JP7194466B1 - A ship with a bow valve that has a hull structure that reduces impact on the hull bottom - Google Patents

Abstract

[Problem] A bow valve having a hull structure capable of reducing punching and slamming at the bottom of the hull without impairing the hull form and performance required for light and small ships, and reducing the impact and burden on the hull, crew and equipment. Provide ships with SOLUTION: This ship is provided with a cushioning member on the bottom of the ship on the bow side from at least the central portion in the length direction of the ship. The cushioning member is attached so as to cover at least part of both side surfaces of the box keel or bar keel from the box keel or bar keel to a position spaced from the attachment portion of the box keel or bar keel on the bottom of the ship. [Selection drawing] Fig. 1(a)

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ship with a bow bulb having a ship bottom structure provided with cushioning members that reduce the impact of waves on the ship bottom at the bow.

A bow bulb (also known as a bulbous bow or bulbous bow) is a spherical protrusion on the bow of a ship. It is possible to suppress the generation of waves by causing the waves to interfere with each other and canceling out both waves. Therefore, the bow valve can reduce the wave resistance to the ship, which is effective in improving the sailing speed and fuel efficiency. A bow valve is originally effective when it is submerged below the waterline, but it has been found to be effective in reducing wave-making resistance and improving fuel efficiency even in small ships that are not submerged.

On the other hand, in recent years, the number of fishing boats made of aluminum alloy is rapidly increasing due to advances in ship construction technology. Aluminum alloy fishing boats are lightweight and highly resistant to corrosion, making it possible to reduce the burden on the environment by reducing the burden of maintenance and reducing the amount of plastic used. In addition, the lightweight aluminum alloy fishing boat is able to achieve both high-speed running and energy saving due to the effects of improved engine performance and lighter weight.

In aluminum alloy fishing boats, as the speed increases, the impact of waves applied to the bow and the bottom of the boat in a certain area near the bow also increases. When a ship repeatedly pitches and rolls violently in rough weather, the bottom of the bow and stern of the ship is hit by waves and receives a large impact (punching), or due to the gravity and waves rising when the ship falls. Due to the action of force, a phenomenon (slamming) occurs in which the bottom of the ship collides with the water surface and receives a large impact. There is a flat part in the center of the width direction of the bottom of the ship, and the impact applied to this flat part by punching and slamming is large, especially the part 1/8 to 1/6 of the length behind the bow is the most severe impact. will receive When punching or slamming occurs, the ship is forced to slow down so as not to place a heavy burden on the crew and on-board equipment, and repeated unreasonable sailing causes dents in the bottom of the ship and damage to the internal frame, requiring extensive repairs. It may become

As a technique for reducing the impact of waves on the bottom of a ship, for example, a technique described in Patent Document 1 (Japanese Patent Application Laid-Open No. 2018-122711) has been proposed. In this technique, the hull shape on the stern side of the ship is made into a curvilinear shape that protrudes toward the inner side of the hull within a range from the lowermost end to a predetermined height. A ship using this technology is said to be able to improve the course stability of the ship by giving the hull itself a course keeping function, and to reduce the impact of waves caused by pitching of the hull.

JP 2018-122711 A

Many small fishing boats are designed so that more cargo can be loaded on the bow than in the center in the longitudinal direction. For this reason, the bow side, where cargo is loaded, is heavy, and many ship structures have a nearly flat bottom and a large bottom area in order to secure a load capacity. Especially in Hokkaido, where a large amount of fish are caught in a short period of time depending on the season, there are many small fishing boats with such a structure. These small fishing boats are prone to punching and slamming due to the bottom of the boat, which has a small angle of inclination (the angle of the bottom of the boat with respect to the horizontal in the cross-section perpendicular to the length of the hull) even near the bow, and the wave resistance is large and the energy loss is large. When an empty small fishing boat is heading offshore to a fishing ground, the oncoming waves exert a greater impact on the bottom of the boat. In addition, the sea in Hokkaido in particular is cold and has a high viscosity, so-called hard sea surface, so the waves exert a greater impact on the bottom of the ship.

