JP5405872B2 - Ship propulsion device and ship equipped with the same - Google Patents

Description

  The present invention relates to a marine vessel propulsion apparatus using a screw propeller and a marine vessel equipped with the propulsion device, and more particularly, to provide a fin on a boss cap attached to a boss of a screw propeller to improve the propulsion performance of the screw propeller. The present invention relates to a propulsion device and a ship equipped with the same.

  Many ships use screw propellers as propulsion units, and improving propeller characteristics such as propulsion unit efficiency greatly contributes to an improvement in fuel consumption. For this reason, research on propeller blades such as the number of propeller blades, blade shape, deployment area, pitch angle, and skew angle has been conducted, and various blade shapes have been developed.

  In order to improve the propeller characteristics, as shown in FIGS. 15 to 18, bosses with rectifying fins that increase propulsion efficiency by reducing the hub vortex in the wake of the propeller boss cap 5 in the vicinity of the propeller boss 2. A cap 5 has been developed (see, for example, Patent Document 1).

  In this boss cap 5 with rectifying fins, the number of fins 6 (four in FIG. 15) attached to the boss cap 5 is made equal to the number of propeller blades (propeller blades) 3 (four in FIG. 15). As shown in FIG. 18, the angle α of the fin 6 has a relationship of (−20 ° ≦ α−ε ≦ + 30 °) with respect to the geometric pitch angle ε of the root portion of the propeller blade 3. ing. With respect to the length direction of the fin 6, the front edge of the fin 6 is equal to the rear edge of the root of the propeller blade 3 and the front-rear direction of the propeller, or is rearward of the rear edge (b ≧ 0). Further, it is provided at the position of the gap between the roots of adjacent propeller blades 3 (a> 0). Further, as shown in FIGS. 16 and 17, the maximum diameter (2r) of the fin 6 from the axis of the cap 5 main body is larger than the diameter Dba of the cap mounting end 2a of the boss 2 and the propeller diameter (2R). Of 33% or less.

  As a function and effect of the boss cap 5 with the rectifying fin, the rectifying fin does not generate thrust by itself, but acts as a rectifying plate that reduces the generation of hub vortex in the wake of the boss cap. When the hub vortex downstream of the boss cap is diffused and the induced drag due to the vortex on the propeller blade surface is reduced, the propeller characteristics (propulsion efficiency) are greatly improved without increasing the torque. Has been.

  In addition, in ship propellers that have a hub vortex eliminator that erases vortices from the propeller hub, such as the rectifying fins, the hub vortex extinguishing device fully performs its function to increase the total efficiency of the propeller, At the same time, for the purpose of obtaining an advantage in terms of strength, a propeller for a ship having a hub vortex eliminator in which the pitch or camber of the blade root of the propeller is made larger than the pitch or camber of the middle part of the propeller has been proposed. (For example, refer to Patent Document 2).

  In addition, without a fin on the boss cap, a propeller boss with fins is provided on the side peripheral surface of the boss part excluding the boss cap, on the side peripheral surface of the boss cap, with the same number of rectifying fins as the blade. Has been proposed (see, for example, Patent Document 3 and Patent Document 4).

  On the other hand, the present inventors consider that the efficiency of the propeller can be further improved depending on the shape of the fin of the marine vessel propulsion device using the boss cap 5 with the rectifying fins, and based on various ideas. A water tank experiment using a specially designed fin shape was conducted, and the following propulsion device using a screw propeller that can further improve the propeller efficiency and a vessel equipped with the propulsion device were reached.

Japanese Examined Patent Publication No. 7-121716 Japanese Patent No. 3491890 Japanese Utility Model Publication No. 5-7599 No. 7-34795

  An object of the present invention is to provide a marine vessel propulsion device formed of a screw propeller using a propeller boss cap with fins and a marine vessel using the propeller boss cap with fins in the prior art. It is an object of the present invention to provide a marine vessel propulsion device that has improved workability and is lighter than a propulsion device and a marine vessel equipped with the propulsion device, and a marine vessel equipped with the propulsion device.

In order to achieve the above object, a marine vessel propulsion device is provided with a fin on a propeller boss cap attached to the rear side of a propeller boss of a screw propeller, and the fin is disposed behind the propeller blades. In the above, the front end diameter of the propeller boss cap is a reference diameter, the shape of the latter half of the fin is 2.0 times the reference diameter at the center position of the front end and the rear end of the fin root, and more preferably 1.8 times, the circle around the propeller rotation center, the diameter at the rearmost end position of the fin is 1.5 times the reference diameter, more preferably 1.3 times, the propeller rotation center It is formed so as to be contained in a truncated cone having a circle centered on the bottom.

