereon. How
ever, this configuration is also capable of detecting occur
rence of cavitations and thereby effectively taking measures.

US 2011/0259440 A1

In this case, a detector detecting variation in thrust force or
torque, a detector detecting vibration, a detector detecting
generated Sounds, imaging means, a ultrasonic sensor, apneumatic sensor and the like, can be adopted as the bubble
convolvement detection means. Further, control on the propeller side, and control on injecting of gas (control on the rate,
the direction, and the number of working nozzles), and a
combination of both and the like, can be adopted as control
method.

0148. In order to solve the problems, a frictional resistance
reduction device for a vessel corresponding to claim 18 of thepresent application includes: a vessel; a plurality of gas out
lets injecting bubbles at least to the bottom of the vessel; gas
Supply or charged air means for blowing pressurized gas tothe plurality of gas outlets via a path; gas control means forcontrolling injecting of the pressurized gas from the gas out
lets; and a control device that adjusts the gas control means
according to a condition of navigational condition detectionmeans for detecting a navigational condition of the vessel
and/or the vessel conditions determination means and per
forms control of starting/stopping injecting gas from the gas
outlet.

0149. Here, the vessel conditions determination means
generally represents means, apparatuses and equipment for
determining situations where the vessel resides in a broad
sense, such as operating conditions of the engine of the vessel,
the specific fuel consumption of the engine, a GPS (Global
Positioning System) detecting which waters and location thevessel resides in, a gyro, a radar, an amount of freight mea
Surement. The navigational condition of the vessel represents
physical quantities varying according to navigation of thevessel (the relative velocity between water and the hull,height of waterline of the vessel, inclination of the hull, shear
force acting on the hull, depth of water in the navigational
region, etc.) owing to influences of waves, currents, winddirections, wind force, the waterline of the vessel and the like.

The vessel conditions represent conditions grasped by meansof determining the conditions where the vessel resides, suchas engine operating conditions, specific fuel consumption, aGPS, a gyro, a radar, an amount of freight measurement.
0150. In the above case, starting/stopping conditions may
include cases where waves become weaker/stronger, currents
become weaker/stronger, winds become weaker/wilder, therelative velocity become higher/lower, the waterline becomes
lower/higher, the shear force becomes stronger/weaker, thedepth of water becomes deeper/shallower, the engine starting
upfin stop operation, the specific fuel consumption becomesworse? better, leaving/approaching a port, and another vessel
leaving/approaching.
0151 Conditions for controlling the amount of bubbles
may include control that increases/decreases the amountaccording to the relative velocity becomes higher/lower, thewaterline becomes lower/higher, the shear force becomesstronger/weaker, and the depth of water becomes deeper/shallower.

0152 Methods (and advantageous effects) of starting/stopping include preliminarily operating the gas Supply or
charged air means and then opening the valve? preliminarily
closing the valve and then stopping the gas Supply or charged
air means (preventing seawater from coming in the air Supplypipe), opening/closing at a prescribed relative Velocity (injecting gas at a relative Velocity having frictional reduction
effect), and stopping when entering a port/opening whenleaving the port (preventing eutrophication).

Oct. 27, 2011

0153. With such a configuration, the navigational condition detection means detects the navigational condition of thevessel and/or the vessel conditions determination means
determines the situations where the vessel resides and thedevice adjusts the gas adjustment means on the basis of thedetection result and/or the determination result, injects gas
from the gas outlet and stop the injecting, thereby effectively
controlling injecting of bubbles according to the navigational
conditions and the vessel conditions. With respect to thispoint, previously, there is no concept that adjusts the gas
adjustment means according to the navigational conditions of
the vessel and/or the vessel conditions and performs control
that starts/stops injecting of gas. With the adjustment of thegas adjustment means according to the navigational condi
tions of the vessel and/or the vessel conditions in the configu
ration, injecting of air is started/stopped responsive to thenavigational conditions of the vessel. Such as waves, currents,
the wind direction, wind force, the draft of the vessel, and thevessel conditions, such as engine operating conditions andspecific fuel consumption. This exerts advantageous effects,
Such as prevention of noise and prevention of adverse influ
ences to fishing boats and ports, in addition to an energy
consumption effect.
0154) In the configuration in claim 18, when the naviga
tional condition detection means and/or the vessel conditions
determination means detects/determines that the vessel isstopped, the gas Supply or charged air means may be stopped.
0155 Methods (effects thereof) of stopping the gas supply
or charged air means may include stopping after stopping thevalve (preventing seawater from coming in), stopping before
stopping the engine (stopping before power-down of the elec
tric generator and stopping the turbocharger), stopping simul
taneously with the stop of the engine (operating together withthe turbocharger), stopping after unloading of the freight(adjustment of the draft).
0156 With such a configuration, when it is detected/determined that the vessel is stopped, the control device stops
the gas Supply or charged air means to stop the injecting of gas
from the gas outlet. In a case of using the turbocharger,
injecting of gas may be stopped in a linked manner to the stopof the turbocharger accompanying a stop of the engine. Further, the injecting is stopped by determining a stop of thevessel. This can prevent navigational condition detectionmeans from performing erroneous detection owing to resi
dence of bubbles at the hull accompanying a stop of the vessel(measurement of the depth of water when entering a port,etc.).
0157. In configurations in claims 1, 2, 6 and 18, the navi
gational condition detection means may be a relative Velocity
detector detecting a relative velocity between the hull and thewater, and adopt a configuration where the number of gas
outlets and/or the inject rate of gas are increased or decreased
according to increase or decrease of the relative Velocity.
0158. The systems of the relative velocity detectors (sensors) may include an ultrasonic system, an electromagnetic
system, and a laser system. When the relative velocity detec
tor is used for an air-lubricated method, a lot of bubbles

intervene at the Surface of the sea, thereby allowing measure
ment to be more accurate because of diffused reflection incases of the laser system and the ultrasonic relative Velocity
SSO.

0159. With such a configuration, the number of nozzles
and/or the inject rate of gas are controlled according toincrease and decrease of the relative velocity between the hullUS 2011/0259440 A1

and a water system, Such as seawater or river water, instead ofan absolute ground velocity of the vessel. Because the control
is performed according to detection of the relative velocity,
the control becomes more accurate than that using a displace
ment, kinetic, acceleration sensors. Further, the relative

Velocity sensor can be shared for another use such as mea
Surement of currents.

0160. In the configurations in claims 1, 2, 6 and 18, thenavigational condition detection means may be a draft detec
tor detecting the draft of the vessel, and adopt a configuration
where the number of gas outlets and/or the inject rate of gas
are increased or decreased according to the height of thewaterline.

0161 The draft of the vessel can be shared for used for
managing the amount of freight. In principle, it is controlled
Such that injecting of gas is available when the pressure of thepressurized gas and/or the exhaust gas is equal to or more thanthat at the draft, and injecting of gas is stopped when thepressure of the pressurized gas and/or the exhaust gas is equal
to or less than that at the draft. Because this control appropri
ately injects gas, the seawater does not cause backflow.
0162. In the configurations of claims in 1, 2, 6 and 18, thenavigational condition detection means may be an inclination
detector detecting an inclination of the hull, adopt a configu
ration where the number of working gas outlets laterally
arranged on the vessel and/or the inject rate of gas is con
trolled according to the inclination.
0163 The inclination detector can be used for anotherapplication for the vessel (e.g., the air inject rate of air isdecreased or stopped when freight conditions are verified andwhen variation in inclination is large, etc.).
0164. With such a configuration, the gas adjustment
device is controlled according to the degree of inclination of
the hull detected by the inclination detector. Because thenumber of gas outlets and/or the inject rate of gas is appro
priately adjusted when turning and rolling, the bubble diffusion conditions are appropriately controlled by decreasing thenumber of working nozzles where gas is injected at a shallow
side of the inclination and increasing the number of working
noZZles where gas is injected at a deep side of the inclination
when the vessel is inclined, thereby allowing effectiveness infrictional resistance reduction to be improved.
0.165. In the configurations of claims 1, 2, 6 and 18, thenavigational condition detection means may adopt a configu
ration of being attached to a spot at least without receiving
influences of the bubbles.

0166 The navigational condition detection means
includes what is arranged at a prescribed part of the hull
facing water, Such as a depth sounder measuring a depth ofwater at a navigational region. A principal object of thepresent application is to reduce the frictional resistance by
causing bubbles injected from the gas outlet to flow aroundthe bottom of the vessel while retaining the bubbles therearound. The inject condition of gas is controlled on the basisof the various types of detection results from the navigational
condition detection means. Accordingly, optimization of thedetection condition improves the reliability of the detection
result, forms a desired inject condition and thereby improves
the reduction in frictional resistance.

0167. With such a construction, the position where thenavigational condition detection means facing water isarranged at a position without receiving influences of theinjected gas. More specifically, the position is a spot where
the navigational condition detection means is not covered

Oct. 27, 2011

with gas during detection, gas does not come into a detection
region and a stable detection condition can be maintained.
This allows a desired detection result to be reliably acquired.
Because attachment of the navigational condition detectionmeans does not receive influences owing to bubbles, foulingof marine organisms is a little, which can prevent unexpected
failures, malfunctions, accidents and the like owing to thefouling from occurring. Systems of the navigational condition detection means include a relative Velocity detector, adraft detector and an inclination detector. When any one ofthese is used, attachment on the position without receiving
influences of bubbles can be performed.
0.168. In the configurations of claims 2, 6, 7, 11 and 18 aconfiguration may be adopted that the path is raised on or
above the waterline and then connected to the gas outlet.
0169. With this configuration, the piping passes at a heightequal to or above the waterline. This can prevent seawaterfrom coming into the gas outlet arranged on or below thewaterline, thereby allowing security of the main engine to befurther increased.

0170 That is, a heavy main engine (in a case of using aturbocharger) and the gas Supply or charged air means can bearranged on or below the waterline while backflow of water isprevented, thereby improving stability of the vessel. In thiscase, the backflow of water can be prevented in a threefold
manner by a structure where the path is raised once at thewaterline or higher and then connected to the gas outlet, a
structure with open and close means arranged before the gas
outlet, and a structure of cooperation with a valve arranged
after the turbocharger and the gas Supply or charged air
CaS.

0171 In the configurations of claims 2, 6, 7, 11 and 18, aconfiguration may be adopted that the path is blocked at theproximity of the gas outlet when injecting of the pressurizedgas and/or the exhaust gas is stopped.
0172 Blocking of the path includes, for example, a man
ner where an open/close valve, which passes and blocks the
air Supply pipe connected to the gas Supply or charged airmeans and the gas outlet, opens always at least during gas
Supply or charged air and closes when gas Supply or charged
air is stopped. The operation of opening and closing can berealized by a gate value that open and closes the fluid path byoperation of a disc-shaped valve body stored in a valve box ofthe valve in a right angle with respect to the fluid path, a stop
valve capable of adjusting the flow rate by closing the valve
body stopping the flow of the fluid, a check valve that unidi
rectionally maintains the fluid and prevents backflow or the
like. The open/close can be performed manually or automati
cally according to control on the basis of a predetermined
condition on sailing.
0173 According to this configuration, provision of theconfiguration blocking the path allows the path to be blocked
when gas Supply or charged air is stopped, or gas does not
pass. This can prevent backflow of water in the air Supply
pipe. Further, without contact with water, corrosion in the air
Supply pipe, and fouling owing to adhesion and reproductionof algae and shellfish, Such as barnacles and oysters, can beprevented. Moreover, since the opening is closed whenbubbles are not injected, increase in frictional resistance canbe suppressed.
0.174. In this case, a method can be considered for thecontrol of blocking the path. This method blocks the path in
the proximity of the gas outlet, first. Next, the bypass valve isclosed and Subsequently the turbocharger is stopped. A presUS 2011/0259440 A1

Sure is thus reserved in the piping path. Accordingly, intrusionof water can further be prevented.
ADVANTAGES OF THE INVENTION

0.175. According to the present invention, bubbles are
injected from the plurality of gas outlets arranged at thebottom of the vessel, by controlling the plural pieces of gas
Supply or charged air means provided corresponding to therespective gas outlets, according to the navigational condition. Therefore, rise of bubbles can be inhibited by the bottomof the vessel itself, the bubble retention effect can be maintained, and the frictional resistance can effectively be reduced
by a small amount of bubbles, in comparison with an arrange
ment only at the sides of the vessel. Further, the case ofarrangement only on the sides of the vessel, since the depth ofwater is shallow, influences of waves cannot be ignored whenthe vessel is used in the ocean. However, at the bottom of thevessel, the influences of waves are alleviated. This allows

bubbles to be stably injected, thereby effectively exerting thefrictional resistance reduction effect. One piece of gas Supply
or charged air means are correspondingly provided withrespect to one gas outlet. Accordingly, injecting of bubbles
can easily be controlled with respect to each separate gas
outlet, and the problem of variation in inject rate of bubbles
owing to waves can also be alleviated. Further, the conditionof gas Supply or charged air can be controlled according to thedetection result from the navigation detection means. Accord
ingly, the injecting of bubbles can finely be controlled accord
ing to the navigational condition in comparison with a case of
constantly injecting gas. A further frictional resistance reduction effect can thus be expected.
0176 Further, according to the present invention, the gas
Supply or charged air from the gas outlets symmetricallyarranged with respect to the planar center line of the hull issymmetrically controlled according to the detection result
from the navigational condition detection means. Accord
ingly, in particular, when the vessel is sailing in a straight line,
a uniform frictional resistance reduction effect can be

expected. This can prevent the ability to hold a straight linefrom being impaired owing to the injecting of bubbles. Further, control is symmetrically performed on the laterally
arranged gas outlets. Accordingly, the control can be performed by means of circuits with the laterally same configu
rations, the same circuit, or output from the same port. This
allows the control to be simplified and can facilitate rational
ization of the circuits.

0177. Further, according to the present invention, the gas
Supply or charged air means is arranged on the top of the hulland the gas from the gas Supply or charged air means is guided
into the bottom of the vessel via the air supply pipe. This can
reduce variation in inject rate of bubbles along with variationin pressure owing to influences of waves in a case of use in theocean, by a buffer effect due to the volume of the air supply
pipe. This indicates that, because the air Supply pipe has aconsiderable volume from the top of the hull to the bottom of
the vessel, the gas intervening in this Volume space is allevi
ated by a resiliency effect when being compressed anddecompressed, and variation in pressure in the gas outlets
owing to variational height of the waves are reduced. Further,bend of the path at the bottom of the vessel at the right angle
causes an effect that the gas changes the direction and two
dimensionally spreads. However, the gas is guided into thegas outlet. This can solve the problem of impairing the dis

Oct. 27, 2011

tribution of Velocity of flow of gas at the gas outlet, particu
larly in the direction parallel to the bottom of the vessel.
0.178 Further, according to the present invention, a plural
ity of perforated plates having pluralities of apertures arearranged in series Such that the positions of apertures are
displaced, and configures the gas outlet. Accordingly, theplurality of perforated plates cause the flow of gas to be bent,
and can exert a so-called baffle plate effect. This baffle plate
causes an effect that the plurality of displaced perforated
plates provide resistance, and is capable of injecting gas fromthe gas outlet in a uniform state. Further, this allows theplurality of perforated plates having the same aperture pitch
to be utilized, and manufacturing economies of Scale can be
expected in view of in view of industry, thereby enabling a
product to be provided at low cost.
0179 Moreover, according to the present invention, thegas Supply or charged air means may be the positive-displace
ment gas Supply or charged air device. This enables the gas tobe blown more stably, in view of a problem of injected amountof bubbles along with variation in pressure at the gas outlet
owing to influences of waves caused in case of using in theocean and a problem of variation in pressure acting on the gas
outlet along with the amount of freight, that is the height ofwaterline. As a result, this can prevent impairment in frictional reduction effect along with variation in the injectedamount of bubbles owing to variational height of waves andthe height of the waterline. When the wave is high, the appar
ent waterline becomes deeper, and the frictional resistancetends to increase. Accordingly, the reduction in frictional
resistance by bubbles is expected. However, the conventional
method increases the pressure at the bubble nozzle. Accord
ingly, there is a phenomenon that the amount of bubbles isconversely decreased. Further, when the amount of freight isincreased and the waterline is deepened, the contact area ofthe hull is increased. Thus, further reduction in frictional

resistance is expected. However there is a problem that theamount of bubbles is also decreased. In view of these phenomena, the positive-displacement gas Supply or charged air
device is used; the gas Supply or charged air devices are used
for the respective gas outlets; the gas outlets are arranged at
the bottom of the vessel. Accordingly, this enables a stableamount of bubbles to be injected without receiving influencesof waves and the draft.

0180 Further, according to the present invention, the plu
rality of gas outlets are arranged along the fore shape of thebottom of the vessel. This enables the gas to be injected,
without making vacant and useless Surface at the bottom of
the vessel. Accordingly, the frictional reduction effect can befurther improved. In particular, the bottom of the vessel at thebow section corresponds to a distal end of a so-called boat
shape. The plurality ofgas outlets are laterally arranged at thisportion, and the injecting of gas is controlled. Accordingly, inparticular, when the relative velocity of the vessel is slow or
the waterline is shallow, the bottom of the vessel can evenly
be covered with a small amount of bubbles, and the sides ofthe vessel can be covered with bubbles rising in the water,
thereby allowing the effect of reduction in frictional resis
tance to be further improved.
0181 Moreover, according to the present invention, thegas adjustment means adjusts and injects gas from the plural
ity of gas outlets arranged at least at the bottom of the vessel,
according to the detection result from the navigational con
dition detection means detecting the navigational conditionof the vessel. Therefore, rise of the bubbles can be inhibitedUS 2011/0259440 A1

by the bottom of the vessel itself, the bubble retention effectcan be maintained, and the frictional resistance can effec

tively be reduced by a small amount of bubbles, in compari
son with an arrangement of the gas outlets only on the sides ofthe vessel. In particular, a case where influences of waves andthe draft is considered, the gas outlet at the bottom of thevessel is mainly used, and these influences can be alleviated.
Further, injecting of bubbles can easily be controlled by thegas adjustment means with respect to each separate gas outlet.
In particular, in a case of use in the ocean, the problem ofvariation in inject rate of bubbles owing to waves can also be
alleviated by predicting variation in pressure and adjusting
the blowing gas. Moreover, the gas adjustment means cancontrol the blowing condition according to the detection
result from the navigation detection means. Accordingly, theinjecting of bubbles can finely be controlled according tonavigational situations in comparison with a case of uni
formly injecting gas, and further frictional resistance reduction effect can be expected.
0182 Further, according to the present invention, the relative velocity detector detects the relative velocity between thehull and water, and the number of working gas outlets and/or
the inject rate of gas are increased and decreased according toincrease and decrease in relative Velocity. Accordingly, frictional resistance can finely be reduced according to the navi
gational condition of the vessel. The reduction in frictional
resistance is determined by the relative velocity between cur
rents in the ocean or the water flow in the river and the hull,instead of a ground Velocity where the navigational speed of
the vessel is by use of the GPS or a beacon. Therefore, thenumber of working gas outlets and/or the inject rate of gas are
increased when the relative velocity is large on the basis of thehull and the water. The number of gas outlets and/or the injectrate of gas are reduced when the relative velocity is small.
This allows the net reduction effect of the frictional resistanceto be increased.

0183 Moreover, according to the present invention, therelative velocity detector is attached to a spot of the hull
without receiving influences of waves and/or bubbles.
Accordingly, in particular, this can prevent error from being
generated in the relative velocity of the vessel used in theocean. For example, various types, such as an ultrasonicsystem, an electromagnetic system and a heat wave system,
can be considered as the relative velocity detector. However,any one of these causes an error, with intervention of bubbles
and also with influences of waves. Accordingly, attachment of
the relative velocity detector to the spot without these influ
ences can eliminate the error, and realize an appropriate control of injecting gas.
0184 Moreover, according to the present invention, bymeans of the draft detector detecting the draft of the vessel,
responsive to the height of waterline, the number of working
gas outlets and/or the inject rate of gas is increased anddecreased. Thus, the frictional resistance can finely be
reduced according to the navigational condition of the vessel.
More specifically, when the amount of freight to the vessel islarge, the waterline rises (becomes deeper). In this case, thecontact area of the hull with water is increased. In this case,increase of the number of working gas outlets and/or the
inject rate of gas can reduce the frictional resistance more
effectively. In contrast, in a state where the amount of freight
is Small, the balance is maintained by ballast water, and thewaterline is lowered (becomes shallower), decrease of thenumber of working gas outlets and/or the inject rate of gas canOct. 27, 2011

reduce the net frictional resistance with maintaining the bal
ance without use of power of the drive device in vain.
0185. Further, according to the present invention, theinclination of the hull is detected by the inclination detector
and the number of working gas outlets laterally arranged on
the vessel and/or the inject rate of gas are controlled. Therefore, the frictional resistance can effectively be reduced without using the power in vain when the vessel is turning androlling. More specifically, in a state where the one side of thebottom of the vessel is raised owing to turning or rolling, thecontact area of the hull with water becomes smaller on theraised side than that of the opposite Sunk side. Accordingly, inorder to appropriately distribute injecting of gas, it is preferable that the number of working gas outlets and the inject rateof gas be decreased on the risen side, and increased on the
opposite side. In this case control is performed only on thenumber of working gas outlets, or only on the inject rate ofgas, or on both of them simultaneously. In any event, inclina
tion detector detects the hull and the gas adjustment means
adjusts the injecting of gas, thereby allowing the net frictional
resistance to be reduced automatically and appropriately
without using power in vain.
0186. Further, according to the present invention, the gas
adjustment means performs adjustment at least on the plural
ity of gas outlets injecting bubbles to the bottom of the vessel
and controls starting/stopping injecting gas according to thenavigational condition of the vessel and/or the vessel condi
tions. In particular, in a case of the frictional resistance reduction effect by injecting gas cannot be expected, the injecting
bubbles is stopped. In a case of the reduction effect can be
expected, bubbles are injected. This prevents the power frombeing used in vain, and can effectively reduce the net frictional resistance. The frictional resistance at the hull is sub

stantially proportional to a square of the relative Velocity
between the hull and water. Accordingly, if the relative veloc
ity between the hull and water is decreased, the frictional
resistance is Suddenly decreased, and the power and energy
consumed by the gas Supply or charged air means becomelarger than the frictional reduction effect. In Such a case, it isdesirable to stop injecting of gas from a systematical standpoint. Accordingly, when the Velocity becomes equal to aprescribed Velocity or less, and when approaching a port, theinjecting of gas is stopped. When the Velocity becomes theprescribed velocity or more, and when a prescribed time
elapsed after departing the port, the injecting gas is started.
These determinations are made by the navigational condition
detection means and/or the vessel conditions determinationmeans, and the injecting of bubbles are started/stopped. This
enables the control to be appropriately performed.
0187 Further, according to the present invention, when it
is detected/determined that the vessel is stopped, the gas
Supply or charged air means is stopped, and injecting bubbles
from the gas outlet is stopped, the gas Supply or charged airmeans blowing gas can be stopped if the reduction in frictional resistance is not required. This negates use of powerand energy consumption in vain, and can realize a frictional
resistance reduction device for a vessel that has systemati
cally high energy efficiency and is economic.
0188 Moreover, according to the present invention, thegas is injected from the gas outlet, and a plurality of end plates
are arranged in an aft direction at Substantially ends of thebottom of the vessel in a longitudinal direction. Accordingly,
the injected bubbles can flow along the bottom of the vessel
over the entire bottom of the vessel in the water. This allows

US 2011/0259440 A1

the frictional resistance to effectively be reduced. The opera
tion of the end plate can prevent the bubbles from being
distributed to a part with lower water pressure, even when thevessel is inclined owing to disturbance Such as waves andflows. This can stably facilitate reduction in frictional resis
tance.

0189 Further, according to the present invention, the plu
rality of end plates are substantially symmetrically arranged
along with the planar shape of the bottom of the vessel. This
can Substantially prevent (the group of) the end plates frombeing a resistance impeding the sailing of the vessel. Moreover, this allows the gas outlets to be arranged along with thefront planar shape of the bottom of the vessel to the front mostsurface in the proximity of the bow section, thereby facilitat
ing reduction infrictional resistance over the entire bottom of
the vessel.

0190. Further, according to the present invention, (thegroup of) the end plates is made into a shape analogous to theplanar shape of the bottom of the vessel, thereby enabling theeffect of retaining bubbles to be further improved.
0191 Moreover, the present invention may adopt a con
figuration where the end plate is defined by a substantiallytriangular profile whose base is at the bottom of the vessel ora curve Such as a quadratic function curve. This profile allows
the contact area with water to be decreased, and allows thefrictional resistance owing to arrangement of the end plates tobe reduced, in comparison with a case of using a flat plate.
This further improves the effect of substantially avoiding theresistance of impeding the sailing of the vessel owing to (thegroup of) the end plates. The bubbles in the water pertaining
to the injected airflow while being effectively retaining along
the bottom of the vessel.

0.192 Further, according to the present invention, the fore
and aft ends of the end plate have a streamlined shape at thefore and/or the aft end, and thereby minimizes the water
resistance. This allows the frictional resistance owing toarrangement of the end plates to be further reduced, and the
bubbles in the water pertaining to the injected air effectively
flow along the bottom of the vessel.
0193 Moreover, according to the present invention, theconcave portion is formed at the bottom of the vessel in thelongitudinal direction, the astern direction with reference tothe gas outlet. This further improves the effect that the
bubbles in the water pertaining to the injected air effectively
flow along the bottom of the vessel while being retained up to
the end of the concave portion of the bottom of the vessel. The
effect of the concave portion can prevent the bubbles frombeing diffused to a part with a lower water pressure even whenthe vessel is inclined owing to disturbance of waves andflows, and stably facilitates reduction infrictional resistance.
0194 Further, according to the present invention, theuneven profile whose sectional width is at least one withrespect to the height in the longitudinal direction with reference to the gas outlet is formed. Accordingly, the bubbles in
the water pertaining to the injected air adhere to the concave
portion by the resistance. This allows the bubbles to flow
while being retained up to the end of the uneven profile of thebottom of the vessel.