The impact on the bottom of the ship can be mitigated by increasing the angle of inclination of the bottom of the bow. and safety. In addition, in a small fishing boat, if the inclination of the hull becomes large, a phenomenon (broaching phenomenon) in which the bow pierces the forward wave during following waves and overturns is likely to occur. In addition, increasing the angle of inclination of the bow and bottom of the bow reduces the payload. Therefore, fishing boats that place importance on work efficiency and load capacity often reduce the angle of inclination of the bottom of the bow.
Therefore, there is a demand for a hull bottom structure that reduces the impact of waves while reducing the angle of inclination of the hull's bow.

The present invention is a bow having a bottom structure that can reduce punching and slamming at the bottom of the ship without impairing the hull shape and performance required for light and small ships, and can reduce the impact and burden on the hull, crew and equipment. An object of the present invention is to provide a ship with a valve.

The present invention includes a hull bottom and a box keel or bar keel attached to the hull bottom so as to extend in the lengthwise direction of the hull bottom central portion, and is configured to reduce impact on the hull bottom due to collision with the sea surface. To provide a ship with a bow valve having a hull structure with a bottom structure. A ship according to the present invention includes a cushioning member on the bottom of the ship on the bow side of at least the central portion in the length direction of the ship. The cushioning member is attached so as to cover at least part of both side surfaces of the box keel or bar keel from the box keel or bar keel to a position spaced from the box keel or bar keel attachment portion on the bottom of the ship.

In one embodiment, the cushioning member is preferably attached over a range of 1/6 to 1/4 of the length of the vessel from the datum of measure toward the stern side from the datum of measure. Here, the reference point of measurement for the length (L) of the ship is the forward end position of the upper deck of the ship. In another embodiment, it is preferable that the cushioning member is also provided at the bow bulb ahead of the datum point.

In one embodiment, the cushioning member is preferably a flat plate that is linearly arranged between the box keel or bar keel and the bottom of the ship when viewed in a cross section perpendicular to the length of the ship. In another embodiment, the damping member is arranged between the box keel or bar keel and the bottom of the ship and convexly toward the side of the box keel or bar keel when viewed in a cross section perpendicular to the length of the ship. It can also be a curved plate.

In one embodiment, the angle between the flat plate and the sides of the box keel or bar keel is preferably 40 degrees to 70 degrees, more preferably 45 degrees to 65 degrees, most preferably 60 degrees. .

In one embodiment, the cushioning member may have one or more openings for the entry of seawater between the cushioning member and the box keel or bar keel.

According to the present invention, cushioning members are provided from the box keel or bar keel of the bow valve-equipped vessel toward the bottom plates on both sides. That is, the ship with a bow valve according to the present invention has a ship bottom structure in which a triangle having three sides formed by the cushioning member and the ship bottom protrudes downward from the ship bottom when viewed in a cross section orthogonal to the length direction of the ship. have. Therefore, when the bottom of a vessel collides with the sea surface during navigation, the bottom of the triangle (i.e., the bottom of the box keel or bar keel) lands on the sea surface before the bottom of the ship, and the two sides of the triangle (i.e., the cushioning members) A water stream is formed that flows backward along the surface). This water current acts as a cushion for the flow toward the bottom of the ship, thus reducing the impact of the waves on the bottom of the ship. In addition, since the flat hull bottom near the longitudinal centerline is hidden inside the triangle, the flat area of the hull bottom is reduced, and the impact applied to the hull bottom can be reduced accordingly.