  In addition, in this center position, it means in the plane of a fin perpendicular | vertical to the line segment which includes this center position and connects the front end of the root part of a fin, and the rear end of a root part. The term “rear end position” means that the position is within the plane of the fin that includes this rear end position and that is perpendicular to the line segment connecting the front end 6f of the root portion of the fins 6A to 6E and the rear end 6a of the root portion.

Alternatively, the ship propulsion apparatus for achieving the above object, the fin is provided on the rear portion of the propeller blades of professional Perabosu the screw propeller, the ship the fins disposed behind between the propeller blades wherein the propulsion device, as the propeller reference diameter the diameter of the root portion of the rear end of the blade in the propeller boss, the shape of the second half of the fin, the diameter at the center position of the front end and the rear end of the root portion of the Fi down and 2.0 times the reference diameter, more preferable properly is 1.8 times, and the circle around the propeller rotation center, the diameter had contact to the rearmost end position of the fin is 1.5 times the reference diameter, more preferably 1.3 times, is formed to fit inside the truncated cone of the bottom and a circle centered on the propeller rotation center.

  Further, in the ship propulsion device, the shape of the front half portion of the fin is a distance in a direction connecting the front end and the rear end of the root portion from the front end of the fin root portion to the foremost end 0.0 times the reference diameter. To 0.3 times, and the diameter of the circle passing through the outermost part of the fin is 1.0 to 2.5 times the reference diameter, more preferably 1.0 to 2.3 times, The diameter of the circle passing through the outermost part of the fin at the central position of the fin is 1.0 to 2.0 times the reference diameter, more preferably 1.0 to 1.8 times. The

  In the fin of the prior art, the first half and the second half are formed in a shape that is substantially symmetrical with respect to the center. However, since the flow rapidly contracts behind the propeller blade, In the latter half, the shape with the trailing edge of the fin cut is easier to work than the fin shape of the prior art because the fin resistance is reduced while maintaining the fin effect against the contraction flow behind the propeller. The manufacturing cost can be reduced, the weight can be reduced, and it has been found from an aquarium experiment or the like that it is effective in improving the propulsion device efficiency. Furthermore, as a result of analyzing the flow of the fin surface by numerical fluid dynamics calculation (CFD (Computational Fluid Dynamics) calculation), the trailing edge of the outer periphery of the fin is a resistance, and cutting this part improves the propulsion unit efficiency. I understood.

  Moreover, the ship for achieving said objective is comprised provided with the propulsion apparatus of said ship. Accordingly, it is possible to provide a ship provided with a ship propulsion device that has improved workability and is lighter than a ship provided with a ship propulsion device that uses a fin shape with fins of the prior art.

  According to the marine vessel propulsion device of the present invention, in the propulsion device formed with a screw propeller using a propeller boss cap with fins, the shape of the fin is a shape obtained by cutting the trailing edge side in the second half portion, so that the propeller rear The fin effect is reduced by reducing the resistance of the fin while increasing the propeller efficiency while maintaining the fin effect on the contracted flow of the fin, and it is smaller than the fins of the prior art, making the fin work easier and smaller The weight can be reduced.

  Moreover, according to the ship provided with the ship propulsion apparatus of the present invention, since the ship propulsion apparatus having high propulsion efficiency is used, the propulsion efficiency can be improved. If this propulsion efficiency is improved even a little, in the case of a ship that operates for more than a dozen years and consumes a large amount of fuel, a very large fuel saving is achieved. Further, since the propulsion device is slightly reduced in weight, the propulsion shaft and the support structure for the propulsion shaft can be reduced in weight accordingly.