0.195. Further, according to the present invention, theuneven profile may have a profile where substantially trian
gular shapes are laterally arranged. Since the height of thetriangle is formed equal to or less than the height capable ofbeing sufficiently covered with bubbles, the bubbles actuallyadhere to the concave portion pertaining to the triangle

Oct. 27, 2011

because of the differential pressure. This allows the bubbles
to flow while being retained up to the end of the uneven profileof the bottom of the vessel. Moreover, since the substantiallytriangular shapes are laterally arranged, a lot of vertices of the
Substantially triangular shapes exist. This facilitates opera
tion of carrying the vessel on bases under docking situations,
thereby allowing the operation to be improved.
0196. Further, according to the present invention, the plu
rality of end plates arranged at Substantially end portion of thebottom of the vessel in the aft direction with reference to thegas outlet also serve as stabilization means of the vessel. Thisfurther improves the effect of Suppressing rolling and turningover onto the side of the vessel Owing to natural phenomena
and a collision object, and allows the injected bubbles to flow
while being retaining up to the end of the bottom of the vesselin the water. Moreover, the effect of the plurality of end plates,
which also serve as the stabilization means, makes the vessel
resistant to inclination even under disturbance Such as waves

and flows. Even when the vessel is inclined to a certain extent,

the effect by the end plates prevents the bubbles from being
diffused to a part with lower water pressure, thereby allowing
the frictional resistance to be stably reduced.
0.197 Further, the present invention negates the need of
separately providing the stabilization means, or allows theperformance, functionality and equipment of the stabilizationmeans to be minimize, thereby enabling economic efficiencyof the vessel to be improved.
0198 Moreover, the present invention enables the equip
ment of the bilge keel to be saved, and allows the resistance of
currents acting on the vessel to be reduced because the heightof the end plate is less than that of the bilge keel.
0199 Further, according to the present invention, bubbles
injected from the gas outlet by the gas Supply or charged airmeans driven by the drive device adhere to the surface of thebottom of the vessel by the fluid effect of a difference of steps
attracting the bubbles, and can flow over the entire bottom of
the vessel while being retained, thereby allowing the reduction effect of the frictional resistance to be improved.
0200 Further, the present invention enables the bubbles
injected from the gas outlet to be drawn by bubble drawingmeans at the position where the bubbles leave the bottom of
the vessel and start diffusion. This can avoid diffusion of
bubbles in the water.

0201 According to the present invention, bubble is supplied by the gas Supply or charged air means and bubbles are
injected from the gas outlet arranged at the bottom of thevessel. Therefore, rise of the bubbles is suppressed by thebottom of the vessel itself. This allows the bubble retention

effect to be maintained, and enables the frictional resistanceto be effectively reduced by a small amount of bubbles. In
particular, in a case of using the vessel in the ocean, theinfluences of waves have been incapable of being ignored.
However, the influences of the waves are alleviated at thebottom of the vessel, thereby enabling the bubbles to be stably
injected. Moreover, the convolvement prevention structure
preventing bubbles from being convolved into the propellermeans allows the bubbles to escape without receiving influ
ences of waves and currents and without being convolved into
the propeller means. This can prevent the efficiency of thepropeller means from being decreased, and prevent the pro
pulsion from being decreased, and allows the net reduction
effect in frictional force to be improved.
0202 In addition to the injecting of bubbles from the bot
tom of the vessel, injecting from a part other than the bottomUS 2011/0259440 A1of the vessel also exerts an analogous effect. Moreover,arrangement of the convolvement prevention structure at apart other than the bottom of the vessel also exerts an analo
gous effect.
0203 Further, according to the present invention, the pro
tuberance having the curved surface, which is the convolve
ment prevention structure, causes the bubbles to escape, andthe bubbles are never convolved into the propeller means.
This can prevent the efficiency of the propeller means frombeing decreased, and prevent the propulsion from being
decreased. Moreover, the protuberance having the curved
Surface can be configured as a simple structure. Accordingly,
the protuberance never becomes an obstacle under docking
situations. Since a flow along the bottom of the vessel
Smoothly changes at the protuberance having the curved Sur
face, convolvement of bubbles can effectively be prevented
without increasing the frictional resistance at the hull. Further, the streamline goes downwards at the protuberance hav
ing the curved surface, and the flow velocity below the propeller means is decreased. Accordingly, improvement inpropeller efficiency can be expected.
0204 Further, according to the present invention, theV-shaped mound, which is the protuberance and laterally
spreads centered at the planar center line of the hull, canprevent bubbles from being convolved into the propellermeans. This allows bubbles to effectively escape in a sym
metric manner from the symmetric propeller means arrangedon the planarcenterline. Moreover, the mound has a V-shaped
form. This further improves the effect of causing the bubbles
to escape, and can prevent increase in frictional resistance ofthe flow along the bottom of the vessel. Further, the symmet
ric shape facilitates manufacture.
0205 Further, according to the present invention, thebubble protection arranged in the proximity of the propellermeans prevents only bubbles reaching the proximity of thepropeller means from being coming into the propeller means.
This can prevent the bubbles from being convolved without
impeding a flow of water into the propeller means.
0206. Further, according to the present invention, at the
bubble protection that has a plurality of apertures andarranged in a Substantially V-shape, the apertures act as a
resistance against bubbles in a part below the propeller means
where bubbles whose distribution of velocity of flow aresubstantially V-shaped are easily convolved and are thereby
capable of effectively preventing convolvement. Moreover,the bubble protection has a plurality of apertures, and an area
above the Substantially V-shaped part is vacant. Accordingly,
the water flow into the propeller means is not impeded, andthe propulsive efficiency is never decreased.
0207. According to the present invention, the bubble
drawing means arranged at the fore part of the propellermeans draws the bubbles to be convolved into the propellermeans before convolvement, and discharges the drawn
bubbles to the outside, thereby causing the bubbles not toreach the propeller means. This can reliably prevent bubbles
from being convolved. Further, since the bubble drawingmeans is arranged in the proximity of the propeller means, thefrictional reduction effect by the bubbles injected to the bot
tom of the vessel can sufficiently be exerted.
0208 Further, according to the present invention, in the
bubble drawing means, the gas-liquid separation mechanism
separates the drawn bubbles and water from each other. This
prevents water from being mixed into the bubble drawingmeans such as a blower, a compressor and a pump, thereby

Oct. 27, 2011

allowing the functionality to be stably exerted. The water
separated by the gas-liquid separation mechanism can beused for another application of the vessel. Such as for coolingwater and an anti-rolling tank.
0209 Further, according to the present invention, the con
Volvement prevention structure preventing convolvement of
bubbles is arranged after the bubble drawing means. Accord
ingly, even if residual bubbles having not been drawn flow outof the bubble drawing means owing to various disturbances,the convolvement prevention structure causes the bubbles toescape, and can reliably prevent the convolvement into thepropeller means. Accordingly, the bubble drawing means canbe stopped and only the convolvement prevention structure
can be operated, in a case where the amount of bubbles is
Small, or according to the vessel conditions or the naviga
tional condition. This can prevent the efficiency of the propeller means from being reduced, and prevent the propulsion
from being decreased, in a finer manner.
0210. According to the present invention, when the bubble
convolvement detection means detects the convolvement of

the bubbles into the propeller means, the inject condition of
the gas outlet and/or the operating condition of the gas Supply
or charged air means are changed. This can further prevent the
bubbles from being convolved, and prevent the reduction inpropeller efficiency to be continued. This can also prevent
vibration and noise at the propeller means along with theconvolvement of bubbles from being generated, thereby
allowing damage of the propeller means to be reduced, andpreventing the harmful effect on the vessel.
0211. According to the present invention, when the bubble
convolvement detection means detects convolvement of

bubbles into the propeller means, change of the operating
condition of the propeller means can increase the number of
revolutions to maintain the propulsion and can decrease thenumber of revolutions to reduce the convolvement of bubbles

if the propulsion of the propeller is decreased owing to con
volvement of bubbles. Further, the operation condition ischanged such that the number of revolutions is decreased for
addressing vibration and noise, or the angles of blades arechanged in a case of a variable-pitch propeller, thereby chang
ing the condition into that with less influence against mixing
ofbubbles. This enables the influence owing to convolvementof bubbles to be reduced.

0212. According to the present application, a part of thepressurized gas and/or the exhaust gas among the residual gas
from the turbocharger can be reused as bubbles. This facili
tates reduction in resistance without any need of energy for
generating bubbles, thereby allowing energy consumption
thereof to be reduced. Further, control where, for example,
variation in vessel velocity is reflected over time can be
attuned without adversely affecting the main engine. Morespecifically, this can prevent shortage of gas Supply or
charged air rate, reduction in efficiency of the main engine
and deterioration of the exhaust gas owing to over drawing,
and also prevent analogous events owing to too much gas
from occurring. Further, effective use of the residual gas fromthe turbocharger and the exhaust gas from the main engine are
improved as much as possible.
0213 Further, according to the present application, opti
mal values can be set for the respective conditions varying
over time on the basis of the scavenging gas pressure and theexhaust gas temperature, which are physical quantities allow
ing the operating conditions represented as the heat load on
the main engine to be grasped in the most appropriate manner,

US 2011/0259440 A1

and the turbocharger efficiency, which is characteristics of theturbocharger, and various operations can be automaticallyprocessed. Moreover, use of the setting values allows theenergy consumption efficiency utilizing the vessel resistance
reduction effect using bubbles to be automatically maxi
mized.

0214. Further, according to the present application, the gas
Supply or charged air and the Scavenged gas from the turbo
charger can be reused as bubbles. This facilitates reduction inresistance without any need for energy for generating
bubbles, thereby allowing the energy consumption thereof tobe reduced. Moreover, the gas Supply or charged air bypass
rate and/or the scavenging bypass rate are controlled on thebasis of the physical quantity related to the heat load on themain engine and the characteristics of the turbocharger.
Accordingly, a inject gas control device perfuming control inwhich, for example, variation in vessel velocity and the likeare reflected over time can be realized, without adversely
affecting the main engine. More specifically, this can prevent
shortage of gas Supply or charged air rate, reduction in effi
ciency of the main engine and deterioration of the exhaust gas
owing to over drawing, and also prevent analogous events
owing to too much gas from occurring. Further, effective useof the residual gas (gas Supply or charged air and Scavengedgas) from the turbocharger is improved as much as possible.
0215. Further, according to the presentapplication, the gas
Supply or charged air and/or the Scavenged gas are heated andSupplied to the gas outlet. This can reduce the water viscosity
resistance, further improve the frictional resistance reduction
effect of the vessel, and still further improving reduction inenergy consumption.
0216. Moreover, according to the present application, theexhaust gas from the turbocharger can be reused as bubbles.
This facilitates reduction in resistance without energy for
generating bubbles, thereby allowing the energy consump
tion thereof to be reduced. Further, the exhaust gas bypass rateis controlled on the basis of the physical quantity related to theheat load on the main engine and the characteristics of theturbocharger. This realizes a inject gas control device per
forming control in which, for example, variation in vessel
velocity is reflected over time is realized without adversely
affecting the main engine. More specifically, this can prevent
shortage of gas Supply or charged air rate, reduction in effi
ciency of the main engine and deterioration of the exhaust gas
owing to over drawing, and also prevent analogous events
owing to too much gas from occurring. Further, effective useof the residual gas from the turbocharger is improved as muchas possible.
0217. Further, according to the presentapplication, the gas
Supply or charged air means is driven by the exhaust gas
bypass from the turbocharger, and the bubbles generated fromthe gas Supply or charged air means is used. This facilitates
reduction in resistance without energy for generating
bubbles, and allows the energy consumption thereof to be
reduced. Moreover, in this time, the exhaust gas bypass rate iscontrolled on the basis of the physical quantity related to theheat load on the main engine and the characteristics of theturbocharger. This facilitates optimization of the energy effi
ciency in which, for example, variation in vessel Velocity andthe like are reflected over time, without adversely affecting
the main engine. Accordingly, the residual gas of the turbo
charger can effectively be used as a driving source of the gas
Supply or charged air means.

Oct. 27, 20110218. Further, according to the present application, theexhaust gas bypass from the turbocharger drives the electric
generator in the gas Supply or charged air means. The electric
power from the electric generator drives the blower. The
bubbles generated from the blower are used. Accordingly, theresidual gas that includes high pressure and high temperature
gas and has a high energy value is effectively reused for a
Source of electric generation, among residual gases. Moreover, the blower is driven by the electric power. This facili
tates control of the number of revolutions and, in a case ofplural arrangements, operations where the numbers of revo
lutions are differentiated.

0219 Moreover, according to the present application, theexhaust gas bypass from the turbocharger drives the turbine in
the gas Supply or charged air means. The drive at the turbine(e.g., a coaxial configuration) drives the blower. The bubbles
generated by the blower are used. Accordingly, the residual
gas that includes high pressure and high temperature gas andhas a high energy value can be effectively reused for the direct
driving Source of the blower, among residual gases. In par
ticular, the drive by the turbine directly drives the blower,
thereby increasing efficiency of conversion.
0220. Further, according to the present application, thepiping path is arranged at above the waterline and then con
nected to the gas outlet on or below the waterline. This canprevent backflow of seawater from the gas outlet, thereby
allowing the security of the main engine to be further secured
in view of the device.

0221) Moreover, according to the present application, thegas pressure is made to adaptively vary with respect to theplurality of piping path (System) arranged for the respective
gas outlets symmetrically arranged. This enables the injecting
ofbubbles from the nozzles arranged at a shallow spot and thenozzles arranged at a deep position to be substantially uni
formly controlled even in a case under rolling conditions(rolling) of the vessel.
0222 Further, according to the present application, starting/stopping Supplying the pressurized gas and/or the exhaustgas to the gas outlet is controlled by adjusting the pressurizedgas rate adjustment means and/or the exhaust gas rate adjust
ment means, according to the pressure of the pressurized gas
and/or the exhaust gas and the draft of the vessel. The controlof the adjustment means enables the Supply to be started whena sufficient condition for injecting bubbles is realized, andenables the supply to be stopped when the condition becomesinsufficient. This allows the gas Supply or charged air at an
appropriate inject condition. An event of backflow of seawa
ter into the main engine can be prevented.
0223) Moreover, according to the present application,
drawing rates of pressurized gas and/or the exhaust gas arecontrolled on the basis of the physical quantity related to theheat load on the main engine and the characteristics of theturbocharger. This can continuously optimizes, as a device,
the energy efficiency pertaining to reduction in resistance by
use and generation of bubbles by the exhaust gas, from thestarting of the operation of the engine, and then operation andto the stopping of the engine, without adversely affecting themain engine.
0224 Moreover, according to the present application, thepath is blocked properly. This minimizes a possibility of adangerous event that seawater comes into the main engine
against the intention.
0225. According to the present application, the variablemeans are controlled whenever necessary. This can always

US 2011/0259440 A1

optimize the condition of the inflow gas flowing into theturbocharger, and improve the gas Supply or charged air characteristics. For example, the inflow condition (direction, presSure, Velocity, etc.) of the gas is controlled by means of acertain variable varying according to increase and decrease of
the exhaust gas rate. Accordingly, the turbocharger operates
without receiving a strong influence of the rate of the inflow
gas flowing into the turbocharger. Therefore, the pressurizedgas can preferably supplied to the main engine without reduc
ing the turbocharger efficiency, thereby maintaining the over
all efficiency of the main engine in a prescribed extent. Further, the inject condition (e.g., direction, inject rate, Velocity,etc.) of the gas is controlled. This can minimize influences
received from the navigational condition and the like, inject
the gas to desired regions and positions in the proximity of thehull. That is, a preferable frictional resistance reduction effectis acquired, useless injecting of gas is prevented, and theenergy efficiency is improved. Moreover, the gas is controlled
by the limiting means having a transformable shape in orderto maintain the effect pertaining to the highly efficient injecting of gas for a long time. This can prevent diffusion owing to
the influence of the navigational condition, and realize reduction infrictional resistance more preferably. Further, this also
allows the maintenance to be easily performed. Therefore, anintegrated combination of these allows energy saving in theentire sailing of the vessel.
0226 Further, according to the present application, a prescribed variable part pertaining to the variable nozzle is con
trolled responsive to the conditions of the pressurized gas
derived from between the turbocharger and the main engine
and/or the exhaust gas. This allows the inflow condition into
the turbocharger to be optimized, irrespective of increase or
decrease of the drawing flow rate pertaining to the pressurizedgas or the exhaust gas. Therefore, the pressurized gas canpreferably be Supplied to the main engine without decreasing
the turbocharger efficiency. That is, highly efficient drive ofthe turbocharger can be realized, thereby allowing the main
engine efficiency to be maintained within a prescribed extent.
0227. Moreover, according to the present application, theinject conditions, such as the direction in which the gas is
injecting according to the navigational condition, the injectrate and the velocity, can be controlled. This allows the inject
ing region, amount, time period, timing and the like of the gas
injected in the proximity of the hull to be preferably specified.
For example, the hull is inclined in various directions byreceiving forces transversely and slantly owing to waves andcurrents. However, the inclination is detected as the naviga
tional condition, and the inject condition is controlled respon
sive to the inclination, thereby allowing the optimal frictional
resistance reduction effect to be acquired.
0228. Moreover, according to the present application, thelimiting means for limiting the diffusion of gas is configured
to be retractable. Accordingly, the limiting means is retracted
in cases where the limiting means can be a navigational
obstacle. Such as a case where the vessel without injecting gas
is sailing in shallow waters, and a case where the hull is fixedunder docking situations. This can prevent the limiting meansfrom being an obstacle or a load on operation. Therefore,
energy-saving measures can be taken on sailing by retracting
the limiting means. In a case other than that on sailing, thelimiting means does not become an obstacle, thereby allow
ing the working efficiency to be improved.
0229. Further, according to the present application, thevariable nozzle improving the gas Supply or charged air char

Oct. 27, 2011

acteristics of the turbocharger can control the opening/clos
ing degree of the Vane, the aperture setting and the like,
responsive to increase and decrease of the bypassed pressur
ized gas and the exhaust gas rate. This allows the inflow
condition of the exhaust gas Supplied to the turbocharger to bepreferably controlled. Moreover, in the control of the variable
nozzle, the control is performed according to the pressurizedgas and exhaust gas drawing rates, physical quantity related tothe heat load on the main engine, and the characteristics of theturbocharger, thereby enabling the control to be performed inconsideration both of the drawing of the pressurized gas or theexhaust gas and the condition of the main engine. Accord
ingly, the pressurized gas can preferably be supplied to themain engine without deteriorating the characteristics of theturbocharger. The pressurized gas and the exhaust gas can be
drawn while the overall efficiency of the main engine ismaintained within a prescribed extent. The effect of variable
nozzle improves the characteristics of the turbocharger incases where light or heavy load other than the standard load isapplied. This enables the bypass rate of the pressurized gas
and the exhaust gas to be drawn more.
0230. Moreover, according to the present application, theScavenging gas pressure and the exhaust gas temperature,
which are necessarily utilized as physical quantities forgrasping the operating condition of the main engine, is used,
and the control is performed on the basis of the turbocharger
efficiency as the characteristics of the turbocharger, thereby
enabling the variable nozzle to be optimally controlled
responsive to various conditions varying over time. Further,
existing detection means and the like can be used. Operations
corresponding to the load on the main engine can automati
cally be processed.
0231. Further, according to the present application, theinject condition can be controlled, responsive to the detection
result of the navigational condition detection means, in con
sideration of the condition of bubbles after injecting, before
injecting the gas, which is Supplied from the gas Supply or
charged air means, into the proximity of the hull. This allows
the gas to be injected in a manner more analogous to a desir
able one. Moreover, the navigational conditions varying
according to various scenes of the vessel that can appear on
sailing can be detected as numerical information by the navi
gational condition detection means, and the detection result
can be Supplied as information to another device and the like.
0232 Moreover, according to the present application, theinject rate and the inject direction injected from the gas outlet
can be controlled according to the navigational condition. For
example, in cases of big waves, strong winds and turning of
the vessel, the inject direction of gas is preliminarily be
adjusted according to the direction and inclination of thebottom of the vessel, thereby allowing the frictional resis
tance to be efficiently reduced. Further, the inject rate of gas
may be adjusted to be small, standard and large amounts,
according to the navigational conditions, such as cases of aslow speed in a port and the like and cruising on sailing. The
inject direction may be adjusted in the center direction withrespect to the bottom of the vessel and gas is locally injected
therein. Instead, the gas may be injected Substantially parallel
thereto. This enables the inject condition of gas to be arbi
trarily operated according to the navigational condition of thevessel, allows the frictional resistance to be reduced, thereby
enabling the energy consumption rate to be further improved.
0233. Further, according to the present application, since
the gas outlet does not protrude, the gas outlet does notUS 2011/0259440 A1

Oct. 27, 201120

become a navigational resistance of the vessel. More specifi
cally, there is no part that receives the water resistance andincreases the degree of resistance by adhesion of algae and thelike. This facilitates further reduction in frictional resistanceto be generated on sailing. Moreover, this does not become aload or an obstacle or operation under docking situations
either. For example, when the hull is mounted on the blocks
and the like where the hull is fixed, the gas outlet has no
protrusion. Accordingly, the same plane with Substantiallysame degree of height as that of the bottom of the vessel canbe configured. Therefore, there is no need to consider damage
and the like owing to concentration of stress. Further, when
the bottom of the vessel is repaired, the inject nozzle can be
dealt with as with another part. Accordingly, the working
efficiency is not decreased either. Therefore, this also facili
tates reduction in working hours for repair and the like.
0234. Further, according to the present application, thestraightening plate preliminarily defines the fluid path of the
bubbles. This facilitates more preferable adjustment of theinject direction of the gas. Moreover, the straightening plate
can also serve as a structural element of the vessel, and canstrengthen the gas outlet. Without protrusion, the strengthen
plate does not become load on operation under docking situ
ations. That is, the Straightening plate exerts an effect of an
adjustment element of the inject direction of gas and an effectof the structural element. Further, with respect to sailing of
the vessel, the bottom of the vessel has no protrusion, thereby
reducing worries for an operator of the vessel.
0235 Moreover, according to the present application, thediffusion limiting means adopts the retractable configuration.
This allows the diffusion limiting means to be efficiently usedaccording to the injecting conditions of gas and the naviga
tional conditions of the vessel. For example, in low speed
sailing where the frictional resistance effect is low, injectingof gas is stopped and the diffusion limiting means is retracted
in an intentional and predetermined manner. This eliminatesa protrusion from the hull, and the diffusion limiting means
does not become a resistance. Further, the diffusion limiting
means can serve as a function as a resistance against rolling of
the hull, in addition to the bubble diffusion limiting effect, by
protruding from the hull. The diffusion limiting means canalso allow the hull to be stabilized by lowering the center ofgravity. If the diffusion limiting means can be retracted
according to the docking situations such as maintenance, theobstacle against operation is eliminated, thereby reducing theload on operators. Accordingly, in view of improving effi
ciency in energy resources and operation, the present invention is significantly useful.
0236 Further, according to the present application, a part(the distal end etc.) of the diffusion limiting means can be ina state without protrusion. Accordingly, the diffusion limiting
means never becomes an obstacle under docking situations,and the vessel can be fixed. Moreover, this negates a casewhere the diffusion limiting means acts as an obstacles andadversely affecting operations such as repair of the bottom of
the vessel. More specifically, the state where the diffusion
limiting means is retracted and does not protrude by the loadof the hull itself when the hull is fixed can be maintained. In

this state, the substantially same plane as the bottom of thevessel is configured, and operation can be applied thereto aswith the other part. Therefore, working efficiency is not
impaired.
0237 Further, according to the present application, thefolded diffusion limiting means is provided. Accordingly, thefolded diffusion limiting means is smoothly protruded incursing and the Substantially straight line sailing is maintained, Suppresses the bubble diffusion owing to an inclina
tion caused in normal operation and sailing and a Swing of thevessel occurring suddenly, and causes the bubbles to flow
while retaining the bubbles in the proximity of the bottom of
the vessel. On the other hand, when the diffusion limiting
means is folded under docking situations, the diffusion lim
iting means never becomes an obstacle. Accordingly, thevessel can be fixed, and influence to be adversely affected on
operations such as repair of the bottom of the vessel isnegated. Moreover, for example, only if the diffusion limiting
means is mounted on the bilge portion of the hull and slightly
bent outward, the difference of height with the bottom of thevessel is eliminated. This increases the degree of freedom ofarrangement, negates the need of securing a space for retraction in the hull, and facilitates maintenance. Moreover, afunction of a bilge keel is included into the diffusion limiting
means. This can contribute to stabilization of the hull insailing.
0238 Further, according to the present application, theretractable diffusion limiting means may be configured to be
expandable. This can change the degree of protrusion accord
ing to increase and decrease of the inject rate of gas, preventthe diffusion limiting means itself from becoming a cause of
the frictional resistance and from becoming a navigational
obstacle by contracting at a location of shallow sea bottom.
0239 Moreover, according to the present application, thediffusion limiting means may droop by gravity, or beurged bya spring. This negates the need for a power source when the
diffusion limiting means operates, thereby the consumptionof energy thereof to be saved. On the other hand, the self
weight of the hull is added, and thereby the diffusion limiting
means is automatically retracted under docking situations.
Accordingly, the diffusion limiting means does not become
an obstacle, the vessel can be fixed, and the influence toadversely affect operations, such as repair of the bottom of thevessel, is negated.
0240 Moreover, according to the present application,
separate arrangement of pieces of diffusion limiting means in
a line allows the material with standard dimensions to be

used, the weight of diffusion limiting means which is not soheavy is sufficient, thereby enabling the productivity to be
improved. Further, a configuration can be adopted that is
capable of retracting only the piece of the diffusion limiting
means at the spot of receiving the load from the blocks underdocking situations or configured in a foldable structure, rein
forcement is also easy, and the configuration can prevent thedamage of diffusion limiting means owing to the concentration of stress and the like. Accordingly, the necessity of repairof the diffusion limiting means itself is also reduced, thereby
realizing more efficient operation.
0241 Further, according to the present application, thediffusion limiting means may be configured to be transform
able according to internal and/or external forces. This enables
the shape of the diffusion limiting means to be flexibly
changed, in contrast to a fixed diffusion limiting means. Morespecifically, if application of the internal force can maintainthe expanded State, the function as the diffusion limiting
means is exerted, and the bubble diffusion owing to influencesof the normal sailing maintaining a Substantially straight sailing and an inclination of the vessel caused in sailing androlling caused suddenly is suppressed, thereby causing the
bubbles to flow while retaining the bubbles in the proximity ofUS 2011/0259440 A1

the bottom of the vessel. On the other hand, the diffusion

limiting means can be transformed responsive to influences of
stopping of the internal force and/or the external force. If theretraction is not especially performed, this can prevent the
diffusion limiting means itself from being a navigational
resistance and from being an obstacle against under docking
situations. Moreover, for example, the internal force may be
increased and the degree of protrusion is increased, thereby
improving the function as the stabilization means for address
ing the rolling of the hull. Further, when the waterline is deep,
the bubbles injected in the proximity of the hull are small andthe degree of protrusion (transformation) of the diffusion
limiting means may be small, transformation and contraction
is caused by an influence of the draft (external force). This canprevent the diffusion limiting means from being a cause ofincrease infrictional resistance. Therefore, the present invention is more effective in view of improving efficiency inenergy resources and operation.
0242 Further, according to the present application, thediffusion limiting means having a hollow structure may be
adopted. This allows the diffusion limiting means to be
expanded by pressurization from the inside by means of aflow of fluid, such as gas or liquid, or powder. Moreover, after
the expansion, for example, closing of the valve can maintainthe pressure constant. Accordingly continuous flow is not
required, thereby allowing the amount of energy consump
tion for supplying the fluid to be saved. Further, the fluid caneasily be discharged, a short time period is sufficient forcontraction, and discharge by the self weight of the hull can be
performed under docking situations, thereby allowing thevessel to be fixed in a short time period.
0243 Further, according to the present application, thehollow structure can serve as the function of the air supply
pipe and transfers the gas generated by the gas Supply or
charged air means to the gas outlet. In this case, the hollow
structure is expanded by pressurization of gas, and can Suppress the bubble diffusion caused by an inclination of thevessel, and also serve as the function of the diffusion limiting
means. Moreover, for example, the hollow structure candirectly be connected to the gas Supply or charged air meansor the air Supply pipe, thereby allowing the path of theinjected gas to be formed. This allows both the function as the
diffusion limiting means and the function of the air Supply
pipe to be exerted.
0244. Further, according to the present application, thediffusion limiting means may have a hollow structure that isconfigured with an elastic material and the inside is hollow.
This allows the inside of the hollow structure to be pressur
ized, be enlarged and contract by means of the power of fluid
accompanying the sailing of the vessel, without separately
injecting fluid into the hollow structure. Accordingly, theforce of the fluid accompanying the sailing of the vessel canbe utilized and thereby allows the diffusion limiting means tobeformed. This negates the need for a device and the like forinjecting gas and the like into the hollow structure, thereby
allowing the energy to be effectively utilized. Moreover,unless the vessel is sailing, the fluid force cannot be gener

Oct. 27, 2011adjusted responsive to starboard and port inclinations of thehull. For example, the diffusion limiting means may be pro
truded at the bottom of the vessel on the side where thewaterline becomes shallow owing to the inclination, thereby
enabling diffusion of gas along with the inclination to belimited. Accordingly, the frictional resistance reduction effectsignificantly suitable for the sailing conditions can beattained.

