Vessel with hexagonal underwater section for propulsion of a barge

Abstract

 Disclosed is a vessel comprising an upper side shell (9) having a cylindrical shape; a lower side shell (10) having the shape of a hexagonal prism and being provided below the upper side shell (9); and thrusters (23) capable of rotating in the horizontal direction and being provided on the bottom of the vessel at symmetrical positions about a hull center line (3) connecting opposing dihedral angles of the lower side shell (10) as an axis of symmetry.

Description

TECHNICAL FIELD

[0001] The present invention relates to vessels, and more particularly to a vessel whose underwater outer circumference, as viewed from above, is hexagonal. Furthermore, the invention relates to a barge that is pushed by the aforementioned vessel.

BACKGROUND ART

[0002] A ship docking vessel (tugboat) whose bottom has an elliptical shape is described in JP H10-100987A. This vessel is intended to enable towing and pushing in any direction.

[0003] Furthermore, the thruster using a pump water flow that is described in Japanese Patent No. 4273168 by the present applicant can also be applied to a vessel according to the present invention.

[0004] JP 2002-331992A is directed to a device for coupling a pusher boat and a barge, and describes a pusher boat including a connecting shaft that is retractable by a cylinder, and a barge including a recess into which the front-end of the pusher boat is fitted and a connecting groove into which the connecting shaft is fitted.

[Patent Document 1] JP H10-100987

[Patent Document 2] JP 2002-331992

SUMMARY OF THE INVENTION

[0005] From ancient times, a "traditional boat" that is circular when viewed from above is known in Japan as a "Taraibune" (English: "tub boat"), but this tub boat has never been developed into a power vessel for practical use. The reason lies, for example, in that its waterline is circular and thus it tends to rotate, making it physically difficult to move it in a straight line, and that it is an extremely wide, shallow-draft vessel having a length/breadth ratio of 1 and thus has a large head resistance and a large wave-making resistance component, which makes the commercialization of this boat as an industrial product impossible.

[0006] However, a hull configuration having a length/breadth ratio of 1 can achieve the minimum surface area as a structure, and can be simple in its structure. For this reason, it is possible to reduce the materials used, the man-hours for construction, and the maintenance cost.

[0007] Furthermore, a thrust generating apparatus capable of turning 360 degrees has recently been put into practical use, and is available as an excellent thruster with good controllability and course keeping performance.

[0008] By combining a hexagonal underwater hull inscribed in a circle with a rotatable thrust generating apparatus, additionally providing a hybrid power generation system or the like, which has now been put into a widespread use as the power source thereof, and also improving the hull configuration, for example, by attaching a bulbous bow, the above-described vessel can be developed into a highly economical vessel having versatile applications in the field of small vessels that are commonly used at low to medium speed in calm water.

[0009] The present invention proposes a small-to-medium hull configuration that is intended to rationalize the material cost and the cost of construction by improving the problem of increased resistance during forward and backward movements, which is a drawback of the circular hull configuration, and keeping a smooth rotational motion achieved by a strong rudder effect, which is an advantage thereof, while maintaining the course stability, and minimizing the hull configuration.

[0010] Furthermore, a work ship according to the present invention is small and circular, and has a thrust generating function at the central portion of the hull. Accordingly, detachably incorporating the work ship as a separable power unit of a large barge at the rear end of the barge enables the integration of the work ship with the large barge, thereby improving the seakeeping performance, which is a weak point of the vessel of the present invention, and realizing a rational barge transporting system as an efficient transportation mode.

[0011] A barge, which does not include a power plant, is moved by being pushed or towed by a pusher boat or a tow boat, which navigates by its own. Examples of commonly used pushing/towing methods include a method that uses a wire rope and a method that performs coupling using a mechanical device. When a tow boat uses a wire rope to tow a barge, there is the problem that it is difficult to maneuver the barge freely. In the case of performing towing/pushing using a mechanical device, it is difficult to perform easy coupling or decoupling of the tow/pusher boat with the barge since they separately make various motions.

[0012] Therefore, the present invention proposes a barge that can solve the above-described problems by operating in cooperation with the vessel according to any of first to eighth aspects of the invention.

[0013] The vessel according to the present invention is configured as follows.

