CN108712983B

CN108712983B - Ship with a detachable cover

Info

Publication number: CN108712983B
Application number: CN201680083311.6A
Authority: CN
Inventors: 桧垣幸人
Original assignee: Imabari Shipbuilding Co ltd
Current assignee: Imabari Shipbuilding Co ltd
Priority date: 2016-03-09
Filing date: 2016-10-18
Publication date: 2020-07-03
Anticipated expiration: 2036-10-18
Also published as: CN108712983A; KR20180114084A; WO2017154259A1; KR102122480B1; JP2017159767A; JP6129373B1

Abstract

The invention provides a ship capable of reducing a wave making phenomenon derived from a stern end and frictional resistance generated by heave and inhibiting the wave making phenomenon at a side part of a stern ship. The ship (1) according to the present invention is provided with: first flange sections (21) having a predetermined length and provided at positions on both sides of a hull Center Line (CL) of a bottom (10b) across a stern side (10 a); a second flange portion (22) having a predetermined length and provided at a position outside the first flange portion (21); a first channel (31) which is provided between the first flange parts (21) and has a concave shape; a second channel (32) which is provided between the first flange part (21) and the second flange part (22) and has a concave shape; a first rear-end projecting portion (41) provided at the stern end (10a) of the first flow path (31) so as to connect the first flange portions (21) to each other; and a second rear-end projection (42) provided at the stern end (10a) of the second flow path (32) so as to connect the first flange section (21) and the second flange section (22).

Description

Ship with a detachable cover

Technical Field

The invention relates to a ship, in particular to a ship sailing with a Froude number of about 0.2-0.4.

Background

Using Froude number Fn (Fn ═ ship speed/(vertical line length × gravity acceleration)^1/2) Ships such as ferry ships or transport ships dedicated for automobiles, which are about 0.2 to 0.4, navigate by using the propulsive force generated by the propeller. Such a ship is called a ship having good shipping performance because the ship speed is increased by a small hull resistance during navigation. Therefore, when designing a ship, the shape for reducing the hull resistance is found and determined by experiments or experiences while satisfying design conditions such as the shipping state and the displacement. The hull resistance is generally caused by a wave making phenomenon at the bow, a wave making phenomenon accompanied by the fluctuation of a side wave flowing along the side, and the rise of a stern wave derived from the stern endPhenomena, etc. Therefore, in order to reduce hull resistance, it is desirable to improve the bow wave-making phenomenon, the bow wave-making phenomenon caused by the side waves, and the bow wave-making phenomenon.

In a ship, a water flow flowing from a bow along a bottom surface and a side surface of the ship is suddenly interrupted at a stern end, so that the water flow rises near the center of the stern end near the water surface and spreads near the side surface of the ship. In addition, when the ship is underway, a sinkage (sinkage) phenomenon occurs in which the hull sinks to the water surface. Frictional resistance is generated between the hull surface under the water surface and the viscous sea water, and the frictional resistance increases as the submerged area increases, and this frictional resistance becomes hull resistance. Among them, ships disclosed in patent documents 1 to 3 are known as ships that reduce hull resistance by paying attention to a wake wave caused by a water flow at a stern end and frictional resistance caused by heaving.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2001-219892

Patent document 2: japanese patent No. 3490392

Patent document 3: japanese patent No. 5634567

Disclosure of Invention

Problems to be solved by the invention

However, in any of these vessels, a rear-end projecting portion called a trim or a wedge is provided at the stern end to suppress a bow wave derived from the stern end and reduce frictional resistance due to heaving, but it is difficult to suppress a bow wave at the side of the stern, and there is a problem that sufficient reduction in hull resistance cannot be obtained.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a ship capable of reducing a wave-making phenomenon derived from a stern end and a frictional resistance due to heave, and suppressing a wave-making phenomenon at a side portion of a stern.