1 is a side view of an entire hull of a fishing boat having a hull structure according to one embodiment of the present invention; FIG. 1 is a side view of a front portion of a hull including a portion provided with a cushioning member, showing a fishing boat having a hull structure according to an embodiment of the present invention; FIG. It is a figure which shows the cross section of the fishing boat which has the hull-bottom structure by one Embodiment of this invention, and is an enlarged cross-section of the hull-bottom part in arrow AA of FIG.1(b). FIG. 4 is a diagram showing the flow of water in the bottom of a fishing boat having a bottom structure according to one embodiment of the present invention, showing the flow of water when the front part of the hull including the portion provided with the cushioning member is viewed from the bottom direction. FIG. 2 is a diagram showing the flow of water in the bottom of a fishing boat having the hull structure according to one embodiment of the present invention, showing the flow of water when the bottom is viewed from the bow direction. It is a figure which shows the cross section of the fishing boat which has the hull structure by another embodiment of this invention, and is a cross section corresponding to the same position as the AA arrow cross section of FIG.1(b). FIG. 4 is a diagram of a fishing boat having a hull structure according to another embodiment of the present invention, showing a cushioning member provided with seawater inlets and outlets;

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a diagram showing a small fishing boat with a bow valve (hereinafter simply referred to as a fishing boat) having a hull structure according to one embodiment of the present invention. FIG. 1(a) is a side view of the entire hull, and FIG. 1(b) is a side view of the front part of the hull including a portion provided with cushioning members. Also, FIG. 2 shows an enlarged cross-section of the bottom portion of the ship along the arrow AA in FIG. 1(b). In the following description, a small fishing boat will be used as an example, but the present invention can of course be applied to other vessels as well.

A hull 1 of a fishing boat has a hull length L as shown in FIG. . A bow valve 4 is provided below the bow 3 . The bow valve 4 protrudes forward from the upper deck 2 below the upper deck 2 . A box keel or bar keel (hereinafter referred to as a keel 6) extending in the length direction of the bottom 5 is provided at the center of the bottom 5 in the direction (width direction) perpendicular to the length direction.

In this embodiment, a buffer member 7 is provided on the ship bottom 5 from the bow valve 4 to a predetermined position in the stern direction. The cushioning member 7 is composed of a starboard plate 7a and a port plate 7b, which are plate-like bodies having a length extending in the longitudinal direction of the hull 1 . As shown in FIG. 2, the starboard plate 7a has one long side 7a1 fixed to the lowermost end 6a1 of the side surface 6a of the keel 6, and the other long side 7a2 extending from the mounting portion 6a2 of the keel 6 on the ship bottom 5 toward the starboard side. is fixed at a position 5a away from the Similarly, the port board 7b has one long side 7b1 fixed to the lowermost end 6b1 of the side surface 6b of the keel 6, and the other long side 7b2 is located at a position 5b away from the mounting portion 6b2 of the keel 6 on the ship bottom 5 in the port direction. fixed to That is, when viewed in a cross section orthogonal to the length direction of the hull 1, a downward-pointing substantially triangle having the bottom side of the hull 5 and the other two sides of the starboard plate 7a and the port plate 7b protrudes from the hull 1. formed in

The positions where the long sides 7a1 and 7b1 are fixed are preferably the lowermost ends 6a1 and 6b1 of the keel 6, but are not limited thereto. The positions of the long sides 7a1 and 7b1 may be positions moved in the direction of the mounting portions 6a2 and 6b2 from the lowermost ends 6a1 and 6b1. It can be either position. By fixing the long sides 7a1, 7b1 in this position, all or part of the side surfaces 6a, 6b of the keel 6 can be covered by the cushioning member 7 to generate a water flow as described below. Further, the positions 5a and 5b of the ship bottom 5 to which the long sides 7a2 and 7b2 are fixed are preferably outside the flat portion 51 in the center portion of the ship bottom 5 in the width direction. By providing the cushioning member 7 so as to fix the long sides 7a2 and 7b2 at this position, the flat portion 51 where the impact of waves is particularly large can be hidden inside the cushioning member 7. FIG.

The angle θ between the starboard plate 7a and port plate 7b and the side surfaces 6a, 6b of the keel 6 is preferably 40 to 70 degrees, more preferably 45 to 65 degrees, and is 60 degrees. is most preferred. If the angle θ is too small, a water flow as will be described later is not generated, and the impact on the bottom of the ship cannot be mitigated. If the angle θ is too large, the impact of waves on the starboard plate 7a and the port plate 7b themselves becomes large, and as a result, the impact on the hull cannot be mitigated.