[0014] According to the first aspect of the present invention, an upper side shell having a cylindrical shape; a lower side shell having the shape of a hexagonal prism and being provided below the upper side shell; and thrusters capable of rotating in the horizontal direction and being provided on the bottom of the vessel at symmetrical positions about a hull center line connecting opposing dihedral angles of the lower side shell as an axis of symmetry are provided.

[0015] According to the second aspect of the present invention, in the vessel according to the first aspect, bottom plating is provided with a downwardly open duct, along the hull center line across the entire length of the bottom plating.

[0016] According to the third aspect of the present invention, in the vessel according to the second aspect, a pillar is provided at the top of the duct at a hull central point where lines connecting opposing dihedral angles of the lower side shell intersect.

[0017] According to the fourth aspect of the present invention, in the vessel according to any of the first to third aspects, skegs whose lower ends are located below a lower end of the thruster are provided at the bottom of the vessel.

[0018] According to the fifth aspect of the present invention, in the vessel according to any of the first to fourth aspects, a fender is provided around the entire circumference of an upper end of the upper side shell.

[0019] According to the sixth aspect of the present invention, in the vessel according to any of the first to fifth aspects, a bulbous bow serving as a bow figure configured to be raised or lowered above or below the water line separately from a main hull is provided.

[0020] According to the seventh aspect of the present invention, in the vessel according to any of the first to sixth aspects, a nozzle-equipped thruster that uses a flow of water discharged from a pump as thrust is provided.

[0021] According to the eighth aspect of the present invention, in the vessel according to the seventh aspect, the thruster is provided so as to be removable in the horizontal direction below the bottom plating.

[0022] Furthermore, a U-shaped recess in which the vessel according to any of the fifth to eighth aspects can be housed is provided at the stern of a barge.

[0023] Effects that can be achieved by the present invention configured as described above will now be described.

[0024] A ship of a novel shape that is circular when viewed from above can be provided, and moreover, providing a rotatable thruster at symmetrical positions enables performing turning on the spot (the vessel according to the first aspect).

[0025] Since a duct is provided at the bottom of the vessel, it is possible to reduce the head resistance and pitching during forward and backward movements, and realize the course stabilization (the vessel according to the second aspect).

[0026] Since a pillar is provided at the top of the duct at the hull central point, it is possible to support the deck load, thereby increasing its rigidity. Furthermore, a low-capacity passenger elevator, electric circuits for lighting, various pipes, communication cables and the like can be provided inside the pillar in a centralized manner (the vessel according to the third aspect).

[0027] Skegs whose lower ends are located below the lower end of the thruster are provided at the bottom of the vessel, so that it is possible to protect the thruster at the time of grounding and support the hull weight (the vessel according to the fourth aspect).

[0028] Since a fender is provided around the entire circumference of the upper side shell, the vessel can come along with another ship at any location to perform pushing (the vessel according to the fifth aspect).

[0029] The vessel according to the present invention has a circular shape when viewed from above, and therefore the crew, passengers and the like may often find it difficult to determine the directions of the bow and stern. For this reason, a bow figure that is installed so as to be raised or lowered above or below the water line separately from the mail hull is provided. For example, when it is necessary to notify the crew and the like of the location of the bow, the bow figure is brought into the bow position and raised. Since this bow figure is provided to serve the function of a bulbous bow as well, it can serve the function of a bulbous bow when lowered below the water line. That is, it is possible to reduce the wave drag (the vessel according to the sixth aspect).

[0030] Since a discharged flow of a pump is utilized, it is not necessary to provide a motor or a drive that is connected to the thruster itself in a propeller hub, unlike a propeller-type thruster using mechanical shafting or an electric drive. Accordingly, it is possible to simplify the structure (the vessel according to the seventh aspect).

[0031] Since a discharged flow of a pump is utilized, it is not necessary to provide a mechanical structure or electrical wiring or the like inside the thruster, so that the thruster can be provided so as to be removable from the outside of the bottom plating. This facilitates installation work and maintenance (the vessel according to the eighth aspect).

[0032] A barge according to the present invention sails while housing the vessel according to any of the fifth to eighth aspects in a recess provided at the stern. That is, a rudder effect is exerted in a mode in which the barge and a tow/ pusher boat are directly in contact with each other, without performing pulling using a wire rope or coupling using a mechanical device. Therefore, the difficulty in maneuvering as in the case of performing pulling using a wire rope, and the difficulty in coupling/decoupling as in the case of performing coupling using a mechanical device will not occur.