Means for solving the problems

The ship according to the present invention includes: first flange portions provided at positions on both sides of a hull center line across a bottom on a stern side, and having a predetermined length: a second flange portion provided at an outer position of the first flange portion and having a given length; a first channel which is provided between the first flange parts and has a concave shape; a second flow path which is provided between the first flange portion and the second flange portion and has a concave shape; a first rear-end projecting portion provided at the stern end of the first flow path so as to connect the first flange portions; and a second rear-end projecting portion provided at the stern end of the second flow path so as to connect the first flange portion and the second flange portion.

The ship according to the present invention is provided with the first flange portion and the second flange portion at the bottom of the stern, and thereby, when the ship is underway, the water flow along the bottom surface of the hull near the center line of the hull near the planned waterline of the stern and the water flow flowing along the side of the stern can be sucked, and turbulence such as a separation phenomenon can be rectified and guided toward the stern end. At this time, since the first flow path is provided between the first flange portions, the water flow is contracted and accelerated in the first flow path. The water current after the contraction and acceleration collides with a first rear end projection provided at the stern end of the first flow path, thereby suppressing the water current derived from the stern end from rising. Further, since the second flow path is provided between the first flange portion and the second flange portion, the wave-making phenomenon of the stern-side wave can be suppressed. Further, since the first rear-end protrusion and the second rear-end protrusion are provided at the stern end, an angle of attack can be provided for the water flow that is guided toward the stern end with acceleration. Therefore, the water flow decelerates and deflects towards the rear below, the wing theoretical effect of improving the pressure of the bottom surface of the stern end ship is brought, and the tail part of the ship body can be lifted. Although the entire hull is sunk, which is called heaving, when the ship is sailed, the posture of the ship can be changed by the lift effect of the stern end due to the first rear-end protrusion and the second rear-end protrusion, and the hull can be raised as a whole. This reduces the water-immersed area of the hull, thereby reducing the frictional resistance on the hull surface.

In the ship of the preferred embodiment, the first flow path is curved upward in a concave shape with respect to a straight line connecting the first flange portion and the hull center line, and is curved upward in a concave shape with respect to a straight line connecting the front end and the rear end of the center line between the first flange portion and the hull center line, and the second flow path is curved upward in a concave shape with respect to a straight line connecting the first flange portion and the second flange portion, and is curved upward in a concave shape with respect to a straight line connecting the front end and the rear end of the center line between the first flange portion and the second flange portion.

In a preferred further embodiment, the first flow path is curved upward in a concave shape with respect to a straight line connecting the first flange portions, and is curved upward in a concave shape with respect to a straight line connecting front and rear ends of a center line between the first flange portions, and the second flow path is curved upward in a concave shape with respect to a straight line connecting the first flange portions and the second flange portions, and is curved upward in a concave shape with respect to a straight line connecting front and rear ends of a center line between the first flange portions and the second flange portions.

By forming the first and second flow paths in a smooth concave curved shape in this manner, it is possible to suppress the flow of water passing through the first and second flow paths from coming into contact with the corners of the flow paths and causing separation or undulation, and thus further suppress the swell of the flow of water derived from the stern end or the wave-making phenomenon of the stern-side wave.

In the ship according to the preferred embodiment, the first flow path is provided upward from a position 0.3 times the planned draft below the planned draft line, and the second flow path is provided upward from a position 0.1 times the planned draft below the planned draft line.

In the ship according to the preferred embodiment, the first flow path and the second flow path are provided rearward from positions 0.2 times longer than the stern vertical line toward the front vertical line.

In the ship according to the preferred embodiment, the lower end of the first rear-end projection is located within a range from a position 0.2 times the planned draft above the planned draft to the planned draft, and the lower end of the second rear-end projection is located within a range from a position 0.3 times the planned draft above the planned draft to the planned draft.

In a preferred embodiment, the ship has a froude number of 0.2 to 0.4.

