JP5281559B2 - Ship propulsion performance improvement device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a propulsion performance improving device of a ship, which prevents a propeller from being damaged by a vortex generated by reaction fins. <P>SOLUTION: This propulsion performance improving device 41 includes a plurality of reaction fins 71B-73B arranged on the front side of a propeller 20 to generate a swirling flow in the inverse direction of the rotational direction of the propeller 20 and radially extending with a rotary shaft S of the propeller 20 as the center. The plurality of reaction fins 71B-73B include the reaction fin 71B extending obliquely upward and the reaction fins 72B and 73B extending in the horizontal direction or obliquely downward. A first distance to the blade end of the reaction fin 71B from the rotary shaft S is larger than a propeller radius of the propeller 20. A second distance to the blade end of the reaction fins 72B and 73B from the rotary shaft S is smaller than the propeller radius. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a ship propulsion performance improving apparatus, and more particularly to a ship reaction fin.

  With reference to FIG. 1, the reaction fin apparatus disclosed by patent document 1 is demonstrated. The reaction fin device includes a plurality of reaction fins that project substantially radially about the propeller shaft upstream of the propeller in order to give the flow flowing into the propeller for propulsion at the stern part in a direction opposite to the propeller rotation direction. 171A to 173A and 171B to 173B. The reaction fins 171A to 173A are arranged on the port side. Reaction fins 171B to 173B are arranged on the starboard side. The reaction fins 171A and 171B provided at the upper level of the propeller shaft are relatively long, and the reaction fins 173A and 173B provided at the lower level of the propeller shaft are relatively short, and the reaction fin 172A provided at the same level as the propeller shaft. And 172B are intermediate lengths. Since the reaction fins 173A and 173B provided in the region below the propeller shaft where the flow velocity of the water flow is relatively large are relatively short, the advantages of the reaction fins 173A and 173B generated by the rotation flow in the direction opposite to the propeller rotation direction can be reduced. It can be more than a demerit due to an increase in resistance due to 173B. Therefore, the propulsion performance is greatly improved by the cooperation of the plurality of reaction fins 171A to 173A and 171B to 173B.

JP-A-5-185986

  The objective of this invention is providing the propulsion performance improvement apparatus of the ship by which it is prevented that a propeller is damaged by the vortex which generate | occur | produces with a reaction fin.

  The means for solving the problem will be described below using the numbers used in the (DETAILED DESCRIPTION). These numbers are added to clarify the correspondence between the description of (Claims) and (Mode for Carrying Out the Invention). However, these numbers should not be used to interpret the technical scope of the invention described in (Claims).

  The ship propulsion performance improving apparatus according to the present invention is disposed on the front side of the propeller so as to generate a swirling flow in a direction opposite to the rotation direction of the propeller (20), and is radially centered around the rotation axis (S) of the propeller. A plurality of reaction fins (71A to 73A, 71B to 73B, 74) extending in the direction. The plurality of reaction fins include first reaction fins (71A, 71B) extending obliquely upward and second reaction fins (72A, 72B, 73A, 73B) extending horizontally or obliquely downward. A first distance from the rotation axis to the blade tip of the first reaction fin is larger than a propeller radius (Dp / 2) of the propeller. A second distance from the rotation axis to the blade tip of the second reaction fin is smaller than the propeller radius.

  The first distance is 110% or more of the propeller radius. The second distance is 70% or more and 95% or less of the propeller radius.

  The plurality of reaction fins are arranged symmetrically.

  The plurality of reaction fins are arranged asymmetrically.

  The plurality of reaction fins include a third reaction fin (74) extending right above. A third distance from the rotation axis to the blade tip of the third reaction fin is larger than the propeller radius.