[0033] Hereinafter, the effects will be described in detail more specifically.

[0034] In the case of using the vessel of the present invention as a tourist ship, it is possible to maintain the course accurately, and also to perform turning on the spot at a varied pace. Accordingly, it is possible to sail a planned route while repeatedly performing this. That is, the tourists in the passenger cabin can enjoy a 360 degree panoramic view without changing their line of sight.

[0035] In the case of using the vessel of the present invention as a work ship, the center line of the hull can be readily made to coincide with an extension of the tow line used for a towing operation, so that it is possible to separate the tow line readily and safely, and dispose the towing device at the rear end of the hull in a centralized manner. Accordingly, it is possible to reduce the hull length, and as a result, it is easy to downsize the hull configuration.

[0036] The vessel of the present invention can be maneuvered in the same manner as a tow boat including a commonly used Z-shaped or L-shaped thrust shaft or two Voith Schneider thrusters. However, in the case of the vessel of the invention having a turning shaft at the hull center, it is possible to change the azimuth angle more easily Also, in the case where the vessel of the invention has a fender around the entire circumference of the hull, the vessel can come alongside with another ship at any location, and thus can come alongside with a desired location of a boat that is to be towed, and promptly generate the necessary thrust.

[0037] Furthermore, the above-described work ship can be coupled with a barge for use. As shown in FIG. 8, by forming a U-shaped recess 38 at the stern portion of a large barge 37, and performing mooring by fitting a cylindrical upper side shell 9 into the U-shaped recess 38 with a fender 36 disposed therebetween, the coupling operation can be performed safely, easily and reliably, making it possible to obtain a greater rudder effect. Moreover, the drawback of the above-described vessel, i.e., the problem of the small length/breadth ratio can also be solved. That is, in a state in which the vessel is housed in the recess of the barge, a length/breadth ratio to which the length of the barge has been incorporated is achieved, so that it is possible to achieve a reduction in wave drag and an improvement in seakeeping performance, thereby realizing transportation not only within a harbor, but also on a coastal route.

[0038] Furthermore, since the work ship of the present invention is small and circular, and includes a thrust generating apparatus at the hull center, it has the following characteristic function when pushing a barge.

[0039] Ordinarily, when a pusher boat pushing a powerless mother barge tries to maneuver the mother barge, the hulls of the two vessels require turning moment for forming a dog-leg shape ("<"-shaped) when viewed from above (this is in the case of right swinging; the inverted shape thereof in the case of left swinging). Therefore, a mooring device located between the two vessels needs to withstand that force. On the other hand, in the case of the work ship of the present invention, the circular hull is incorporated at the rear end of the mother barge as shown in FIG. 8, and therefore directly pushes the tail portion of the mother barge to the left and the right with its steering force, so that no moment will be generated. Accordingly, the mooring device mainly serves to prevent the work ship from being decoupled in the rear direction, so that the device can be simplified.

[0040] Furthermore, the work ship according to the present invention is located on a water surface surrounded by the tail portion of the mother barge on three sides, and therefore has the characteristics that the influence of wind waves is alleviated and the weight of the overall mooring device is reduced.

[0041] Then, the hull configuration according to the present invention is based on a geometric shape of a circle and a regular hexagon when viewed from above, and does not require a complex analog curve, and thus can be easily designed and constructed.

[0042] In addition, by performing block splitting based on the size of the container used for transporting blocks, shipping can also be simplified, and the vessel can be completed by assembly and weldbonding.

[0043] Moreover, at the time of construction or repairs at the site, when a nozzle-equipped jet pump type is used as a thruster, providing a joint 39 at the portion of a discharge pipe that is located directly below the bottom of the vessel enables attachment or detachment by laterally moving the entire device. Therefore, the vessel of the present invention does not require a large space therebelow that would be required when attaching or detaching a thrust mechanism including a Z-shaped thrust shaft or a thrust mechanism containing a motor-driven thrust mechanism in a housing is not necessary, so that the construction and repair facilities can be simplified. This results in an effect that would be a particularly important advantage when using a lake sure and the like.