Effects of the invention

According to the ship of the present invention, the wave making phenomenon derived from the stern end and the frictional resistance due to heave are reduced, and the wave making phenomenon at the side of the stern ship can be suppressed.

Drawings

Fig. 1 is a perspective view showing an embodiment of a stern portion of a ship according to the present invention.

Fig. 2 is a side view of the vessel of fig. 1.

Fig. 3 is a bottom view of the vessel of fig. 1.

Fig. 4 is an end view of the line a-a of the vessel of fig. 2.

Fig. 5 is a B-B line end view of the vessel of fig. 2.

Fig. 6 is a comparison of stern side waveforms.

Fig. 7 is a comparative graph of hull resistance curves.

Fig. 8 is an end view of a stern portion of a ship according to another embodiment of the present invention, which is cut along line a-a of fig. 2.

Fig. 9 is an end view of a ship tail section according to another embodiment of the present invention, which is cut along line a-a of fig. 2.

Fig. 10 is an end view of a stern portion of a ship according to another embodiment of the present invention, which is cut along line a-a of fig. 2.

Fig. 11 is an end view of a ship tail section according to another embodiment of the present invention, cut along the line a-a of fig. 2.

Fig. 12 is an end view of a stern portion of a ship according to another embodiment of the present invention, which is cut along line a-a of fig. 2.

Detailed Description

An embodiment of a ship according to the present invention will be described below with reference to fig. 1 to 5. The ship 1 of the present invention is a displacement-type general commercial ship such as a ferry or an automobile-dedicated carrier, which travels around a froude number of 0.2 to 0.4, and includes a hull 10, a propeller 2 for generating propulsive force at the stern, and a rudder 3 (see fig. 2) for steering the travel. In fig. 1 and 3, the propeller 2 and the rudder 3 are omitted for easy understanding of the drawings. Hereinafter, the bow side is defined as the front, the stern side is defined as the rear, and in the horizontal plane, the direction orthogonal to the front-rear direction is defined as the left-right direction, and the directions orthogonal to the front-rear direction and the left-right direction are defined as the up-down direction. The fore-and-aft direction, i.e., the ship length direction, is defined as the X direction, the lateral direction, i.e., the ship width direction, is defined as the Y direction, and the vertical direction is defined as the Z direction.

The ship bottom 10b on the stern 10a side of the ship body 10 includes: first flange portions 21 provided at both sides of a hull center line CL; and a second flange portion 22 provided at a position outside the first flange portion 21. The hull center line CL is a line passing through the center of the hull 10 in the width direction. In the present embodiment, a protrusion 23 is provided along the hull center line CL at the bottom 10b on the stern 10a side (see fig. 4). A first flow path 31 is provided in a portion of the bottom 10b between the first flange portion 21 and the hull center line CL, and a second flow path 32 is provided in a portion of the bottom 10b between the first flange portion 21 and the second flange portion 22. Further, a first rear-end projecting portion 41 is provided at the stern end 10a of the first flow path 31 so as to connect the first flange portions 21 to each other, and a second rear-end projecting portion 42 is provided at the stern end 10a of the second flow path 32 so as to connect the first flange portions 21 to the second flange portions 22.

As shown in fig. 4 and 5, the first flange portion 21 and the second flange portion 22 have a cross-sectional shape with a sharp tip and extend a predetermined length in the ship length direction (X direction in fig. 1 to 3). Specifically, the first flange portion 21 and the second flange portion 22 extend from positions forward of the stern perpendicular line AP by a predetermined distance L toward the stern end 10 a. To avoid an increase in hull resistance, the predetermined distance L is preferably short, and is approximately 0.2 times shorter than the vertical line length Lpp.

The forward end P21F and the rearward end P21A of the first flange portion 21 are provided at positions where the distances B21F and B21A from the hull center line CL are respectively 0.6 times or less the maximum half width (length of half the maximum width) BH of the hull 10. The forward end P22F and the rearward end P22A of the second flange portion 22 are provided at positions that are greater than the distances B21F and B21A from the hull center line CL by distances B22F and B22A, respectively, and that are 0.4 times or more the maximum half width BH of the hull 10.

