JP3356006B2 - Ship bow shape - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bow shape of a ship.

[0002]

2. Description of the Related Art As shown in a schematic side view of a bow portion in FIG. 5, generally, a bow portion 2 of a hull 1 is viewed from the side from the viewpoint of reduction of wave resistance during navigation and aesthetics. In many cases, the shape protrudes obliquely from the lower part to the upper part. In the conventional hull, the angle (represented by α in FIG. 5) between the inclined lower surface 2a of the protruding bow and the draft line LWL is generally more than 50 °.

[0003] It is known that in order to reduce the wave resistance of the hull during navigation, the lower part of the bow below the draft line should be formed as protruding as sharply as possible. However, in the case of a so-called enlarged ship, such as a tanker or a bulk cargo ship, in which 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 a sharp overhang, The hull must be lengthened by the amount of the overhang, but such a drastic change of the hull cannot be performed due to restrictions such as the load capacity.

[0004] Therefore, in the case of an enlarged 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 be almost upright. As a result, there was a problem from the viewpoint of reducing wave resistance during navigation.

Various studies have been made on the method of reducing the wave resistance of such a large ship, and for example, Japanese Patent Application Laid-Open No. 57-66087 discloses a side view in FIG. 6 and a front view in FIG. As shown in the figure, the bow part 2 above the draft line LWL is formed in a streamline shape that is more toward the stern side than the bow side when viewed from the side, and near the bow perpendicular 5, Also disclosed is a hull (hereinafter, referred to as prior art) in which a cross section of an upper bow portion has a shape having an upwardly convex roundness.

According to the prior art, the bow portion 2 above the draft line is formed in a streamline shape from the bow side to the stern side when viewed from the side. ,
As the waves flow along the bow deck, the impact of the waves can be reduced.

[0007]

However, according to the prior art, even if the resistance to short wavelength waves can be reduced, the wave resistance increases in the case of long wavelength waves. Occurs. Furthermore, because of the above-mentioned bow shape, anchors, mooring lines and the like cannot be arranged like a normal hull, and special equipment needs to be installed, which is not practical.

Therefore, the applicant of the present application has previously filed Japanese Patent Application No.
According to No. 4983, the bow portion above the draft line of the hull is formed to project obliquely at a predetermined angle from the lower portion to the upper portion as viewed from the side and project forward, and then to cross the forwardly projecting bow portion. We have developed a bow shape with a downward wedge shape at a predetermined angle and applied for a patent.

According to the above-mentioned bow shape, 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, wave resistance during navigation is properly reduced. Can be done.

However, on the other hand, it is inevitable that the protruding portion of the bow becomes longer than that of the conventional hull, and therefore, depending on the type of ship, it may be considered that the port entry limit for the entire length of the hull may be exceeded. Also, due to the long protruding part, the steel weight required for the construction of the bow increases,
It is also conceivable that the payload may decrease.

[0011] Accordingly, an object of the present invention is to solve the above-mentioned problems, and to improve the cruising speed 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. Ships that can appropriately reduce the wave resistance at the point of view, and do not cause the bow part to become long and restrict entry into ports at the port with respect to the total length of the hull, or reduce the weight of cargo due to the increase in steel weight To provide a bow shape.

[0012]

SUMMARY OF THE INVENTION The present inventors have found that even in the case of a large vessel such as a tanker or a bulk cargo ship,
Wave resistance during navigation can be reduced accurately, and port entry restrictions due to long bows,
Intensive research was conducted to develop a bow shape that would not cause a decrease in the deadweight due to an increase in steel weight.

[0013] As a result, the bow shape above the draft line is inclined upward at a predetermined angle from the lower side to the upper side as viewed from the side, and is formed so as to protrude forward. If the tip of the protruding part of the specified range that does not impair the effect of reducing the wave resistance due to the protruding part of the bow is cut off at the angle wedge shape, entry into the port due to the length of the bow becomes longer, and the weight of the load due to the increase in steel weight It was found that the wave resistance during navigation could be reduced without any decrease in the sea level.