0246. Further, according to the present application, thelimiting flow generation means may generate the flow limit
ing the diffusion of gas. Accordingly, the so-called pseudo
wall (endplate) can beformed, the bubble diffusion caused by
the diffusion of injected bubbles and the inclination of thevessel can be suppressed, and the bubbles are caused to flow
while the bubbles are retained around the hull. Further, thediffusion of gas is limited by the effect of the fluid. This
enables the elements not to protrude from the hull, negates theneed to consider the positions of blocks under docking situ
ations, thereby eliminating obstacle on operation. Therefore,
working hours for repair and the like can be reduced.
0247. Further, according to the present application, theopen and close means for closing the path when gas is notinjected, which is arranged in the path in the proximity of thegas outlet, may block the inflow of water when the gas Supply
or charged air is stopped, can prevent backflow of water into
the gas Supply or charged air means, and thereby can preventthe air Supply pipe from being damaged. More specifically,
this eliminates rust owing to moisture and fouling of marineorganisms in the path, Suppresses the increase in frictional
resistance when injecting gas, negates the need for mainte
nance, and thereby enables the air Supply pipe to be used fora long term. Moreover, closing of the path by the open andclose means can prevent the frictional resistance owing to
inflow of the water flowing into the path during sailing frombeing increased.
0248. Further, according to the present application, in acase of arranging the navigational condition detection meansin the water, arrangement at a part without receiving influ
ences from the bubbles injected from the gas outlet negates
the influence of disturbance of bubbles, and allows stabledetection of various conditions. Moreover, this can prevent
fouling of organisms that dwell at Seashore. Such as barnacles,
and easily reproduce because of existence of air, thereby
allowing the navigational condition to be stably detected for along term.
BRIEF DESCRIPTION OF THE DRAWINGS

0249 FIG. 1 (a) is a side view of a vessel to which africtional resistance reduction device for a vessel of anembodiment of the present invention is applied: FIG. 1 (b) is
a top view of the same vessel; FIG. 1 (c) is a bottom view ofthe same vessel;(0250 FIG. 2 (a) is a side view of a blower used for thefrictional resistance reduction device for a vessel of theembodiment of the present invention; FIG. 2 (b) is a side viewof the same blower; FIG. 2 (c) is a diagram showing theated. This allows the hollow structure to contract under dockinternal structure of the same blower;

ing situations, and the fixation of the vessel can immediately
be performed. The diffusion limiting means never becomes
an obstacle, and does not influence operations such as repair

the frictional resistance reduction device for a vessel of theof the bottom of the vessel.

0245 Moreover, according to the present application, thedegree of protrusion of the diffusion limiting means can be

0251

FIG.3 is a perspective view of the gas outlet used for

embodiment of the present invention;
0252 FIG. 4 is a conceptual view showing operation of thegas outlet used for the frictional resistance reduction device
for a vessel of the embodiment of the present invention;

US 2011/0259440 A1

Oct. 27, 2011
220253 FIG.5 is a sectional view showing attachment of thegas outlet, which is used for the frictional resistance reduction
device for a vessel of the embodiment of the present invention, to the bottom of the vessel;

0254 FIG. 6 is a sectional view showing another mannerof attachment of the gas outlet, which is used for the frictional
resistance reduction device for a vessel of the embodiment of

the present invention, to the bottom of the vessel;
0255 FIG. 7 is a control block diagram used for the frictional resistance reduction device for a vessel of the embodi

ment of the present invention;
0256 FIG. 8 is a sectional view of a shear force sensor
used for the frictional resistance reduction device for a vesselof the embodiment of the present invention:
0257 FIG. 9 is a bottom view of a vessel to which africtional resistance reduction device for a vessel of a second

embodiment of the present invention is applied;
0258 FIG. 10 (a) is a side view of a vessel to which abubble retention device for a vessel of an embodiment of thepresent invention is applied: FIG. 10 (b) is a top view of thesame vessel; FIG. 10 (c) is a bottom view of the same vessel;
0259 FIG. 11 is a sectional view of the hull according toan embodiment of the present invention taken along line X-X(of FIG. 10);0260 FIG. 12 is a sectional view of the hull according toanother embodiment of the present invention taken along line
X-X (of FIG. 10);0261 FIG. 13 is a sectional view of the hull according toyet another embodiment of the present invention taken alongline X-X (of FIG. 10);0262 FIG. 14 is an enlarged view of a broken line Y part of
FIG. 11 according to yet another embodiment of the present
invention;

0263 FIG. 15 is a sectional view of the hull according tostill another embodiment of the present invention taken alongline X-X (of FIG. 10);0264 FIG. 16 is a sectional view of the hull according toyet another embodiment of the present invention taken alongline X-X (of FIG. 10);0265 FIG. 17 is a conceptual view showing a state ofretaining of bubbles in a case where end plates according to anembodiment of the present invention are arranged;
0266 FIG. 18 is a conceptual view showing a state wherebubbles flowing when a vessel is sailing in a case of arranging
end plates according to an embodiment of the present invention whose fore and stern have streamline shapes;
0267 FIG. 19 is a sectional view conceptually showing astate of retaining bubbles when a vessel whose bottom has atriangular uneven profile in a sectional view is sailing, accord
ing to still another embodiment of the present invention;
0268 FIG. 20 is a sectional view conceptually showing astate of retaining bubbles at a vessel having a configuration
including a mound that has a wing profile in a sectional view
and arranged at the bottom of the vessel when the vessel issailing, according to still another embodiment of the present
invention;

0269 FIG. 21 is a sectional view conceptually showing astate of retaining bubbles at a vessel whose bottom has aconfiguration having a gentle step profile toward the stern ina sectional view when the vessel is sailing, according to yet
another embodiment of the present invention;
0270 FIG.22 is a sectional view for illustrating a configu
ration of a gas-liquid separator in a bubble retention device
according to another embodiment of the present invention;

0271 FIG. 23 is a conceptual view showing a method ofusing the gas-liquid separator in the bubble retention device
according to another embodiment of the present invention;
0272 FIG. 24 is a conceptual view showing a method ofusing a gas-liquid separator in a bubble retention device
according to another embodiment of the present invention;
0273 FIG. 25 is a diagram showing a situation pertaining
to use of the gas-liquid separator in the bubble retention
device according to another embodiment of the present invention;

0274 FIG. 26 (a) is a side view of a vessel to which abubble convolvement prevention device of the vessel isapplied according to sill another embodiment of the present
invention: FIG. 26 (b) is a top view of the same vessel; FIG.
26 (c) is a bottom view of the same vessel;(0275 FIG. 27 is a block diagram of a bubble convolve
ment prevention device of a vessel of yet another embodimentof the present invention;
0276 FIG. 28 is a conceptual view showing operation ofan air nozzle used for a bubble convolvement prevention
device of a vessel according to still another embodiment of
the present invention;
0277 FIG. 29 is a diagram showing distribution of veloc
ity of flow of water at a propeller of a vessel according to yet
another embodiment of the present invention;
0278 FIG. 30 is a bottom view of a vessel to which abubble convolvement prevention device of the vessel isapplied according to still another embodiment of the present
invention;
0279 FIG. 31 is a sectional view principally showing a
gas-liquid separation system used in another embodiment of
the present invention;
0280 FIG. 32 is a bottom view of a vessel to which abubble convolvement prevention device of the vessel isapplied according to still another embodiment of the present
invention;

0281 FIG. 33 is a conceptual view showing operation ofan air intake used for a bubble convolvement prevention
device of a vessel according to yet another embodiment of thepresent invention;
0282 FIG.34 (a) is a perspective view of a bubble protec
tion plate used for a bubble convolvement prevention deviceof a vessel of another embodiment of the present invention;
FIG. 34 (b) is a rear elevation view of the bubble protection
plate;
0283 FIG.35 is a diagram sectionally showinga inject gas
control device according to one embodiment of the present
invention and an overview of a vessel equipped with thisdevice;0284 FIG. 36 pertains to an embodiment where a injectgas control device according to the embodiment of the present
invention is applied to a vessel used in the ocean; FIG. 36 (a)shows a side sectional view of the vessel; FIG. 36 (b) shows
a top view thereof;
0285 FIG. 37 is a system diagram showing a system
bypassing a turbocharger according to an embodiment of thepresent invention;
0286 FIG.38 is a diagram showing an actual relationshipbetween main engine loads and turbocharger efficiency
according to an embodiment of the present invention;
0287 FIG. 39 is a block diagram showing an arrangementof devices according to this embodiment, various sensors
acquiring basic data of control according to the present appliUS 2011/0259440 A1

cation, actuators and the like for the sake of realizing thecontrol of the present invention;
0288 FIG. 40 is a control block diagram for illustrating acontrol system of the present application;
0289 FIG. 41 is a diagram sectionally showing an overview of a vessel equipped with a frictional resistance reduction device for a vessel according to an embodiment of thepresent invention;
0290 FIG.42 is an enlarging diagram principally showing
a variable nozzle according to an embodiment of the present
invention;

0291 FIG. 43 is a characteristics diagram showing an
example of relationship between a main engine load and an
efficiency of a turbocharger according to presence or absenceof a variable nozzle according to an embodiment of thepresent invention;
0292 FIG. 44 is a block diagram showing an arrangementof a turbocharger and peripheral elements according to anembodiment of the present invention;
0293 FIG. 45 is a control block diagram of control means
according to an embodiment of the present invention;
0294 FIG. 46 is a sectional view showing a concept of agas outlet according to an embodiment of the present invention;

0295 FIG. 47 is a transparent perspective view of a gas
outlet including a straightening plate according to an embodi
ment of the present invention;
0296 FIG. 48 is a sectional view of a vessel including a
retractable diffusion limiting section as diffusion limiting
means capable of being stored according to an embodiment of
the present invention;
0297 FIG. 49 is an enlarged view of a retractable diffusion
limiting section (broken line part in FIG. 48) as the diffusion
limiting means capable of being stored according to anembodiment of the present invention;
0298 FIG. 50 is an enlarged view/showing anotherembodiment of a retractable diffusion limiting section (broken line part in FIG. 48) as the diffusion limiting means
capable of being stored according to another embodiment of
the present invention;
0299 FIG. 51 is a sectional view of a vessel including abending diffusion limiting section as a diffusion limiting
means capable of being stored according to an embodiment of
the present invention;
0300 FIG. 52 is an enlarged view of a bending diffusion
limiting section (broken line part in FIG. 51) according to anembodiment of the present invention;
0301 FIG. 53 is a sectional view of a vessel including abending diffusion limiting section as a diffusion limiting
means capable of being stored according to another embodi
ment of the present invention;
0302 FIG. 54 is an enlarged view of a bending diffusion
limiting section (broken line part in FIG. 53) according toanother embodiment of the present invention;
0303 FIG.55 is a sectional view of a vessel including a
diffusion limiting means transformable according to internal
force/external force pertaining to an embodiment of thepresent invention;
0304 FIG. 56 is a side view of a vessel including a diffusion limiting means of another embodiment transformableaccording to internal force/external force pertaining to theembodiment of the present invention;
0305 FIG. 57 is a side view of a vessel including a diffusion limiting means of still another embodiment transform

Oct. 27, 2011able according to internal force/external force pertaining to
the embodiment of the present invention;
0306 FIG. 58 is a sectional view of a vessel including a
diffusion limiting section adjusting the degree of protrusion
according to inclination of Starboard and port as diffusion
limiting means capable of being stored according to anembodiment of the present invention; and(0307 FIG. 59 is a sectional view of a vessel including
limiting flow generation means according to an embodimentof the present invention.
BEST MODE FOR CARRYING OUT THE
INVENTION

0308. A best mode for carrying out the present invention
will hereinafter be described with reference to the drawings
using embodiments. Hereinafter, an extent necessary fordescription for the sake of attaining the object of the present
invention will schematically be shown. An extent necessary
to describe an applicable part of the present invention will
principally described. A part on which the description isomitted is pursuant to conventional techniques.
First Embodiment0309 FIG. 1 (a) shows an embodiment where a frictional
resistance reduction device for a vessel of an embodiment of

the present invention is applied to a vessel used on Ocean.
FIG. 1 (a) is a side view of the vessel. FIG. 1 (b) is a top view
thereof. FIG. 1 (c) is a bottom view thereof. In FIG. 1, a
principal configuration is exposed for the sake of illustration.
0310 Blowers 11, 12, 13, 14 and 15 as gas supply or
charged air means are arranged in a line on a deck 2 of a vessel
1. These blowers 11, 12, 13, 14 and 15 are arranged in casing
in order to avoid splash of seawater broken at the bow on thedeck 2. Air, as gas, is taken from a side opposite to thetraveling direction of the hull for the sake of avoiding theSplash as much as possible.
0311. The air taken into the blowers 11, 12, 13, 14 and 15
are pressurized, passes through air supply pipes 16, 17, 18, 19
and 20 having bent portions, and guided into gas outlets 21,
22, 23, 24 and 25 arranged in the proximity of the bottom3 ofthe vessel. In a case of this embodiment, the gas outlets 21, 22.
23, 24 and 25 are arranged substantially in a line, symmetri
cally with respect to a planar center line CL of the hull 4, infore of the bottom 3 of the vessel. The gas outlets 21, 22, 23.
24 and 25 are arranged on the bottom3 of the vessel is because
of intentions that allow injected bubble to stay longer aroundthe bottom 3 of the vessel and alleviate variation in pressure
owing to waves and the like. The arrangement thereof inforeof the bottom 3 of the vessel is adopted in order to make theinjected bubbles stay over the entire bottom of the vessel 3 asmuch as possible.
0312 The arrangement of the gas outlets 21, 22, 23, 24 and25 Substantially in a line simplifies the configuration, and also
facilitates arrangement of the blowers 11, 12, 13, 14 and 15,
the air supply pipes 16,17.18.19 and 20 and the like arranged
corresponding thereto. Further, in this example, the numberof gas outlets 21, 22, 23, 24 and 25 is five, which is an odd
number. Accordingly, arrangement of the center one (gasoutlet 23) on the planar center line CL can realizes one spot
injecting of bubbles with ability of the vessel 1 to hold astraight line.
0313 End plates 5, 5", 6, 6', 7 and 7", which guide thebubbles injected from the gas outlets 21, 22, 23, 24 and 25 soUS 2011/0259440 A1

Oct. 27, 201124

as not to dissipate the bubbles, are arranged on the bottom3 ofthe vessel also symmetrically with respect to the planar centerline CL of the hull 4. In addition thereto, shear force sensors

50,51,52.53 and 54, which are shear force detectors detecting
shear forces acting on the hull 4 owing to seawater andbubbles, are arranged on the bottom 3 of the vessel on the
Stern side.

0314. Further, relative velocity sensors 55 and 56, as relative Velocity detectors, are arranged on the stern side. Anotherrelative velocity sensors 57 are arranged on the sides 8 of thevessel. The relative velocity sensors 55 and 56 are arranged
apart from the gas outlets 21, 22, 23, 24 and 25. The relative
velocity sensors 57 are arranged on a spot on the sides 8 of thevessel without influence of bubbles even if the spots are in theproximity. In particular, the relative velocity sensors 57 arearranged at lower parts away from influence of waves on theside 8 of the vessel. These relative velocity sensors 55, 56 and
57 adopt ultrasonic system, are capable of being used underwater, and reduce influences owing to waves and currents.
0315. Further, video cameras 58 and 59, which monitor
conditions of the injected bubbles, are arranged at fore and aftparts of the bottom3 of the vessel. Images taken by the video
cameras 58 and 59 are monitored by a person, and thereby
being utilized for analyzing inject conditions of the bubbles.
0316 FIG. 2 is a detailed diagram showing the blowers 11,
12, 13, 14 and 15. FIG. 2 (a) shows a front view. FIG. 2 (b)shows a side view. FIG. 2 (c) shows a sectional view partiallyrepresenting an internal structure. The blowers 11, 12, 13, 14
and 15 are Roots-type positive-displacement blowers, andadopt a structure where an inverter-type motor 60 as the drive
device drives two rotors 62 and 63 in the blower via a belt 61,
the air taken between the blower interior wall 64 and therotors 62 and 63 is compressed as the rotors 62 and 63 rotate,and supplied. Since the blowers 11, 12, 13, 14 and 15 are thepositive-displacement type, the blowers are capable of Sup
plying stably a predetermined rate of air even with previous
variation in pressure. Although the Roots-type blower is thesame positive-displacement type, the Roots-type blower isdifferent from the piston type in that the Roots-type blower
pressurizes air Substantially continuously and thereby
reduces pulsing, and can eliminate a tank and the like for
Smoothing pressure. Further, the rotation is Smooth and vibration and noise are reduced. Accordingly, even with thearrangement of blowers 11, 12, 13, 14 and 15 on the deck 2.
resonance cannot easily occur in the cabins therebelow.
0317 FIG.3 is a perspective view conceptually showing adetailed configuration of the gas outlets 21, 22, 23, 24 and 25.
For the sake of simplicity of description, FIG. 3 shows atypical example of the plurality of air Supply pipes and gas
outlets. The air blown from the blower via the air supply pipe
16 is bent at right angle at a chamber 70 of the gas outlet 21
connected to the air Supply pipe 16. A distribution component
71 having triangular profile for dispersing the blown air isarranged immediately below the connection part of the air
Supply pipe 16. A configuration is adopted according to which
the air is bent at right angle at this part and dispersed laterally
by the distribution component 71. As the air is bent at rightangle, the air tends to uniformly spread along directions in ahorizontal plane. However, the air tends to flow only toward
perforated plates 72 and 73 in front thereof by presence ofinterior walls of the chamber 70 in the recess and at the right,
left, top and bottom. Here, presence of the distribution com
ponent 71 further uniformizes the lateral distribution of the air
with respect to the perforated plates 72 and 73.

0318. A lot of perforations 74 and 75 are formed at theperforated plates 72 and 73. The positions of the perforated
plates 72 and 73 are laterally displaced from each other,
thereby forming an arrangement with perforations in a displaced manner. This embodiment shows an example using
two perforated plates 72 and 73. Instead, the number thereof
may be another number, such as three or four. Since perfo
rated plates 72 and 73 are arranged so as to displace thepositions of the perforations, the perforated plates 72 and 73
function as a so-called baffle plates, which bend the airflow toprovide resistance. Accordingly, in addition to further uni
formization of the air in the lateral direction, the air in thevertical direction is also uniformized, thereby enabling the air
to be injected from a inject port 76 on a front surface.
0319. Here, the perforated plates 72 and 73 are manufac
tured by continuously making round perforations on a corrosion resistant sheet metal. Such as stainless steel by a press,
and the arrangement with displaced perforation positions canbe realized by cutting. This offers excellent productivity. If
configured with a stainless material, since the perforations areround, edge portions are omitted, nearly preventing the stressfrom being concentrated when being pressed, in contrast to acase with square perforations. This alleviates progress ofstress corrosion from the edge parts, even if used in seawater.
The perforated plates 72 and 73 may be manufactured byusing resin and by means of molding. In a case of using theresin, the shapes of the perforations are arbitrary in view ofcorrosion. However, in view of molding, round perforations
are preferable.
0320 FIG. 4 a conceptual view showing effects of theconfiguration where the air guided by the air Supply pipe 16 isbent into a Substantially right angle and spread, and injected
via perforated plates 72 and 73 arranged in series in a displaced manner.
0321 FIG. 5 shows a sectional view where the gas outlet
21 of this embodiment is attached to the bottom 3 of thevessel. In this figure, for the sake of simplicity of description,a typical example of the plurality of air Supply pipes, gas
outlets and the like is shown. The chamber 70 is arranged so
as to protrude from the plane of the bottom3 of the vessel. The
air supply pipe 16 runs through the bottom3 of the vessel andis connected to the chamber 70. The inject port 76 opens
toward a downstream direction with respect to the water flow.
A resistance reduction plate 80 is arranged at the front surfaceof the chamber 70, thereby allowing a configuration in con
sideration that the chamber 70 does not become a resistanceowing to the water flow.
0322 FIG. 6 shows another embodiment of attachment of
the gas outlet 21 to the bottom 3 of the vessel. In this anotherembodiment, the shape of the bottom 3 of the vessel isdesigned in consideration that the shape forms a Substantiallysame plane surface even if the chamber 70 intervenes. In thiscase, it is unnecessary to provide the resistance reduction
plate 80, which has been provided in the above embodiment.
However, considerations are taken Such that a part of thebottom 3 of the vessel in the downstream side after the gas
outlet 21 is configured as a curved Surface, thereby allowing
the bubbles injected from the inject port 76 to smoothly flow,
to easily adhere to the bottom 3 of the vessel and not toincrease resistance.

0323. The above embodiment shown in FIG. 5 exerts anadvantageous effect that realizes easy attachment to the bot
tom3 of the vessel, including posterior attachment of the gas
outlet 21. In the another embodiment shown in FIG. 6, it isUS 2011/0259440 A1

unnecessary to especially provide the resistance reduction
plate 80 and the like, exerting an advantageous effect expect
ing that increase in frictional resistance owing to attachmentof the gas outlet 21 can be suppressed.
0324 FIG. 7 is a control block diagram of this embodi
ment.

