JP3271243B2 - How to modify the hull bow - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for converting the bow of an existing hull into a bow having a shape with less wave resistance.

[0002]

2. Description of the Related Art It has been known that in order to reduce the wave resistance of a hull during navigation, a portion below a draft line at a bow portion may be formed to have an overhanging shape as sharp as possible.
However, like tankers and bulk carriers,
In the case of a so-called enlarged ship, where the ratio of the width to the length of the hull is relatively large, in order to make the lower part of the draft line at the bow part an acute overhang, the hull must be lengthened by the overhang. Such a drastic change of the hull cannot be performed due to restrictions on the load capacity and the like.

[0003] Therefore, in the case of a large hull ship, the lower part of the draft line at the bow is not made to have an overhanging shape at an acute angle but to have a substantially upright shape. As a result, there was a problem from the viewpoint of reducing wave resistance during navigation.

[0004] In order to solve the above-mentioned problems, it is possible to reduce the wave resistance during navigation even in the case of an enlarged ship such as a tanker or a bulk cargo ship having a relatively large width-to-length ratio. Regarding possible bow shapes, the present inventor has previously developed a new bow shape disclosed in Japanese Patent Application Laid-Open No. 9-290796.

FIG. 1 is a schematic side view of the bow of the new bow shape, and FIG. 2 is a schematic front view thereof. As shown in the drawing,
The new bow shape is such that a bow portion 2 above a draft line LWL of a hull 1 is formed to project obliquely upward from a lower portion to an upper portion as viewed from the side, and to protrude forward, and to protrude forward. The cross section of the section 2 has a downward wedge shape, and the projecting inclined lower surface 2a of the bow section 2 and the draft line LW
The angle (α) with L is in the range of 10 to 50 °,
The downward wedge angle (β) is in the range of 30 to 120 °.

According to the new bow shape described above, the bow 2 of the hull 1 is formed so as to protrude at an angle larger than that of the conventional bow 7 at the above-mentioned angle, so that it is used for tankers and bulk carriers. Even in the case of a large vessel with a large ratio of the width to the length of the hull, the waves that collided with the bow during navigation collapsed in front of the bow, resulting in less reflected waves, resulting in significantly more waves than the conventional bow. Resistance can be reduced.
Therefore, not only in the case of a new ship, but also in an existing ship, wave resistance can be reduced by modifying the bow portion to the above-mentioned new bow shape.

[0007]

However, there are the following problems in modifying the bow of an existing ship to the above-mentioned new bow shape.

As shown in FIG. 1, a hose pipe 4 for leading an anchor chain from the inside of a ship to the outside of a ship, and a bell attached to a periphery of an opening end of the bow pipe of the hose pipe 4 are provided on a bow 2 of a hull 1. A mouse 3 is provided.

FIG. 3 is a schematic plan view showing the shape of the water line (AA) of the hull 1 at the mounting position of the bell mouth 3 shown in FIG. In FIG. 3, 2b shows a water line at the bow water line surface (AA) in FIG. 1, and B shows a water line surface (AA) at the bellmouth height and the bow lower surface 2a in FIG.
C indicates the intersection of the water line 2b on the water line of the new bow and the water line 7a on the water line of the bow of the existing ship.

In order to remodel an existing ship and make its bow a new bow shape, first, the bow 7 of the existing ship is cut in the vicinity of a cross section passing through the point C, and the front of the cut surface 5 is cut. Remove the bow part 7 of. Then, on the removed part,
A bow 2 having a new bow shape is attached and connected to the hull 1 by welding. Thus, the hull having the bow of the new bow shape is converted.

When the hull bow of an existing ship is modified in this way, as shown in FIG. 3, a bell mouth 3 is provided at a bow 7 to be removed in front of a cutting plane 5, and a hose pipe 4 is cut. If you are crossing face 5,
Cut the hose pipe 4 on the way, and
4, the bow 2 to which the new bellmouth 3a and a part 4a of the hose pipe 4 prepared in advance must be joined to the hull 1 of the existing ship, as shown in FIG. At this time, it is necessary to join the existing hose pipe 4 and the new hose pipe 4a on site, but this joining operation is extremely difficult in terms of the control of the machining accuracy, and the remodeling cost increases.

Accordingly, the present invention solves the above-mentioned problems, and easily remodels the hull bow of a large vessel such as a tanker or a bulk carrier to a new bow with less wave resistance at a low cost. It is an object of the present invention to provide a method for remodeling a hull bow.

[0013]

SUMMARY OF THE INVENTION According to the present invention, a wedge whose cross section is downwardly protruded forward from a lower part of a hull above a draft line so as to be inclined upward from a lower part as viewed from a side. Wave resistance, wherein the angle between the inclined lower surface of the protruding bow and the draft line is in the range of 10 to 50 ° and the downward wedge angle is in the range of 30 to 120 °. When remodeling to a smaller bow, the existing hull bow is cut off at a cross section passing through a point immediately before the bellmouth which does not affect the bellmouth provided on the bow, and after removing it, the removal is performed. The part has a waterline determined by a line passing through the point immediately before the bellmouth and the intersection of the waterline surface at the height of the bellmouth and the lower surface of the bow portion. Attached and connected integrally to the hull by welding It is characterized by being continued.