[0044] Furthermore, a bulbous bow is provided to increase the length/breadth ratio of the hull, thereby reducing the wave drag. In addition, when the bulbous bow is constantly stood up and used as a bow figure, it can be used a character figure representing the vessel.

BRIEF DESCRIPTION OF THE DRAWINGS

[0045] 

FIG. 1 is a plan view of an upper deck.

FIG. 2 is a plan view of an interior portion of a hull that is located below the upper deck.

FIG. 3 is a longitudinal cross-sectional view of the hull.

FIG. 4 is a transverse cross-sectional view of the same hull.

FIG. 5 is a plan view of a passenger cabin deck of a deckhouse.

FIG. 6 is a plan view of a control cabin deck of the same deckhouse.

FIG. 7 is an external view for a case where the vessel according to the present invention is used as a work ship.

FIG. 8 is a plan view for a case where the vessel of the present invention is coupled to a large barge as a work ship.

FIG. 9 is a plan view showing another embodiment of the large barge.

FIG. 10 is a partial cutaway view schematically showing the configuration of a thruster.

FIG. 11 is a side view of a bow figure (bulbous bow).

DETAILED DESCRIPTION OF THE INVENTION

[0046] Hereinafter, a small passenger ship on which a thruster including a thrust generating apparatus, in particular, a thrust generating apparatus including a nozzle for increasing a discharge flow is installed, will be described as a preferred embodiment, and a case where the small passenger ship is used as a tugboat (hereinafter, referred to as a "work ship") used as a tow /pusher boat will be described additionally.

[0047] The details of the drawings that are referred to below are as follows.

[0048] FIG. 1 is a plan view of an upper deck; FIG. 2 is a plan view of an interior portion of a hull that is located below the upper deck; FIG. 3 is a longitudinal cross-sectional view of the hull; FIG. 4 is a transverse cross-sectional view of the same hull; FIG. 5 is a plan view of a passenger cabin deck of a deckhouse; FIG. 6 is a plan view of a control cabin deck of the same deckhouse; FIG. 7 is an external view for a case where the vessel according to the present invention is used as a work ship; FIG. 8 is a plan view for a case where the vessel of the present invention is coupled to a large barge as a work ship; FIG. 9 is a plan view showing another embodiment of the large barge; FIG. 10 is a view schematically showing the configuration of a thruster according to the seventh aspect of the present invention; and FIG. 11 is a side view schematically showing a bulbous bow also serving as a bow figure. It should be noted that the portion below the water line in FIG. 7 is the same as that of FIG. 3, and therefore has been omitted).

[0049] The vessel according to the present invention has a characteristic, left-right symmetrical hull configuration that includes a circular upper deck, a cylindrical upper side shell in contact with the lower portion of the upper deck, and a lower side shell having the shape of a tortoise-shell (hexagon) as viewed from above and being inscribed within the upper side shell.

[0050] As shown in FIGS. 1 to 4, when one of the dihedral angles of the hexagon is positioned as a bow 1, the dihedral angle that is longitudinally opposite the bow 1 is a stern 2, and together they form a hull center line 3. The lines connecting the remaining two pairs of dihedral angles 4, each on the left and right sides, respectively at the port and the starboard naturally form parallel portions 5 of the side shells of the vessel, and a lateral axis 6 connecting the centers thereof intersects a longitudinal axis 3 at a central point 7 of the longitudinal axis 3 at a right angle.

[0051] It should be noted that, by setting a nominal water line 8 at a tortoise-shell shaped lower side shell 10, rather than at a cylindrical upper side shell 9 having a length/breadth ratio of "1", the ratio is geometrically about "1:1.16", which is more advantageous in terms of the wave drag than in the case where the nominal draft line is set to a circular water plane area.

[0052] Next, the structures of the various portions will be described.

[0053] As shown in FIG. 4, the cylindrical upper side shell 9, which is contiguous with a round upper deck 11, extends downward, and the hexagonal cylinder lower side shell 10, which is contiguous with the upper side shell 9 above the nominal water line, extends further downward and is fixed to flat bottom plating 12. In that case, the gap between the upper side shell 9 and the lower side shell 10 is filled with a bottom member 13, while forming a chain line, and the upper side shell 9 and the lower side shell 10 are thus fixed to each other, thereby forming a hull 14 at the central portion of the ship.