0325 The vessel conditions determination unit 100
includes a GPS 101 detecting the location of the vessel, a fuelmeasurement unit 102 measuring fuel consumption ofengines of the vessel, and an engine operation detector 103
detecting operational conditions of the engines of the vessel.
The vessel conditions determination unit 100 specificallydetermines the present conditions of the vessel, and deter
mines the present conditions that vary in a small degree on
sailing or vary gradually. For example, the GPS 101 grasps
the location of the vessel on a map, and detects a distance toa port or a destination, an absolute velocity with respect to theground and the like.
0326. These are used for determining which locating or
position on the map the bubble are injected and stopped. The
measurement of the absolute velocity with respect to theground is also used for the sake of complementing the relative
velocity sensors 55, 56 and 57. The fuel measurement unit
102 measures how the engines consumes fuel per prescribed
time, and also used for stopping the injecting of bubbles if thefuel consumption efficiency becomes lower than a prescribedfuel consumption efficiency. The engine operation detector
103 is used for acquiring information Such as detection ofoperating conditions of the engines of the vessel, stop of
injecting bubbles when the engines stop operation, or start of
injecting bubbles a lapse of a prescribed time after operationis started. The engine operation detector 103 is also used for
detecting the numbers of revolutions of the engines andchanging the number of working gas outlets and/or the injectrate of bubbles. In addition thereto, the vessel conditions
determination unit 100 further includes means for determin

ing situations where the vessel resides, such as detectors for
outputs of the engines, a gyro, a radar and means for measur
ing the amount of freight and condition of ballast water, andcan be used for controlling injecting of bubbles according to
the purposes.
0327. The navigational condition detector A110 includes
relative velocity sensors 55, 56 and 57; a draft sensor 111
detecting the draft level of the hull; and an inclination sensor
112 detecting so-called rolling, which is a lateral inclination
with respect to the traveling direction of the hull. Separately
therefrom, the shear force sensors 51, 52, 53, 54 and 55

configure a navigational condition detector B115. Thesenavigational condition detectors A and B115 detects physicalquantities that relatively easily vary as the vessel is sailing, orfor the sake of changing the quantities. The configurations ofshear force sensors 51, 52, 53 and 54 will be described indetailed later. In addition thereto, the navigational condition
detection unit further includes sensors detecting Swaying(SWaying), pitching (pitching). Surging (Surging), heaving(heaving) and yawing (yawing) of the hull 4.
0328. An oceanographic condition determination unit 120
includes a wave sensor 121, a wind sensor 122 and a current

sensor 123. The wave sensor 121 detects wave heights, direc
tions, periods of waves and the like. The wind sensor 122
detects wind velocities, directions of winds and the like. The
current sensor 123 detects current velocities, directions,heights of currents and the like. In addition thereto, theoceanographic condition determination unit is used for con

Oct. 27, 2011

sidering information on waves, winds and currents and fur
ther the weather and the like, for example, stopping injectingof bubbles when the oceanographic condition is stormy, andinjecting bubbles when the condition recovers.
0329 Such information from the vessel conditions deter
mination unit 100 and information from the oceanographic
condition determination unit 120 are transmitted to a condition setting unit 130. The condition setting unit Systematicallysets conditions for injecting bubbles to the bottom 3 of thevessel. The conditions include starting/stopping of injecting
bubbles, which gas outlets 21, 22, 23, 24 and 25 are caused to
inject bubbles, how the inject rate is, how the timing of injecting is, how the temporal bubble inject sequence is composed,
and when the injecting is started and when the injecting is
stopped. In the setting unit, the conditions for injecting
bubbles are set such that shear forces acting on the hull, therelative velocity of the hull, the draft, the inclination and thelike are also considered. Condition setting for control accord
ing to these signals is also performed. The condition setting
unit performs condition setting according to a condition set
ting instruction 131 for reducing the frictional resistance, andfurther performs condition setting according to condition set
ting instruction 132 for adjusting the waterline level by meansof injecting bubbles, which will be described later.
0330. A comparator 140 compares signals according to
the setting by the condition setting unit 130. The blowers 11,
12, 13, 14 and 15 are controlled via a controller 150. These

comparator 140 and controller 150 collectively configure acontroller. The controller 150 also controls valves 161,162,
163, 164 and 165 arranged on the discharge side of the blowers 11, 12, 13, 14 and 15. These are added for the sake ofacquiring a desired air rate by adjusting these valves 161,162,
163, 164 and 165, when controlling air rate lower than thecontrol ranges of the motors by means of inverters of theblowers 11, 12, 13, 14 and 15, and when quickly adjusting thewaterline level using the signal from the draft sensor 111. As
to conditions where bubbles are injected from the gas outlets
21, 22, 23, 24 and 25, inject conditions of the bubbles andconditions where the bubbles stay at the bottom3 of the vessel
are imaged by video cameras 58 and 59. The images are
utilized for analyzing and examining conditions of injecting
a10331. At the bottom3 of the vessel, the shear force sensors
51,52,53,54 and 55 are attached to the gas outlets 21, 22, 23,
24 and 25 downstream from the bottom 3 of the vessel. In

order to deepen analysis of variation in shear force owing to
injecting of bubbles, a corresponding number thereof areattached. Signals from the shear force sensors 51, 52, 53, 54
and 55 are fed back to the comparator 140. The signals arecompared with shear force values preliminarily set by thecondition setting unit 130. The operating conditions of theblowers 11, 12, 13, 14 and 15 are finely adjusted via thecontroller 150 pursuant to a prescribed rule, an algorithm anda constants according to the deviations. Further, the relative
velocities between the hull and seawater are detected by the
relative velocity sensors 55, 56 and 57, subjected to a prescribed Statistical process, and the representative value istransmitted to the comparator 140. Signals from the draft
sensor 111 and the inclination sensor 112 are also transmitted

to comparator 140.
0332 First, the comparator 110 compares the processed
representative value by the relative velocity sensors 55, 56
and 57 and the condition setting value preliminarily set by thecondition setting unit 130 with each other. For example, whenUS 2011/0259440 A1

Oct. 27, 201126

the relative velocity of the hull exceeds the setting value,
controls can be performed including increase of the numberof working gas outlets, increase of the amount of bubbles, andincrease both of them according to the deviations. When therelative Velocity becomes lower than the setting value, controls can be performed including decrease of the number ofworking gas outlets, decrease of the amount of bubbles, anddecrease of both of them. When decreasing the number ofworking gas outlets, it is preferable to stop outer gas outlets.
0333 For example, the gas outlets 21 and 25 are stopped,or the gas outlets 21 and 22 and the gas outlets 25 and 24 are
stopped. Likewise, the inject rates of bubbles are controlled.
The inject rate of bubbles of gas outlets 21 and 25 aredecreased or increased to the same degree. Further, the injectrate of bubbles of gas outlet 22 and 24 are decreased orincreased to the same degree. Thus, symmetrical arrangementof the gas outlets with respect to the planar center line CL of
the hull and the symmetrical control of the inject rates of
bubbles can acquire a uniform frictional resistance reduction
effect, in a case where the vessel is sailing in a straight line,
which can frequently occur. Accordingly, ability of the vessel
to hold a straight line can be maintained, and fuel consump
tion is decreased. Further, this facilitates the circuit configu

bubbles but also for ballast water adjustment that detects theinclination of the hull 4 and maintains the balance in a shareda.

0337 FIG.8 representatively shows a schematic overview
of the shear force sensor 51.

0338 A detection plate 1200 is arranged at the substan
tially same height as the bottom3 of the vessel. The detection
plate 1200 is configured so as to be suspended by leaf springs
1201 and 1202. The leaf springs 1201 and 1202 are supported
by pivots 1203 and 1204. A detector 1205 is attached to thedetection plate 1200. The other end of the detector 1205 is
fixed to a casing 1206. When a flow occurs, distribution ofvelocity of flow, which is as shown in the lower part of FIG.
8, is generated on a surface of the detection plate 1200. The
leaf springs 1201 and 1202 are bent according to the shear
force acting on the detection plate 1200 by distribution ofvelocity of flow, thereby displacing the detector 1205.
0339. The displacement of the detector 1205 is electricallydetected, and the shear force is detected. The faster the flow,

the higher the detection value becomes. The slower the flow,
the lower the detection value becomes. In a condition wherebubbles are mixed in seawater, the shear force acting on thedetection plate 1200 is decreased and the detection value isdecreased in comparison with a condition only with seawater

ration and the control method of the control device.

where bubbles are not mixed. A condition where bubbles are

0334. The comparator 140 compares a value detected by
the draft sensor 111 and a condition setting value preliminar
ily set by the condition setting unit 130. For example, when
the waterline of the hull 4 exceeds the setting value (when theamount of freight is large and the draft rises), controls are
performed including increase of the number of working gas

mixed and effectively acting on the bottom3 of the vessel canbe estimated by preliminarily measuring a relationshipbetween a relative velocity with seawater where bubbles are
not mixed and a shear force and a relationship between theamount of bubbles mixed therein, a relative velocity and ashear force. Further, a frictional resistance acting on the botoutlets, increase of the amount of bubbles or increase both ofthem according to the deviation. When the waterline falls (thefreight is unloaded and the vessel is in a condition of ballast
water), controls are performed including decrease of the num
ber of working gas outlets, decrease of the amount of bubbles
or decrease of both of them. In cases of decrease, it is preferable to control in an analogous fashion to that describedabove.

0335. When swells come, the valves 161, 162, 163, 164
and 165 are controlled using signals from the draft sensor
111, and the pressures acting on the gas outlets 21, 22, 23, 24
and 25 are finely adjusted by increasing or decreasing in an
immediate manner, thereby further alleviating variation in
inject rate of bubbles.
0336. The comparator 140 compares an inclination valueof the hull detected by the inclination sensor 112 and a con
dition setting value preliminarily set by the condition setting
unit 130 with each other. For example, the inclination of thehull exceeds the setting value owing to turning or rolling of
the vessel, the inject spots of the gas outlets are changed or theamount of bubbles is increased or decreased according to thedeviation. For example, the hull is inclined to the left viewed
from the traveling direction, the right side of the bottom of thevessel is elevated. In this case, the frictional resistance can beeffectively reduced without wastefully injecting bubbles byperforming controls including increase of the number ofworking gas outlets on the left where an apparent waterline
rises, increase of the inject rates thereof or increase both ofthem and performing controls including decrease of the num
ber of working gas outlets on the right, decrease of the inject
rates thereof or decrease of both of them. The inclination

sensor 112 can be used not only for controlling injecting of

tom3 of the vessel or the entire hull can be estimated from theshear force. The shear force can be measured more accurately
by increasing the number of the shear force sensors. However,also in an economic aspect, the entire state can be estimatedby arranging a plurality of sensors in a limited area in thebottom 3 of the vessel.

0340. In this embodiment, the values from the shear force
sensors 51, 52,53,54 and 55 are statistically processed by thenavigational condition detector B115, and the representativevalue is fed back to the comparator 140. The comparator 140
compares the fed back representative value of the shear force
sensors and the condition setting value set by the condition
setting unit 130. The blowers 11, 12, 13, 14 and 15 arecontrolled via the controller 150 according to the deviation,and the inject rate of bubbles from the gas outlets 21, 22, 23.
24 and 25 are controlled. When the shear force is greater than
the setting value, or deviation is large, control is performed so
as to increase inject rate of bubbles from the gas outlets 21 and25. When the deviation is small, control is performed so as todecrease the rate. The feedback control acquires a desiredcondition-set shear force. The detection values of the shear

force sensors 51, 52,53,54 and 55 are also used as indicatorsfor verifying the reduction effect of the frictional resistance.
0341 In Summary, control of starting/stopping injecting
gas includes a case mainly pursuant to determination by thevessel conditions determination unit 110, a case pursuant todetermination by the oceanographic condition determination
unit 120, and a case pursuant to the detection result of thenavigational condition detectors A and B115. In the casepursuant to the vessel conditions determination unit 110.
injecting of bubbles is stopped when the GPS 101 determinesthat the vessel is approaching a port or a destination, injecting
is started when leaving the port, injecting is stopped when theUS 2011/0259440 A1

Oct. 27, 201127

vessel is approaching waters where is a Swirling current
region, injecting is started when the vessel is leaving thewaters, injecting of bubbles is stopped when operations of theengines are stopped, and injecting of bubbles is started apredetermined time after the engines start. When the fuelconsumption efficiency detected by the fuel detector 102
becomes below a predetermined one, injecting of bubbles are
stopped. When it is estimated that the fuel consumption effi
ciency is improved, injecting of bubbles is started. When theoceanographic condition determination unit 120 determinesthat it is stormy Such as a typhoon and rough weather, injecting of bubbles is stopped. When it recovers, injecting isstarted.

0342. Further, when the wave height detected by the wave
sensor becomes a prescribed value or more, injecting of
bubbles is stopped; when the wave height becomes a prescribed value or less, injecting is started. The detection resultsof the navigational condition detectors A and B are comparedwith a set preset value; on the basis of magnitude of deviation,
injecting is stopped when the deviation becomes a predeter
mined threshold or less, and injecting is started when thedeviation exceeds the threshold. For example, the values fromthe relative velocity sensors 55, 56 and 57 are statisticallyprocessed and the representative value is transmitted to thecomparator 140. When the velocity of the vessel 1 isdecreased and the value becomes lower than a prescribed
threshold set by the condition setting unit 130, the injecting of
bubbles are stopped; when the value exceeds the value, theinjecting is started. On the basis of temporal variation in
statistically processed representative value from the relative
velocity sensors 55, 56 and 57, when the vessel 1 starts
moving and accelerates, the threshold is set to be reduced andbubbles are injected a little earlier. When the frictional resis
tance reduction effect is effectively exerted and the vessel isdecelerated, the threshold may be reset upward and injectingof bubbles may be stopped a little earlier because the speed isdecreased and bubbles still stay at the bottom 3 of the vessel.
0343 AS to the conditions for starting/stopping injecting
gas, control may be performed according to precedence.
When detection error, failure or an unpredictable event
occurs, control may be performed complementarily using
another condition. In any event, injecting of bubbles can berealized by starting/stopping injecting of bubbles under aprescribed condition in consideration of an actual frictional
resistance reduction effect, or stopping injecting of bubbles
when detecting/determining that the vessel is stopped.

along the fore shape, the bubbles can be injected from a spot
such that the bubbles can be retained longest also for the stern.
This allows reduction in frictional resistance to be further

improved, and enables the fore having a large frictional resis
tance to be effectively covered. In this case, since the number
ofgas outlets 21, 22, 23, 24 and 25 is odd, the centergas outlet
23 can be arranged at the distal end of the so-called boat
shape. This enables the bubbles to be injected from the one
gas outlet 23 while maintaining the ability of the vessel 1 tohold a straight line, and allows the bottom3 of the vessel to becovered with the bubbles most effectively.
0347 As described above, these embodiments adopt theconfiguration where the plurality of gas outlets 21, 22, 23, 24
and 25 and the plurality of blowers 11, 12, 13, 14 and 15
blowing air to the plurality of gas outlets 21, 22, 23, 24 and 25
are arranged at the bottom3 of the vessel, and the blowers are
driven by respective inverter-type motors 60 as the drive
device. Further, as the navigational condition detectionmeans for detecting the navigational condition of the vessel 1,
the relative velocity sensors 55, 56 and 57, the draft sensor
111 and the inclination sensor 112 are provided at the navi
gational condition detector A, and the shear force sensors 51,
52, 53, 54 and 55 are provided at the navigational condition
detector B115. The control device controls the motors 60 of

the respective blowers according to detection results from thenavigational condition detectors A110 and B115.
0348 According to this configuration, the rise of the
bubbles is suppressed by the bottom3 of the vessel itself, andthe bubble retention effect can be maintained, thereby allow
ing the frictional resistance to be effectively reduced by asmall amount of bubbles. Further, influences of waves are

alleviated at the gas outlets 21, 22, 23, 24 and 25 arranged at
the bottom 3 of the vessel, in comparison with a case ofarrangement at the sides of the vessel. This enables bubbles tobe stably injected. As a result, frictional resistance reduction
effect at the hull can be exerted. Moreover, one blower isbottom 3 of the vessel.

arranged for one gas outlet correspondingly. This facilitates
the bubble injecting control with respect to the separate gas
outlets 21, 22, 23, 24 and 25, and can alleviate the problem ofvariation in inject rate of bubbles owing to waves particularly
in a case of using in the ocean. Further, the gas blowing
condition can be controlled according to the detection resultsfrom the navigational condition detectors A110 and B115.
This allows the injecting of bubbles to be finely controlled ina variable manner, responsive to navigational conditions, incomparison with a case of injecting gas contently. Accord
ingly, reduction in frictional resistance that further improves
the net reduction effect can be expected.
0349 The arrangement of the gas outlets 21, 22, 23, 24 and25 substantially in a line allows the configuration to be sim
plified, and can also facilitate the arrangement of blowers 11,
12, 13, 14 and 15 and the air supply pipe 16, 17, 18, 19 and 20,
which are provided accordingly. Moreover, since the numberof the gas outlets 21, 22, 23, 24 and 25 is odd, the center one(gas outlet 23) can be arranged on the planar center line CL.
This can realize one spot injecting of bubbles while holding
the ability of the vessel to hold a straight line.
0350 Since the distribution component 71, which has thetriangular profile and disperses the blown air, is arranged
immediately below the connection part of the air supply pipe
16, the distribution component 71 laterally disperses and0346. This allows the bubbles injected from the gas outlets

uniformizes air.

Second Embodiment0344 FIG. 9 shows a second embodiment of the embodi
ments of the present invention. The second embodiment will
be described on difference from the first embodiment. The

other elements adopt configurations analogous to those in thefirst embodiment.

(0345. In FIG.9, the gas outlets 21, 22, 23, 24 and 25 arearranged on the bottom 3 of the vessel 1, as shown in the
figure. More specifically, a planar portion of the fore of thebottom 3 of the vessel is configured to be a so-called boat
shape as indicated by broken lines. The gas outlets 21, 22, 23.
24 and 25 are arranged symmetrically with respect to theplanar center line CL of the hull 4 along the fore shape of the21, 22, 23, 24 and 25 to cover the entire surface of the bottom

3 of the vessel most effectively. Further, since the bubbles are

0351. The apertures of the perforated plates 72 and 73
used for the gas outlets 21, 22, 23, 24 and 25 are configured toUS 2011/0259440 A1

Oct. 27, 201128

be round apertures. This eliminates edges. In a case of using
stainless material, concentration of stress cannot easily occur
during pressing, thereby alleviating development of stresscorrosion even in use in seawater.

0352. The Roots-type blower is used as the gas supply or
charged air means. This type is different from the piston-type,even though both types are the same positive-displacement
type. The Roots-type blower pressurizes air substantiallycontinuously and thereby reduces pulsing, and can eliminate
a tank and the like for Smoothing pressure. Moreover, therotation is Smooth and vibration and noise are reduced.

Accordingly, even with the arrangement of the blowers 11,
12, 13, 14 and 15 on the deck 2, occurrence of resonance canbe prevented in the cabins therebelow.
0353. The number of gas outlets 21, 22, 23, 24 and 25 isodd. This enables the centergas outlet 23 to be arranged at the
distal end of the so-called boat shape, enables the bubbles tobe injected from the one gas outlet 23 while maintaining theability of the vessel 1 to hold a straight line, and enables thebottom 3 of the vessel to be covered with bubbles most effec
tively.
0354. The inverters of the motors 60 and the valves 161,
162, 163, 164 and 165 controlled by the controller 150 areprovided as the gas adjustment means for controlling inject
ing gas from the gas outlets 21, 22, 23, 24 and 25. This enables
the inject conditions, such as starting/stopping injecting
bubbles and the inject rate of bubbles, to be arbitrarily con
trolled, thereby allowing the net frictional resistance to beeffectively reduced.
0355 The relative velocity sensors 55.56 and 57 adopt theultrasonic system. This allows use in the water, and enabling
influences of waves and currents to be reduced.

0356. The relative velocity sensors 55, 56 and 57 detect
relative velocities with seawater. The prescribed statisticalprocessing is applied thereto. The representative value istransmitted to the comparator 140, and used. Accordingly, thedetection errors are reduced, thereby allowing accurate control.

0357 The draft sensor used for the bubble injecting con
trol can also be used for estimating the amount of freight inthe vessel 1 and adjusting the draft of the vessel 1.
0358. The inclination sensor 112 can be shared for detect
ing the inclination of the hull 4 and adjusting the ballast water
for maintaining balance, in addition to use for the bubble
injecting control.
0359. The shear force sensors 51, 52, 53, 54 and 55 preliminarily measure the relationship between the relative
velocity and the shear force in seawater without mixture of
bubbles, and the relationship between the amount of bubble
mixture, the relative velocity and the shear force in seawaterwith mixture of bubbles. Accordingly, the condition of bubble
mixture effectively acting on the bottom3 of the vessel can be
estimated. Further, the frictional resistance acting on the bot
tom 3 of the vessel and the entire hull can be estimated fromthe shear force.

0360. The vessel conditions determination unit 100 is pro
vided in addition to the navigational condition detectors A110
and B115. The control of starting/stopping injecting gas fromthe gas outlets 21, 22, 23, 24 and 25 is performed according tothese detection/determination conditions.

0361. In a case where the reduction effect in frictional
resistance by injecting bubbles cannot be expected according
to this configuration, the injecting bubbles are stopped. In acase where the reduction effect can be expected, the bubbles

are injected. This can prevent power from being used in vain,
and allows the frictional resistance reduction effect to beeffectively exerted.
0362. A difference according to threshold is provided in
the representative value, which has been subjected to thestatistical processing of relative velocities. When the vessel 1
is stopped, the injecting of bubbles is stopped earlier, thereby
effectively utilizing the residual bubbles. This can realizes theinjecting of bubbles in consideration of the substantial frictional resistance reduction effect.

0363 The waterline level is adjusted on the basis of thecondition setting instruction 132. This allows distinction withthe condition setting instruction 131 for reducing the frictional resistance, and enables the waterline level to be

adjusted using the same gas outlets 21, 22, 23, 24 and 25 andthe blowers 11, 12, 13, 14 and 15 for reducing the frictional
resistance.

0364. Further, according to the present application, thebubble size is made large when the relative velocity is fast,
and the bubble size is made smaller when the relative velocity
is slow. This can exert the advantageous effect specific to thepresent application that the buoyancy is increased when the
bubble size become larger, and the bubbles adhere well to thebottom of the vessel even with the fast relative velocity.
0365. When the waterline becomes deep, the bubble size
becomes small and the frictional resistance reduction effect isreduced. However, according to the present application, theamount of bubbles is controlled according to the draft. Therefore, even in this case, this can exert the advantageous effectspecific to the present application that can perform comple
ment by increasing the amount of bubbles.
Third Embodiment

0366 FIG. 10 is an embodiment where a bubble retention
device according to an embodiment of the present invention isapplied to a vessel used in the ocean. FIG. 10 (a) shows a sideview of the vessel. FIG.10(b) shows atop view thereof. FIG.
10(c) shows a bottom view. A part of a principal configurationis represented in an exposed manner.
0367 The blowers 10, 11, 12, 13 and 14 as the gas supply
or charged air means are arranged in a line on the deck 2 of thevessel 1. These blowers 10, 11, 12, 13 and 14 are arranged ina casing on the deck 2 in order to avoid splash of seawater
broken at the bow. For the sake of avoiding a splash as muchas possible, the air as gas is taken from a direction opposite to
the traveling direction of the hull.
0368. The blowers 10, 11, 12, 13 and 14 are Roots-type
positive-displacement blowers, and adopt a structure (notshown) where an inverter-type motor 60 (not shown) as thedrive device drives two rotors in the blower via a belt, the air
taken between the blower interior wall and the rotors is com

pressed as the rotors rotate, and Supplied (not shown). Since
the blowers 10, 11, 12, 13 and 14 are the positive-displace
ment type, the blowers are capable of Supplying stably apredetermined rate of air even with previous variation inpressure. Although the Roots-type blower is the same posi
tive-displacement type, the Roots-type blower is different
from the piston type in that the Roots-type blower pressurizes
air Substantially continuously and thereby reduces pulsing,and can eliminate a tank and the like for Smoothing pressure.
Further, the rotation is smooth and vibration and noise are

reduced. Accordingly, even with the arrangement of blowers
10, 11, 12, 13 and 14 on the deck 2, resonance cannot easily
occur in the cabins therebelow.

US 2011/0259440 A1

Oct. 27, 2011
290369. The air taken by the blowers 10, 11, 12, 13 and 14 ispressurized, passes through the air supply pipe 16, 17, 18, 19
and 20 having bent portions, and guided to gas outlets (hereinafter, also referred to as “air nozzle”) 21, 22, 23, 24 and 25
arranged in the proximity of the bottom3 of the vessel. In thisembodiment, the gas outlets 21, 22, 23, 24 and 25 arearranged substantially symmetrically with respect to the pla
nar center line CL of the hull 4 substantially in a line, on thefore surface of the bottom 3 of the vessel. The gas outlets 21,
22, 23, 24 and 25 are arranged on the bottom3 of the vessel isfor the sake of causing the injected bubbles to be retained
longer at the bottom 3 of the vessel, and alleviating variationin pressure owing to waves. The arrangement at the fore of thebottom 3 of the vessel is for the sake of causing the injectedbubbles to be retained over the entire bottom3 of the vessel asmuch as possible.
0370. The arrangement of the gas outlets 21, 22, 23, 24 and25 substantially in a line is for the sake of simplifying theconfiguration, and also facilitating the arraignment of theblowers 10, 11, 12, 13 and 14 and the air supply pipes 16, 17.
18, 19 and 20, which are provided correspondingly. In thisexample the number of the air nozzles 21, 22, 23, 24 and 25 isfive, which is an odd number. Accordingly, the center one (airnozzle 23) may be disposed on the planar center line CL. Thiscan realize one spot injecting of bubbles while maintaining
the ability of the vessel 1 to hold a straight line. In this case,the air nozzles 21, 22, 23, 24 and 25 can adopt a configuration
where the nozzles are arranged Substantially symmetricallywith respect to the planarcenterline CLofthehull 4 along theplanar shape of the fore of the bottom 3 of the vessel.
0371. The end plates 5, 5, 6, 6, 7 and 7" for guiding
bubbles injected from the air nozzles 21, 22, 23, 24 and 25
Such that the bubbles do not escape are arranged also sym
metrically with respect to the planar center line CL of the hull
4 on the bottom3 of the vessel. The end plates 6 and 6' and 7
and 7" are illustrated so as to be in the same dimensions in thisfigure. However, the end plates 7 and 7" may have smaller
dimensions than those of the end plates 6 and 6'. The numberof end plates is not limited to that represented in this figure. In
addition thereto, the shear force sensors 50,51,52, 53 and 54

as shear force detectors for detecting shear forces owing toseawater and bubbles acting on the hull 4 are arranged on thebottom 3 of the vessel.