It is the figure seen from the back of the ship which shows the structure of the propulsion apparatus of the ship in embodiment of this invention. It is a side view of the propulsion apparatus of the ship of FIG. It is a side view of a propeller boss cap. It is a figure which shows the range of the external shape of a fin. It is a figure which shows the 1st shape of the fin of the propulsion apparatus of the ship in embodiment of this invention. It is a figure which shows the shape of a fin at the time of rotating the propeller boss cap and fin of FIG. 5 around the propeller rotating shaft. It is a figure which shows the 2nd shape of the fin of the propulsion apparatus of the ship in embodiment of this invention. It is a figure which shows the shape of a fin at the time of rotating the propeller boss cap and fin of FIG. 7 around the propeller rotating shaft. It is a figure which shows the 3rd shape of the fin of the propulsion apparatus of the ship in embodiment of this invention. It is a figure which shows the shape of a fin at the time of rotating the propeller boss cap and fin of FIG. 9 around the propeller rotating shaft. It is a figure which shows the 4th shape of the fin of the ship propulsion apparatus in embodiment of this invention. It is a figure which shows the shape of a fin at the time of rotating the propeller boss cap and fin of FIG. 11 around the propeller rotating shaft. It is a figure which shows the 5th shape of the fin of the propulsion apparatus of the ship in embodiment of this invention. It is a figure which shows the shape of a fin at the time of rotating the propeller boss cap and fin of FIG. 13 around the propeller rotating shaft. It is the figure which looked at the ship which shows the structure of the propulsion apparatus of the ship in a prior art from back. FIG. 16 is a side view of the marine vessel propulsion device of FIG. 15. It is a side view which shows the shape of the propeller boss cap in a prior art. It is a side view which shows the positional relationship of the propeller blade | wing and fin in a prior art. It is a side view which shows the attachment angle of a fin. It is AA sectional drawing of FIG. 19 seen from the back which shows the rake angle of a fin.

  Hereinafter, embodiments of a ship propulsion device according to the present invention and a ship including the same will be described with reference to the drawings. Here, the example in which the fin disposed behind the propeller blade is disposed in the propeller boss cap has been described, but the present invention can also be applied to the case where the fin is provided in the rear portion of the propeller blade of the propeller blade. When provided in the rear part of the propeller blade, the reference diameter is the diameter of the root of the rear end of the propeller blade in the propeller boss.

  For easy understanding, FIGS. 1 to 20 show different shapes and dimensions of propeller bosses, propeller blades, propeller boss caps, fins, etc., and these shapes and dimensions are different from actual ones. Also, in FIGS. 3 to 14 and FIGS. 15 to 20, the propeller blades and fins that are visible and natural are omitted for ease of viewing and for convenience of drawing and explanation.

  As shown in FIGS. 1 to 14, a marine vessel propulsion device 1A, 1B, 1C, 1D, 1E (hereinafter, 1A to 1E) according to an embodiment of the present invention includes a propeller boss (propeller hub) 2 and the propeller boss. 2, a propeller boss cap (propeller hub cap) 5 </ b> A connected to the rear end of the propeller labs 2, and fins 6 </ b> A, 6 </ b> B, 6 </ b> C, 6 </ b> D, 6 </ b> E provided on the propeller boss cap 5 </ b> A ( Hereinafter, it is comprised with the screw propeller which consists of 6A-6E).

  The propeller boss cap 5A is formed of a rotating body having the propeller rotation axis Pc as a rotation axis, and the rear end portion 5a of the propeller boss cap 5A is formed by an end face. The rotating body is formed in a shape that tapers toward the rear while forming a rotation generating line with a smooth curve or straight line.

  Here, the front end diameter Dcf of the propeller boss cap 5A is set as a reference diameter Ds, and the total length Lc of the propeller boss cap 5A is preferably 0.28 to 0.76 times the reference diameter Ds. The diameter Dca of the rear end portion 5a of the boss cap 5A is preferably 0.35 to 0.95 times the reference diameter Ds. The diameter Dcf of the front end portion 5f corresponds to the flange diameter of the propeller boss cap 5A.

  As shown in FIG. 3, when the generatrix of the rotating body forming the outer peripheral surface 5b of the propeller boss cap 5A is a straight line, the shape of the propeller boss cap 5A is a truncated cone, which is very easy to manufacture. Although not shown in the figure, even when the generatrix is a smooth curve, the shape of the rear end portion 5a of the propeller boss cap 5A is perpendicular to the propeller rotation axis Pc. In a simple cross section, the deviation from the shape of the truncated cone is set to be within 20% of the total length Lc of the propeller boss cap 5A.

  Further, the end surface of the front end portion 5 f of the propeller boss cap 5 </ b> A is formed in a planar shape from the relationship of joining to the rear end surface 2 a of the propeller boss 2. On the other hand, as shown in FIG. 3, the end surface of the rear end portion 5a of the propeller boss cap 5A is preferably formed as a flat surface from the viewpoint of work, but may be formed as a cone or a rotating body close to the flat surface. Good. Even in this case, the shape of the rear end portion 5a is configured so that the distance in the front-rear direction between the peripheral edge portion and the central portion is within a range of 20% of the total length Lc of the propeller boss cap 5A.