The front end P21F of the first flange portion 21 and the front end P22F of the second flange portion 22 are substantially flush with the bottom surface 10b of the ship so as not to serve as hull resistance. The rear ends P21A and P22A of the first and

second flange portions

21 and 22 are also located at substantially the same positions as the lower ends of the first and second

rear end protrusions

41 and 42, respectively, so that the ship's hull resistance is not generated.

The first flow path 31 is provided between the first flange portions 21, and in the present embodiment, the first flow path 31 is divided into left and right by the protrusions 23 along the hull center line CL. The first flow path 31 has a center line T1 between the first flange portion 21 and the hull center line CL, and is disposed at a position close to the hull center line CL. The bottom surface of the first flow path 31 is curved concavely upward with respect to a straight line L1 connecting the first flange portion 21 and the hull center line CL, and curved concavely upward with respect to a straight line L3 connecting the front end PT1F and the rear end PT1A of the center line T1. The first flow path 31 is disposed from a shallow water level below the planned water line DL to a position above the planned water line DL. Specifically, the front end PT1F of the center line T1 of the first flow path 31 is arranged such that the distance Z4 below the planned waterline DL is within 0.3 times the planned draught d and the distance L forward from the stern perpendicular line AP is within 0.2 times the perpendicular line length Lpp.

The second flow path 32 is formed by the first flange portion 21 and the second flange portion 22, has a center line T2 between the first flange portion 21 and the second flange portion 22, and is disposed at a position closer to the ship side. The bottom surface of the second channel 32 is curved concavely upward with respect to a straight line L2 connecting the first flange portion 21 and the second flange portion 22, and curved concavely upward with respect to a straight line L4 connecting the front end PT2F and the rear end PT2A of the center line T2. The second flow path 32 is disposed above the planned water line DL from a shallow water area below the planned water line DL or near the planned water line DL. Specifically, the front end PT2F of the center line T2 of the second flow path 32 is disposed such that the distance Z3 above or below the planned waterline DL is within 0.1 times the planned draft d and the distance L forward from the stern perpendicular line AP is within 0.2 times the perpendicular line length Lpp.

The first flow path 31 and the second flow path 32 preferably extend above the propeller 2 and the rudder 3. With such a configuration, the flow of water on the surface of the hull 10 near the hull center line CL is rectified and guided toward the rudder 3. This can reduce an increase in resistance due to the rudder 3, improve the effect of the rudder 3 during steering, and contribute to improvement in drivability and safety.

The first rear-end protrusion 41 and the second rear-end protrusion 42 are formed in a substantially triangular shape extending vertically on the stern end 10a side and obliquely extending at a predetermined angle on the front side in side view. The inclination on the front side can be any inclination as long as it provides an angle of attack with respect to the water current flowing toward the stern end 10 a. The rear end PT1A of the first rear-end protrusion 41 at the center line T1 is arranged above the planned waterline DL by a distance Z11, and the distance Z11 is within 0.2 times the planned draft d. Similarly, the rear end PT2A of the second rear-end protrusion 42 at the center line T2 is also arranged above the planned waterline DL by a distance Z12, and the distance Z12 is within 0.3 times the planned draft d.

The most depressed portion of the first flow path 31 in the ship length direction of the center line T1 is located above the rear end PT1A of the first rear-end protrusion 41 on the center line T1 by a distance Z21, and the distance Z21 is within 0.2 times the planned draft d. Similarly, the position of the most depressed portion of the second flow path 32 in the ship length direction of the center line T2 is a position that is a distance Z22 above the rear end PT2A of the second rear-end protrusion 42 at the center line T2, and the distance Z22 is within 0.2 times the planned draft d.