[0014]

Next, the present invention will be described with reference to the drawings. FIG. 5 is a schematic plan view of the bow showing one embodiment of the method of remodeling the hull bow of the present invention. As shown in the drawings, in the present invention, the conventional bow 7 in the hull 1 of an existing ship is crossed through a point D of the bow just before the bellmouth which does not affect the bellmouth 3 provided on the bow. Cut and remove at face 6. Next, at the position where the above-mentioned conventional bow 7 is removed, it passes through the point D of the bow just before the bellmouth, and the intersection B between the water line surface (AA) of the bellmouth height and the bow lower surface 2a. A new bow portion 2 having a waterline shape 2c determined by the line and having a low wave resistance is mounted.

The water line shape of the new bow 2 described above may be a combination of a straight line 2d connecting points D and B and shackled in the middle, as shown in a schematic plan view of the bow in FIG.
Alternatively, it may be a curve 2e or 2f connecting the point D and the point B as shown in a schematic plan view of the bow portion in FIG. However, in any case, it is necessary that the angle (γ) formed by the straight line parallel to the front and rear line at the point D is larger than 0 degree.

As shown in FIGS. 1 and 2 described above, the shape of the new bow portion is such that the bow portion 2 above the draft line LWL of the hull 1 is inclined from the lower portion to the upper portion as viewed from the side. The bow 2 is formed so as to protrude forward and project forward, and the cross-sectional shape of the forward protruding bow 2 is a downward wedge shape, and the inclined lower surface 2a of the protruding bow 2 and the draft line L
The angle (α) to the WL should be in the range of 10 to 50 °, and the downward wedge angle (β) should be in the range of 30 to 120 °.

The inclined lower surface 2a of the bow 2 and the draft line LWL
Is less than 10 °, the inclined lower surface 2
a is too close to the flat water surface, and as a result,
Waves and suspended matter come into contact with a, and the bow 2 is likely to be damaged. On the other hand, when the angle exceeds 50 °, the draft line L
The protruding length of the bow portion 2 above the WL becomes short, and the wave resistance cannot be reduced.

If the angle (β) of the downward wedge forming the cross-sectional shape of the protruding bow 2 is less than 30 °,
The width of the bow 2 becomes short, and an extreme step occurs at the connection between the abdomen and the bow, causing a problem that the wave resistance increases at this portion. On the other hand, the angle (β) of the downward wedge shape is 120 °
Is exceeded, the width of the bow portion 2 becomes too wide, resulting in a rounded shape, and the effect of reducing wave resistance is lost.

FIG. 8 is a schematic side view showing another example of the new bow portion. In this example, a portion of the bow 2 ahead of the position of the maximum height where the wave front comes, that is, the draft line LW
L, which passes through the position X at the maximum wavefront height 8 from the flat water surface on the bow-shaped inclined lower surface 2a protruding from L.
The bow part 2 in front of the line BB intersecting with the front end is cut off. With such a shape, the wave resistance can be reduced and the length of the bow can be shortened. Can be prevented from decreasing.

[0020]

As described above, according to the present invention,
An industrially useful effect can be obtained, in which the hull bow of a large vessel such as a tanker or a bulk cargo ship can be easily remodeled to a new bow with less wave resistance at a small cost with a small cost.

[Brief description of the drawings]

FIG. 1 is a schematic side view of a bow showing an example of a new bow shape.

FIG. 2 is a schematic front view of a bow portion having a new bow shape.

FIG. 3 is a schematic plan view showing a waterline shape of a hull at a bellmouth mounting position.

FIG. 4 is a schematic plan view showing a bow portion to which a new bell mouth and a part of a hose pipe prepared in advance in the related art are mounted.

FIG. 5 is a schematic plan view of a bow showing an example of the method of the present invention.

FIG. 6 is a schematic plan view of a bow showing another example of the method of the present invention.

FIG. 7 is a schematic plan view of a bow showing still another example of the method of the present invention.

FIG. 8 is a schematic side view of a bow showing another example of a new bow shape.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Hull 2 Bow 2a Bow inclined lower surface 3 Bell mouth 4 Hose pipe 5 Bow cross section 6 Bow cross section 7 Conventional bow 8 Wave height from flat water surface

Claims (1)

(57) [Claims] 1. A bow portion above a draft line of a hull protrudes forward in an inclined manner from a lower portion to an upper portion as viewed from a side surface, and has a downward wedge-shaped cross-sectional shape. The angle between the inclined lower surface of the bow and the draft line is 10
５０50 ° and the downward wedge angle is 30〜1.
When remodeling a bow with less wave resistance within the range of 20 °, a cross section of the existing hull bow passing through a point immediately before the bellmouth which does not affect the bellmouth provided on the bow After cutting it and removing it at
A point just before the bellmouth, having a waterline determined by a line passing through the intersection of the waterline surface of the bellmouth height and the lower surface of the bow, wearing a new bow having a shape with less wave resistance, A method of remodeling a hull bow, wherein the hull bow and the hull are integrally connected by welding.