  The fins 6 </ b> A to 6 </ b> E are provided on a propeller boss cap 5 </ b> A attached to the rear side of the propeller boss 2 of the screw propellers 1 </ b> A to 1 </ b> E, and the fins 6 </ b> A to 6 </ b> E are disposed behind the propeller blades 3. That is, when viewed in the rearward direction of the propeller shaft Pc, the front ends 6f of the root portions of the fins 6A to 6E are disposed between the rear ends of the root portions of the propeller blades 3. Further, when viewed from the side, the front ends 6f of the root portions of the fins 6A to 6E are arranged behind the rear ends of the root portions of the propeller blades 3. The fins 6A to 6E may be formed with positive and negative cambers, but a flat plate shape is suitable from the viewpoint of simplicity in work and reduction in manufacturing cost. The fins 6A to 6E may be attached with positive and negative rake angles.

  In the present invention, as shown in FIGS. 4 and 5 as seen from the side of the hull, and when the propeller boss cap 5A and the fins 6A to 6E are rotated around the propeller rotation axis, as shown in FIG. The shapes of 6A to 6E are as follows. In FIG. 4, for comparison with the fins 6 </ b> A to 6 </ b> E according to the embodiment, the substantially symmetric shape of the fin 6 of the prior art is indicated by a thin line. Generally speaking, the fin area (shaded portion) of the rear half of the conventional fin 6 is reduced as in the fin 6A shown in FIG.

  Regarding the shape of the front half of the fins 6A to 6E, as shown in FIGS. 6 to 14, the length direction of the fins 6A to 6E, that is, the line segment connecting the front end 6f and the rear end 6a of the roots of the fins 6A to 6E. For the direction of, the distance Lf from the front end 6f of the root of the fins 6A to 6E to the foremost end of the fins 6A to 6E is set to 0.0 to 0.3 times the reference diameter Ds (= Dcf). That is, the maximum value Lfmax of the distance Lf is set to 0.3 × Ds.

  Further, regarding the height direction of the fins 6A to 6E (the direction perpendicular to the propeller rotation axis Pc), as shown in FIG. 6, the diameter D1 of the first circle C1 passing through the outermost part of the fins 6A to 6E is used as a reference. The diameter Ds is 1.0 to 2.5 times, more preferably 1.0 to 2.3 times, and the fins 6A to 6F at the center positions Xm of the front ends 6f and the rear ends 6a of the roots of the fins 6A to 6E. The diameter D2 of the second circle C2 passing through the outermost part of 6E is set to 1.0 to 2.0 times, more preferably 1.0 to 1.8 times the reference diameter Ds.

  As for the shapes of the latter half portions of the fins 6A to 6E, as shown in FIGS. 5 and 6, the diameter D3 is a reference diameter at the center position Xm of the front end 6f and the rear end 6a of the roots of the fins 6A to 6E. In the third circle C3, which is 2.0 times Ds, more preferably 1.8 times, and the rearmost position Xe of the fins 6A to 6E, the diameter D4 is 1.5 times the reference diameter Ds, more preferably 1. A fourth circle C4 is set to be tripled, and the third circle C3 and the fourth circle C4 are formed so as to be contained within a truncated cone having a bottom portion.

  The center position Xm means in the plane of the fin including the center position Xm and perpendicular to the line segment connecting the front end 6f of the root portion of the fins 6A to 6E and the rear end 6a of the root portion. . In addition, in the last end position Xe, it means in the plane of the fin that includes this last end position Xe and that is perpendicular to the line segment connecting the front end 6f of the root portion of the fins 6A to 6E and the rear end 6a of the root portion. is there.

  Regarding the length of the fins 6A to 6E, the front end 6f and the rear end 6a of the roots of the fins 6A to 6E need to be disposed on the propeller boss cap 5A, and therefore the fins 6A to 6E with respect to the rotation center line of the propeller boss cap 5A. Due to the relationship with the mounting angle, it is naturally limited. For example, the front edges of the fins 6 </ b> A to 6 </ b> E are equal to or behind the rear edge of the rear edge of the propeller blade 3 and the propeller 2.