[0054] Then, in order to reduce the hull resistance at the time of forward movement of the vessel according to the present invention, the bottom member 13 forms a chain line 15 from a portion near the front end and the rear end of the parallel portions 5 of the hull 14, while extending from above the nominal water line 8 toward the bow end and the rear end of the upper deck 11. Further, as shown in FIG. 3, in order to reduce the resistance during forward and backward movements, the joint between the lower side shell 10 and the bottom plating 12 is cut upward to the bow end and the stern end in the form of a knuckle line 16, together with the bottom plating 12, thereby reducing the wetted surface area.

[0055] Further, as shown in FIG. 4, the bottom plating 12 is provided with a downwardly open duct 17 along the a hull center line 3 across the entire length of the bottom plating 12, with the top face of the duct 17 located above the nominal water line 8, thereby reducing the head resistance during forward and backward movements as well as pitching, and thus realizing course stabilization.

[0056] Furthermore, as shown in FIG. 4, skegs 18 and 19 are disposed on the ship bottom so as to protect thrusters at the time of grounding and to support the hull weight. The skegs 18 and 19 are disposed so that their lower ends are located below the lower end of thrusters 23. In addition, it is preferable that small horizontal fins 60 for suppressing heaving are attached to the lower ends of the skegs 18 and 19.

[0057] Furthermore, a pillar 20 is provided at the top of the duct 17 at the hull central point 7 so as to support the weights of the upper deck 11 and the decks of superstructures 21.

[0058] In addition, bilge keels 22 are attached to the knuckle line 16 of the hull parallel portions 5 in order to reduce rolling during ordinary forward movement and to realize course stabilization.

[0059] With the vessel according to the present invention, the course stability at the time of maneuvering at a small rudder angle can be ensured by arranging the thrusters 23, which are capable of rotating 360 degrees, at right-and-left symmetrical positions on the lateral axis 6 on the outer board side. Further, by rotating the rudder angles of the left and right thrusters in reciprocal directions, or stopping the thruster on one side of the vessel, a light turning moment can be promptly obtained in the course, so that it is possible to perform a complete "turning on the spot" on the course even in a narrow waterway or the like in which the course is limited. This is a characteristic motion performance that can be only achieved by the thrusters and the present hull configuration having the center of rotation at the hull center and capable of performing turning on the spot. As the thruster 23, it is possible to use general-purpose Z-shaped thrust shafts, Voith-Schneider thrusters or pod thrusters.

[0060] It is even more preferable that nozzle-equipped thrusters 23 that expand a flow of water discharged from a pump are used as the thrusters 23. As shown in FIG. 2, drive pumps 24 of the nozzle-equipped thrusters 23 are disposed inside a power house 26 that is divided into front and back portions by a partition wall 25, and are driven by power from a power supply apparatus 27 in the power house. This apparatus is a generator using a power generating motor 28 (internal combustion engine) or a large-capacity secondary battery, or a combination thereof, and is integrally installed at the central portion of the power house 26. A sea chest 29 is disposed directly below the drive pump 24 so as to reduce the length of a suction pipe and hence the resistance in the suction pipe. Ajoint 39 formed by a flange is provided at a portion of the discharge pipe 40 located directly below the vessel bottom, and is fastened with a bolt, a nut or the like. This allows the nozzle-equipped thrusters 23 to be attached or detached easily. In addition, a steering device 41 capable of turning 360 degrees is disposed at a mid point of the discharge pipe 40, thereby enabling the thrusters 23 according to each of the aspects of the present invention to rotate.

[0061] As shown in FIG. 10, the nozzle-equipped thruster 23 discharges seawater sucked from the sea chest 29 through the discharge pipe 40 into a nozzle 42 having a bell-shaped outer casing, thereby expanding and straightening the water flow before discharging the water flow. Inside the nozzle 42, a ring 43 having a blade-shaped cross section is fixed as an inner casing via flow straightening plates 45 along with a shell-shaped cone 44 located on the center line. In addition, the interior of the cone 44 is hollow, and the bottom thereof is open. Also, the ring 43 and the cone 44 are fixed to each other with the flow straightening plates 45. A half spindle-shaped housing 46 is provided for the purpose of straightening the water flow outside the bell-shaped nozzle 42 and the discharge pipe 40 used as a pintle.

