WO2023223617A1

WO2023223617A1 - Ship

Info

Publication number: WO2023223617A1
Application number: PCT/JP2023/005544
Authority: WO
Inventors: 大輔松本; 信川淵; 雅也窪田
Original assignee: 三菱重工業株式会社
Priority date: 2022-05-19
Filing date: 2023-02-16
Publication date: 2023-11-23
Also published as: CN118591491A; JP2023170395A

Abstract

This ship comprises a stern end surface, and a stern bottom surface connected to the stern end surface. The stern bottom surface comprises: a main bottom surface spreading out in a ship width direction, and sloping upward toward the stern side; and a stern lower portion that has a sloping surface provided at a central portion in the ship width direction of a rear end of the main bottom surface and extends downward toward the stern side, and a rear surface connected to the stern side of the sloping surface and being flush with the stern end surface. The main bottom surface and the stern lower portion are smoothly connected without forming a connection line at a boundary between the main bottom surface and the stern lower portion.

Description

ship

TECHNICAL FIELD This disclosure relates to ships.
This application claims priority based on Japanese Patent Application No. 2022-082117 filed in Japan on May 19, 2022, the contents of which are incorporated herein.

Patent Document 1 discloses a ship in which an additional member with a triangular cross section is attached to the stern end of an existing transom stern. This additional member projects rearward from the stern end and is inclined slightly backward from horizontal. This reduces wave-making resistance when the ship navigates.

Japanese Patent No. 3490392

Incidentally, in recent years, ships are increasingly required to reduce operating costs by improving fuel efficiency. Therefore, it is important to reduce the hull resistance during navigation, and it is desired to further reduce the hull resistance by improving the above-mentioned conventional stern shape.

The present disclosure has been made to solve the above problems, and an object of the present disclosure is to provide a ship that can reduce hull resistance.

In order to solve the above problems, a ship according to the present disclosure includes a stern end surface and a stern bottom surface connected to the stern end surface, and the stern bottom surface extends across the width direction of the ship and extends upward toward the stern side. a main bottom surface that slopes toward the stern; a slanted surface that is provided at the center of the rear end of the main bottom surface in the width direction of the ship and extends downward toward the stern side; a lower stern having a rear surface flush with the stern end surface, the main bottom surface and the lower stern being smoothly connected without forming a connecting line at the boundary between the main bottom surface and the lower stern. ing.

According to the ship of the present disclosure, hull resistance can be reduced.

FIG. 1 is a side view of a ship according to an embodiment of the present disclosure. FIG. 2 is a downward perspective view showing the stern of the ship according to the embodiment of the present disclosure. 1 is a diagram of the stern of a ship according to an embodiment of the present disclosure viewed from the rear. FIG. 1 is a view of the stern of a ship according to an embodiment of the present disclosure viewed from below. FIG. 1 is a side view of the stern of a ship according to an embodiment of the present disclosure. FIG. FIG. 3 is a diagram showing a change in the coefficient of residual resistance with respect to the Froude number for a ship according to an embodiment of the present disclosure.

Hereinafter, a ship 1 according to an embodiment of the present disclosure will be described with reference to FIGS. 1 to 6. In the present embodiment, the ship 1 will be described using, as an example, a slender ship with a fast sailing speed. Examples of such ships 1 include ferries such as ROPAX, passenger ships, container ships, pure car and truck carriers (PCTCs), and cargo ships such as RORO ships.

(ship)
As shown in FIG. 1, a ship 1 has a transom stern structure. The ship 1 is formed into an elongated shape in the traveling direction D1. That is, the captain direction of the ship 1 coincides with the traveling direction D1 of the ship 1.
Hereinafter, the direction perpendicular to the traveling direction D1 of the ship 1 and the direction along the horizontal plane may be referred to as the ship width direction D2.

As shown in FIGS. 1 and 2, the ship 1 includes a hull 2, a propulsion device 20, and a rudder 30.

(hull)
The hull 2 includes a side 3, a bottom 4, an upper deck 5, a bow 6, and a stern 10.