Next, a description will be given of how much the ship 1 of the present invention can suppress the ship side waves and how much the hull resistance can be reduced, in comparison with the comparative example. Comparative example 1 is a conventional general ship, and is a ship of a type having no first flow path, second flow path, first rear-end protrusion, and second rear-end protrusion at the bottom of the ship. Comparative example 2 is a ship of the type in which the first flow path 31 and the first rear-end protrusion 41 are provided on the bottom of the ship.

Fig. 6 shows ship-side waveforms of the present invention, comparative example 1, and comparative example 2. The ship-side waveform represents the range from the center of the hull to the rear in the ship longitudinal direction, and 0.0 represents the position of the center of the hull and 0.5 represents the position of the stern perpendicular line AP in X/Lpp (vertical line length) on the horizontal axis. In addition, the position of the horizontal axis 0.52 represents the stern end 10 a. The vertical axis Z/Lpp is a value obtained by dividing the height Z of the waveform by the vertical line length Lpp and performing non-dimensionalization. As shown in fig. 6, in the present invention, the height of the waveform is lower at the stern end 10a than in comparative example 1. Further, the wave shape is also smaller in front of the stern end 10a than in comparative examples 1 and 2, and the bulge of the wake derived from the stern end 10a (the wave shape behind the stern end) is also smaller. As the height Z of the waveform becomes smaller as described above, the wave-making phenomenon of the stern 10a is improved, and thus it is confirmed from fig. 6 that the present invention can suppress the wave-making phenomenon of the stern 10 a.

Fig. 7 shows hull resistance of the present invention, comparative example 1, and comparative example 2. The horizontal axis Fn is the froude number during sailing, and the vertical axis rR is the hull resistance. As is clear from fig. 7, the hull resistance of the present invention is smaller than that of comparative examples 1 and 2 at froude numbers around the sea speed, and it is confirmed that the present invention can reduce the hull resistance.

In the ship 1, the flow of water flowing from the bow along the bottom surface 10b and the side surface of the ship is suddenly interrupted at the stern end 10a, so that the flow rises near the center of the stern end 10a near the water surface, and the flow spreads near the side surface of the ship, thereby generating a wake wave called a back wave (back wave). Further, if the wave making phenomenon at the stern end 10a is large, the hull resistance increases.

However, in the present embodiment, by providing the first flange portion 21 on the bottom 10b on the stern 10a side, it is possible to perform acceleration guidance while rectifying a turbulent flow such as a separation phenomenon that occurs along the bottom surface 10b in the vicinity of the hull center line CL near the planned waterline DL of the stern 10a when the ship 1 is underway. Further, by providing the second flange portion 22 at the bottom 10b of the stern 10a, the water flow flowing along the side of the stern 10a can be sucked, and the acceleration guide can be performed while suppressing the spreading phenomenon of the stern wave. At this time, since the first flow path 31 is provided between the first flange portions 21, the water flow is contracted and accelerated in the first flow path 31. The contracted and accelerated water flow collides with the first rear-end protrusion 41 provided at the stern end 10a of the first flow path 31, thereby suppressing the rise of the water flow derived from the stern end 10 a. Further, since the second flow path 32 is provided between the first flange portion 21 and the second flange portion 22, the wave-making phenomenon of the stern-side wave can be suppressed.

Further, since the first rear-end protrusion 41 and the second rear-end protrusion 42 are provided at the stern end 10a, an angle of attack can be provided for the water flow that is accelerated and guided toward the stern end 10 a. This makes the water flow to be decelerated and deflected downward and rearward, and the wing theoretical effect of increasing the pressure of the bottom surface 10b of the stern end 10a is brought about, so that the hull stern portion 10a can be raised. Although the phenomenon called heaving occurs when the entire hull 10 sinks when the ship 1 is underway, the posture during sailing can be changed by the lift effect of the stern end 10a produced by the first rear-end protrusion 41 and the second rear-end protrusion 42, and the hull 10 can be raised as a whole. This reduces the water-immersion area of the hull 10, thereby reducing the frictional resistance of the surface of the hull 10.