[0062] Inside the pillar 20 extending from the central point 7 in the power house 26 into the superstructures 21, a working elevator, electric circuits for lighting, various pipes, communication cables and the like are provided in a centralized manner, and are connected to the various devices installed in the vicinity of the pillar 20 in the power house 26.

[0063] In FIGS. 1 to 6, an opening 30 for the required maintenance, and the surrounding wall and the entrance chamber of the opening 30, a crew space, a deck store and the like are provided on the upper deck located directly above the power house 26. A passenger cabin and related facilities are provided on a cabin deck 31 located directly above this deckhouse. A control cabin deck 32 is further provided above the cabin deck 31, devices relating to maneuvering are provided in a steering cabin 33 in a centralized manner, and a mast 35 is installed on a top deck 34.

[0064] When the outline of the deckhouses on the above-described decks are all in a tortoise-shell shape when viewed from above, the crew and the passengers have the common perception that one of the dihedral angles is the bow, and this meets the requirement for ensuring security, for example, by providing guidance in case of emergency. Accordingly, in addition to the foregoing, it is effective to attach a bow figure (or figurehead) or the like to the dihedral angle portion of the bow/stern end, for example.

[0065] In this respect, a case will be described in detail where a bow figure as shown in FIG. 7 below is provided to control the wave drag of a wide-width, shallow draft hull configuration such as the vessel according to the present invention.

[0066] In FIGS. 7 and 11, numeral 47 denotes a bow figure, which in this case is provided with a shape resembling the head of a marine mammal such as a "dolphin". In the present invention, the bow figure 47 is not simply fixed to the bow, but is rather provided so as to be raised or lowered, projecting on the center line from the tip of the dihedral angle at the bow. That is, a steel ball 49 is embedded in a horizontal support fin 48 fixed across the two side walls of the duct 17, and a spherical groove formed in the lower end of the bow figure 47 is loosely fitted around the steel ball 49. By lowering the bow figure 47 with the steel ball 49 as the pivot point, it is possible to position the bow figure 47 below the water line 8 substantially horizontally. On the other hand, by raising the bow figure 47 with the steel ball 49 as the pivot point, it is possible to move the bow figure 47 to its stow-away position.
This raising or lowering operation is performed by connecting a wire 51 to a small eye plate 50 attached at the top of the bow figure 47, and pulling the wire 51 with a small winch 53 attached to the front of the deckhouse 52. Thus, the present invention provides the bow figure 47 with the function as a bulbous bow (hereinafter, the bow figure is also referred to as a "bulbous bow").
Stopper fins 59 are provided on both sides of the bow figure (bulbous bow) 47. The stopper fins 59 serve to suppress swaying of the bulbous bow 47.

[0067] Additionally, the upper deck 11 is also cut into a U-shape, and a surrounding wall 54 is provided around the upper deck 11 so that the space between the upper deck 11 and a top face 17a of the duct is watertight. A bulwark 55 is also cut so as to allow the figure 47 to be rotated, and furthermore, it is recessed in a U-shape toward the outside of the bow figure so as to prevent waves from coming onto the upper deck 11 as shown in FIG. 1. A fender 36 is also open as shown in FIG. 1 so as to allow figure 47 to be rotated and raised or lowered.

[0068] Characteristically, the body of the bow figure 47 is made of an elastic body such as synthetic rubber so that the impact of waves on the bulbous bow 47 will not be exerted on the eye plate 48, the wire 51, and the winch 53. The winch 53 makes it possible to detect the tension of the wire 51, to observe the behavior of a pole 47a provided at the tip of the bulbous bow 47, and to enable adjusting the trim of the bulbous bow 47 itself so that an excessive load will not be generated. By using a character freely selected from various images having a PR effect as the bow figure 47 for a local passenger ship, and streamlining the bow figure 47 into the necessary shape as the bulbous bow 47 for its function under water, a greater PR effect can be expected. Furthermore, as shown in FIG. 3, by similarly using the tail of an underwater creature as a stern figure corresponding to the bow figure, it is possible to improve the course keeping performance with a bulbous stern, and straighten a complex turbulence of flow in the region at the rear end of the hull, thereby reducing the resistance and increasing the energy saving effect, while achieving a greater PR effect.