A pair of sides 3 are provided facing each other in the ship width direction D2. Each side 3 extends in the traveling direction D1. The bottom 4 connects the lower portions of the pair of sides 3. The bottom 4, like the side 3, extends in the traveling direction D1. The boundary between the bottom 4 and the side 3 is shown by a broken line in FIG. 2, but the bottom 4 and the side 3 are smoothly connected without forming a connecting line at the boundary between the bottom 4 and the side 3. There is. The upper deck 5 is provided over the upper portions of the pair of sides 3. The upper deck 5, like the side 3, extends in the traveling direction D1. A superstructure (not shown) such as a bridge is installed on the upper deck 5. The bow 6 is located on the front side of the hull 2 in the traveling direction D1. The stern 10 is located on the rear side of the hull 2 in the traveling direction D1. The bow 6 and the stern 10 are connected by the side 3, the bottom 4, and the upper deck 5.
The hull 2 is formed into a box shape by the side 3, bottom 4, upper deck 5, bow 6, and stern 10.

Hereinafter, the front side of the ship 1 in the traveling direction D1 will be referred to as the "bow side", and the rear side of the ship 1 in the traveling direction D1 will be referred to as the "stern side".

(stern)
The stern 10 includes a stern end surface 11 and a stern bottom surface 12.

(stern end surface)
The stern end surface 11 is formed into a planar shape extending vertically in the up-down direction. In this embodiment, the stern end surface 11 is perpendicular to the traveling direction D1 (ship direction). The stern end surface 11 is formed symmetrically with respect to a hull centerline C extending in the traveling direction D1 of the hull 2. The dimension of the stern end surface 11 in the ship width direction D2 gradually becomes smaller toward the bottom. The lower edge of the stern end surface 11 is formed into a dome shape that is curved downward when viewed from the stern side.

(bottom of stern)
The stern bottom surface 12 is continuous with the stern end surface 11. Further, the stern bottom surface 12 is continuous with the side 3 and the bottom 4 of the ship.
Details of the shape of the stern bottom surface 12 will be described later.

(propulsion device)
The propulsion device 20 is provided below the stern bottom surface 12. The propulsion device 20 of this embodiment is a propeller 21.

The stern 10 of this embodiment is a so-called single-shaft stern. One propeller 21 is arranged on the hull centerline C when viewed from below. The propeller 21 is connected to the bottom 4 via a propeller shaft 22. The propeller shaft 22 extends in the traveling direction D1. The propeller shaft 22 passes through the bottom 4 of the ship. The front end of the propeller shaft 22 is connected to a prime mover (not shown) provided in the bottom 4 of the ship. The driving force of a prime mover within the ship bottom 4 is transmitted to the propeller 21 via a propeller shaft 22 . The propeller 21 is rotated by the driving force of the prime mover. The rotation of the propeller 21 generates a propulsive force on the ship 1 .
Note that the ship 1 may have a center skeg and two propellers 21 or two azimuth propulsors instead of the single-shaft stern and one propeller 21.

(rudder)
The rudder 30 is located closer to the stern than the propeller 21. The rudder 30 is provided along the hull center line C when viewed from below. The rudder 30 is attached to the stern bottom surface 12 via a rudder post 31. The rudder post 31 projects downward from the stern bottom surface 12. The lower end of the rudder post 31 is connected to the front portion of the upper end of the rudder 30 . The rudder 30 is provided around a rudder post 31 so that its angle can be changed.

Hereinafter, a perpendicular that passes through the intersection of the load waterline WL and the bow 6 and extends in the vertical direction will be referred to as a front perpendicular F. P. A perpendicular line passing through the central axis of the rudder post 31 and extending vertically is called a rear perpendicular line A. P. It is called. Also, the front perpendicular F. P. and rear perpendicular A. P. The distance between the two in the traveling direction D1 is referred to as the perpendicular length Lpp. In addition, a perpendicular line passing through the center of the propeller 21 and extending in the vertical direction is a propeller center perpendicular line P. C. It is called. Also, connect the rear end of the stern bottom surface 12 to the stern end A. E. It is called.

(Details of the shape of the bottom of the stern)
The details of the shape of the stern bottom surface 12 will be described below with reference to FIG. 2 and FIGS. 3 to 5.
As shown in FIG. 2, the stern bottom surface 12 includes a main bottom surface 13 and a stern lower portion 14.

(Main bottom surface)
The main bottom surface 13 is smoothly connected to the bottom 4 of the ship. The main bottom surface 13 extends rearward in the traveling direction D1 from the rear end of the boat bottom 4 toward the stern end surface 11. Hereinafter, the perpendicular line passing through the front end of the main bottom surface 13 will be defined as line AA. Line AA is the propeller center perpendicular line P. in the traveling direction D1. C. and rear perpendicular A. P. It is located between.