  Further, as shown in FIG. 18, regarding the mounting angle α of the fins 6 </ b> A to 6 </ b> E, (−20 ° ≦ α−) with respect to the geometric pitch angle ε of the root of the propeller blade 3, as in the prior art. (ε ≦ + 30 °) is attached. Further, it is provided at the position of the gap between the roots of adjacent propeller blades 3. As a fin mounting angle, a rake angle γ as shown in FIG. 19 and FIG. FIG. 20 shows a case where the rake angle γ of the fins 6A to 6E is attached with 0 and a case where the fins 6A to 6E are attached with a positive angle (+ γ) or a negative rake angle (−γ).

  The shape ranges of the fins 6A to 6E that have been limited to the above are shapes in which the latter half of the fins 6A to 6E can be accommodated in the hatched portions as shown in FIGS.

  In the fin 6A shown in FIGS. 5 and 6, the foremost protrusion Lf is larger than zero, the front end position Xs protrudes slightly before the root front end 6f, and the rearmost position Xe is the root portion. The rear end 6a is the same as the rear end 6a. FIG. 5 is a schematic view of the fins 6A viewed from the side of the hull, and FIG. 6 is a schematic lateral view when the propeller boss cap 5A and the fins 6A are rotated around the propeller rotation axis. A line Lxm indicates a line in the plane of the fin perpendicular to the root line at the center position Xm of the front end 6f and the rear end 6a of the root of the fin 6A.

  The fin 6B shown in FIGS. 7 and 8 has a feature that the outermost portion protrudes considerably before the front end 6f of the root portion, and the position Xe of the rear end is the same as the rear end 6a of the root portion. Have. FIG. 7 is a schematic view of the fins 6B as viewed from the side of the hull, and FIG. 8 is a schematic lateral view when the propeller boss cap 5A and the fins 6B are rotated around the propeller rotation axis.

  The fin 6C shown in FIGS. 9 and 10 has an outermost portion that protrudes slightly before the front end 6f of the root portion, and a position Xe of the rearmost end is behind the rear end 6a of the root portion. It has characteristics. FIG. 9 is a schematic view of the fins 6C as viewed from the side of the hull, and FIG. 10 shows a schematic lateral projection when the propeller boss cap 5A and the fins 6C are rotated around the propeller rotation axis.

  11 and 12, the front end protrusion amount Lf is zero, the front end position Xs is the same as the front end 6f of the root, and the rear end position Xe is the rear end of the root. It has the feature that it is on the rear side than 6a. FIG. 11 is a schematic view of the fins 6D as viewed from the side of the hull, and FIG. 12 is a schematic horizontal projection when the propeller boss cap 5A and the fins 6D are rotated around the propeller rotation axis.

  In the fin 6E shown in FIGS. 13 and 14, the foremost protrusion amount Lf is zero, the front end position Xs is the same position as the front end 6f of the root portion, and the rearmost protrusion amount Le is zero. The rear end position Xe is the same as the rear end 6a of the root portion. FIG. 13 is a schematic view of the fins 6E viewed from the side of the hull, and FIG. 14 is a schematic lateral projection when the propeller boss cap 5A and the fins 6E are rotated around the propeller rotation axis.

  Further, regarding the thickness direction of the fins 6A to 6E, it is easier to work with a flat plate with a uniform thickness. In addition, a camber can be provided by bending a flat plate, or a camber can be provided in a wing shape. When this camber is provided, the root of the fins 6 </ b> A to 6 </ b> E is considered in consideration of the relationship with the shape of the propeller boss cap 5. In this case, it is preferable to provide a camber in a direction different from the camber of the propeller blade 3 so that the torque Qp generated in the opposite direction to the torque Qp generated by the propeller blade 3 is generated.

  According to the above-described ship propulsion devices 1A to 1E, the fins 6A to 6E are shaped by cutting the trailing edge in the rear half, thereby maintaining the fin effect against the contracted flow behind the propeller while maintaining the fin effect on the fin 6A. The resistance of ˜6E is reduced to increase the efficiency of the propeller and become smaller than the fins of the prior art. Therefore, the machining of the fins 6A to 6E is facilitated, and the weight can be reduced by the reduction.

  The present invention can also be applied to the case where the fin is provided in the rear part of the propeller blade of the propeller boss. When provided in the rear part of the propeller blade, the reference diameter is the diameter of the root of the rear end of the propeller blade in the propeller boss. When the fins 6 </ b> A to 6 </ b> E are attached to the boss cap 5, the front edge of the fin 6 is equal to the rear edge of the root of the propeller blade 3 and the front-rear direction of the propeller, because of the physical restriction that the cap is installed behind the propeller. Although the rear edge is behind (b ≧ 0), when the fin 6 is provided behind the propeller blade 3 of the propeller boss 2, the front end of the fin 6 may be disposed between the propeller blades. In this case, b may be negative, preferably −0.5 × Dcf <b <0. By doing in this way, the length of the propeller boss can be shortened as much as possible to reduce the weight.