0372. The relative velocity sensors 55 and 56 as the relative velocity detectors arearranged aft. Other relative velocity
sensors 57 are arranged on the sides 8 of the vessel. These
relative velocity sensors 55 and 56 are arranged apart from the
air nozzles 21, 22, 23, 24 and 25. On the other hand, therelative velocity sensors 57 are arranged on spots without any
influence of bubbles on the sides 8 of the vessel, even if the

spot is near the nozzles. In particular, the relative Velocity
sensors 57 are arranged at lower spots without receiving theinfluence owing to waves, even though the spots are on thesides 8 of the vessel. These relative velocity sensors 55, 56
and 57 adopt ultrasonic systems. This allows use in the water,and reduces the influence owing to waves and currents.
0373 The video cameras 58 and 59 for monitoring condi
tions of injected bubbles are arranged at fore and aft parts ofthe bottom 3 of the vessel. Images taken by these video
cameras 58 and 59 are monitored by a person and utilized foranalyzing the inject condition of bubbles.
0374 FIG. 11 is a sectional view of the hull 4 according to
one embodiment of the present invention taken along line
X-X (in FIG.10). As shown in this figure, the end plates 5 and5' and the bilge keels 101 and 101"are disposed. Typically, forexample, the vessel is equipped with bilge keels arranged atconnecting portions (bilge portion) between the bottom 3 ofthe vessel and the sides 8 of the vessel in order to facilitatestability on sailing. This can Suppress rolling and turning over
onto the side of the vessel, against natural phenomena, Such as
waves and currents, and a collision object. The end plates 5
and 5' according to the present invention can be arranged
separately from the bilge keels 101 and 101'. The arrange
ment spots are preferably inside of the bilge keels 101 and101" with respect to the planar center line CL.
0375. On the other hand, the end plates 5 and 5' may be
used for stabilizing the vessel. In this case, the performances
pertaining to stabilization of the bilge keels 101 and 101" canbe modified to an extent where the end plates 5 and 5' takecharge of the stabilizing function. In this case, the design ispreferably performed in consideration of structures, dimensions, arrangement spots and the like of the end plates 5 and5' and the bilge keels 101 and 101", so as not to impede sailingof the vessel. The original purpose pertaining to the end plates
5 and 5' is to cause the bubbles to flow while retaining the
bubbles at the bottom3 of the vessel. Accordingly, designs of
the end plates 5 and 5' and the bilge keels 101 and 101' are to
be adopted in consideration of this.
0376 FIG. 12 is a sectional view of the hull 4 according toanother embodiment of the present invention taken along line
X-X (in FIG. 10). This figure shows a mode where the profileof the end plate is configured as a Substantially triangle. As
shown in this figure, the end plates 5a and 5a' have a substan
tially triangular shape whose base is the bottom 3 of thevessel. These end plates are different from the end plates 5 and5 pertaining to FIG. 11 only in that the shapes are different.
Accordingly, the detailed description thereof is omitted.
0377 Here, in comparison between contact areas withwater in cases of using this Substantially triangular profile andthe end plate 5 or 5 of the flat plate, the sum of two sides of thetriangle is longer than one side. The adoption of the Substan
tially triangle shape narrows the contact area with water, andallows the frictional resistance by arrangement of the end
plates to be reduced. These end plates 5a and 5a' having a
Substantially triangular shape allow increase in frictional
resistance of the end plates to be Suppressed.
0378 FIG. 13 is a sectional view of the hull 4 according tostill another embodiment of the present invention taken alongline X-X (FIG. 10). This figure shows a mode where theprofile of the end plate is quadratic function curve or the like.
As shown in this figure, the end plates 5b and 5b' have a shape
to be a curve. Such as a quadratic function curve, whose baseis the bottom 3 of the vessel. These end plates 5b and 5b' aredifferent from the end plates 5 and 5 pertaining to FIG. 11
only in that the shapes are different. Accordingly, the detailed
description thereof is omitted. These end plates. 5a and 5a
having the shape to be a curve. Such as a quadratic function
curve, allows increase infrictional resistance of the end plates
to be suppressed.
0379 FIG. 14 is an enlarged view of a broken line Y part of
FIG. 11 according to yet another embodiment of the present
invention. This figure shows a mode where the fore of the end
plate is a streamlined shape. As shown in this figure, the end
plate 5 is preferably formed as a streamlined shape at its innerside with reference to the planarcenterline CL. It is necessary
to perform the design in consideration that the end plate does
not impede sailing of the vessel. More specifically, the distal
end of the end plate 5 preferably has a shape similar to a shapeUS 2011/0259440 A1

Oct. 27, 201130

where the angle of the surface is finely changed as with the
distal end of a Sword for facilitating cut an object. In cases
where the end plate 5 has already been provided on the bottom
3 of the vessel, a component pertaining to the streamlined
shape may be attached to the end plate 5. It is preferable thatthe aft part of the end plate also have a streamlined shape (notshown).
0380 FIG. 15 is a sectional view of the hull 4 according tostill another embodiment of the present invention taken alongline X-X (of FIG. 10). This figure shows a mode where aconcave portion is formed at the bottom 3 of the vessel. As
shown in this figure, there are adapted a configuration where
the end parts 5c and 5c are left instead of the end plates 5 and
5' shown in FIG. 11 and other parts are cut out, or a configu
ration where a configurational member pertaining to the con
cave portion having the end parts 5c and 5c' is arranged, or aconfiguration where the end parts 5c and 5c are attached tothe already provided bottom3 of the vessel, or a configuration
where the bottom 3 of the vessel itself has the concave portion. The forces of the end parts 5c and 5c may be streamlined
shapes as shown in FIG. 14. These end parts are different fromthe end parts 5 and 5' pertaining to FIG. 11 only in that theshape is different. Accordingly, further detailed description isomitted. The end parts 5c and 5c and the concave portion
sandwiched between these end parts enable bubbles to flow
while being retained at the bottom of the vessel.
0381 FIG. 16 is a sectional view of the hull 4 according toyet another embodiment of the present invention taken alongline X-X (of FIG. 10). This figure shows a mode where aconcave portion is formed at the bottom 3 of the vessel. As
shown in this figure, there are adapted a configuration where
the end parts 5d and 5d are left instead of the end plates 5 and
5' shown in FIG. 11 and other parts are cut out, or a configu
ration where a configurational member pertaining to the con
cave portion having the end parts 5d and 5d is arranged, or aconfiguration where the end parts 5d and 5d are attached tothe already provided bottom 3 of the vessel. These end parts
are different from the end parts 5c and 5c pertaining to FIG.
15 in the shapes at a part of the quadratic curve. The forces ofthe end parts 5d and 5d may be streamlined shapes as shownin FIG. 14. These end parts are different from the end parts 5
and 5' pertaining to FIG. 11 only in that the shape is different.
Accordingly, the detailed description is omitted. The end
parts 5d and 5d and the concave portion sandwiched between
these end parts enable bubbles to flow while being retained at
the bottom of the vessel.

0382 Next, operation and a method of using the bubble
retention device according to one embodiment of the present
invention will be described using the conceptual view.
0383 FIG. 17 is a conceptual view showing a state ofretaining of bubbles in a case where end plates 5 and 5
according to an embodiment of the present invention arearranged. This figure shows a state of retaining bubbles whenthe vessel is inclined. In this case, in the sectional view taken

along line X-X in FIG. 10, the inclination of the vessel causes
a differential pressure between opposite ends of the bottom 3of the vessel, and the bubbles moves to a low pressure part.
This diffuses the bubbles out of the extent of the bottom 3 ofthe vessel, thereby reducing the frictional reduction effect by
the bubbles. On the other hand, in the present application, theend plates 5 and 5' are arranged at the opposite ends of thebottom 3 of the vessel, thereby suppressing the bubble diffusion. More specifically, the bubbles moves from a high presSure part to a low pressure part, and it is impossible to movefrom the low pressure part to the high pressure part. Accord
ingly, to move to the low pressure part, the bubbles should
detour around a barrier pertaining to the end plate 5. Thus, itis necessary to move to the high pressure part. Therefore,
according to the above principle, the bubbles can be retainedat the bottom 3 of the vessel. Likewise, in a case of reversed
inclination. Even without the inclination of an extent shownin this figure, the bubbles detect a slight differential pressure
according to a slight rolling and the like in sailing, and the
bubbles move to a low pressure part in an analogous manner.
However, the end plate 5 suppresses the diffusion owing to
movement of bubbles, and the bubbles flow to the end of theend plate 5 while being retained. This allows the bubbles to beretained against the inclination of the vessel occurring Owing
to disturbance Such as waves and flows and turning, and caneffectively facilitate reduction in frictional resistance.
0384 FIG. 18 is a conceptual view showing a state wherebubbles flow when a vessel is sailing in a case of arrangement
pertaining to the end plates 5 and 5' according to an embodi
ment of the present invention whose fore and aft parts havestreamlined shapes. In this figure, the fore parts of the end
plates 5 and 5' have symmetrical shapes with respect to thecenterline. Accordingly, end plates 5 and 5' can avoid becom
ing a resistance impeding sailing of the vessel as much as
possible. The aft parts of the end plates 5 and 5' have a smooth
curve or inclination based on the center line from a deep aftpart terminating a shallow aft part to form a streamlined
shape. The bubbles are not released from the retained state
Suddenly attermination point pertaining to the aft parts of theend plates 5 and 5' as a boundary. Instead, the dimensions of
the end plates 5 and 5' become smaller at the starting point of
the Smooth curve or inclination pertaining to the aft parts as aboundary. This shape Smoothly releases the state of retaining
bubbles. Accordingly, the bubbles gradually diffuse into thewater. Further, a configuration where the aft parts open causes
the bubbles, which have flowed while sufficiently covering
the bottom of the vessel, to flow outwardly. This eliminates
convolvement of the bubbles into the propeller (not shown)provided at the stern, and can thereby prevent the propulsion
from dropping.
Fourth Embodiment0385 FIG. 19 is a sectional view conceptually showing astate of retaining bubbles when a vessel whose bottom 3 hasa triangular uneven profile in a sectional view is sailing,according to still another embodiment of the present invention. In this figure, in a case where the section of the bottom 3of the vessel is an uneven profile pertaining to triangles,
inclinations are formed by first and second triangles adjacent
to each other whose bases are the bottom 3 of the vessel

pertaining to the uneven profile. Differential pressures gen
erated by the inclinations move the bubbles to a low pressure
part. The bubbles surrounded by one triangular profile flow in
the aft direction along the longitudinal direction with a low
resistance, because crossing over the vertices of the triangles
faces a resistance. This Suppresses movement and diffusion of
bubbles even by the differential pressure generated by the
inclination of the hull on sailing of the vessel or a slightdifferential pressure generated by slight rolling. Accordingly,
the bubbles flow while being retained at the bottom 3 of thevessel. The height dimension of the triangle whose base is thebottom 3 of the vessel is preferably equal to or less than 10
mm with reference to the bottom3 of the vessel. The basic of

this concept is to that the triangle is formed to have a heightUS 2011/0259440 A1

equal to or less than a height sufficiently covered with the
bubbles. More specifically, the height dimension of the tri
angle whose base is the bottom3 of the vessel is not limited tothat equal to or less than 10 mm with reference to the bottom
3 of the vessel. Instead, the height may be about that where thebottom is sufficiently covered with bubbles.
0386 FIG. 20 is a sectional view conceptually showing astate of retaining bubbles at a vessel having a configuration
including a mound that has a wing profile in a sectional view
when the vessel is sailing, according to still another embodi
ment of the present invention. In this figure, water flows in the
opposite direction to the traveling direction of the vessel.
Likewise, the bubbles also flow in the direction of the flowing
water. On the other hand, as the bubbles flow downstream, thebubbles diffuse in the water. Accordingly, the frictional
reduction effect by the bubble is reduced. However, a wingprofile mound 102 is provided on the bottom 3 of the vessel.
This attaches the bubbles to the bottom 3 of the vessel again,
and improving the frictional reduction effect. More specifi
cally, the bubbles flow along the shape of the wing profile
mound 102. In order to cause the bubbles to flow along theshape of the wing profile mound 102, the surface shape of thewing profile mound 102 is required to be a shape having a
Smoothly curved profile in a sectional view. In a case where
the starting end of wing profile mound 102 has an angle thatis not smooth, there is a possibility that the surface of the wingprofile mound 102 becomes a barrier and the bubbles diffuse
at a collision. In a case where the terminating end of the wingprofile mound 102 has an angle that is not smooth, the bubbles
Suddenly moves to a low pressure part pertaining to the bot
tom 3 of the vessel because of a differential pressure causedby an inclination between the terminating end and the bottom
3 of the vessel. This shape makes a part where bubbles do notaccompanies the bottom 3 of the vessel. Accordingly, use of
the differential pressure caused at the wing profile mound 102
having Such a shape can Suppress the bubble diffusion andimprove the frictional reduction effect.
0387 FIG. 21 is a sectional view conceptually showing astate of retaining bubbles at a vessel whose bottom 3 has aconfiguration having a gentle step profile toward the stern ina sectional view when the vessel is sailing, according to yet
another embodiment of the present invention. In this figure,analogous to the above, water flows in the opposite direction
to the traveling direction of the vessel. Likewise, the bubbles
flow in the flowing water direction. On the other hand, as the
bubbles flow downstream, the bubbles diffuse in the water.

This reduces the frictional reduction effect by the bubbles.
However, the bottom3 of the vessel has the gentle step profile
toward the stern in a sectional view. This attaches the bubbles

to the bottom 3 of the vessel again, and allows the frictional
reduction effect to be improved. More specifically, fluid force
effect because of the shapes of the first and second differencesof steps allows the bubble diffusion to be suppressed, andenables the frictional reduction effect to be maintained.

Analogous to the above, it is necessary that the terminating
end of the difference of steps have a gently curved shape.
Without this shape, the bubbles suddenly move to a low
pressure part pertaining to the bottom 3 of the vessel, by adifferential pressure caused by an inclination between theterminating end pertaining to the first difference of steps andthe starting end of the second difference of steps. This forms
a part where the bubbles do not attach to the difference ofsteps or the bottom 3 of the vessel is formed.
Fifth Embodiment0388 FIG.22 is a sectional view for illustrating a configu
ration of a gas-liquid separator 200 in a bubble retention

Oct. 27, 2011device according to a fifth embodiment of the present invention. As shown in this figure, the gas-liquid separator 200
includes a main body 201, a bubble separation facilitating
filter 202, a gas transfer pipe 203, a gas release port 204, aliquid transfer section 205, and valves 206a, 206b and 206c.
The principle of the water displacement is applied to thegas-liquid separator 200. FIGS. 23 and 24 are conceptual
views showing a method of using the gas-liquid separator 200
in the bubble retention device according to second embodi
ment of the present invention.
0389. The main body 201 includes a moisture intake B.
which is always open. The main body 201 internally includes
a function of separating liquid and air from each other via the
bubble separation facilitating filter 202. The bubble separation facilitating filter 202 has a conical shape Surrounding ahollow cylinder having a moisture intake. The filter is formed
into a conical shape. The gas transfer pipe 203 has a configu
ration where one opening is disposed inside of the main body201, and the other opening is outside of the main body 201.
The blower 208 has a function of drawing air from the open
ing pertaining to the outside via the valve 206a. The blower
208 is preferably has a configuration capable of transferring
air even if water is mixed therein. A gas release port 204 isarranged on the top of the main body 201. A configuration
capable of releasing unnecessary air to atmosphere via thevalve 206b is adopted. On the other hand, the liquid transfer
section 205 is provided inside of the main body 201, in amanner where the bubble separation facilitating filter 202 is aboundary, and a configuration capable of drawing water by apump 207 via the valve 206C is adopted.
0390 Next, FIG. 25 is a diagram showing a situation per
taining to use of the gas-liquid separator 200 in the bubble
retention device according to the fifth embodiment of thepresent invention. In this figure, (a) (hereinafter, also referred
to as “(a)”) is a conceptual view showing a frictional reduction effect when blowers 10, 11, 12, 13 and 14 according to anembodiment of the present invention blow air. In this figure,the abscissa axis represents a distance, and the ordinate axis
represents what is converted from the frictional reduction
effect into numeric value within an extent from 0.0 to 1.0.1.0

represents the maximum value of the frictional force. 0.0
represents the minimum value of the frictional force (without
friction). Further, in the figure, (b) (hereinafter, also referred
to as "(b)) is a diagram showing a bubble diffusion conditionin the water after blowing by the blowers 10, 11, 12, 13 and 14
according to an embodiment of the present invention. In thisfigure, the direction of the water flow is a direction from left
to right. (a) and (b) have a relationship that both are corre
spond to each other. Accordingly, description will hereinafter
be made using both figures and FIG. 22 as necessary.
0391 First, as shown in (b), air injected via the air nozzle
20 drifts around the bottom 3 of the vessel. Accordingly,
referring to (a), a state almost without friction because of thefrictional reduction effect can be confirmed. However, referring to (b), once the bubbles are injected, the bubbles movealong with the water flow. Accordingly, the bubbles diffuse in
the water, and leave the proximity of the bottom 3 of thevessel. Therefore, referring to (a), the frictional reduction
effect is suddenly reduced (the frictional force is suddenly
increased). Subsequently, the frictional force increases at a
certain rate (the numeric value approaches 1.0 from 0.0). Thiscan also be considered as a phenomenon that occurs because
moisture intrudes between the bubbles and the bottom3 of thevessel. Therefore, referring to (b), the moisture intake B is

US 2011/0259440 A1

Oct. 27, 201132

arranged for drawing the incoming moisture before thebubbles diffuse (when the bubbles leave the bottom 3 of thevessel by about 5 to 7 mm) on the bottom3 of the vessel in theastern direction (downstream direction of the water flow)
with reference to the air nozzle 20. The gas-liquid separator
200 shown in FIG. 22 draws a small amount of moisture via

the moisture intake B. This attracts the bubbles to the prox
imity of the bottom3 of the vessel again. Accordingly, referring to (a), the frictional force is suddenly decreased imme
diate after drawing moisture. This recovers the frictional
reduction effect. After the drawing, the bubbles diffuse in thewater again, thereby gently increasing the frictional force.
0392 Operation and a method of using of the gas-liquid
separator 200 pertaining to the bubble retention device
according to one embodiment of the present invention will
hereinafter be described with reference to FIGS. 22, 23 and24. The gas-liquid separator 200 pertaining to FIG.22 is thatthe gas-liquid separator pertaining to FIGS. 23 and 24 isviewed sectionally from the rear. Accordingly, FIGS. 23 and24 and FIG.22 are laterally inverted.
0393 As shown in FIG. 22, the moisture intake Balways
opens. Accordingly, the configuration is adopted where mois
ture comes inside of the main body 201 pertaining to thegas-liquid separator 200 via the moisture intake B. Here,water in the main body 201 can be retrieved by drawing of thepump 207. In retrieval, the bubble separation facilitating filter
202 separates gas included in water and liquid from eachother. Accordingly, only liquid can be retrieved via the liquidtransfer section 205. The retrieved moisture can be used forcooling water for the engine of the vessel. Presence andabsence of drawing water can be operated by opening andclosing the valve 206c. The pump 207 may always be driven.
On the other hand, the gas separated by the bubble separation
facilitating filter 202 can be retrieved by drawing of blower
208 via gas transfer pipe 203. Presence and absence of draw
ing gas can be operated by opening and closing the valve
206c. The blower 208 may always be driven.
0394. Therefore, as shown in FIG. 23, the air drawn by theblower 208 is released to atmosphere, and the gas in the main
body 201 is released to atmosphere via the valve 206b.
Accordingly, the gas-liquid separator 200 can attract the gas
to the proximity of the bottom3 of the vessel again. As shownin FIG. 24, the gas drawn by the blower 208 can be injectedagain via the retrieved air nozzle C, thereby also allowing thefrictional reduction effect to be amplified.
Sixth Embodiment0395 FIG. 26 shows an example where the bubble con
Volvement prevention device for a vessel according to one
embodiment of the present invention is applied to a vessel
used in the ocean. FIG. 26 (a) is a side view of the vessel. FIG.
26 (b) is a top view thereof. FIG. 26 (c) is a bottom view. A
part of a principal configuration is represented in an exposeda.

0396 The blowers 10, 11, 12, 13 and 14, as the gas supply
or charged air means, are arranged on the deck 2 of the vessel
1. The taken air is separately pressurized, passes through the
air supply pipes 3016,3017,3018,3019 and 3020 having bent
portions, and guided to the air nozzles 21, 22, 23, 24 and 25,
which are gas outlets arranged in the proximity of the bottom
3 of the vessel. In this embodiment, the air nozzles 21, 22, 23,

24 and 25 are arranged at the fore of the bottom3 of the vessel,
symmetrically with respect to the planar center line CL of thehull 4, substantially in a line. The arrangement of the air

nozzles 21, 22, 23, 24 and 25 at the bottom 3 of the vessel isfor the sake of prolonging the retention of the injected bubbles
over the entire bottom3 of the vessel and alleviating variationin pressure owing to waves and the like. The arrangement at
the fore of the bottom3 of the vessel is for the sake of causing
the injected bubbles to be retained over the entire bottom3 ofthe vessel as much as possible.
0397) The blowers 10, 11, 12, 13 and 14 are Roots-type
positive-displacement blowers. Since the blowers are thepositive-displacement type, the blowers are capable of stably
Supplying a predetermined rate of air even with previous
variation in pressure. The Roots-type blower is capable ofpressurizing air Substantially continuously. Accordingly,
pulsing is reduced, the rotation is Smooth and vibration andnoise are also reduced. Even with the arrangement of blowers
11, 12, 13, 14 and 15 on the deck 2, resonance cannot easily
occur in the cabins therebelow.

0398. The end plates 5, 5, 6, 6', 7 and 7", which guide thebubbles injected from the air nozzles 21, 22, 23, 24 and 25 so
as not to escape, are arranged on the bottom 3 of the vessel
symmetrically with respect to the planar center line CL of thehull 4. In addition thereto, the shear force sensors 50, 51, 52,

53 and 54, which detect shear forces owing to seawater andbubbles acting on the hull 4 are arranged aft on the bottom 3of the vessel.

0399. The relative velocity sensors 55 and 56 are arranged
aft. Another relative velocity sensor 57 is arranged on thesides 8 of the vessel. These relative velocity sensors 55 and 56
are arranged apart from the air nozzles 21, 22, 23, 24 and 25.
On the other hand, the relative velocity sensor 57 is arranged
on a spot without any influence of bubbles on the sides 8 of thevessel, even if the spot is near the nozzles. In particular the
relative velocity sensor 57 is arranged on a lower part of thesides 8 of the vessel without receiving influences of waves.
0400. The video cameras 58 and 59 for monitoring condi
tions of injected bubbles are arranged at fore and aft parts ofthe bottom3 of the vessel, respectively. Images taken by thesevideo cameras 58 and 59 are monitored by a person andutilized for analyzing the inject condition of bubbles.
0401 Here, a screw type propeller 80 is provided at thestern 9 of the hull 4 of the vessel 1. A rudder 81 is arranged aftthereof. Inside of the hull 4, the thrust torque gage 83 detect
ing the thrust force and torque is attached to the drive shaft 82
of the propeller 80. A vibration sensor 84 detecting vibration
is attached in the proximity of the drive shaft 82. The thrust
torque gage 83 may be a straingage arranged on the Surface ofthe drive shaft 82 of the propeller 80. Since the drive shaft 82
rotates, the thrust torque gage 83 picks up a signal wirelessly
such that wires are not tangled. The vibration sensor 84 isarranged on the bearing or the like in the proximity of thedrive shaft 82, and picks up vibration electrically.
0402 V-shaped mound 190, which has a V-shape laterally
spreading centered at the planar center line CL of the hull 4,
is arranged on the bottom3 of the vessel, as a protuberance ofthe bubble convolvement prevention structure. The mound isformed so as to include a wrapping portion 191 spreading
around up to the sides 8 of the vessel.
0403. The air nozzles will be described using the figure of
the first embodiment. FIG. 3 is a perspective view conceptu
ally showing the detailed structures of the air nozzles 21, 22.
23, 24 and 25. For the sake of simplicity of description, FIG.
3 shows a typical example of the plurality of air supply pipes
and the air nozzles. The air blown from the blower 14 via the

air supply pipe 16 is bent at right angle at a chamber 70 of theUS 2011/0259440 A1

Oct. 27, 2011

air nozzle 21 connected to the air supply pipe 16. A distribu
tion component 71 having triangular profile for dispersing theblown air is arranged immediately below the connection partof the air Supply pipe 16. A configuration is adopted accord
ing to which the air is bent at right angle at this part anddispersed laterally by the distribution component 71. This
uniformizes the lateral distribution of the air with respect tothe perforated plates 72 and 73.
0404 A lot of perforations 74 and 75 are formed at theperforated plates 72 and 73. The positions of the perforated
plates 72 and 73 are laterally displaced from each other,
thereby forming an arrangement with the perforations in adisplaced manner. Since perforated plates 72 and 73 arearranged so as to displace the positions of the perforations, theperforated plates 72 and 73 function as a so-called baffle
plates, which bend the airflow to provide resistance. Accord
ingly, in addition to further uniformization of the air in themation on waves, winds, currents and the like including infor
mation on a general weather, and is used for determining thatthe injecting of bubbles is stopped when the oceanographic
condition is stormy, and bubbles are generated when thelateral direction, the air is uniformized also in the vertical

dition setting unit 130. The condition setting unit systemati
cally sets conditions for injecting bubbles to the bottom 3 ofthe vessel. The conditions include starting/stopping injecting

ment.

the bubbles are injected from, which inject rate is to be set,
which timing the injecting is started on, how a temporal
bubble inject sequence is composed, when injecting is started
and stopped and the like.
0412. The condition setting unit also sets the inject condition and the operating condition of the air nozzles 21, 22, 23.
24 and 25 and the blowers 10, 11, 12, 13 and 14 along withbubble convolvement, and the controlling thresholds of thethrust torque gage 83 and the vibration sensor 84 in order tochange the operating condition of the propeller 80. In addition
to the thresholds, the condition setting unit further performs
condition setting of the inject condition and the operating
condition according to the detection values from the thrust
torque gage 83 and the vibration sensor 84, condition setting
for changing the operating condition of the propeller 80.
combination condition setting, correction condition setting
and the like. The condition setting instruction 131 for reduc
ing the frictional resistance, and a condition setting instruction 131 for preventing bubble convolvement are also input
into the condition setting unit 130.
0413. According to the settings in the condition setting
unit 130, the comparator 140 compares signals. The blowers
10, 11, 12, 13 and 14 and the propeller 80 are controlled via

direction, thereby enabling the air to be injected from a inject
port 76 on a front surface.
04.05 FIG. 27 is a control block diagram of this embodi
0406. The vessel conditions determination unit 100
includes a GPS 101 detecting the location of the vessel 1, afuel measurement unit 102 measuring fuel consumption ofengines of the vessel 1, and an engine operation detector 103
detecting operational conditions of the engines of the vessel
1. The vessel conditions determination unit 100 specificallydetermines the present conditions of the vessel 1, and deter
mines the present conditions that vary in a small degree on
sailing or vary gradually.
0407. The GPS 101 is used for determining which position
or location on the map the bubble is injected or stopped. The
fuel measurement unit 102 is used for measuring how muchthe engine consumes fuel in a prescribed time period and,
when the fuel consumption efficiency falls below a prescribed
efficiency, the injecting bubbles is stopped. The engine opera
tion detector 103 detects various operating conditions includ
ing starting/stopping the engine of the vessel 1, and is used for
acquiring information on stopping injecting bubbles when theoperation of the engine is stopped, and starting injecting
bubbles a prescribed time period after starting the operation.
The engine operation detector 103 is also used for detecting
the numbers of revolutions of the engines, and changes thenumber of working air nozzles and/or the inject rate ofcondition is recovered.