Although the boundary between the main bottom surface 13 and the gunwale side 3 is shown by a broken line in FIG. It is connected. Similarly, although the boundary between the main bottom surface 13 and the hull bottom 4 is shown as a broken line in FIG. Connected smoothly without any problem.

In FIG. 3, the stern end surface 11 and the outline of the cross section of the stern 10 as seen from the stern side are disclosed. The cross section of the stern 10 disclosed in FIG. 3 is a cross section perpendicular to the traveling direction D1. In FIG. 3, as a representative example, the outline of the cross section along line AA (double-dashed line) and the rear perpendicular line A. P. The outline of the cross section along the line (dotted chain line) and the stern end A. E. An outline (solid line) of the stern end surface 11 along the stern end surface 11 is shown.

In FIG. 4, the outline of the cross section of the stern 10 as seen from below is disclosed. The cross section of the stern 10 disclosed in FIG. 4 is a cross section perpendicular to the vertical direction. In FIG. 4, a plurality of outlines of the cross section of the stern 10 having different heights (z) of the bottom 4 from the base line BL are disclosed. Assuming that the heights (z) of the bottom 4 from the base line BL are z=a, b, c, and d in descending order, FIG. Illustrated. z=a is the stern end A. E. z=d is the height of the upper end of the stern bottom surface 12. The dimensional differences ba, cb, and dc are all equal. Furthermore, in addition to the outlines of the four cross sections with heights z=a, b, c, and d, FIG. The outline of the cross section at the height between z=c and d is shown.

Further, in FIG. 4, as a comparative example, an example of the knuckle line NL is illustrated with a broken line at the position of the cross section at height z=a. The knuckle line NL shown in FIG. 4 is just a comparative example and does not exist in this embodiment.

In FIG. 5, the outline of the cross section of the stern 10 as seen from the ship width direction D2 is disclosed. The cross section of the stern 10 disclosed in FIG. 5 is a cross section perpendicular to the ship width direction D2. In FIG. 5, the outline of a cross-section along the hull centerline C and the outline of a plurality of cross-sections located outside the hull centerline C in the ship width direction D2 are disclosed. The lower end of the outline of each cross-section shown in FIG. 5 is located upward as it is located further outward in the ship width direction D2 from the hull center line C.
3 to 5, only the shape of the hull 2 is illustrated, and the propulsion device 20 and rudder 30 are omitted.

As shown in FIGS. 3 to 5, the main bottom surface 13 extends across the ship's width direction D2 and is connected to the side 3. The main bottom surface 13 is inclined upward toward the stern side. Further, the main bottom surface 13 is formed into a smooth curved surface without any ridgeline.

(lower stern)
As shown in FIG. 2, the stern lower part 14 is provided at the center of the rear end of the main bottom surface 13 in the ship width direction D2. The stern lower part 14 is smoothly connected to the main bottom surface 13 without forming a connecting line at the boundary. In this embodiment, the stern lower part 14 is integrally formed with the main bottom surface 13. That is, the lower stern section 14 is not an addition to the hull 2, but is the outer shape of the hull 2 itself. The lower stern section 14 has an inclined surface 15 and a rear surface 16.

Although the boundary between the inclined surface 15 and the main bottom surface 13 is illustrated by a broken line in FIG. Connected smoothly without any problem. The inclined surface 15 extends downward toward the stern side (see especially FIG. 5). Among the outline lines of the cross section shown in FIG. 5, the rear perpendicular line A. P. The shape of the inclined surface 15 is disclosed on the stern side. The front end of the inclined surface 15 is connected to the line AA and the rear perpendicular line A. P. It is located between. In this embodiment, the front end of the inclined surface 15 is connected to the rear perpendicular line A. P. It is located above. That is, in this embodiment, the center portion of the stern bottom surface 12 in the ship width direction D2 is located from the AA line to the rear perpendicular line A. P. up to the rear perpendicular A. P. From the stern end A. E. It slopes downward toward the stern.

The inclined surface 15 is located closer to the stern than the propulsion device 20. The lower edge of the rear end of the inclined surface 15 is located below the lower edge of the stern end surface 11. The lower edge of the inclined surface 15 is formed into a dome shape that is curved downward when viewed from the stern side.