  The marine vessel propulsion performance improving apparatus according to the present invention includes a plurality of reaction fins (75A, 75B, 72A, 72B) arranged on the front side of the propeller so as to generate a swirling flow opposite to the rotation direction of the propeller (20). 73A, 73B). The plurality of reaction fins include first reaction fins (75A, 75B) and second reaction fins (72A, 72B, 73A, 73B). The first reaction fin includes an upper portion (76A, 76B), a bent portion (77A, 77B), and a lower portion (78A, 78B). The lower portion extends obliquely upward from a bossing (11) supporting the propeller shaft (21) of the propeller to the bent portion. The upper portion extends upward from the bent portion and is connected to the hull skin. The lower part and the upper part have different extending directions. The second reaction fin extends horizontally or obliquely downward from the boshing. The first distance from the rotation axis (S) of the propeller to the bent portion is larger than the propeller radius (Dp / 2) of the propeller. A second distance from the rotation axis to the blade tip of the second reaction fin is smaller than the propeller radius.

  ADVANTAGE OF THE INVENTION According to this invention, the propulsion performance improvement apparatus of the ship by which it is prevented that a propeller is damaged by the vortex which generate | occur | produces with a reaction fin is provided.

FIG. 1 shows a conventional reaction fin device. FIG. 2 is a side view of the stern portion of the hull provided with the propulsion performance improving apparatus according to the first embodiment of the present invention. FIG. 3 shows the propulsion performance improving apparatus according to the first embodiment. FIG. 4 shows the locus of vortices generated at the tip of the reaction fin when the reaction fin diameter is smaller than the propeller diameter. FIG. 5 shows the locus of vortices generated at the tip of the reaction fin when the reaction fin diameter is larger than the propeller diameter. FIG. 6 shows a propulsion performance improving apparatus according to the second embodiment of the present invention. FIG. 7 shows a propulsion performance improving apparatus according to the third embodiment of the present invention. FIG. 8 shows a propulsion performance improving apparatus according to the fourth embodiment of the present invention. FIG. 9 shows a bilge vortex near the stern portion of the hull. FIG. 10 shows a propulsion performance improving apparatus according to the fifth embodiment of the present invention. FIG. 11 shows a propulsion performance improving apparatus according to the sixth embodiment of the present invention. FIG. 12 shows a propulsion performance improving apparatus according to the seventh embodiment of the present invention. FIG. 13 shows a propulsion performance improving apparatus according to the eighth embodiment of the present invention. FIG. 14 shows a propulsion performance improving apparatus according to the ninth embodiment of the present invention.

  With reference to the accompanying drawings, a mode for carrying out a ship propulsion performance improving apparatus according to the present invention will be described below.

(First embodiment)
FIG. 2 shows a side view of the stern portion of the hull 10 provided with the propulsion performance improving apparatus 41 according to the first embodiment of the present invention. The hull 10 includes a bossing 11 and a stern overhang portion 12. The bossing 11 supports the propeller shaft 21 of the propeller 20 so that the propeller 20 for propulsion can rotate around the rotation axis S. The stern overhang portion 12 is disposed above the propeller 20. The propulsion performance improving device 41 includes six-wing reaction fins arranged on the front side (upstream side) of the propeller 20 so as to generate a swirling flow opposite to the rotation direction of the propeller 20 during forward movement. The 6-wing reaction fins are provided on the bossing 11. The six-wing reaction fin includes reaction fins 71 </ b> B to 73 </ b> B provided on the starboard side of the hull 10. The reaction fin 71 </ b> B extends obliquely upward from the boshing 11. The reaction fin 72B extends in the horizontal direction from the boshing 11. The reaction fin 73B extends obliquely downward from the boshing 11. In FIG. 2, the reaction fins 71 </ b> B and 73 </ b> B and the wings of the propeller 20 are shown as actual lengths rather than projection lengths from the side.