0410. The convolvement detector 180 includes an axial
thrust torque gage 83 provided on the drive shaft 82 of thepropeller 80, and the vibration sensor 84 arranged in theproximity of the drive shaft 83. These gage and sensors detectthat bubbles are convolved into the propeller 80, and at least
used for changing the operating conditions and the injectconditions of the blowers 10, 11, 12, 13 and 14 and the air

nozzles 21, 22, 23, 24 and 25, and changing the operating
condition of the propeller 80.
0411. The information from the vessel conditions deter
mination unit 100 and information from the oceanographic
condition determination unit 120 are transmitted to the con

bubbles, which ones of the air nozzles 21, 22, 23, 24 and 25

the controller 150. The controller 150 also controls the valves

bubbles.

161,162, 163, 164 and 165 arranged on the discharge sides of0408. The navigational condition detector A110 includes
the relative velocity sensors 55, 56 and 57, the draft sensor
111 detecting the waterline level of the hull, and the inclina
tion sensor 112 detecting the lateral inclination with respect
to the traveling direction of the hull, which is so-called rolling. Separate therefrom, the shear force sensors 51, 52,53,54
and 55 configure the navigational condition detector B115.
These navigational condition detectors A and B detect physi
cal quantities that relatively easily vary along with sailing of
the vessel 1, or are controlled for the sake of changing.
04.09. The oceanographic condition determination unit

the blowers 10, 11, 12, 13 and 14. These are attached for the

120 includes the wave sensor 121, the wind sensor 122 andthe current sensor 123. The wave sensor 121 detects the wave

height, direction, period and the like of a wave. The wind
sensor 122 detects the wind velocity and direction of a wind.
The current sensor 123 detects the current velocity, direction,height and the like of a current. In addition thereto, theoceanographic condition determination unit considers infor

sake of adjusting the valves 161, 162, 163, 164 and 165 andattains a desired air rate, in a case of controlling an air rate
below the control region of the motors of the blowers 10, 11,
12, 13 and 14, and in a case of quickly adjusting the waterline
level using the signal from the draft sensor 111.
0414. Further, comparator 140 compares the detection sig
nals from the thrust torque gage 83 and the vibration sensor 84
of the convolvement detector 180 and the thresholds thereof

set by the condition setting unit 130. When it is determinedthat convolvement of bubbles above the threshold occur, theinject conditions of the air nozzles 21, 22, 23, 24 and 25
and/or the operating conditions of the blowers 10, 11, 12, 13
and 14 are changed, and the inject conditions are thuschanged to those based on which the propeller 80 does noteasily convolve the bubbles. When it is determined that con
volvement of bubbles above the threshold occurs, the operat
ing conditions of the propeller 80 are changed. This prevents

US 2011/0259440 A1

Oct. 27, 201134

the reduction in propeller efficiency from continuing, andreduces generation of vibration and noise and damage to thepropeller 80. Under certain situations, the operating condi
tions of the propeller 80 are changed, thereby maintaining the
propulsion. These changes in the inject condition of bubbles,
the blower operating conditions, and the operating conditionsof the propeller are used solely or in combination. The priority
condition, changing procedures and the like are pursuant tothe condition setting instruction 131 for reducing the frictional resistance, and the condition setting instruction 131 forthe bubble convolvement prevention.
0415. The signals from the shear force sensors 51, 52,53,
54 and 55 attached on the bottom 3 of the vessel are fed backto the comparator 140, compared with the share force value
preliminarily set by the condition setting unit 130. The oper
ating conditions of the blowers 10, 11, 12, 13 and 14 are finely
adjusted via the controller 150 pursuant to a prescribed ruleaccording to the deviation, an algorithm and constants. The
relative velocities between the hull 4 and seawater aredetected by the relative velocity sensors 55, 56 and 57, andSubjected to the prescribed Statistical processing, and therepresentative value is transmitted to the comparator 140. The
signals from the draft sensor 111 and the inclination sensor
112 are also transmitted to the comparator 140.
0416) The comparator 140 compares the processed repre
sentative value from the relative velocity sensors 55, 56 and57 and the setting value preliminarily set by the condition
setting unit 130 with each other. The number of working
nozzles, the inject rate of bubbles, and the bubble injecting
pattern are controlled.
0417. The comparator 140 also compares the value
detected by the draft sensor 111 and the setting value prelimi
narily set by the condition setting unit 130 are compared witheach other. The number of working nozzles and the inject rateof bubbles are controlled according to the draft of the hull 4.
When swells come, the valves 161,162,163, 164 and 165 arecontrolled, and the pressures acting on the air nozzles 21, 22.
23, 24 and 25 are finely adjusted quickly by increasing anddecreasing.
0418. The comparator 140 also compares the inclination
value of the hull 4 detected by the inclination sensor 112 andthe setting value preliminarily set by the condition setting unit
130 with each other. The lateral inject spots of working air
noZZles are changed responsive to the inclination of the hull 4.
and inject rate of bubbles is increased or decreased, thereby
allowing the frictional resistance to be effectively reduced.
0419. Here, operation control on injecting of bubbles andthe propeller using the signal from the convolvement detector
180 will be described. When bubbles are convolved into thepropeller 80, the apparent density of seawater on which thepropeller 80 is acting is reduced. This causes the propulsion to
be decreased, and varies the thrust power and the torque of thepropeller drive shaft 82. The thrust torque gage 83 attached tothe drive shaft 82 detects this variation. In this case, detection

may be made on the one. However, in this embodiment, bothof them are detected and output in order to improve accuracy.
In a region for a prescribed amount of convolvement, thepropeller 80 vibrates. The vibration sensor 84 detects thevibration, applies processing, and output a signal thereof.
This embodiment uses both the thrust torque gage 83 and thevibration sensor 84. However, any one of them may be suffi
cient.

0420. In this embodiment, the thrust torque gage 83 is usedmainly, and the vibration sensor 84 is used auxiliary forcomplement. The signal from the convolvement detector 180
is transmitted to the comparator 140.
0421. The detection values from the thrust torque gage 83
and the vibration sensor 84 are also used as detection signals
when cavitations occur at the propeller 80. The comparator
140 compares the thresholds as the setting values of the thrust
power and the torque set by the condition setting unit 130 andthe values of the thrust power and the torque detected by the
convolvement detector 180 with each other. The threshold as

the setting value of vibration set by the condition setting unit
130 and the detection value detected by the vibration sensor
84 are compared with each other. If any one of these threedetection values falls below or exceeds the threshold, thenumber of working nozzles, the spots, and the inject rate of
bubbles are controlled.

0422 The bubble injecting control is performed by con
trolling the air nozzles 21, 22, 23, 24 and 25, the blowers 10,
11, 12, 13 and 14, and the valves 161,162,163, 164 and 165.

The basic concept is to change the inject condition of bubbles
when occurrence of convolvement of bubbles into the propel
ler 80 is detected. For example, the valves 161,162, 163, 164
and 165 are controlled and the amount of bubbles is finely
adjusted; the blowers 10, 11, 12, 13 and 14 are controlled andthe amount of bubbles are decreased, thereby eliminating theconvolvement of bubbles into the propeller 80; the working
nozzles among the air nozzles 21, 22, 23, 24 and 25 arechanged, and for example the injecting of bubbles from the air
nozzle 23 disposed at the center is stopped by changing
nozzles; or the air nozzles 22, 23 and 24 are stopped. The
control of the number of nozzles, spots, and inject rate ofthese air nozzles 21, 22, 23, 24 and 25, blowers 10, 11, 12, 13
and 14, and valves 161,162, 163, 164 and 165 can be used inany combination. However, the optimal combination is preliminarily acquired on the basis of a simulation, a modelexperiment, and a substantiative experiment. The optimal
control condition is set by the condition setting unit 130.
0423. In these optimal controls, the signals from theoceanographic condition determination unit 120 and the ves
sel conditions determination unit 100 are also used. For

example, when the currents detected by the current sensor
123 is moving from a right diagonal to a left diagonal withrespect to the traveling direction of the vessel 1, the bubbles
are also drifted a little by the currents. Even under conditions
where the convolvement of bubbles into the propeller 80 is
typically detected and the air nozzles 22, 23 and 24 are
stopped, in this case, this condition is changed to a condition
for stopping the air nozzles 21 and 22. When, for example, theengine operation detector 103 detects change in output of theengine driving the propeller 80, the thrust power and thetorque of the propeller drive shaft 82 are changed as a matterof course. Further, the threshold set by the condition setting
unit is corrected in consideration of the change in output. This
enables the thrust power and the torque against the convolve
ment of bubbles to be appropriately evaluated.
0424. In any event, when the convolvement detector 180
detects the convolvement of bubbles into propeller 80, the air
nozzles 21, 22, 23, 24 and 25, the blowers 10, 11, 12, 13 and14, and the valves 161,162, 163, 164 and 165 are controlled,

and the operation conditions, such as the number of working
nozzles, the spots and the inject rate of bubbles, are changed.
This prevents the bubbles convolved into propeller 80, andprevents the reduction in propeller efficiency from continu
ing. Further, this can prevent vibration and noise at the propeller 80 along with the convolvement of bubbles from occurUS 2011/0259440 A1

ring, reduce damage to the propeller 80, and prevent a
harmful effect on vessel 1. Thus, the bubble injecting control
improves the thrust power, the torque and the detection valueof the vibration. When every detection value exceeds or falls
below the threshold, the injecting of bubbles are returned tothe original control conditions.
0425 Next, the control of changing the operating condi
tions of the propeller 80 when convolvement of bubbles is
detected will be described. When the detection value detectedby the thrust torque gage 83 falls below the threshold, and theconvolvement of bubbles into the propeller is detected, in acase of performing output-oriented control, the output of theengine is increased, the rotation of the propeller drive shaft 82
is increased, and the thrust power and the torque are returnedto the original. In this case, the propeller efficiency falls andthe engine efficiency usually falls too. However, the output ofthe propeller 80 is maintained. Accordingly the hull velocity
and the like do not fall. Under characteristics and conditions

where the engine efficiency is not decreased even if the rotation is increased, the operation can be continued without
decreasing the engine efficiency. In a case of performing
efficiency-oriented operation with respect to propeller 80, theoutput of the engine is decreased, the rotation of the propeller
drive shaft 82 is decreased, and the thrust power and thetorque are further decreased. This attains results that alleviate
the convolvement of bubbles into the propeller 80, recover theoverall propeller efficiency, do not cause much decrease inthrust power and the torque, and can prevent vibration andnoise along with convolvement of bubbles.
0426. Thus, when the propulsion of the propeller 80
decreases along with convolvement of bubbles, change inoperating conditions of the propeller 80 can increase thenumber of revolutions, and decrease the number of revolu

tions for addressing vibration and noise. The change in oper
ating condition of the propeller 80 allows the influences
owing to convolvement of bubbles to be reduced. When cavi
tations occur at the propeller 80, use of the detection values
from the thrust torque gage 83 and the vibration sensor 84 cansuppress occurrence of vibration and noise at the propeller 80,
and also prevent damage to the propeller 80.
0427. Here, effects of the V-shaped mound 190 and thewrapping portion 191 will be described.
0428 The bubbles injected from the air nozzles 21, 22, 23.
24 and 25 to the bottom 3 of the vessel flow along the bottom
3 of the vessel, and are guided by the end plates 5.5", 6, 6', 7
and 7". However, a part of the bubbles rises along the sides 8of the vessel to the surface of the sea. As the bubbles approach
the propeller 80 side on the bottom3 of the vessel, the bottom
3 of the vessel is gradually narrower, and the sides 8 of thevessel are gradually inclined. A part of bubbles having flowed
along the inclined surface from the upstream direction winds

Oct. 27, 2011

portion 191 having a similar protuberance. This further prevents the bubbles from flowing along the sides 3 of the vessel
toward the propeller 80.
0429 FIG. 29 shows the situations of the flow around thepropeller 80. FIG. 29 illustrates how flow velocities aroundthe propeller 80 distribute with respect to the navigational
speed of the vessel 1. Lines where the velocities become
slower by 10%, 20% and 30% with respect to the navigational
speed are represented as iso-velocity lines. As apparent in
FIG. 29, the flow velocities around the propeller 80 distributein a Substantially V-shaped manner. The Velocities are high at
lower part of the propeller 80, and low at the upper part. In
view of propulsion of the vessel 1, the lower the flow veloci
ties exert on the propeller 80, the higher the efficiency is. In
comparison with the upper and lowerparts of the propeller 80,
the upper part effectively acts in view of propulsion. On theother hand, in view of the effect of bubbles, as a phenomenon,
bubbles escape in a direction where the water pressure is low.
If the Velocity is high, the dynamic pressure component
becomes high and the static pressure component becomes
low, according to the Bernoulli theorem. That is, in compari
son at the same level of depth of water, the bubbles tend toaccumulate at an area with a high flow velocity, and tend to
escape from an area with a low pressure.
0430. The effects of the V-shaped mound 190 includes
effects that separate the bubbles from the bottom 3 of thevessel by the V-shaped mound 190, lower the streamline
downward further from the bottom 3 of the vessel, and slows

the flow velocities at the lower part of the propeller 80.
Accordingly, presence of the V-shaped mound 190 exerts aneffect that separates the bubbles from the bottom 3 of thevessel, and causes the bubbles quickly wind around the sides
8 of the vessel. Since the flow velocities of the lower part ofthe propeller 80 are slowed, an effect that suppresses con
volvement of bubbles into the propeller 80, and an effect that
improves the propulsion of the propeller 80 are exerted. Further, since the V-shaped mound is formed so as to laterally
spread centered at the planar center line CL of the hull 4, thebubbles can escape symmetrically and effectively apart fromthe propeller 80 arranged symmetrically on the planar centerline CL. Since the mound has the substantially V-shape,
increase infrictional resistance of the flow along the bottom 3of the vessel against the hull 4 is further suppressed. The
symmetric shape facilitates manufacture thereof. As to effectsof the mound, since the mound can be formed as the protu
berance made of a strength member at the bottom 3 of thevessel, the operation can proceed without any obstacles whenthe vessel 1 is carried in a dock and mounted on bases. The

V-shaped mound 190 may be made of a strength member.
This improves the strength in fore and aft directions at thebottom 3 of the vessel, and realizes a strong hull structure
against bending Owing to redundant wave forces (sagging andhogging) exerted on the vessel 1.

around the slanted sides 3 of the vessel and rises to the water

surface. However, a considerable amount still flows along thebottom 3 of the vessel. When the bubbles reach the V-shaped
mound 190, the V-shaped mound 190 causes the bubbles tomove apart from the bottom 3 of the vessel, as shown in FIG.
28. This is because of effects that the shape of the V-shaped
mound 190 is a structure slightly low at the fore portion andprotuberant at the aft portion and Smoothly continuous,
thereby causing the bubble to leave the bottom3 of the vessel.
The bubbles wind to the sides 3 of the vessel at the V-shaped
mound 190 are guided to the water surface by the wrapping

Seventh Embodiment

0431 FIG. 30 shows a seventh embodiment of the present
invention. The seventh embodiment will be described only on
difference from the sixth embodiment. Other elements havethe same configurations as those of the sixth embodiment.
0432. In FIG. 30, the air nozzles 21, 22, 23, 24 and 25
injecting bubbles are arranged on the bottom3 of the vessel 1.
On the other hand, a bubble intake 85 drawing bubble-mixed
seawater is arranged in fore of the propeller 80 provided at theUS 2011/0259440 A1

Oct. 27, 201136

stern 9 of the hull 4. FIG. 31 shows the detail of this part
together with the gas-liquid separator.
0433. In FIG. 31, a gas-liquid separation chamber 86 as
gas-liquid separation mechanism is formed inside of a bubble
intake Barranged at the bottom 3 of the vessel. The bubble

exerting the function. The water separated by the gas-liquid
separator 86 can be used for another application for the vessel
1. Such as the cooling water, Supply water for the anti-rollingtank.

mixed seawater drawn from the bubble intake B enters thegas-liquid separation chamber 86 via the cylinder 87. The
gas-liquid separation chamber 86 is formed so as to secure asufficient volume. The bubble-mixed seawater flowed there

into is sufficiently slowed down and the bubbles rise andaccumulated as air. An air intake pipe 91 is connected to thegas-liquid separation chamber 86. The air intake pipe 91 is fordischarging the air accumulated in the upper part by theblower 208 from the air connection pipe 203 via the air valve
206a, to the outside such as the atmosphere, where the propeller 80 does not cause reconvolvement. An air discharge
pipe 92 discharging air is connected to the upper part. The air
valve 206b is provided also at the air discharge pipe 92. The
bubble separation filter 202 having a lot of apertures is pro
vided at lower part of the gas-liquid separation chamber 86.
Here, a resistant effect by the multiple apertures further sepa
rates the bubbles having not risen well. The seawater fromwhich bubbles have been drawn is drawn by the pump 207
from the water intake pipe 94 via the water valve 206C, andtransferred via the water pipe 97 for use for cooling water andanti-rolling tank of the vessel 1. A water level sensor 98 fordetecting the water level is provided at the gas-liquid separation chamber 86. The number of revolutions of the blower 208

is controlled so as to provide certain air accumulation in theupper part. The blower 208 is a positive-displacement typeeven capable of blowing seawater-mixed bubbles, and madeof an anti-corrosion material. The air connection pipe 203
faces downward from the top surface of the gas-liquid sepa
ration chamber 86, to which the air discharge pipe 92 isconnected, and has a structure where the air is left in the upper
part even if the balance of the pump 207 and blower 208 is
lost, and absorbs the pulsing of pressure while the pump 207
operates. The bubble separation filter 202 is formed as aconical shape, and disposed in a slanted manner in a sectionalview. This exerts a high bubble separating effect, and canprevent foreign matters from being mixed from the ocean into
the pump 207 or the pipe 97. These bubble intake B, gasliquid separation chamber 86, blower 208, pump 207 and thelike configure the bubble drawing system.
0434. With such a configuration, the bubble intake B
arranged in fore of the propeller 80 draws the bubbles to be
convolved into propeller 80 in advance, and reliably prevents
the bubbles from reaching the propeller 80, thereby prevent
ing the propeller efficiency from decreasing. The bubble
intake B is arranged in the proximity of the propeller 80.
Accordingly, the frictional reduction effect by bubbles
injected to the bottom 3 of the vessel is sufficiently exerted,and subsequently the bubbles are drawn and discharged to theoutside, where reconvolvement does not occur, thereby suf
ficiently exerting the frictional reduction effect. Even in caseof trouble in any one of the blower 208 of the bubble drawing
system and the pump 207, convolvement of bubbles can beprevented to a certain extent by closing the valve of the system
concerned and opening the air valve 206b of the air discharge
pipe 92.
0435 The bubble-mixed seawater drawn from the bubble
intake B is separated to sucked-in bubbles and water by thegas-liquid separator 86. This eliminates mixture of water into
the blower 208 and the pump 207, and is capable of stably

Eighth Embodiment0436 FIGS. 32 and 33 show an example of an eighth
embodiment of the present invention. The eighth embodimentis an example of combination between the previous V-shaped
mound and the bubble drawing system.
0437. However, in the eighth embodiment, a bubble intake
99 has a substantially V-shaped appearance in conformity
with the V-shaped mound 190, and is disposed in fore of the
V-shaped mound 190, as shown in FIG. 32.
0438 FIG. 33 shows the detailed operation thereof. The
V-shaped mound 190 for preventing the convolvement of
bubbles is arranged in the aft of the bubble intake 99. Accord
ingly, even if the bubbles having not been drawn yet flow outof the bubble intake 99 owing to various disturbances, theV-shaped mound 190 can cause the bubbles to escape, andreliably prevent convolvement into the propeller 80. Accord
ing to a case where the amount of bubbles is Small, situationsof the vessel 1, and the navigational condition, the blower 208
and the pump 207 are stopped, thereby enabling only the
V-shaped mound 190 to operate. This allows the reduction
effect of the net frictional force to be improved in a finermanner. The V-shaped mound 190 is arranged in the proxim
ity of an aft region of the bubble intake 99. In addition to theabove effect of the V-shaped mound 190, this exerts an effectthat causes the bubbles to escape because the flow velocity islowered at the V-shaped mound 190, and an effect that facili
tates that the bubbles having escaped is drawn from the
bubble intake 99.
Ninth Embodiment0439 FIG. 34 shows a ninth embodiment of the present
invention. FIG.34 (a) shows a perspective view thereof. FIG.
34 (b) shows an elevation view from the stern. Bubble pro
tection plates 3200 and 3201 are arranged symmetrically at apropeller attachment section 9 at the stern so as to develop
from an elongated section 3' of the bottom of the vessel in a
substantially V-shaped manner when viewed from the stern.
The bubble protection plates 3200 and 3201 are provided so
as to be fixed to an elongated section 8' of the sides of thevessel, and formed so as to develop also toward the propeller
80 aft. A lot of round apertures 3202 are perforated at the
bubble protection plate. The bubbles injected from the air
nozzles 21, 22, 23, 24 and 25, flowing from the upstream andnearly drawn by the propeller 80 are baffled by the resistanceof the bubble protection plates 3200 and 3201, and flow awayalong the shape of the bubble protection plates 3200 and 3201
while spreading around the propeller 80. On the other hand,the seawater flows into the inside of the bubble protection
plates 3200 and 3201 by rotation of the propeller 80 from theround apertures 3202 perforated at the bubble protection
plates 3200, and 3201 and reaches the propeller 80. In thiscase, in comparison with a case without the bubble protection
plates 3200 and 3201, the distribution of velocities of flow at
the lower part of the propeller is slightly slow, owing topresence of the bubble protection plates 3200 and 3201. This
improves the propulsive efficiency of the propeller 80, andallows efficient operation from an overall aspect.

US 2011/0259440 A1

Oct. 27, 201137

0440 Thus, the bubble protection plates 3200 and 32.01
cause the bubbles to escape away from the propeller 80, slow
the flow velocity of seawater flowing along the hull 4 to flow
therein, and slow the distribution of velocities of flow aroundthe propeller 80. This therefore exerts effects that slow the
distribution of velocities of flow at the lower part of thepropeller and improves the propeller efficiency. Only for the
purpose that bubble protection plates 3200 and 3201 cause thebubbles to escape and prevent the efficiency of propeller 80
from being decreased, the apertures 3202 are unnecessary.
The bubble protection plates may be elongated more upward
or more aft, or shortened downward or more fore. In any
event, presence of the bubble protection plates 3200 and 3201
allows the amount of convolvement of bubbles into the propeller 80 to be reduced, and can prevent the propulsive effi
ciency of the propeller from being decreased, even with varying degrees. The multiple round apertures 3202 are perforated
at the bubble protection plates 3200 and 3201. If a shape withedges such as square apertures is adopted, in a case where thebubble protection plates 3200 and 3201 are configured withstainless steel, the residual stress at the edges owing to press
ing facilitates stress corrosion. As measures therefor, theround apertures, whose residual stress is Small when beingpressed, are perforated. Further, as to the effect of the bubble
protection plates 3200 and 3201, since these plates arearranged at a region in fore of the propeller 80 where the flow
Velocity is high, it is prevented that the oceanic floating mat
ters and algae are tangled into the propeller 80.
0441 The advantageous effects of the sixth to ninth
embodiments as described above will hereinafter be
described.

0442 First, the configuration includes the vessel 1, the air
nozzles 21, 22, 23, 24 and 25 injecting bubbles at least to thebottom 3 of the vessel 1, the blowers 10, 11, 12, 13 and 14

blowing air to the air nozzles 21, 22, 23, 24 and 25, thepropeller 80 arranged at the stern 9 of the hull 4 of the vessel
1, and the substantially V-shaped mound 190, which prevents
the convolvement of bubbles into propeller 80, at the aft of the
air nozzles 21, 22, 23, 24 and 25 toward the stern at least on
the bottom 3 of the vessel.

0443 With this configuration, the rise of the bubbles are
impeded by the bottom 3 of the vessel itself, the bubble
retaining effect can be maintained, and a small amount of
bubbles can effectively reduce the frictional resistance. The
influences of waves are alleviated at the air nozzles 21, 22, 23,

24 and 25 arranged on the bottom3 of the vessel, in compari
son with a case of arrangement on the sides of the vessel. This
allows the stable frictional resistance reduction effect of thehull 4. In particular, the substantially V-shaped mound 190
exerts effects that separate the bubbles flowing along thebottom3 of the vessel from the bottom3 of the vessel, preventthe bubbles from flowing into the propeller 80, slow the flow
velocity at the lower part of the propeller 80 by the V-shaped
mound 190, suppress the reconvolvement of bubbles, andimprove the propulsion of the propeller. In particular, theshape of the substantially V-shaped mound 190 is a structureslightly low at the fore portion and protuberant at the aft
portion and Smoothly continuous. This makes these effects
remarkable.

0444 The substantially V-shaped mound 190 can beformed so as to have a strength member as the protuberance atthe bottom 3 of the vessel. Accordingly, there is no obstacle
when the vessel 1 is carried on the bases under docking
situations, thereby facilitating the operation.

0445. The mound has the substantially V-shape. Accord
ingly, the configuration with the strength member improves
the strength of the bottom 3 of the vessel in the fore and aftdirections, and realizes a hull structure strong against bending
owing to redundant wave forces exerted on the vessel 1.
0446. The bubble protection plates 3200 and 3201 arearranged in the proximity and in fore of the propeller 80,
where the flow velocity is high. This can prevent the oceanic
floating matters and algae from being tangled into the propel
ler 80.