Further, the rear end portion of the stern bottom surface 12 including the inclined surface 15 changes from a downward slope to an upward slope as it goes outward in the ship width direction D2. This point will be explained in more detail with reference to FIG.

For example, as shown in FIG. 3, in the cross section of the stern 10 perpendicular to the traveling direction D1, the stern end A. E. The outline (solid line) of the stern end surface 11 in A. and the rear perpendicular A. P. The outline line (dotted chain line) of the cross section intersects between the hull center line C in the ship width direction D2 and the outermost end (end on the side 3 side) in the ship width direction D2. In FIG. 3, the stern end A. E. The outline of the stern end surface 11 and the rear perpendicular line A. P. The position in the ship width direction D2 where the outline of the cross section intersects is shown by line BB. On the inside of the BB line in the ship width direction D2, the stern end A. E. The outline of the stern end surface 11 at A. P. The rear perpendicular line A. is located below the outline of the cross section at A. P. approaches upwardly the outline of the cross section at . Further, at the outer side of the BB line in the ship width direction D2, the stern end A. E. The outline of the stern end surface 11 at A. P. The rear perpendicular line A. P. It is spaced upward from the outline of the cross section at. Furthermore, when approaching the gunwale side 3, the stern end A. E. The outline of the stern end surface 11 at A. P. , and almost overlap at the outermost end in the ship width direction D2.

In this way, the rear end portion of the stern bottom surface 12 including the inclined surface 15 is inclined downward as it goes toward the stern side on the inside of the BB line in the ship width direction D2, and is also wider than the BB line. On the outside in direction D2, it slopes upward toward the stern side. That is, the boundary between the inclined surface 15 and the main bottom surface 13 in the ship width direction D2 is located on the line BB.

Further, as shown in FIG. 4, at the rear end of the stern bottom surface 12 including the inclined surface 15, the outline at the same vertical position expands in the transverse direction D2 as it goes toward the stern side.

Further, at the rear end portion of the stern bottom surface 12 including the inclined surface 15, the outline at the same vertical position changes upward to be perpendicular to the ship width direction D2. More specifically, the contour line at the same vertical position at the rear end of the stern bottom surface 12 including the inclined surface 15 becomes less concave toward the hull center line C as the height from the bottom 4 increases. At the same time, it approaches the gunwale 3, and near the gunwale 3 it has a convex shape that slightly protrudes to the side opposite to the hull centerline C. Further, the outline of the rear end portion of the stern bottom surface 12 including the inclined surface 15 at the same vertical position has a shape extending along the side 3 at the same height as the side 3.

Further, as shown in FIGS. 3 and 4, the entire stern bottom surface 12 including the inclined surface 15 is formed into a smooth curved surface.

As shown in FIG. 3, the rear surface 16 is connected to the stern side of the inclined surface 15 and is flush with the stern end surface 11. Although the boundary between the rear surface 16 and the stern end surface 11 is illustrated by a broken line in FIGS. 2 and 3, the rear surface 16 and the stern end surface 11 form a connecting line at the boundary between the rear surface 16 and the stern end surface 11. Connected smoothly without any problem. The rear surface 16 is formed into a U-shape that opens upward when viewed from the stern side.

(Ship dimensions)
Next, the planned speed and dimensions of the ship 1 according to this embodiment will be explained.
In the ship 1 of this embodiment, the Froude number Fn of the planned speed is set to 0.20 or more and 0.50 or less.
Moreover, the length Lpp between perpendicular lines of the ship 1 is 50 m or more and 400 m or less. From the base line BL of the bottom 4 to the stern end A. E. The height H1 to the lower end of the stern lower part 14 is set to 70% or more and 130% or less, more preferably 80% or more and 120% or less of the height H2 from the base line BL of the bottom 4 to the load water line WL. . The stern end A. is indicated by line BB in Figure 3. E. The outline of the stern end surface 11 and the rear perpendicular line A. P. The distance W1 in the ship width direction D2 between the hull center line C and the hull center line C is the distance W1 in the ship width direction D2 between the outermost end of the hull 2 in the ship width direction D2 and the hull center line C. The distance W2 of D2 is set to 10% or more and 80% or less, more preferably 20% or more and 60% or less. Note that the distance W2 is 1/2 the dimension of the hull 2 in the width direction D2 (width of the hull 2).