In the present embodiment, the first flow path 31 and the second flow path 32 are formed in a smooth concavely curved shape, so that the flow passing through the first flow path 31 and the second flow path 32 can be prevented from being separated or fluctuating by hitting the corner portions of the flow paths, and the rise of the flow derived from the stern end 10a or the wave-making phenomenon of the stern-side wave can be further prevented.

In the present embodiment, the first flow path 31 and the second flow path 32 are arranged from a shallow water area below the planned waterline DL to above the planned waterline DL, and are also arranged such that the distance L forward from the stern perpendicular line AP is within 0.2 times the vertical line length Lpp in the ship length direction. By providing the first flow path 31 and the second flow path 32 at such positions, the first flow path 31 and the second flow path 32 do not affect the flow of the water flow along the bottom 10b ahead of the propeller 2, and as a result, the influence on the performance of the propeller 2 can be avoided to the maximum extent. Further, if the first flange portion 21 for forming the first flow path 31 is provided from a position greatly distant from the front of the stern perpendicular line AP to the deep bottom surface 10b below the planned waterline DL, the flow along the bottom surface 10b may collide with the first flange portion 21 to increase the resistance, and the first flange portion 21 may adversely affect the flow along the bottom surface 10 b. However, by arranging the first flow path 31 from a shallow water level below the planned waterline DL to above the planned waterline DL and arranging the distance L forward from the stern perpendicular line AP to within 0.2 times the perpendicular line length Lpp in the ship length direction, it is possible to suppress adverse effects on the water flow along the bottom surface 10b to the maximum, and thus it is possible to avoid an increase in hull resistance due to adverse effects on the water flow near the bottom 10 b.

Further, in the present embodiment, by reducing the hull resistance, the fuel consumption consumed when the ship 1 is sailed is improved, and efficient ship sailing can be realized.

Although one embodiment of the present invention has been described above, the present invention is not limited to this embodiment, and various modifications can be made without departing from the spirit and scope of the invention.

For example, the distances L, B21F, B21A, B22F, B22A, Z11, Z12, Z21, Z22, Z3, and Z4 determined in the above embodiment are merely reference values, and can be changed as appropriate depending on the type of the ship 1.

In the above embodiment, the first flange portion 21 and the second flange portion 22 have the cross-sectional shapes having sharp tips, but the cross-sectional shapes of the first flange portion 21 and the second flange portion 22 are not limited to the above embodiment. For example, as shown in fig. 8, the first flange portion 21 and the second flange portion 22 may have a cross-sectional shape in which the distal ends are curved in an arc shape. As shown in fig. 9, the first flange portion 21 may have an arcuate front end and the second flange portion 22 may have a cross-sectional shape with a sharp front end. Of course the reverse could be used.

In the above embodiment, the first flow path 31 is divided into the left and right by the protrusion 23 along the hull center line CL of the first flow path 31, but the first flow path 31 is not limited to the above embodiment. For example, as shown in fig. 9, the first flange portions 21 can be formed on both sides with the hull center line CL therebetween. In this case, the bottom surface of the first flow channel 31 may be curved in a concave shape upward with respect to the straight line L5 connecting the first flange portions 21 and may be curved in a concave shape upward with respect to the straight line connecting the front end and the rear end of the center line between the first flange portions 21.