  FIG. 3 shows the propulsion performance improving device 41 as seen from the rear of the hull 10. The six-wing reaction fins included in the propulsion performance improving device 41 include reaction fins 71A to 73A provided on the port side of the hull 10 in addition to the reaction fins 71B to 73B. The reaction fin 71 </ b> A extends obliquely upward from the boshing 11. The reaction fin 72 </ b> A extends in the horizontal direction from the boshing 11. The reaction fin 73A extends obliquely downward from the boshing 11. The reaction fins 71A to 73A and 71B to 73B are disposed symmetrically and extend radially about the rotation axis S. The reaction fins 72A and 72B are disposed below the reaction fins 71A and 71B. The reaction fins 73A and 73B are disposed below the reaction fins 72A and 72B. The propulsion efficiency of the ship is improved by the swirl flow in the direction opposite to the rotation direction of the propeller 20 generated by the reaction fins 71A to 73A and 71B to 73B.

  The boshing 11 is disposed on the inner side of the propeller circle 25 that indicates the locus of the blade tip of the rotating propeller 20. The wing tips of the reaction fins 71A and 71B are arranged outside the propeller circle 25. The wing tips of the reaction fins 72A, 72B, 73A, and 73B are disposed on the inner side of the propeller circle 25. That is, the diameter Dr of the reaction fins 71A and 71B is larger than the propeller diameter Dp of the propeller 20. The diameter Dr of the reaction fins 72A, 72B, 73A, and 73B is smaller than the propeller diameter Dp.

  Here, the flow velocity distribution of the water flow in the vicinity of the bossing 11 has a relatively small flow velocity above the level of the rotation axis S and a relatively large flow velocity below the level of the rotation axis S. Therefore, even if the wing tips of the reaction fins 71A and 71B are arranged outside the propeller circle 25, the resistance increase is small.

  Referring to FIG. 4, the propeller radius Dp / 2 as a half of the propeller diameter Dp is equal to the distance from the rotation axis S to the blade tip of the propeller 20, and the half Dr / 2 of the diameter Dr of the reaction fin 72A is rotated. It is equal to the distance from the axis S to the tip of the reaction fin 72A. Since the propeller diameter Dp is larger than the diameter Dr of the reaction fin 72A, the wing of the rotating propeller 20 crosses the vortex trajectory 100 generated at the wing tip of the reaction fin 72A. Similarly, the wings of the rotating propeller 20 cross the trajectory of vortices generated at the wing tips of the reaction fins 72B, 73A, and 73B. Since the wing tips of the reaction fins 72A, 72B, 73A, and 73B are arranged at relatively deep water depths, the locus of vortices generated at the wing tips of the reaction fins 72A, 72B, 73A, and 73B is relatively low in water depth. Extend deep.

  Referring to FIG. 5, half Dr / 2 of diameter Dr of reaction fin 71A is equal to the distance from rotation axis S to the tip of reaction fin 71A. Since the propeller diameter Dp is smaller than the diameter Dr of the reaction fin 71A, the wing of the rotating propeller 20 does not cross the trajectory 101 of the vortex generated at the wing tip of the reaction fin 71A. Similarly, the wing of the rotating propeller 20 does not cross the trajectory of the vortex generated at the wing tip of the reaction fin 71B. Since the wing tips of the reaction fins 71A and 71B are arranged at a relatively shallow depth, the locus of vortices generated at the wing tips of the reaction fins 71A and 71B extends at a relatively shallow depth.

  Here, when the vortex flows into the propeller 20, the pressure at the center of the vortex is lower than the surroundings. Therefore, when the vortex passes through the low pressure portion of the suction surface of the blade of the propeller 20, cavitation may occur and the blade may be damaged. There is. Also, cavitation is more likely to occur on the surface of the wing of the propeller 20 as the wing of the propeller 20 is at a shallower depth.

  According to the present embodiment, since the wing of the propeller 20 does not cross the vortex trajectory extending in a relatively shallow water depth such as the vortex trajectory 101, the reaction fins 71A to 73A and 71B to 73B are generated at the wing tips. The vortex prevents the propeller 20 from being damaged.