0447. The bubble protection plates 3200 and 3201 aremade of stainless perforated plate having the round apertures
anticorrosive to seawater. This can reduce the occurrence ofstress corrosion owing to residual stress at the edges, andincrease corrosion resistance.

0448. The bubble intake B at least drawing bubbles isarranged at the aft of the air nozzles 21, 22, 23, 24 and 25 andin fore of the propeller 80, draws the bubbles to be convolved
into propeller 80 in advance, causes the bubbles not to reachthe propeller 80, and discharges the drawn bubbles to atmo
sphere or the outside, where reconvolvement does not occur.
This can reliably prevent the convolvement. Further, thebubble intake B is arranged in the proximity of the propeller
80. Accordingly, the frictional reduction effect by the bubbles
injected to the bottom 3 of the vessel is sufficiently exerted.
Subsequently, the bubbles are drawn, and the frictional resis
tance is reliably reduced. In case of trouble in the blower 208
or the pump 207, convolvement of bubbles can be prevented
to a certain extent by opening the air valve 206b of the air
discharge pipe 92.
0449 The bubble separation filter 202, which is arranged
at the lower part of the gas-liquid separation chamber 86 andhas a lot of apertures allows the bubble separating effect to be
improved, and can prevent mixture of foreign matters fromthe ocean into the pump 207 or the pipe 97.
0450. The substantially V-shaped mound 190 is arrangedin the proximity of the aft region of the bubble intake 99.
Accordingly, the flow velocity is decreased at the Substan
tially V-shaped mound 190. This exert an effect of causing the
bubbles to escape, and facilitates that the bubbles having
escaped are drawn from the bubbles intake 99.
0451. The thrust torque gage 83 detecting the convolve
ment of bubbles into propeller 80 and the vibration sensor 84
are provided. When the gage or the sensor detects the con
volvement of bubbles, the inject conditions of the air nozzles
21, 22, 23, 24 and 25 and/or the operating conditions of theblowers 10, 11, 12, 13 and 14 are changed. This can prevent
further convolvement of bubbles, and prevent the efficiencyof the propeller 80 from being decreased. Further, this canprevent occurrence of vibration and noise at the propeller 80
along with the convolvement of bubbles, prevent the propeller
80 from being damaged, and prevent the harmful effect on thevessel 1.

0452. When the thrust torque gage 83 detecting the con
volvement of bubbles into propeller 80, or vibration sensor 84
detects convolvement of bubbles, the operating conditions of
the propeller 80 are changed. Accordingly, if the propulsionof the propeller 80 is decreased along with the convolvementof the bubbles, the frictional force reduction effect isimproved by increasing the number of revolutions and reduc
ing the number of revolutions as measures against vibrationand noise, while the harmful effect on navigation of the vessel
1 is also prevented. Further, when the cavitations occur, thedetection values from the thrust torque gage 83 and the vibra

US 2011/0259440 A1

tion sensor 84 are utilized, and occurrence of vibration andnoise at the propeller 80 is suppressed, and damage to thepropeller 80 is also prevented.
Tenth Embodiment0453 FIG.35 is a diagram sectionally showinga inject gas
control device according to one embodiment of the present
invention and an overview of a vessel equipped with thisdevice. As shown in this figure, a inject gas control device
4002 is mounted on a vessel 4001 according to the present
application. The inject gas control device 4002 includes amain engine 4010, which is a propulsive main engine of thevessel 4001. In addition thereto, as equipment, the vessel
4001 is equipped with mechanisms necessary for sailing of
the vessel, including: a screw 4003 driven by the main engine
4010 to acquire the propulsion of the vessel; a rudder 4004
changing and adjusting the traveling direction by changing
the water flow using a plate of the vessel 4001 in the water; adeck 4005 as a floorboard; a deck 4006 as an upper floor; anda chimney 4007 discharging exhaust gas 4008 from theengine 4010 to air.
0454) A air supply pipe 4030 is sequentially communi
cated with three bypass pipes, which are attached to the main
engine 4010 and will be described later. The air supply pipe
4030, which includes bent portions, is a pipe for transferringa gas with a certain pressure and temperature to the gas outlet
4040. The piping is installed from a position of collecting thethree bypass pipes so as to be a shape where the piping
plunges once to a height around the bottom of the vessel,
passes the bent portions, is bent at a height higher than thewaterline and laid Substantially horizontally, and passes thebent portions and plunges in the direction toward the bottomof the vessel. The piping path thus passes once at a height of
the waterline or higher. This can prevent seawater from flow
ing reversely into the gas outlets arranged on or below thewaterline, and avoid dangerous situations of the main engine
in view of security. The gas outlet 4040, which is arranged ator in the proximity of the bottom of the vessel and injects
bubbles from an opening perforated at or in the proximity ofthe bottom of the vessel into the water near the bottom9 of thevessel, is connected to the other end of the air Supply pipe
4030. A heater 4050 for heating gas passing through the air
supply pipe 4030 is arranged before the gas outlet 4040 of the
air supply pipe 4030. A flowmeter 4035 is attached to a part of
the air supply pipe 4030 on or below the waterline. The gas
Supply or charged air or the scavenged gas is heated by theheater 4050 using the exhaust gas, thereby reducing the water
Viscosity resistance. This further improves the resistance
reduction effect of the vessel, thereby allowing reduction inresistance to be further improved. As a driving source of theheater 4050, the exhaust gas from the turbocharger 4011 may
be utilized. Instead, an energy generator Such as an electric
generator that is arranged separately may be used.
0455 The main engine 4010 includes a turbocharger 4011
having a mechanism for forcedly blowing compressed air into
the engine (combustion chambers), an intercooler 4012 cooling air compressed by the turbocharger 4011 while maintaining the pressure, an air Supply pipe 4013 transferring thecompressed air, a scavenged gas receiver 4014 for accumu
lating the compressed air, and the exhaust gas receiver 4015
for accumulating the generated gas combusted by the engine
4010. A gas Supply or charged air bypass pipe 23, whichbypasses a part of gas Supply or charged air and guides the air
to the air supply pipe 4030, is communicated with the airOct. 27, 2011

Supply pipe 4013. A scavenging bypass pipe 4024, whichbypasses a part of the scavenged gas and guides the gas to the
air Supply pipe 4030, is communicated with the Scavenged
gas receiver 4014. An exhaust gas bypass pipe 4025, whichbypasses a part of the exhaust gas and guides the gas to the air
Supply pipe 4030, is communicated with the exhaust gas
receiver 4015. The other ends of the gas supply or charged air
bypass pipe 4023, the Scavenging bypass pipe 4024, and theexhaust gas bypass pipe 4025 are sequentially connected tothe air supply pipe 4030.
0456 FIG. 36 pertains to an embodiment where a injectgas control device 4002 is applied to a vessel used in theocean. FIG. 36 (a) shows a side sectional view of the vessel.
FIG. 36 (b) shows a top view thereof. A part of a principal
configuration is represented in an exposed manner. A residualgas (or a part thereof) of the turbocharger from the gas Supply
or charged air bypass pipe 4023 and/or the Scavenging bypass
pipe 4024 and/or the exhaust gas bypass pipe 4025 passes the
air Supply pipe 4030 having the bent portions, and is guided to
the gas outlet 4040 arranged in the proximity of the bottom 9of the vessel. For example, in this embodiment, the gas outlet
4040 is arranged at the fore of the bottom 9 of the vessel andin the proximity of the planar center line of the hull CL. The
arrangement of the gas outlet 4040 in the proximity of thebottom 9 of the vessel is for the sake of prolonging theretention of the injected bubbles at the bottom 9 of the vessel
and alleviating variation in pressure owing to waves. The
arrangement at the fore in the proximity of the bottom 9 of thevessel is for an object for retaining the injected gas over theentire bottom 9 of the vessel as much as possible. Accord
ingly, the gas outlet 4040 may be at a spot other than thebottom 9 of the vessel. The spot may be an appropriate one onor below the waterline.

0457. As shown in this figure, the air supply pipe 4030 (or5030) is installed upwardly immediately after passing themain engine 4010. This exerts advantageous effects specificto the present application according to which a drafting forceof the pressurized gas or the exhaust gas that still retains heatcomplements the frictional resistance of the air Supply pipe
4030 (5030), and can secure the gas supply or charged air rate.
0458 Alternative gas outlets 4040 may adopt a planerarrangement (not shown) so as to be plurally and symmetri
cally arranged with respect to the planarcenterline CL. In thiscase, the air supply pipes 4030 whose number corresponds tothat of the gas outlets 4040 may be arranged. Instead,branched pipes from the air supply pipe 4030 may bearranged correspondingly with respect to the arrangement
number. This allows the configuration to be simplified andcan facilitate the arrangement. Preferably, the number of thedischarge ports is an odd number, and a symmetric arrange
ment is adopted where the center one is disposed on the planarcenter line CL.

0459. It is preferable that end plates 4095,4096 and 4097
guiding bubbles in order not to let the bubbles injected fromthe gas outlet 4040 escape be arranged at the bottom 9 of thevessel. In a case of arranging a plurality of the gas outlets
4040, the end plates are also arranged symmetrically withrespect to planar centerline of the hull CL. In addition thereto,
shear force sensor (not shown), which is a shear force detector
detecting shear forces exerted on the hull owing to seawaterand bubbles, may be arranged on the bottom 9 of the vessel,
for example, at the stern.
0460 Relative velocity sensors 55, which are relative
velocity detectors, are arranged at the stern. Other relativeUS 2011/0259440 A1

Oct. 27, 201139

velocity sensors 57 are arranged at the sides of the vessel. The
relative velocity sensors 55 are arranged apart from the gas
outlet 4040. The relative velocity sensors 57 are arranged atspots without influences of bubbles on the sides of the vessel
even in the proximity thereof. In particular, the relative veloc
ity sensors 57 are disposed at lower parts on the sides 8 of thevessel, on which influences of waves are not exerted. An

ultrasonic system is adopted for these relative Velocity sen
sors 55 and 57. This allows use in the ocean, and reduces

influences owing to waves and currents.
0461 The video cameras 58 and 59 for monitoring condi
tions of injected bubbles are arranged at fore and aft parts ofthe bottom 9 of the vessel. Images taken by these video
cameras 58 and 59 are monitored by a person and utilized foranalyzing the inject condition of bubbles.
0462. The air nozzles will be described using the figure of
the first embodiment. FIG. 3 is a perspective view conceptu
ally showing the detailed structures of the air nozzles 4040.
For the sake of simplicity of description, FIG. 3 shows atypical example of the air Supply pipes and the air nozzles.
The air bypassed via the air supply pipe 16 connected to the
air supply pipe 4030 are bent at a chamber 70 of the gas outlet
4040 connected to the air supply pipe 16. A distribution
component 71 having triangular profile for dispersing theblown air is arranged immediately below the connection partof the air Supply pipe 16. A configuration is adopted accord
ing to which the air is bent at right angle at this part anddispersed laterally by the distribution component 71. As the
air is bent at right angle, the air tends to uniformly spreadalong directions in a horizontal plane. However, the air tends
to flow only toward perforated plates 72 and 73 in front
thereof by presence of interior walls of the chamber 70 in therecess and at the right, left, top and bottom. Here, presence ofthe distribution component 71 further uniformizes the lateral
distribution of the air with respect to the perforated plates 72
and 73.

0463. A lot of perforations 74 and 75 are formed at theperforated plates 72 and 73. The positions of the perforated
plates 72 and 73 are laterally displaced from each other,
thereby forming an arrangement with perforations in a displaced manner. This embodiment shows an example using
two perforated plates 72 and 73. Instead, the number thereof
may be another number, such as three or four. Since perfo
rated plates 72 and 73 are arranged so as to displace thepositions of the perforations, the perforated plates 72 and 73
function as a so-called baffle plates, which bend the airflow toprovide resistance. Accordingly, in addition to further uni
formization of the air in the lateral direction, the air in thevertical direction is also uniformized, thereby enabling the air
to be injected from a inject port 76 on a front surface.
0464. Here, the perforated plates 72 and 73 are manufac
tured by continuously making round perforations on a corrosion resistant sheet metal Such as stainless by a press, and thearrangement with displaced perforation positions can be real
ized by cutting. This offers excellent productivity. If config
ured with a stainless material, since the perforations are roundperforations, edge portions are omitted, nearly preventing thestress from being concentrated when being pressed, in con
trast to a case with square perforations. This alleviates
progress of stress corrosion from the edge parts, even if usedin seawater. The perforated plates 72 and 73 may be manu
factured by using resin and by means of molding. In a case ofusing the resin, the shapes of the perforations are arbitrary inview of corrosion. However, in view of molding, round per
forations are preferable.
0465 FIG. 37 is a system diagram showing a system
bypassing a turbocharger 4011 according to the present appli
cation. The mechanism of the Surplus air bypass from theturbocharger according to the present application will be
described using FIG. 37.
0466. The turbocharger 4011 includes a compressor 4110
that draws atmosphere through a filter 4111 and compresses
the air, a turbine 4112 that rotationally drives the compressor
4110, and a shaft connecting these. According to the mecha
nism of the turbocharger 4011, energy of the exhaust gas(temperature and pressure) having been discharged from theexhaust gas pipe is utilized. The turbine 4112 is driven androtates at high speeds. The compressor 4110 is driven by thisrotational force. The compressed air is transferred into thecylinders 4016 of the main engine (hereinafter, also referred
to as the "cylinder for the sake of the simplicity). Accord
ingly, an amount of mixture over an amount of original aspi
ration of an internal combustion engine is aspirated and com
busted, thereby acquiring an output over an apparent piston
displacement.
0467 High temperature and pressure exhaust gas gener
ated by combustion of fuel in each cylinder 4016 is accumu
lated in the exhaust gas receiver 4015 during the exhaust gas
valve is opened. The pressure is caused to be static pressure.
Adiabatic expansion is accomplished at the turbine nozzle
4116 and the turbine 4112. This generates turbine driving
force, and rotates the turbocharger compressor 4110 directly
connected thereto. The turbocharger compressor 4110 draws
air from the outside, and applies adiabatic compression. The
air is caused to be static pressure at a diffuser 4113 at an outletof the compressor 4110. This generates high pressure andtemperature air (gas Supply or charged air). The air is cooledby an air cooler 4112, accumulated in the scavenged gas
receiver 4014, and supplied to the cylinder 4016. In cases
where the load on the engine 4010 is low and the energy of theexhaust gas is insufficient, Such as a case immediate after
startup, an auxiliary blower 4115 is actuated, draws air andsupport the operation of the turbocharger compressor 4110.
In this configuration, according to the present application, thegas Supply or charged air bypass pipe 4023, the scavenging
bypass pipe 4024, the exhaust gas bypass pipe 4025 are pro
vided and bypass the residual gas.
0468. In more detailed operation, first, atmosphere isdrawn through the filter 4111. Compressed air is generated by
the compressor 4110 driven by the rotational force of theturbine 4112, and communicated to the air supply pipe 4013
via the diffuser 4113. The gas supply or charged air bypass
pipe 4023 is communicated with the air supply pipe 4013, as
described above. A part of the compressed high temperature
air passes through the gas Supply or charged air bypass pipe4023 and thus is bypassed. The draw of gas by this bypass isperformed by opening and closing the gas Supply or charged
air bypass adjustment valve 4023A, whose starting, operating
and stopping are controlled on the basis of sensing of after
mentioned physical quantities. The gas Supply or charged air
acquired through the bypass by the gas Supply or charged air
bypass pipe 4023 is guided to the air supply pipe 4030.
0469. The other air passing the air supply pipe 4013 isintercooled by the intercooler 4012. The intercooled com
pressed air is dehydrated by the mist catcher 4114 disposed in
the communication pipe, passes through a movable gate, andUS 2011/0259440 A1

Oct. 27, 201140

communicated to the scavenged gas receiver 4014. The gas
may be supplied to the scavenged gas receiver 4014 also fromthe auxiliary blower 4115 including an adjustment valve
4115A. The scavenging gas bypass pipe 4024 is communi
cated with the scavenged gas receiver 4014, as describedabove. A part of the compressed air accumulated in the scav
enged gas receiver 4014 passes through the scavenging
bypass pipe 4024 and thus is bypassed. The draw of gas bythis scavenging bypass is performed by opening and closing
the Scavenging bypass adjustment valve 4024A, whose starting, operating and stopping are controlled on the basis ofsensing of after-mentioned physical quantities. The gas Sup
ply or charged air acquired through the bypass by the scav
enging bypass pipe 4024 is guided to the air Supply pipe 4030.
0470 The other air accumulated in the scavenged gas
receiver 4014 passes through the communication pipe and isguided to the cylinder 4016. In the cylinder 4016, fuel isadded by spraying and the like and combusted. The exhaustgas generated by the combustion is guided to exhaust gas
receiver 4015. The exhaust gas bypass pipe 4025 is commu
nicated with the exhaust gas receiver 4015, as describedabove. A part of the exhaust gas accumulated in the exhaustgas receiver 4015 passes through the exhaust gas bypass pipe
4025 and thus is bypassed. The draw of gas by this exhaust gas
bypass is performed by opening and closing the exhaust gas
bypass adjustment valve 4025A, whose starting, operating
and stopping are controlled on the basis of sensing of after
mentioned physical quantities. The gas Supply or charged air
acquired through the bypass by the exhaust gas bypass pipe
4025 is guided to the air supply pipe 4030.
0471. The other exhaust gas in the exhaust gas receiver4015 is guided to the turbine 4112 via the turbine nozzle 4116
having a narrow diameter. A part of this gas rotationally drives
the turbine 4112, and is communicated to the chimney 4007
as the exhaust gas to be discharged.
0472. With respect to the starting point of the invention of
the present application, as described above, there are actual
situations of a tremendous advance in turbochargers andresultant generation of residual gas. FIG. 38 is a diagram
showing an example of a relationship between a main engine
loads and turbocharger efficiency. As shown in this figure, aconsiderable amount of Surplus is actually generated withrespect to a desired value of main engine efficiency. For
example, when the main engine load is 75.0%, 72.7% effi
ciency is actually acquired while the desired value of the main
engine efficiency is 68.0%. This difference causes the gen
eration of the residual gas. This embodiment gives attention
to that this generated gas has originally been discharged invain, and intends to efficiently utilize this gas.
0473 More specifically, the gas supply or charged air orthe exhaust gas is principally used as the bypass gas. Accord
ingly, the temperature of this gas is high. When the gas is
injected as bubbles, the water viscosity resistance is reduced.
This exerts an advantageous effect specific to the present
application, which is further reduction infrictional resistance.
0474 Typically, the entire amount of high pressure scav
enged gas or exhaust gas, which is a product by combustion
thereof, passes through the turbocharger exhaust gas turbine
4112, and is used for driving the turbocharger compressor
4110. However, as described in FIG. 38, in the turbocharger
having efficiency more than or equal to that required for theengine 4010, it is not necessary to Supply the entire amount.
As shown in FIG. 38, if the turbocharger efficiency is morethan 3% of that required by the engine, about 10% of the

Scavenged gas or the exhaust gas can be bypassed without
passing through the turbocharger turbine 4112. In a case ofdriving the power turbine (not shown), the exhaust gas bypass
4025 is effective. With respect to bubbles in this case, cooledhigh pressure air, which is the scavenging bypass 4024, iseffective.

0475. The scavenged gas and the exhaust gas are requiredfor driving the turbocharger 4011 and in turn driving theengine 4010. The bypass rate should strictly be controlledaccording to the heat load on the engine 4010. As a result of
numerous researches, the inventors of the present invention
have found that it is preferable to control the bypass rate on
the basis of the physical quantities related to the heat load on
the main engine and the characteristics of the turbocharger.
For example, the physical quantities may be a scavenging gas
pressure and an exhaust gas temperature (or an exhaust gas
pipe temperature, or an ambient temperature corresponding
to an exhaust gas temperature in a one-to-one relationship).
For example, the characteristics of the turbocharger may beturbocharger efficiency acquired by an after-mentioned
method, or matching characteristics between the main engine
and the turbocharger. As to these physical quantities, necessary values can be acquired by calculation or estimation using
measurement of a part of temperatures, pressures and flow
rates at paths and spots related to the turbocharger 4011 or themain engine.
0476. Here, control of a bypass rate of gas during use of theresidual gas by the turbocharger according to one embodi
ment of the present application, is described.
0477 FIG. 39 is a block diagram showing an arrangementof devices according to this embodiment, various sensors
acquiring basic data of control according to the present appli
cation, actuators and the like for the sake of realizing thecontrol of the present application. As shown in this figure, abarometric sensor S1 and an intake air temperature sensor S2
are arranged before entry of the filter 4111. A rotation speed
sensor S3 is arranged so as to be coupled to the compressor
4110 and the turbine 4112. A scavenging gas pressure sensor
S4 is arranged in the Scavenged gas receiver 4014. An exhaustgas pressure sensor S5 is arranged in the exhaust gas receiver
4015. An exhaust gas temperature S6 and an exhaust gas mass
flow rate sensor S7 are arranged between the exhaust gas
receiver 4015 and the turbine 4112. A post-turbine exhaustgas pressure sensor S8 is arranged after the turbine 4112. A
bypassed mass flow rate sensor S9 is arranged at the air
Supply pipe 4030 communicated from the gas Supply or
charged air bypass pipe 4023, the Scavenging bypass pipe
4024 and the exhaust gas bypass pipe 4025.
0478 FIG. 40 is a control block diagram for illustrating acontrol system of the present application.
0479. The functionality for realizing the control pertaining
to present application includes: a control device 4200 that
controls the above-mentioned various bypasses on the basisof values acquired by the various sensors (S1 to S9) from theturbocharger 4011 and the draft sensor 4230; a vessel condi
tions determination unit 4300 for acquiring and determining
the vessel conditions (positional conditions, fuel conditions,operating conditions, etc.); an oceanographic condition deter
mination unit 4400 for collecting and determining data pertaining to ambient oceanographic conditions; a condition set
ting unit 4220 for setting various conditions on the basis of orin comparison with determinations by the vessel conditions
determination unit 4300 and the oceanographic condition
determination unit 4400; and a gas outlet 4040 that discharges

US 2011/0259440 A1

Oct. 27, 2011

the bypassed gas, on which these functions have calculated
optimal values, into the water around the bottom 9 of therelatively easily vary along with sailing of the vessel or are

vessel.

navigational condition detection unit includes sensors detect
ing Swaying, pitching, Surging, heaving and yawing of the0480. The control device 4200 includes: a processor 42.01
that applies prescribed processing to the characteristics of theturbocharger and data acquired by the various sensors (S1 to
S9 and 230); a basic data unit 4202 having a function of
feeding basic data to the processor 4201; a turbocharger characteristics unit 4203 having a function of calculating andacquiring information pertaining to the characteristics of theturbocharger and providing the information for the basic data
unit 4202; a comparator 4204 having a function of comparing
and calculating the values from the various sensors (S1 to S9and 230) and the values processed by the processor 4201; anda controller 4205 having a function of controlling the com
parator 4204. In particular, the processor 4201 also has afunction of calculating after-mentioned turbocharger effi
ciency on the basis of detection results from a prescribedsensor and the like.

0481. The vessel conditions determination unit 4300 is
equipped with a GPS 4310 detecting a location of the vessel,a fuel measurement unit 4320 measuring a fuel consumptionof the engine of the vessel, and an engine operation detector
4330 detecting the operating conditions of the engine of thevessel. The vessel conditions determination unit 4300 par
ticularly determines present conditions of the vessel, anddetermines present conditions that vary in a small degree orvary slowly during sailing. For example, the GPS 4310 grasps

the location of the vessel on the map, and detects distances toports and destinations, an absolute velocity with respect to theground and the like.
0482. This is utilized for determining which position or
location on the map bubbles are injected or stopped. The
measurement of the absolute velocity with respect to theground is also used for the sake of complementing the rotation
speed sensor S3. The fuel measurement unit 4320 is used formeasuring how much fuel the engine consumes in a prescribed time period, and used for stopping injecting bubbles
when the fuel consumption efficiency becomes lower thanprescribed fuel consumption efficiency. The engine operation
detector 4330 detects the operating conditions of the engineof the vessel, and is used for acquiring information for stop
ping injecting of bubbles when the operation of the engine isstopped, and for starting operation and, prescribed time
period thereafter, starting injecting bubbles. The engine
operation detector 4330 is also used for detecting the numbersof revolutions of the engines and changing the number ofworking gas outlets and/or inject rate of bubbles. In addition
thereto, the vessel conditions determination unit 4300

includes an engine output detector, a gyro, radar, and meansfor determining conditions where the vessel resides, such as
amount of freight measurement, condition of ballast water,
and the like, and can be utilized for the bubble injecting
control according to the purposes.
0483 The vessel conditions determination unit 4300
includes a navigational condition detection unit, which is notshown. The navigational condition detection unit includes therelative velocity sensors 55 and 57, a draft sensor 4230 detect
ing the waterline level of the hull, and an inclination sensor(not shown) detecting so-called rolling, which is lateral incli
nation with respect to the traveling direction of the hull.
Separately therefrom, a configuration also including a shear
force sensor (not shown) may be adopted. The navigational
condition detection units detect physical quantities which

controlled for the sake of variation. In addition thereto, thehull.

0484 The oceanographic condition determination unit
4400 includes a wave sensor 4410, a wind sensor 4420 and acurrent sensor 4430. The wave sensor 4410 detects the wave

heights, directions and periods of waves. The wind sensor
4420 detects wind velocities and directions of winds. The

current sensor 4430 detects current velocities, directions andheights of currents. The oceanographic condition determina

tion unit 4400 considers information on waves, winds, currents and the like including information on a general weather,and is used for determining that for example the injecting of
bubbles is stopped when the oceanographic condition isstormy, and bubbles are generated when the condition isrecovered.