In the above embodiment, the first channel 31 and the second channel 32 are formed so as to curve upward in a concave shape with respect to the straight line L1 and the straight line L2, but the present invention is not limited to this embodiment. For example, as shown in fig. 10 or 11, the first flow path 31 and the second flow path 32 may be formed so as to be recessed upward with respect to the straight line L1 and the straight line L2 in a trapezoidal shape in cross section or a triangular shape in cross section. The first flow path 31 and the second flow path 32 do not necessarily have to have the same cross-sectional shape, and various arbitrary combinations may be employed, for example, the first flow path 31 is recessed upward with respect to the straight line L1 in a trapezoidal shape in cross section, and the second flow path 32 is recessed upward with respect to the straight line L2 in a triangular shape in cross section. In addition, any cross-sectional shape can be adopted as long as the cross-sectional shapes of the first flow channel 31 and the second flow channel 32 are recessed upward. As shown in fig. 12, the first flange portion 21, the second flange portion 22, the first flow path 31, and the second flow path 32 may be formed by attaching a projection 24 having a substantially triangular cross section to the existing bottom 10b by welding or the like. At this time, it is preferable to form the protrusion 24 such that the first flow channel 31 and the second flow channel 32 are concavely curved upward with respect to a straight line connecting the protrusions 24.

In the above embodiment, the stern end 10a side of the first and second rear-

end protrusions

41, 42 extends vertically, but the mode of the stern end 10a side of the first and second rear-

end protrusions

41, 42 is not limited to this mode. For example, in the case where the stern end 10a of the hull 10 has a surface inclined such that the upper portion is located rearward with respect to the vertical plane, the surfaces of the first and second rear-

end protrusions

41 and 42 on the stern end 10a side may extend along the surface of the stern end 10a of the hull 10. The surfaces of the first rear-end protrusion 41 and the second rear-end protrusion 42 on the stern end 10a side do not necessarily have to be along the surface of the stern end 10a of the hull 10, and may extend at an arbitrary inclination with respect to the vertical plane.

Description of the symbols

1 Ship

10a stern

10b bottom of ship

21 first flange part

22 second flange part

31 first flow path

32 second flow path

41 first rear end projection

42 second rear end projection

AP stern perpendicular line

CL hull center line

d plan draught

DL planned waterline

Length between Lpp vertical lines

Center line between first flange part of T1 and hull center line

T2 center line between first and second flange parts

Length direction of X ship

And Y is in the ship width direction.

Claims

1. A ship is provided with:

first flange portions provided at positions on both sides of a hull center line of a bottom on a stern side, and having a given length:

a second flange portion provided at an outer position of the first flange portion and having a given length;

a first flow path which is provided between the first flange portions and has a concave shape;

a second flow path which is provided between the first flange portion and the second flange portion and has a concave shape;

a first rear-end projecting portion provided at a stern end of the first flow path so as to connect the first flange portions; and

a second rear-end projecting portion provided at a stern end of the second flow path so as to connect the first flange portion and the second flange portion,

the first flow path and the second flow path are provided rearward from a position 0.2 times longer than a line perpendicular to the forward direction of the stern.

2. The vessel of claim 1, wherein,

the first flow path is curved upward in a concave shape with respect to a straight line connecting the first flange portion and the hull center line, and is curved upward in a concave shape with respect to a straight line connecting a front end and a rear end of a center line between the first flange portion and the hull center line,

the second flow path is curved upward in a concave shape with respect to a straight line connecting the first flange portion and the second flange portion, and is curved upward in a concave shape with respect to a straight line connecting a front end and a rear end of a center line between the first flange portion and the second flange portion.

3. The vessel of claim 1, wherein,

the first flow path is curved upward in a concave shape with respect to a straight line connecting the first flange portions, and is curved upward in a concave shape with respect to a straight line connecting front and rear ends of a center line between the first flange portions,

4. The vessel of any one of claims 1 to 3,

the first flow path is provided upward from a position lower than the planned draft line by 0.3 times the planned draft,

the second flow path is provided upward from a position lower than the planned draft line by 0.1 times the planned draft.

5. The vessel of any one of claims 1 to 3,

the lower end of the first rear-end projection is located within a range from a position 0.2 times the planned draft above the planned draft line to the planned draft line,

the lower end of the second rear-end projection is in the range from a position 0.3 times the planned draft above the planned draft line to the planned draft line.