  Generally, vortices generated at the blade tips of the reaction fins 71A and 71B approach the rotation axis S by about 10% of the propeller diameter Dp as they go downstream. Therefore, the diameter Dr of the reaction fins 71A and 71B is preferably 110% or more of the propeller diameter Dp. For safety reasons, the diameter Dr of the reaction fins 71A and 71B may be 120% or more of the propeller diameter Dp. Further, if the reaction fins 71A and 71B are too long, the reaction fins 71A and 71B preferably have a diameter Dr of 150% or less of the propeller diameter Dp. Further, the diameter Dr of the reaction fins 72A, 72B, 73A, and 73B can be freely set within a range smaller than the propeller diameter Dp. For example, the diameter Dr of the reaction fins 72A, 72B, 73A, and 73B can be set within a range of 70% to 95% of the propeller diameter Dp.

(Second Embodiment)
With reference to FIG. 6, a propulsion performance improving apparatus 42 according to a second embodiment of the present invention will be described. The propulsion performance improving apparatus 42 is the same as the propulsion performance improving apparatus 41 according to the first embodiment except that the reaction fins 71A and 71B are replaced by reaction fins 75A and 75B, respectively. The propulsion performance improving apparatus 42 includes six wing reaction fins 75A, 75B, 72A, 72B, 73A, and 73B arranged symmetrically. The propulsion efficiency of the ship is improved by the swirl flow in the direction opposite to the rotation direction of the propeller 20 generated by the reaction fins 75A, 75B, 72A, 72B, 73A, and 73B.

The reaction fin 75A is provided on the port side of the hull 10. The reaction fin 75A includes an upper portion 76A, a bent portion 77A, and a lower portion 78A. The reaction fin 75A is bent at the bent portion 77A. The lower portion 78A extends obliquely upward from the bossing 11 to the bent portion 77A. The upper portion 76A extends directly above (in the vertical direction) from the bent portion 77A and is connected to the hull outer plate (the outer plate of the stern overhang portion 12). The reaction fins 75 </ b> B are provided on the starboard side of the hull 10.
The reaction fin 75B includes an upper portion 76B, a bent portion 77B, and a lower portion 78B. The reaction fin 75B is bent at the bent portion 77B. The lower portion 78B extends obliquely upward from the bossing 11 to the bent portion 77B. The upper portion 76B extends directly above (vertically) from the bent portion 77B and is connected to the hull outer plate (the outer plate of the stern overhang portion 12). The position where the upper portions 76A and 76B are connected to the hull skin is outside the propeller circle 25. The lower portion 78A, the lower portion 78B, the reaction fins 72A, the reaction fins 72B, the reaction fins 73A, and the reaction fins 73B extend radially around the rotation axis S. Since the upper portions 76A and 76B extend right above, the length of the upper portions 76A and 76B is short, and the weight of the reaction fins 75A and 75B can be suppressed.

  The bent portion 77A of the reaction fin 75A and the bent portion 77B of the reaction fin 75B are disposed outside the propeller circle 25. That is, the position of the bent portion 77A is determined in the same manner as the position of the wing tip of the reaction fin 71A, and the position of the bent portion 77B is determined in the same manner as the position of the wing tip of the reaction fin 71B.

  Here, the flow velocity distribution of the water flow in the vicinity of the reaction fins 75A, 75B, 72A, 72B, 73A, and 73B has a relatively small flow velocity above the level of the rotation axis S, and relatively low below the level of the rotation axis S. The flow rate is large. Therefore, even if the reaction fins 75A and 75B protrude outward from the propeller circle 25, the resistance increase is slight.

  According to the present embodiment, the reaction fins 75A and 75B do not have blade tips, so that there is little possibility that vortices are generated by the reaction fins 75A and 75B. Further, even when vortices are generated at the bent portions 77A and 77B, the trajectories of the vortices are the same as the trajectories of the vortices generated at the blade tips of the reaction fins 71A and 71B. Therefore, the propeller 20 is prevented from being damaged by the vortices generated in the reaction fins 75A, 75B, 72A, 72B, 73A, and 73B.