0485 The information from the vessel conditions deter
mination unit 4300 and information from the oceanographic
condition determination unit 4400 are transmitted to the con

dition setting unit 4220. The condition setting unit 4220 sys
tematically sets conditions for injecting bubbles to the bottom
9 of the vessel or in the proximity thereof. The conditions
include starting/stopping injecting bubbles, which ones of thegas outlets 4040 the bubbles are injected from in a case ofincluding a plurality of the nozzles, which inject rate is to be
set, which timing the injecting is started on, how a temporal
bubble inject sequence is composed, when injecting is started
and stopped and the like. In the condition setting unit 4220,
the conditions for injecting bubbles are set such that shear
forces acting on the hull, the relative velocity of the hull, thedraft, the inclination and the like are also considered. Condition setting for control according to these signals is also
performed. The condition setting unit 4220 performs condition setting according to a condition setting instruction for
reducing the frictional resistance, and further performs con
dition setting according to condition setting instruction foradjusting the waterline level by means of injecting bubbles.
0486 According to the settings in the condition setting
unit 4220, the comparator 4204 compares signals. The flow
rates and gas acquiring rate of bypass adjustment valves
4023A, 4024A and 4025A are controlled by the controller
4205. The controller 4205 also controls the valve arranged on
the discharge sides of auxiliary blowers (not shown). These
are attached for the sake of adjusting valves of the auxiliary
blowers and attaining a desired air rate, in a case of control
ling an air rate below the control region of the motors of theinverters of the auxiliary blowers, and in a case of quickly
adjusting the waterline level using the signal from the draft
sensor 4230. As to situations where bubbles are injected fromthe gas outlets 4040, inject conditions of the bubbles andconditions where the bubbles stays at the bottom 9 of thevessel and the proximity thereof are imaged by the video
camera 57. The images are utilized for analyzing and exam
ining conditions of injecting air.
0487. At the bottom 9 of the vessel and the proximity
thereof, the shear force sensors (not shown) are attached to thegas outlets 4040 downstream from the bottom 9 of the vessel.
In order to deepen analysis of variation in shear force owing
to injecting of bubbles, a corresponding number thereof areattached. Signals from the shear force sensors are fed back to
the comparator 4204. The signals are compared with shear
force values preliminarily set by the condition setting unitUS 2011/0259440 A1

Oct. 27, 2011
424220. The operating conditions of the blowers and/or bypass
adjustment valves 4023A, 4024A and 4025A are finely
adjusted via controller 4205 pursuant to a prescribed rule, analgorithm and constants according to the deviations. Further,
the relative velocities between the hull and seawater aredetected by the relative velocity sensors 55 and 57 and sub
jected to a prescribed statistical process, and the representa
tive value is transmitted to the comparator 4204. Signals fromthe draft sensor 4230 and the inclination sensor (not shown)
are also transmitted to comparator 4204.
0488 First, the comparator 4204 compares the processed
representative value of the relative velocity sensors 55 and 57
and the condition setting value preliminarily set by the con
dition setting unit 4220 with each other. For example, in acase where the gas outlet 4040 resides as a plurality of gas
outlets 4041, 4042, 4043, 4044 and 4045 when the relative

velocity of the hull exceeds the setting value, controls can be
performed including increase of the number of working gas
outlets 4040 to 4045, increase of the amount of bubbles, orincrease of both of them according to the deviations. Whenthe relative velocity becomes lower than the setting value,
controls can be performed including decrease of the numberof working gas outlets, decrease of the amount of bubbles, ordecrease of both of them. When decreasing the number ofworking gas outlets, it is preferable to stop outer gas outlets.
0489 For example, the gas outlets 4041 and 4045 are
stopped, or the gas outlets 4041 and 4042 and the gas outlets
4045 and 4044 are stopped. Likewise, the inject rates of
bubbles are controlled in an analogous manner. The inject
rates of bubbles of gas outlets 4041 and 4045 are decreased orincreased to the same degree. Further, the inject rates of
bubbles of gas outlet 4042 and 4044 are decreased orincreased to the same degree. Thus, the symmetrical controlof the number of Substantially symmetrically arranged gas
outlets with respect to the planarcenterline CL of the hulland
the inject rates of bubbles can acquire a uniform frictional
resistance reduction effect, in a case where the vessel is sailing in a straight line, which can frequently occur. Accord
ingly, ability of the vessel to hold a straight line can be
maintained, and fuel consumption is decreased. Further, thisfacilitates the circuit configuration and the control method of
the control device.

0490 The comparator 4204 compares a value detected by
the draft sensor 4230 and a condition setting value prelimi
narily set by the condition setting unit 4220. For example,
when the waterline of the hull exceeds the setting value (whenthe amount of freight is large and the waterline has risen),controls are performed including increase of the number ofworking gas outlets, increase of the amount of bubbles orincrease of both of them according to the deviation. When thewaterline has fallen (the freight is unloaded and the vessel isin a condition of ballast water), controls are performed
including decrease of the number of working gas outlets,

0492. The comparator 4204 compares an inclination valueof the hull detected by the inclination sensor (not shown) anda condition setting value preliminarily set by the condition
setting unit 4220. For example, when the inclination of thehull exceeds the setting value owing to turning or rolling of
the vessel, the inject spots of the working gas outlets arechanged or the amount of bubbles is increased or decreased
according to the deviation. For example, if the hull is inclined
to the left viewed from a traveling direction, the right side of
the bottom of the vessel is elevated. In this case, the frictional

resistance of the hull can effectively be reduced without
injecting bubbles in vain by performing controls including
increase of the number of working gas outlets on the left
where an apparent waterline rises, increase of the inject rates
thereof or increase of both of them and performing controls
including decrease of the number of working gas outlets on
the right, decrease of the inject rates thereof or decrease ofboth of them. The inclination sensor can be shared not only
for controlling injecting of bubbles but also for adjusting
ballast water for detecting the inclination of the hull andmaintaining the balance.
0493 Measures for the cases of such rolling adopt a con
figuration where a plurality of gas pipe systems are separately
provided so as to be capable of separately setting pressures.
Accordingly, even if there arise a height difference (presenceof inclination) between starboard and port, desired injectingof bubbles (e.g., Substantially uniform discharge) are
acquired by adjusting pressures. Alternatively, the gas may be
guided from a plurality of gas tubes to spots of injecting
bubbles once by way of a chamber.
0494 Next, the control according to the present application will be described in detail.

0495. As described above, according to the present appli
cation, the pressurized gas (gas Supply or charged air andScavenged gas)/exhaust gas drawing rates are controlled on
the basis of the physical quantities related to the heat load on
the main engine and the characteristics of the turbocharger. In
this case, as typical examples of physical quantities related tothe heat load on the main engine, the scavenging gas pressure
and the exhaust gas temperature (or exhaust gas pipe tem
perature, another ambient temperature corresponding to theexhaust gas temperature in a one-to-one correspondence,etc.) are adopted. As the characteristics of the turbocharger,
the turbocharger efficiency is adopted.
0496 The scavenging gas pressure is detected by the scav
enging gas pressure sensor S4. The exhaust gas temperature is
detected by the exhaust gas temperature sensor S6.
0497. The characteristics of the turbocharger is acquiredby (1) a method of acquiring overall efficiency of the turbo
charger, which will be described below, and (2) correction of
the overall efficiency of the turbocharger in a case with the
Scavenging bypass (exhaust gas bypass).
0498 (1) Method of acquiring overall efficiency of theturbocharger

decrease of the amount of bubbles or decrease of both ofOverall efficiency of the turbocharger=0.9055x T/Tx

them. In cases of decrease, it is preferable to control in an
analogous fashion to that described above.
0491. When swells come, the auxiliary blowers (notshown) and the bypass adjustment valves 4023A, 4024A and4.025A are controlled using signals from the draft sensor
4230, and the pressures acting on the gas outlets 4040 are
finely adjusted by increasing or decreasing in an immediatemanner, thereby further alleviating variation in inject rate of(R,0286-1)/(1-R,0265),

bubbles.

0499

where

(0500 T : turbocharger air intake temperature (e.g. 21
C.)+273:0501) T: pre-turbine exhaust gas temperature (e.g. 400°C.)+273:0502 R: (atmospheric pressure--scavenging gas presSure--intercooler differential pressure)/(atmospheric pressure-turbocharger filter differential pressure); andUS 2011/0259440 A1

0503 R: (atmospheric pressure--post-turbine exhaust gas
pressure)/(atmospheric pressure--exhaust gas receiver presSure).
Compressor efficiency=3614400xTx(R'-1)/(xU2)

0504 where
0505 u: slip ratio (depending on turbocharger types);
0506 D: Vane wheel diameter (depending on turbocharger
types); and0507 U: peripheral speed of a gear TLXDxT/Cspeed.
0508 Turbine efficiency—overall efficiency of the turbo
charger/compressor efficiency.
0509 (2) Correction of overall efficiency of the turbo
chargerina case with Scavenging bypass (exhaust gas bypass)
0510. The overall efficiency of the turbocharger acquiredby (1) is multiplied by a correction expression below.
(m,+me)/m,

0511 where
0512 m. mass flow rate passing through the turbine; and(0513 m, equivalent mass to bypass rate passing throughthe turbine.

0514 Method of controlling scavenging bypass rate
0515 (1) In order to cause the overall efficiency of theturbocharger to be a required value or more,
0516 e.g., for the latest engine, overall efficiency of theturbochargere(58% or more, and0517 e.g., for retrofit engine, overall efficiency of theturbochargere(64% or more.
0518 (2) Control is performed such that the scavenging
gas pressure becomes at least a prescribed value, and theexhaust gas temperature becomes a prescribed value or less.
0519 Here, the temperature, pressure, and the number of
revolutions of the turbocharger are the detection values fromthe respective sensors. The slip ratio and the vane wheel
diameter are read from the basic data. The processor 42.01
calculates overall efficiency of the turbocharger. The cor
rected value is acquired by correction by the processor 42.01
using the exhaust gas/bypass mass flow rate sensors S7 andS9.

0520 Pressure losses of the filter 4111 and the intercooler
4012, which are necessary to acquire the overall efficiency of
the turbocharger, are calculated by the processor 4201 on thebasis of values from the exhaust gas/bypass mass flow rate
sensors (S7 and S9) and a pressure loss coefficient stored in
the basic data unit 4202. Alternatively, instead of the calcu
lation, pressure sensors (S1 to S9, etc.) are attached torequired spots, and the losses are acquired by detection.
0521. The overall efficiency of the turbocharger can becalculated on the basis of a graph or table of turbocharger
overall characteristics preliminarily stored in the basic data
unit 4202. In this case, the load on the main engine 4010
necessary for calculation is acquired on the basis of the fuelconsumption measured by the fuel measurement unit 4320.
0522. In this embodiment, the overall efficiency of theturbocharger is acquired by two different methods.
0523 More specifically, the methods include a method of
calculating by the processor 4201 on the basis of detection
values from the respective sensors (S1 to S9, 230, etc.), and amethod of acquiring on the basis of the graph or table. The
results are compared by the comparator 4204. It is determined
whether both are within a prescribed error range or not. If
deviation from the prescribed error range is detected, a failure

Oct. 27, 2011

in the sensor is considered. Accordingly, the controller 4205
or a warning unit (not shown) issues a warning.
0524. The detection value from the oceanographic condition determination unit 4400 and the vessel conditions deter

mination unit 4300 are used for setting injecting condition of
bubbles. The details are as described above.

0525. The draft sensor 4230 is used for controlling starting/stopping Supply of gas/exhaust gas to the gas outlets 4040
according to pressurized gas/exhaust gas pressures and thedraft. The condition setting unit 4220 sets the inject condition,
the inject rate and the injecting timing and the like of thegas/exhaust gas, according to conditions of the oceanographic condition determination unit 4400 and the vessel
conditions determination unit 4300.

0526. The turbocharger turbine bypass gas includes three
types, as described below, at the spots of the main body of theengine. The characteristics are as described below.
0527. A Exhaust bypass gas (the intake is at the exhaustgas receiver, temperature: 400° C., pressure: 0.2393 MPagage pressure);
0528 BGas supply or charged air bypass gas (intake is at
the air supply pipe (charge air pipe) before intercooler, tem
perature: 135° C., pressure: 0.255 MPa gage pressure); and0529 CScavenged gas bypass gas (intake is at Scavenged
gas receiver, temperature: 35°C., pressure: 0.2533 MPa gagepressure).
0530. The invention of the present application generates
bubbles directly from the bypass gas using the bypass gas
from each spot of the turbocharger or a combination thereof,and secures that the amount thereof is utilized without deteriorating the performance and reliability of the engine.
0531. In order to generate bubbles, it is preferable thatpressure be high and temperature be high. Accordingly, A
exhaust bypass gas is most Suitable. However, a problem thatthe exhaust gas may directly pollute the ocean is assumed, and
it is assumed that there are unusable waters. In the waters

where the exhaust gas bypass gas cannot be used, B gas
Supply or charged air bypass gas or C scavenged gas bypass
gas may be used. B and C are high pressure air. However, if
the temperature is high, the Volume is large. Accordingly, apipe to the gas outlet should be wide and piping loss should beconsidered. In this case, measures, such as thermal insulationand covering, may be taken.
0532. Since the Scavenging bypass gas has low tempera
ture, Small-sized piping can be adopted. A combined configu
ration that heats the gas around bubble discharge port by theexhaust gas bypass gas can be considered. As describedabove, the bypass piping is raised once at the waterline or
higher such that seawater cannot enter the engine 4010. A
flowmeter 4035 is arranged intermediately at the bypass pip
ing and strictly measures the bypass rate.
0533. The control of starting/stopping injecting air can be
Summarized as follows. First, as a principal element of thepresent application, the bypass gas rate is controlled on thebasis of the physical quantity related to the heat load on themain engine and the characteristics of the turbocharger, andthe bypass gas is acquired and utilized as bubbles. Next, theoperation of starting/stopping the Supply operation of thepressurized gas and/or the exhaust gas from the gas outlet iscontrolled on the basis of the exhaust gas pressure and thedraft of the vessel. Further, the controls include a case pursu
ant to the determination by the vessel conditions determina
tion unit 4300, a case pursuant to the determination by theoceanographic condition determination unit 4400 and a caseUS 2011/0259440 A1

Oct. 27, 201144

pursuant to the detection result by the navigational condition
detection unit (not shown). In the case pursuant to the vessel
conditions determination unit 4300, injecting of bubbles is
stopped when the GPS 4310 determines that the vessel isapproaching a port or a destination, injecting is started whenleaving the port, injecting is stopped when the vessel isapproaching waters that is a Swirling current region, injecting
is started when the vessel is leaving the waters; injecting of
bubbles is stopped when operations of the engines are
stopped, and injecting of bubbles is started a predetermined
time after the engines start. When the fuel consumption effi
ciency detected by the fuel measurement unit 4320 becomes
below a predetermined one, injecting of bubbles are stopped.
When it is estimated that the fuel consumption efficiency isimproved, injecting of bubbles is started. When the oceanographic condition determination unit 4400 determines that itis stormy Such as a typhoon and rough weather, injecting of
bubbles is stopped. When it recovers, injecting is started.
Such controls can be performed. The starting/stopping inject
ing bubbles, and the inject rate are controlled in relation to theoperating condition of the main engine. When the main
engine requires air much, injecting is stopped or the inject rate
is reduced.

0534. Further, when the wave height detected by the wave
sensor 4410 becomes a prescribed value or more, injecting of
bubbles is stopped; when the wave height becomes a prescribed value or less, injecting is started. The detection resultsof the navigational condition detector are compared with apreset value; on the basis of the deviation, the injecting is
stopped when the deviation becomes a predetermined thresh
old or less, and the injecting is started when the deviation
exceeds the threshold. For example, the values from the relative velocity sensors 55 and 57 are statistically processed andthe representative value is transmitted to the comparator
4204. When the velocity of the vessel 1 is decreased and thevalue becomes lower than a prescribed threshold set by thecondition setting unit 4220, the injecting of bubbles are
stopped; when the value exceeds the threshold, the injecting isstarted. On the basis of temporal variation in statisticallyprocessed representative value from the relative velocity sen
sors 55 and 57, when the vessel 1 starts moving and acceler
ates, the threshold is set to be reduced and bubbles are injected
a little earlier. When the frictional resistance reduction effectis effectively exerted and the vessel is decelerated, the thresh
old may be reset upward and injecting of bubbles may be
stopped a little earlier because the speed is decreased andbubbles still stay at the bottom 3 of the vessel.
0535. As to the conditions for starting/stopping injecting
gas, control may be performed according to precedence.
When detection error, failure or an unpredictable event
occurs, control may be performed complementarily using
another condition. In any event, injecting of bubbles thatconsiders the actual frictional resistance reduction effect canbe realized by starting/stopping injecting of bubbles under aprescribed condition, and stopping injecting of bubbles when
detecting/determining that the vessel is stopped.
0536. In the above embodiments, as to the examples ofphysical quantities used for controlling the bypass gas rate,
the description has been made principally with the example ofthe scavenging gas pressure and the exhaust gas temperatureof the main engine. As to the examples of the physical quantities to be used for controlling operations of starting/stopping
the Supply operation from the gas outlets of the pressurizedgas and/or the exhaust gas, the description has been madeprincipally with the example of the exhaust gas pressure andthe draft of the vessel. These physical quantities are acquiredby the sensors. However, physical quantities by another sen
Sor may be adopted. In the above description, the example
adopting turbocharger efficiency as the characteristics of theturbocharger has been described. Further, the method ofacquiring the turbocharger efficiency has also been describedabove. Instead or in addition thereto, another characteristics(e.g., matching characteristics between the main engine andthe turbocharger) can be adopted as the characteristics of theturbocharger. Further, in the method of the turbocharger effi
ciency, various equations where constants and variables havebeen replaced can be adopted instead of the above expression
for calculation.

0537. The above description has been made with theexample of injecting the gas (air) bypassed from the turbo
charger directly into the water as bubbles. Instead, it may be
configured Such that the turbine drives an electric generator, ablower (gas Supply or charged air means) is separately driven
using the electric power gained by the electric power genera
tion, and bubbles generated by the blower is discharged fromthe nozzle 4040. Alternatively, turbine may be equipped with,for example, a coaxially driven mechanism, the blower (gasSupply or charged air means) may be driven directly, andbubbles may be generated therefrom.
0538 To grasp and sense the draft, for example, a method
may be adopted that uses sensors for measuring and detecting
pressure below the waterline at the bottom of the vessel andthe sides of the vessel and thereby grasps the draft from a
proportional relationship between pressure and depth. Further, for example, a method may be adopted that takes imagesof situations around the surface of water by cameras from thesides of the vessel, and applies image processing to theimages and thereby estimates the draft.
Eleventh Embodiment0539 FIG. 41 is a diagram showing an overview of avessel equipped with a frictional resistance reduction device
for a vessel according to an embodiment of the present invention. FIG. 41 (a) is a side view of the vessel. FIG. 41 (b) is a
top view thereof. FIG. 41 (c) is a bottom view thereof. A partof a principal configuration is represented in an exposedmanner. As shown in (a), a inject gas control device ismounted on the vessel 1. The inject gas control device
includes a main engine 10 including a propulsive engine ofthe vessel 1.

0540 A air supply pipe 5030 is sequentially communi
cated with three bypass pipes (the gas Supply or charged air
bypass pipe 5023, the scavenging bypass pipe 5024 and theexhaust gas bypass pipe 5025) attached to the main engine
4010. Each bypass pipe includes a bypass adjustment valve.
The air supply pipe 5030, which includes bent portions, is apipe for transferring a gas with a prescribed pressure andtemperature to the gas outlet 5040. The piping is installedfrom a position of collecting the three bypass pipes so as to bea shape where the piping plunges once to a height around thebottom of the vessel, passes the bent portions, is bent towarda height higher than the waterline and laid substantially hori
Zontally, and passes the bent portions and plunges in the
direction toward the bottom of the vessel. The piping paththus passes once at a height of the waterline or higher. Thiscan prevent seawater from flowing reversely into the gas
outlets arranged on or below the waterline in case of a failureof valves such as a bypass adjustment valve, and avoid danUS 2011/0259440 A1

gerous situations of the main engine in view of security. The
gas outlet 5040, which is arranged at or in the proximity of thebottom of the vessel and injects gas as bubbles from an
opening perforated at or in the proximity of the bottom of thevessel into the water near the bottom 9 of the vessel, isconnected to the other end of the air supply pipe 5030.
0541. A residual gas (or a part thereof) of the turbocharger
from the gas supply or charged air bypass pipe 5023 and/or
the scavenging bypass pipe 5024 and/or the exhaust gas
bypass pipe 5025 passes the air supply pipe 5030 having thebent portions, and is guided to the gas outlet 5040 arranged in
the proximity of the bottom of the vessel. For example, in thisembodiment, the gas outlet 5040 is arranged at the fore of thebottom 9 of the vessel, substantially symmetrically withrespect to the planar center line of the hull CL. The arrange
ment of the gas outlet 5040 at the bottom 9 of the vessel is forthe purpose of prolonging the retention of the injectedbubbles at the bottom 9 of the vessel and alleviating influ
ences owing to waves. The arrangement at the fore in theproximity of the bottom of the vessel is for an object forretaining the injected gas over the entire bottom 9 of the vessel
as much as possible. In cases where these purpose and object
are not necessary, the gas outlet 5040 may be at a spot otherthan the bottom 9 of the vessel. The spot may be an appropri
ate one on or below the waterline. Particularly, in a case ofarrangement of the gas outlet 5040 at the bottom 9 of thevessel, it can be expected that the retention of bubbles become
longer. Further, the bubbles with a diameter of at least aseveral hundred um, exerts a buoyant effect. Accordingly, aneffect that bubbles adhere to the bottom of the vessel is also

expected. When the supply of the pressurized gas and/or theexhaust gas is stopped, a blocking valve 5027 is provided
immediately before the gas outlet 5040 in order to prevent
water from entering the air supply pipe 5030. Since the blocking valve 5027 is provided, the air supply pipe 5030 is resis
tant to influences of entry of water. Accordingly, as to material
and thickness, it is unnecessary to consider high anti-corro
siveness and pressure-tightness. To stop the gas Supply or
charged air, it is preferable to preliminarily close the blocking
valve 5027 under the gas pressure. To start the gas supply or
charged air, it is preferable to open this valve after the gaspressure has risen at least to a prescribed value.
0542. Thus, entry of water can be reliably blocked,
thereby preventing entry of water into air supply pipe 5030
and occurrence of backflow. This can prevent the air Supply
pipe 5030 from being damaged. More specifically, this canprevent the formation of rust in the air supply pipe 5030
owing to water, obviate fouling of marine organisms, Suppress increase in frictional resistance when gas is injected,
alleviate maintenance, and in turn allow long-term use of the
air supply pipe 30. It is preferable that the air supply pipe 5030
adopt a material resistant to seawater or Surface coating beapplied thereto. Since the air supply pipe 5030 is closed by theblocking valve 5027, increase infrictional resistance owing toentry of flowing water into the air supply pipe 5030 while thevessel is sailing can be suppressed. The operation of theblocking valve 5027 is pursuant to automatic control of open
ing and closing the valve, depending on presence or absenceof the electric power or pressurized gas. However, undercertain conditions, the control may be pursuant to manual
operation of opening and closing the valve, or semiautomatic
control.

0543. In this embodiment, the gas supply or charged air is
stopped before the main engine is stopped. The method ofOct. 27, 2011

stopping includes preliminarily stopping the blocking valve
5027 and then closing the bypass valve, and subsequently
stopping the main engine and the turbocharger. Starting is
performed inversely. This can exert an advantageous effectspecific to the present application that is capable of reliably
preventing water from entering the air supply pipe 5030 andthe main engine 4010.
0544. When the main engine load becomes below a prescribed value (e.g. 50%), the gas Supply or charged air is
stopped. More specifically, the Supply is stopped with anallowance for turbocharger efficiency required by the main
engine. When the value exceeds the prescribed value, the gas
Supply or charged air is started. This can exert an advanta
geous effect specific to the present application that is capableof supplying without dropping below the gas rate required by
the main engine.
0545. The gas outlets 5040 are arranged in the planar
configuration Such that the plurality thereofare arranged Sub
stantially symmetrically with respect to the planar center line
CL. The air supply pipes 5030 may be provided as many as thegas outlets 5040. Instead, branched pipes from the air supply
pipe 5030 are provided as many as the corresponding number.
This allows the configuration to be simplified and can facilitate the arrangement. Preferably, the number of the discharge
ports is an odd number, and a symmetric arrangement is
adopted where the center one is disposed on the planar centerline CL.

(0546 Preferably, also for the gas outlets 5040, the diffusion limiting sections are disposed substantially symmetricalwith respect to the planar center line of the hull CL. Morespecifically, as shown in (c), end plates 5095,5096 and 5097
limiting diffusion of the gas injected as bubbles from the gas
outlets 5040 are arranged, and end plates 5095a, 5096a and5097a are arranged symmetrically with respect to the planarcenter line CL. The end plates 5096, 5096a, 5097 and 5097a
are illustrated so as to be in the same dimensions in this figure.
However, the end plates 5097 and 5097a may have smaller
dimensions than those of the end plates 5096 and 5096a. The
number of end plates is not limited to that of the figure, andneed not be plural. One end plate may be provided on thelongitudinal direction of the bottom of the vessel.
(0547. A draft sensor 5230 is provided at a spot without
influences of waves and bubbles in the water at the stern. A

relative velocity sensor 55 is provided at a spot without influ
ences of waves and bubbles of the bow. A depth sounder 5060
is provided at a spot without influences of waves and bubbles
in the water at the bow. The depth sounder 5060 performs
Sonic Sounding that emits ultrasonic waves from a side of thevessel and acquires a depth from a time period until theultrasonic waves reflected by the sea bottom and return. It ispreferable to dispose the depth sounder 5060 at an appropri
ate spot resistant to influences of waves and bubbles so as not
to receive influences on transmission and reception of theultrasonic waves. Even in a case of providing a type of sensor
in the water as the relative velocity sensor 55, it is preferable
to provide the sensor at a spot without influences of waves andbubbles.

0548. In addition thereto, a shear force sensor 5240, which
detects a share force exerted on the hull owing to seawater andbubbles, is arranged on the bottom 9 of the vessel, for example
at the stern.

0549. The flow rate sensor S7 detects gas supply or
charged air rate at the air supply pipe 5030, and monitors
whether an appropriate gas rate of gas is transferred or not.