(effect)
The ship 1 of this embodiment has the following effects.
In this embodiment, the stern bottom surface 12 includes a main bottom surface 13 and a stern lower portion 14 . The main bottom surface 13 extends across the ship width direction D2 and slopes upward toward the stern side. The stern lower part 14 is provided at the center of the rear end of the main bottom surface 13 in the ship width direction D2. The stern lower part 14 has an inclined surface 15 that extends downward toward the stern side, and a rear surface 16 that is connected to the stern side of the inclined surface 15 and is flush with the stern end surface 11. The main bottom surface 13 and the stern lower portion 14 are smoothly connected to each other without forming a connecting line at the boundary between the main bottom surface 13 and the stern lower portion 14.

A water current flowing along the stern 10 when the ship 1 navigates is deflected downward by the inclined surface 15 of the stern lower part 14. As a result, the stern 10 is pushed upward, and the amount of sinking of the stern 10 is reduced. Therefore, the hull resistance caused by the sinking of the stern 10 can be significantly reduced. Significant reductions in hull resistance improve fuel efficiency and reduce operating costs.
By the way, as in the comparative example shown in FIG. 4, if there is a sudden change in curvature, such as a knuckle line NL, on the stern bottom surface 12, the water flow changes rapidly in the vicinity of this sudden change in curvature. This causes a sudden change in the hull surface pressure and an increase in hull resistance. In contrast, in this embodiment, the main bottom surface 13 and the stern lower part 14 are smoothly connected, so that the water flow and the hull surface pressure change gradually. This further reduces hull resistance.

In this embodiment, the rear end portion of the stern bottom surface 12 including the inclined surface 15 changes from a downward slope to an upward slope as it goes outward in the ship width direction D2.

This makes it possible to provide the inclined surface 15 only at the submerged portion of the stern bottom surface 12. Therefore, the shape of the conventional ship 1 can be maintained as much as possible. Therefore, it becomes easy to apply the stern 10 of this embodiment.

At the rear end of the stern bottom surface 12 including the inclined surface 15 of this embodiment, the outline at the same vertical position expands in the ship width direction D2 toward the stern side.

According to this embodiment, the proportion of the submerged area of the stern 10 occupied by the inclined surface 15 increases. This increases the lift force that pushes up the inclined surface 15 when the ship 1 navigates. Therefore, the amount of sinking of the stern 10 is further suppressed. Therefore, the hull resistance can be further reduced.

At the rear end portion of the stern bottom surface 12 including the inclined surface 15 of this embodiment, the outline at the same vertical position changes upward to be perpendicular to the ship width direction D2.

Thereby, the shape of the conventional ship 1 can be maintained as much as possible. Therefore, it becomes easy to apply the stern 10 of this embodiment.

The entire stern bottom surface 12 including the inclined surface 15 of this embodiment is formed into a smooth curved shape.

According to this embodiment, the water flow and the hull surface pressure change more gently near the stern bottom surface 12. This further reduces hull resistance.

In this embodiment, the ship 1 further includes a propulsion device 20 below the stern bottom surface 12. The inclined surface 15 is located closer to the stern than the propulsion device 20.

According to the present embodiment, it is easy to maintain the clearance between the propulsion device 20 and the stern bottom surface 12 at a specified interval necessary to maintain vibration characteristics.

In this embodiment, the stern lower part 14 is integrally formed with the main bottom surface 13.

Thereby, when forming the stern lower part 14, it becomes easy to prevent a connection line from being formed at the boundary between the main bottom surface 13 and the stern lower part 14. Therefore, changes in the water flow and hull surface pressure near the stern bottom surface 12 can be made gentler, and hull resistance can be reduced more reliably.

In this embodiment, from the base line BL of the bottom 4 to the stern end A. E. The height H1 to the lower end of the stern lower part 14 is set to 70% or more and 130% or less, more preferably 80% or more and 120% or less of the height H2 from the base line BL of the bottom 4 to the load water line WL. . Also, the stern end A. E. The outline of the stern end surface 11 and the rear perpendicular line A. P. The distance W1 in the ship width direction D2 between the hull center line C and the hull center line C is the distance W1 in the ship width direction D2 between the outermost end of the hull 2 in the ship width direction D2 and the hull center line C. The distance W2 of D2 is set to 10% or more and 80% or less, more preferably 20% or more and 60% or less.