The starboard plate 7a and the port plate 7b are preferably provided continuously in the range from the bottom 4a of the bow valve 4 to the position L/4 in the stern direction from the measurement base point 2a. That is, it is preferable that the starboard board 7a and the port board 7b are arranged so that both side surfaces 6a and 6b of the keel 6 from the bow valve 4 to the L/4 position are hidden.

At the bottom 4a of the bow valve 4, the starboard plate 7a and the port plate 7b are curved so that their long sides 7a2 and 7b2, which are upper sides, match the shape of the bottom 4a. In addition, the long side 7a1 and the long side 7b1, which are the respective lower sides, rise in a curved shape toward the tip direction of the bow valve 4 (portion indicated by 7a11 in FIG. 1(b)), and the tip of the long side 7a1 and the long side 7b1 It is formed so as to be in contact with the ends of 7a2 and the long side 7b2 and smoothly connected to the bottom portion 4a of the bow valve 4 . Further, the starboard plate 7a and the port plate 7b are arranged such that the long side 7a1 and the long side 7b1, which are the lower sides, are curved or straight in the stern direction at a position approximately L/4 from the measurement base point 2a toward the stern direction. (portion indicated by 7a12 in FIG. 1(b)), and the rear ends of the long sides 7a1 and 7b1 are in contact with the rear ends of the long sides 7a2 and 7b2.

By providing such a buffer member 7 in the bottom 5 of the hull 1, a water flow is formed in the bottom 5 of the ship as shown in FIGS. 3(a) and 3(b). That is, when the bottom 5 of the hull 1 collides with the sea surface during navigation, the long sides 7a1, 7b1 of the cushioning members 7 fixed to the lowermost ends 6a1, 6b1 of the keel 6 land on the sea surface before the bottom 5, After that, the ship bottom 5 lands on the water. During the period from when the long sides 7a1 and 7b1 of the cushioning members land on the water until when the ship bottom 5 lands on the water, a seawater flow f1 obliquely rearward is generated along the surfaces of the starboard board 7a and the port board 7b. The flow f1 functions as a cushion against the water pressure of the waves f2 directed toward the bottom 5 of the ship, and reduces the impact of the waves applied to the bottom 5 of the ship. In addition, since the flat portion 51 of the bottom 5 is hidden inside the cushioning member 7, the area of the near-flat portion of the bottom 5 is reduced, and the impact applied to the bottom 5 is reduced in proportion to the reduction in area. be able to. On the other hand, in a hull without the cushioning member 7 according to the present invention, the water pressure of the wave f2 directly acts on the nearly flat portion of the hull bottom, so that a large impact is applied to the hull and the bottom of the hull.

In this embodiment, the buffer member 7 is provided over a range from the bottom 4a of the bow valve 4 to the position L/4 in the stern direction from the measurement base point 2a, but is not limited to this. The rear end of the buffer member 7 may be located on the bow side of the L/4 position (that is, the buffer member 7 may be shortened), and the rear end of the buffer member 7 may be positioned on the stern side of the L/4 position (preferably the hull). ) (that is, the cushioning member 7 may be lengthened). Alternatively, the buffer member 7 may not be provided on the bottom portion 4a of the bow valve 4, and may be provided only in the range from the rear of the bow valve 4 to the position L/4 in the stern direction from the measurement base point 2a. However, it is necessary to provide at least the buffer member 7 in the position where the most severe impact is received by punching or slamming, that is, in the range from the measurement base point 2a of the ship bottom 5 to about L/8 to L/6. That is, the cushioning member 7 is provided at least over a range from the back of the bow valve 4 to the position of L/6 from the measurement base point 2a. It is most preferable to extend from the bottom 4a of the scale base point 2a to the position of L/4.

In this embodiment, as shown in FIG. 2, the cushioning member 7 is a flat plate (starboard plate 7a and port plate 7b) arranged linearly between the lowest ends 6a1, 6b1 of the keel 6 and the bottom 5 of the ship. However, the shape of the cushioning member 7 is not limited to this. The cushioning member 7 may have any shape as long as a flow f1 is generated obliquely rearward along the surface of the cushioning member as shown in FIG. For example, as shown in FIG. 4, the cushioning member 7 is provided between the lowermost ends 6a1, 6b1 of the keel 6 and the bottom 5 of the ship when viewed in a cross section perpendicular to the length direction of the hull 1. It can be a bending plate arranged in a convex shape toward the side surfaces 6a and 6b of the keel 6. FIG.