  The ship provided with the ship propulsion device of the present invention includes the above-described ship propulsion devices 1A to 1E. According to this ship, the propulsion efficiency can be improved because the ship propulsion devices 1A to 1E are used. Further, since the propulsion devices 1A to 1E are slightly reduced in weight, the propulsion shaft and the support structure for the propulsion shaft can be reduced in weight accordingly.

  The ship propulsion device according to the present invention has a fin shape in which the trailing edge side is cut in the second half, thereby reducing the fin resistance while maintaining the fin effect against the contracted flow behind the propeller. Since the efficiency of the vessel is increased and the fin is smaller than the fins of the prior art, the fin can be easily machined, and the weight can be reduced, so that it can be used as a propulsion device for a ship.

  Further, the ship equipped with the ship propulsion device of the present invention can improve the propulsion efficiency and save fuel consumption, and the weight of the propulsion shaft and the propulsion shaft support structure can be reduced by reducing the weight of the propulsion device. It can be used as a large number of ships.

1, 1A, 1B, 1C, 1D, 1E Ship propulsion device 2 Propellerbots 2a Propellerbots rear end surface 3 Propeller blades 4 Propeller rotating shaft 5, 5A Propellerbots cap 5a Propellerbots cap rear end 5b Outer peripheral surface 5f Front end portion of propeller boss cap 6, 6A, 6B, 6C, 6D, 6E Fin 6a Rear end of fin root 6f Front end of fin root a Distance in rotation direction with propeller blade at fin front end b Propeller blade rear end C1 1st circle C2 2nd circle C3 3rd circle C4 4th circle Dca Diameter of the rear end of the propeller boss cap Dcf Diameter of the front end of the propeller boss cap Dp Propeller diameter Ds Reference diameter D1 Diameter of the first circle D2 Diameter of the second circle D3 Diameter of the third circle D4 Diameter of the fourth circle L c Length of propeller boss cap Le Horizontal distance from the rear end to the rearmost end of the fin root in the outer shape of the fin Lf Horizontal distance from the front end to the frontmost end of the fin root in the outer shape of the fin Lfmax Maximum value of Lf Lxm Fin root Line in the plane of the fin perpendicular to the root line at the center position of the front end and the rear end of the fin Xs Position of the front end of the fin Xm Center position of the front end and rear end of the fin Xe Position of the last end of the fin α Mounting angle ε Geometric pitch angle of propeller blade root γ Fin mounting rake angle

Claims (4)

In a propulsion device for a ship in which a fin is provided on a propeller boss cap attached to the rear side of the propeller boss of the screw propeller and the fin is disposed behind the propeller wings, the front end diameter of the propeller boss cap is used as a reference diameter. ,
The shape of the latter half of the fin is a circle whose center is 2.0 times the reference diameter at the center position of the front end and the rear end of the fin base, and a circle centering on the propeller rotation center, and the last end position of the fin in the diameter 1.5 times of the reference diameter, the propeller rotation center propulsion device of a ship, characterized the formed it to fit inside the truncated cone of the bottom and a circle centered on. If the fin is installed in the rear part of the propeller blade of the propeller boss of the screw propeller, Further, in the propulsion device for a ship in which the fins are disposed behind the propeller blades, the prop With the diameter of the root of the rear end of the propeller blade at Loperabos as the reference diameter,
The shape of the rear half of the fin is straightened at the center position of the front end and the rear end of the fin root. The diameter is 2.0 times the reference diameter, the circle centered on the propeller rotation center, and the The diameter at the rear end position is 1.5 times the reference diameter, and the propeller rotation center is the center. A ship propulsion device characterized by being formed so as to fit inside a truncated cone with a bottom of the circle Place. The shape of the first half of the fin
The distance in the direction connecting the front end and the rear end of the root from the front end to the front end of the fin root is 0.0 to 0.3 times the reference diameter,
The diameter of the circle that passes through the outermost part of the fin is 1.0 to 2.5 times the reference diameter, and the diameter of the circle that passes through the outermost part of the fin is the central position of the fin. 2. The marine vessel propulsion device according to claim 1, wherein the propulsion device is 1.0 to 2.0 times the reference diameter.   A ship provided with the ship propulsion device according to claim 1, 2 or 3.

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