[0069] The devices described above can also be applied to a work ship (tow boat). That is, the bow figure 47 is lowered to a predetermined position under water as shown in FIG. 7 as the bulbous bow 47 during cruising to perform energy-saving sailing. When performing a pushing operation, it is pulled up to the position shown in FIG. 11, thereby enabling a quick turning motion. In this case, the bulbous bow 47 will not cause any damage to the side shell of the towed boat, since is made of an elastic body. Furthermore, even if the shell plating of the towed boat has flares, it is easy to provide the bulbous bow 47 with flexibility sufficient to accommodate such flares. This performance makes it possible to avoid damages that could be caused by contacting another vessel even in case of a collision during cruising.

[0070] In the case of using the vessel according to the present invention as a work ship, as shown in FIGS. 7 and 8, sponson portions (eaves portions 56) of the decks of the deckhouses are removed to form tower-shaped superstructures, thereby making it possible to directly view an operation performed on the upper deck 11 from the control cabin deck 32, as shown in FIG. 7. Also in this case, when the decks have a tortoise-shell shape, when visually confirming the accompanying work ship of the present invention from a larger towed boat, it is easy to recognize its bow and stern directions, i.e., the bow and stern directions of the hull center line 3. Furthermore, in the case of visually confirming the work ship of the present invention from the side of another vessel, the determination of the bow and the stern can also be made based on the fact that vessels are ordinarily used with a slight stern trim, the shape of the bulwark, the mast and the like. However, the determination of the bow and stern can be made in the same manner as in the case of ordinary vessels based on the line located below the chain line 15 at which the color of the coating of the vessel bottom and that of the coating of the outer board are separated, and the position of the ship name, the name of the port of registry or the like. Therefore, the operation safety of this hull configuration will not be hindered.

[0071] In addition, the bulbous bow 47 has such an internal structure that it has such an apparent weight under water that the water flow flowing in from an air vent hole 57 and a drain hole 58 at the front and rear ends makes the buoyancy of the spherical body slightly smaller than the weight of water discharged, thereby restricting the floating action of the spherical body during sailing. When the bulbous bow 47 stands upright, water is automatically discharged from the drain hole 58.

[0072] A barge according to the present invention is configured by forming a recess 38 formed by cutting away a stern 37a of a large barge 37, as shown in FIG. 8. Furthermore, by installing a temporary coupling jig 38a having the shape of a recess when viewed from above as shown in FIG. 9 at the stern of the large barge 37 in place of the recess 38, it is possible to use a general-purpose trapezoid large barge as a coupling barge.

Claims

1. A vessel comprising:

an upper side shell (9) having a cylindrical shape;

a lower side shell (10) having the shape of a hexagonal prism and being provided below the upper side shell (9); and

thrusters (23) capable of rotating in the horizontal direction and being provided on the bottom of the vessel at symmetrical positions about a hull center line (3) connecting opposing dihedral angles of the lower side shell (10) as an axis of symmetry.

2. The vessel according to claim 1,
wherein bottom plating (12) is provided with a downwardly open duct (17) whose top plating is located in the vicinity of a water line, along the hull center line (3) across the entire length of the bottom plating (12).

3. The vessel according to claim 2,
wherein a pillar (20) is provided at the top of the duct (17) at a hull central point (7) where lines connecting opposing dihedral angles of the lower side shell (10) intersect.

4. The vessel according to any of claims 1 to 3,
wherein skegs (18) and (19) whose lower ends are located below a lower end of the thruster are provided at the bottom of the vessel.

5. The vessel according to any of claims 1 to 4,
wherein a fender (36) is provided around the entire circumference of an upper end of the upper side shell (9).

6. The vessel according to any of claims 1 to 5,
wherein a bulbous bow (47) serving as a bow figure configured to be raised or lowered above or below the water line separately from a main hull is provided.

7. The vessel according to any of claims 1 to 6,
wherein the thrusters (23) are nozzle-equipped thrusters that use a flow of water discharged from a pump as thrust.

8. The vessel according to claim 7,
wherein the nozzle-equipped thrusters (23) are configured to be removable.

Drawing