  The upper portion 76A may extend obliquely upward from the bent portion 77A and be connected to the hull outer plate, and the upper portion 76B may extend obliquely upward from the bent portion 77B and be connected to the hull outer plate. Also in this case, the upper portion 76A and the lower portion 78A have different extending directions, and the upper portion 76B and the lower portion 78B have different extending directions.

(Third embodiment)
With reference to FIG. 7, a propulsion performance improving apparatus 43 according to a third embodiment of the present invention will be described. The propulsion performance improving device 43 is the same as the propulsion performance improving device 41 according to the first embodiment except that reaction fins 74 are added. The reaction fin 74 extends right above the bossing 11. The reaction fin 74 extends along the hull center line C of the hull 10. The bossing 11 is disposed on the hull center line C. The reaction fins 71A to 73A, 71B to 73B, and 74 extend radially about the rotation axis S. The propulsion efficiency of the ship is improved by the swirl flow in the direction opposite to the rotation direction of the propeller 20 in which the reaction fins 71A to 73A, 71B to 73B, and 74 are generated.

  The wing tip of the reaction fin 74 is disposed outside the propeller circle 25. That is, the diameter Dr of the reaction fin 74 is larger than the propeller diameter Dp of the propeller 20.

  Here, the flow velocity distribution of the water flow in the vicinity of the bossing 11 has a relatively small flow velocity above the level of the rotation axis S and a relatively large flow velocity below the level of the rotation axis S. Therefore, even if the blade tip of the reaction fin 74 is arranged outside the propeller circle 25, the resistance increase is slight.

  The half Dr / 2 of the diameter Dr of the reaction fin 74 is equal to the distance from the rotation axis S to the blade tip of the reaction fin 74. Since the propeller diameter Dp is smaller than the diameter Dr of the reaction fin 74, the wing of the rotating propeller 20 does not cross the trajectory of the vortex generated at the wing tip of the reaction fin 74. Since the wing tip of the reaction fin 74 is disposed at a relatively shallow depth, the locus of the vortex generated at the wing tip of the reaction fin 74 extends at a relatively shallow depth.

  According to this embodiment, since the wing of the propeller 20 does not cross the trajectory of the vortex generated at the wing tips of the reaction fins 71A, 71B, 74A, the wing tips of the reaction fins 71A to 73A, 71B to 73B, and 74 are generated. The propeller 20 is prevented from being damaged by the swirling vortex.

  The diameter Dr of the reaction fin 74 is preferably 110% or more of the propeller diameter Dp. For safety reasons, the diameter Dr of the reaction fin 74 may be 120% or more of the propeller diameter Dp. In addition, if the reaction fin 74 is too long, it causes an increase in weight. Therefore, the diameter Dr of the reaction fin 74 is preferably 150% or less of the propeller diameter Dp.

(Fourth embodiment)
With reference to FIG. 8, a propulsion performance improving apparatus 44 according to a fourth embodiment of the present invention will be described. When the propeller 20 is clockwise, the propulsion performance improving device 44 is obtained by removing the reaction fins 71B and 73B on the starboard side from the propulsion performance improving device 41 according to the first embodiment. The four-wing reaction fins 71 </ b> A to 73 </ b> A and 72 </ b> B included in the propulsion performance improving apparatus 44 are arranged asymmetrically. The propulsion efficiency of the ship is improved by the swirl flow in the direction opposite to the rotation direction of the propeller 20 generated by the reaction fins 71A to 73A and 72B.