When the Froude number Fn of the planned speed is set to 0.20 or more and 0.50 or less, and the perpendicular length Lpp of the vessel 1 is 50 m or more and 400 m or less, the lower end height H1 and distance W1 are set as above. By this, the hull resistance reduction effect by the stern lower part 14 of this embodiment is most effectively exhibited.

Next, the results of confirming the effect of the shape of the stern 10 of the present embodiment described above through CFD (Computational Fluid Dynamics) calculation will be explained with reference to FIG. 6. In this CFD calculation, the lower end height H1 is set to 80% or more and 120% or less of the height H2, and the distance W1 is set to 20% or more and 60% or less of the distance W2. The horizontal axis of FIG. 6 shows the Froude number Fn, and the vertical axis shows the residual resistance coefficient Cr. Here, the residual resistance coefficient Cr is a coefficient indicating the magnitude of residual resistance, and the residual resistance includes viscous pressure resistance and wave-forming resistance.

The triangular points in the figure are the CFD calculation results of the comparative example (ship 1 not equipped with the stern 10 of this embodiment), and the diamond points are the CFD calculation results of the ship 1 equipped with the stern 10 of this embodiment. . The CFD calculation results of the ship 1 equipped with the stern 10 according to the present embodiment are connected by straight lines and illustrated as a so-called line graph.

FIG. 6 shows the transition of the residual resistance coefficient Cr with respect to the Froude number Fn in the range from 0.23 to 0.26. In each calculation result shown in FIG. 6, the residual resistance coefficient Cr changes in the range from 0.003 to 0.009. The residual resistance coefficient Cr of the ship 1 including the stern 10 of this embodiment increases as the Froude number Fn increases.

As shown in FIG. 6, when the Froude number Fn is around 0.245, the residual resistance coefficient Cr is reduced by about 7% from the comparative example. This result shows that the ship 1 of this embodiment has the effect of reducing hull resistance.

(Other embodiments)
Although the embodiment of the present disclosure has been described above in detail with reference to the drawings, the specific configuration is not limited to this embodiment, and includes design changes within the scope of the gist of the present disclosure. .
In the above embodiment, the line AA is the propeller center perpendicular line P. in the traveling direction D1. C. and rear perpendicular A. P. However, it is not limited to this. For example, line AA is the propeller center perpendicular line P. C. and the advancing direction D1 position may overlap.

Note that in the above embodiment, the stern lower part 14 is formed integrally with the main bottom surface 13, but the present invention is not limited to this. For example, the stern lower part 14 may be provided on the main bottom surface 13 afterward.

<Additional notes>
The ship 1 described in each embodiment is understood as follows, for example.

(1) The ship 1 according to the first aspect includes a stern end surface 11 and a stern bottom surface 12 continuous to the stern end surface 11, and the stern bottom surface 12 extends across the ship width direction D2 and extends toward the stern side. Therefore, the main bottom surface 13 slopes upward, and the slope surface 15 is provided at the center of the rear end of the main bottom surface 13 in the ship width direction D2 and extends downward toward the stern side. a stern lower part 14 having a rear surface 16 connected to the stern side of the stern end face 11 and flush with the stern end surface 11, and the main bottom surface 13 and the stern lower part 14 are connected to the stern end surface 11, and the main bottom surface 13 and the stern lower part 14 are are connected smoothly without forming a connecting line at the border.

A water current flowing along the stern 10 when the ship 1 navigates is deflected downward by the inclined surface 15 of the stern lower part 14. As a result, the stern 10 is pushed upward, and the amount of sinking of the stern 10 is reduced. Therefore, the hull resistance caused by the sinking of the stern 10 can be significantly reduced.
By the way, if there is a sudden change in curvature, such as a knuckle line, on the stern bottom surface 12, the water flow changes rapidly in the vicinity of this sudden change in curvature. This causes a sudden change in the hull surface pressure and an increase in hull resistance. In contrast, in this embodiment, the main bottom surface 13 and the lower stern portion 14 are smoothly connected, so that the water flow and the hull surface pressure change gradually. This further reduces hull resistance.

(2) A ship 1 according to a second aspect is the ship 1 according to (1), in which the rear end portion of the stern bottom surface 12 including the slope surface 15 is inclined downwardly toward the outside in the ship width direction D2. It may also change to an upward slope.