In this embodiment, the buffer member 7 is attached so as to form a closed space between the keel 6 and the starboard plate 7a and port plate 7b. However, if the closed space due to the buffer member 7 exceeds a predetermined volume (1 m ³ ), it will be added as the volume (tonnage) of the hull. In addition, if the closed space increases, the buoyancy of the bottom of the ship increases, which is a factor in deteriorating the stability of the hull. Therefore, when there is no margin in the allowable gross tonnage of the hull, or when it is not desired to increase the buoyancy of the bottom of the hull, a forward float for allowing seawater to flow between the cushioning member 7 and the keel 6 as shown in FIG. Openings 71 and/or rear openings 72 are preferably provided in the damping member 7 . The front opening 71 and/or the rear opening 72 can be provided in each of the starboard plate 7a and the port plate 7b, or a plurality of them can be provided. When the front opening 71 is provided, it is preferable to provide the rear opening 72 so that the inflowing seawater can be discharged.

1 hull 2 upper deck 2a datum point 3 bow 4 bow valve 4a bottom 5 bottom 51 flat portion 5a starboard plate mounting position 5b port plate mounting position 6 keel 6a, 6b side 6a1, 6b1 lowermost end 6a2, 6b2 mounting portion 7 cushioning member 7a Starboard board 7a1, 7a2 Long side 7b Port board 7b1, 7b2 Long side 71 Front opening 72 Rear opening L Hull length f1, f2 Flow of sea water

Claims (8)

Equipped with a hull (5) and a box keel or bar keel (6) attached to the hull bottom so as to extend in the lengthwise direction of the hull bottom in the central part of the hull, so as to mitigate the impact on the hull bottom due to collision with the sea surface. A ship (1) with a bow valve having a constructed hull structure,
Mounting portions (6a2, 6b2) of the box keel or bar keel on the bottom of the ship (1) from the box keel or bar keel (6) at the bottom (5) on the bow side of at least the central portion in the longitudinal direction of the ship (1). to a position (5a, 5b) away from the box keel or bar keel in the direction of both sides (7a, 7b) attached to cover at least a part of both side surfaces (6a, 6b) of the box keel or bar keel A vessel with a bow valve, characterized in that: The front end position (2a) of the upper deck of the ship is the measurement base point of the length (L) of the ship,
The cushioning members (7a, 7b) are mounted over a range from 1/6 to 1/4 of the length from the measurement reference point toward the stern side from the measurement reference point, A ship with a bow valve according to claim 1. 3. Vessel with bow bulb according to claim 2, characterized in that the buffer member is also provided on the bow bulb (4) forward of the datum point of measure. The cushioning members (7a, 7b) are arranged in a straight line between the box keel or bar keel (6) and the bottom (5) when viewed in a cross section orthogonal to the longitudinal direction of the ship. 4. Ship with bow bulb according to any one of claims 1 to 3, characterized in that it is flat. 5. A bow bulb vessel according to claim 4, characterized in that the angle between the plate and the sides of the box keel or bar keel is between 40 and 70 degrees. 6. A bow bulb vessel according to claim 5, characterized in that the angle between the plate and the sides of the box keel or bar keel is between 45 and 65 degrees. The cushioning members (7a, 7b) are arranged between the box keel or bar keel (6) and the ship bottom (5) when viewed in a cross section orthogonal to the longitudinal direction of the ship. 4. A ship with a bow valve according to any one of claims 1 to 3, characterized in that it is a bent plate arranged convexly toward the side of the bow. Said damping members (7a, 7b) are characterized in that they have one or more openings for the inflow of sea water between said damping members (7a, 7b) and said box keel or bar keel (6). A ship with a bow valve according to any one of claims 1 to 7.

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