  With reference to FIG. 9, the case where the propeller 20 rotates clockwise refers to a case where a forward thrust of the hull 10 is generated when the propeller 20 rotates clockwise as viewed from the rear of the hull 10. Here, when the hull 10 moves forward, a port bilge vortex 111 and a starboard bilge vortex 112 are generated in the vicinity of the propeller 20. Since the direction of the port bilge vortex 111 is the same as the direction of rotation of the propeller 20 and the direction of the starboard bilge vortex 112 is opposite to the direction of rotation of the propeller 20, the number of reaction fins arranged on the starboard side is There may be fewer than the number of reaction fins arrange | positioned at.

  When the propeller 20 is counterclockwise, the propulsion performance improving device 44 is obtained by removing the reaction fins 71A and 73A on the port side from the propulsion performance improving device 41 according to the first embodiment.

  When the propeller 20 is clockwise, the reaction fin 73B may be removed from the propulsion performance improving device 42 according to the second embodiment. When the propeller 20 is counterclockwise, the reaction fin 73A may be removed from the propulsion performance improving apparatus 42 according to the second embodiment.

(Fifth embodiment)
With reference to FIG. 10, a propulsion performance improving apparatus 45 according to a fifth embodiment of the present invention will be described. When the propeller 20 is clockwise, the propulsion performance improving device 45 is obtained by removing the reaction fins 71B and 73B on the starboard side from the propulsion performance improving device 43 according to the third embodiment. The five-wing reaction fins 71A to 73A, 72B, and 74 included in the propulsion performance improving device 45 are arranged asymmetrically. The propulsion efficiency of the ship is improved by the swirl flow in the direction opposite to the rotation direction of the propeller 20 in which the reaction fins 71A to 73A, 72B, and 74 are generated.

  When the propeller 20 is counterclockwise, the propulsion performance improving device 45 is obtained by removing the reaction fins 71A and 73A on the port side from the propulsion performance improving device 43 according to the third embodiment.

(Sixth embodiment)
With reference to FIG. 11, a propulsion performance improving apparatus 46 according to a sixth embodiment of the present invention will be described. When the propeller 20 is clockwise, the propulsion performance improving device 46 is obtained by removing the starboard side reaction fins 71B to 73B from the propulsion performance improving device 41 according to the first embodiment. The three-wing reaction fins 71A to 73A included in the propulsion performance improving device 46 are arranged asymmetrically. The propulsion efficiency of the ship is improved by the swirl flow in the direction opposite to the rotation direction of the propeller 20 generated by the reaction fins 71A to 73A.

  When the propeller 20 is counterclockwise, the propulsion performance improving device 46 is obtained by removing the reaction fins 71A to 73A on the port side from the propulsion performance improving device 41 according to the first embodiment.

  When the propeller is clockwise, the reaction fins 72B and 73B may be removed from the propulsion performance improving apparatus 42 according to the second embodiment. When the propeller is counterclockwise, the reaction fins 72A and 73A may be removed from the propulsion performance improving device 42 according to the second embodiment.

(Seventh embodiment)
With reference to FIG. 12, a propulsion performance improving apparatus 47 according to a seventh embodiment of the present invention will be described. When the propeller 20 is clockwise, the propulsion performance improving device 47 is obtained by removing the starboard side reaction fins 71B to 73B from the propulsion performance improving device 43 according to the third embodiment. The four-wing reaction fins 71A to 73A and 74 included in the propulsion performance improving device 47 are arranged asymmetrically. The propulsion efficiency of the ship is improved by the swirl flow opposite to the rotation direction of the propeller 20 in which the reaction fins 71A to 73A and 74 are generated.

  When the propeller 20 is counterclockwise, the propulsion performance improving device 47 is obtained by removing the reaction fins 71A to 73A on the port side from the propulsion performance improving device 43 according to the third embodiment.