This makes it possible to provide the inclined surface 15 only at the submerged portion of the stern bottom surface 12. Therefore, the shape of the conventional ship 1 can be maintained as much as possible.

(3) The ship 1 according to the third aspect is the ship 1 according to (1) or (2), in which the rear end portion of the stern bottom surface 12 including the inclined surface 15 has an outline at the same vertical position. may expand in the ship width direction D2 toward the stern side.

According to this aspect, the proportion of the submerged area of the stern 10 occupied by the inclined surface 15 increases. This increases the lift force that pushes up the inclined surface 15 when the ship 1 navigates. Therefore, the amount of sinking of the stern 10 is further suppressed.

(4) The ship 1 according to the fourth aspect is the ship 1 according to (3), in which at the rear end portion of the stern bottom surface 12 including the inclined surface 15, the outline at the same vertical position points upward. Accordingly, it may change perpendicularly to the ship width direction D2.

Thereby, the shape of the conventional ship 1 can be maintained as much as possible.

(5) A ship 1 according to a fifth aspect is the ship 1 according to any one of (1) to (4), in which the entire stern bottom surface 12 including the inclined surface 15 is formed into a smooth curved surface. You can leave it there.

According to this aspect, the water flow and the hull surface pressure change more gently near the stern bottom surface 12.

(6) The ship 1 of the sixth aspect is the ship 1 according to any one of (1) to (5), further comprising a propulsion device 20 below the stern bottom surface 12, and the inclined surface 15 is the ship 1 according to any one of (1) to (5). It may be located on the stern side of the propulsion device 20.

According to this aspect, it becomes easy to maintain the clearance between the propulsion device 20 and the stern bottom surface 12 at a specified interval necessary for maintaining vibration characteristics.

(7) The ship 1 according to the seventh aspect is the ship 1 according to any one of (1) to (6), in which the stern lower part 14 may be integrally formed with the main bottom surface 13.

Thereby, when forming the stern lower part 14, it becomes easy to prevent a connection line from being formed at the boundary between the main bottom surface 13 and the stern lower part 14.

According to the present disclosure, it is possible to provide a ship that can reduce hull resistance.

1... Vessel 2... Hull 3... Broad side 4... Bottom 5... Upper deck 6... Bow 10... Stern 11... Stern end surface 12... Stern bottom surface 13... Main bottom surface 14... Lower stern 15... Inclined surface 16... Rear surface 20... Propulsion device 21 ...Propeller 22...Propeller shaft 30...Rudder 31...Rudder post C...Hull center line D1...Travel direction D2...Ship width direction WL...Load waterline BL...Baseline F. P. ...Front perpendicular line A. P. ...Rear perpendicular line Lpp...Length between perpendicular lines A. E. ...Stern end P. C. ...Propeller center line H1...Lower end height H2...Height W1...Distance W2...Distance NL...Knuckle line (comparative example)

Claims

a stern end surface;
a stern bottom surface connected to the stern end surface;
Equipped with
The bottom surface of the stern is
A main bottom surface that extends across the width of the ship and slopes upward as it goes toward the stern side;
an inclined surface provided at the center in the ship width direction of the rear end of the main bottom surface and extending downward toward the stern side; and a rear surface connected to the stern side of the inclined surface and flush with the stern end surface. a lower stern having a
Equipped with
The main bottom surface and the stern lower part are smoothly connected to each other without forming a connecting line at the boundary between the main bottom surface and the stern lower part.
The ship according to claim 1, wherein the rear end portion of the stern bottom surface including the inclined surface changes from a downward slope to an upward slope as it goes outward in the ship width direction.
The ship according to claim 1 or 2, wherein at the rear end of the stern bottom surface including the inclined surface, an outline at the same vertical position expands in the ship width direction toward the stern side.
The ship according to claim 3, wherein at the rear end of the stern bottom surface including the inclined surface, an outline at the same vertical position changes upward to be orthogonal to the ship width direction.
The ship according to claim 1 or 2, wherein the entire stern bottom surface including the inclined surface is formed into a smooth curved surface.
further comprising a propulsion device below the bottom surface of the stern;
The ship according to claim 1 or 2, wherein the inclined surface is located closer to the stern than the propulsion device.
The ship according to claim 1 or 2, wherein the lower stern portion is integrally formed with the main bottom surface.