(Eighth embodiment)
With reference to FIG. 13, a propulsion performance improving apparatus 48 according to an eighth embodiment of the present invention will be described. The propulsion performance improving device 48 is obtained by removing the reaction fins 73A and 73B from the propulsion performance improving device 41 according to the first embodiment. The propulsion performance improving device 48 includes four wing reaction fins 71A, 71B, 72A, 72B arranged symmetrically. The propulsion efficiency of the ship is improved by the swirl flow opposite to the rotation direction of the propeller 20 generated by the reaction fins 71A, 71B, 72A, 72B. According to the present embodiment, the reaction fins 73A and 73B that cause an increase in resistance are not provided because the water flow velocity is disposed below the level of the rotational axis S that is relatively large in the vicinity of the bossing 11.

  The reaction fins 73A and 73B may be omitted from the propulsion performance improving device 42 according to the second embodiment.

(Ninth embodiment)
With reference to FIG. 14, a propulsion performance improving apparatus 49 according to a ninth embodiment of the present invention will be described. The propulsion performance improving device 49 is obtained by removing the reaction fins 73A and 73B from the propulsion performance improving device 43 according to the third embodiment. The propulsion performance improving device 49 includes four wing reaction fins 71A, 71B, 72A, 72B and reaction fins 74 arranged symmetrically. The propulsion efficiency of the ship is improved by the swirl flow in the direction opposite to the rotation direction of the propeller 20 in which the reaction fins 71A, 71B, 72A, 72B, and 74 are generated.

DESCRIPTION OF SYMBOLS 10 ... Hull 11 ... Bossing 12 ... Stern overhang part 20 ... Propeller 21 ... Propeller shaft 25 ... Propeller circle 41-49 ... Propulsion performance improvement apparatus 71A-73A, 71B-73B, 74, 75A, 75B ... Reaction fin 76A, 76B ... Upper part 77A, 77B ... Bent part 78A, 78B ... Lower part 100, 101 ... Vortex trajectory 111 ... Port side bilge vortex 112 ... Starboard bilge vortex 171A-173A, 171B-173B ... Reaction fin S ... Rotating shaft C ... Hull Center line

Claims (6)

A plurality of reaction fins disposed on the front side of the propeller so as to generate a swirling flow in a direction opposite to the rotation direction of the propeller, and extending radially about the rotation axis of the propeller;
The plurality of reaction fins are:
A first reaction fin extending obliquely upward;
A second reaction fin extending horizontally or obliquely downward,
A first distance from the rotation axis to the blade tip of the first reaction fin is larger than a propeller radius of the propeller;
A propulsion performance improving device for a ship, wherein a second distance from the rotating shaft to a blade tip of the second reaction fin is smaller than the propeller radius. The first distance is 110% or more of the propeller radius;
The ship propulsion performance improving apparatus according to claim 1, wherein the second distance is not less than 70% and not more than 95% of the propeller radius. The marine vessel propulsion performance improving device according to claim 1, wherein the plurality of reaction fins are arranged symmetrically. The marine vessel propulsion performance improving device according to claim 1, wherein the plurality of reaction fins are arranged asymmetrically. The plurality of reaction fins include a third reaction fin extending right above,
The marine vessel propulsion performance improving apparatus according to any one of claims 1 to 4, wherein a third distance from the rotating shaft to a blade tip of the third reaction fin is larger than the propeller radius. A plurality of reaction fins disposed on the front side of the propeller so as to generate a swirling flow opposite to the direction of rotation of the propeller;
The plurality of reaction fins are:
The first reaction fin,
With a second reaction fin,
The first reaction fin is:
An upper part;
Bends,
With a lower part,
The lower portion extends obliquely upward from a bossing that supports the propeller shaft of the propeller to the bent portion,
The upper portion extends upward from the bent portion and is connected to the hull skin.
The lower part and the upper part have different extending directions,
The second reaction fin extends horizontally or obliquely downward from the bossing,
The first distance from the rotating shaft of the propeller to the bent portion is larger than the propeller radius of the propeller,
A propulsion performance improving device for a ship, wherein a second distance from the rotating shaft to a blade tip of the second reaction fin is smaller than the propeller radius.

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