The present invention has been made on the basis of the above findings, and the bow portion above the draft line of the hull, when viewed from the side, is inclined from the lower portion toward the upper portion and projects forward. The cross section of the forward protruding bow is a downward wedge, and the angle between the inclined lower surface of the protruding bow and the draft line is 10 °.
To 50 ° and the downward wedge angle is 30 °.
° to 120 °, and, of the bow, a shape in which a tip portion in front of a position at a maximum height at which a wavefront of the bowed inclined lower surface protruding from the draft line comes comes down. It is characterized by having

[0015]

Next, the present invention will be described with reference to the drawings. FIG. 1 is a schematic side view showing an embodiment of a bow shape according to the present invention, and FIG. 2 is a front view of a bow portion. As shown in FIG. 1, the bow part 2 above the draft line LWL of the hull 1 projects in an inclined manner from the lower part to the upper part when viewed from the side, and is formed to protrude forward, so that the lower part of the bow part 2 is formed. Is formed in a spherical shape 3. Then, as shown in FIG. 2, the cross section of the bow 2 projecting forward has a downward wedge-shaped inverted triangular shape above the draft line LWL. In FIGS. 1 and 2, A
The -A line is a water line surface where a relative wave front is considered to arrive in waves.

In the present invention, the angle (indicated by α in FIG. 1) between the inclined lower surface 2a of the protruding bow 2 and the draft line LWL should be in the range of 10 ° to 50 °. The angle α between the draft line LWL and the inclined bow 2 is 1
If the angle is less than 0 °, the inclined lower surface 2a of the bow 2 becomes too close to the flat water surface as a result of the inclination 2
Waves and suspended matter come into contact with a, and the bow 2 is likely to be damaged. On the other hand, if the angle α exceeds 50 °, the protruding length of the bow 2 above the draft line LWL becomes short, and the wave resistance cannot be reduced.

The angle (represented by β in FIG. 2) of the downward wedge shape of the inverted triangle forming the cross-sectional shape of the bow 2 is 30.
It should be in the range of ° to 120 °. If the downward wedge-shaped angle β is less than 30 °, the width of the bow 2 becomes extremely short, and an extreme step occurs at the connection between the ship's abdomen and the bow. As a result, there is a problem that the wave resistance increases at the step. On the other hand, when the downward wedge angle β exceeds 120 °,
The width of the protruding bow portion 2 becomes too wide, resulting in a rounded shape, and the effect of reducing wave resistance is lost.

The angle α between the inclined lower surface of the bow and the draft line is 10 to 50 ° and the downward wedge angle β is 30.
The bow 2 having an angle of about 120 ° may be projected forward to the range where the wavefront actually comes, that is, the range where the wave resistance is affected.

That is, the bow-shaped inclined lower surface 2a shown in FIG.
The bow projection 2 ahead of the BB line passing through the highest point X where the wavefront comes does not contribute to the reduction of the wave resistance. Therefore, this portion is unnecessary, and it is not necessary to protrude the bow portion 2 to the front of the line BB passing through the highest point X where the wavefront comes.

Therefore, in the present invention, the hull 1
A shape in which the bow part 2 in front of a line BB intersecting with the inclined lower surface 2a passes through the position X at the maximum height 4 where the wave front of the bow inclined lower surface 2a protruding from the draft line LWL is cut off. And In addition, the cut-off of the bow part 2 ahead of the BB line may be a vertical shape like the BB line shown in FIG. 1 or a diagonally forward straight line or a curved inclined shape like the CC line. It is often determined from the viewpoint of restrictions on the total length of the hull, the hull structure and the design of the hull.

The position X at the maximum height 4 where the wavefront of the bow-shaped inclined lower surface 2a protruding from the draft line LWL of the hull 1 described above can be defined as follows. That is, the wavefront height 4 from the draft line LWL is determined by the sum of the rising amount of the water surface (ζs) and the rising amount of the incident wave (ζw) when the ship is traveling in flat water. The amount of rise in water surface (ζs) during sailing in plain water can be estimated using model test results for each ship type or using the following Tasaki's formula.

[0022] However, B: ship width, L: between perpendiculars length, L _E: the bow entrance length Fn: Froude number.

Also, the swell amount (ζw) of the incident wave is
What is necessary is just to determine from the sea condition data of the route which the said ship sails. FIG. 3 is a plan view showing the shape of the bow at the water line plane A-A where the relative wave front is considered to arrive in the waves. In the present invention, the bow portion 2 is formed so as to protrude obliquely at the angle described above.
As shown in FIG. 3 (a), the shape of the water line above the flat water surface, which is considered to reach the relative wave front in the waves, is an acute angle toward the front of the bow. In FIG. 3, (b) shows a water line shape above a flat water surface in a conventional hull.

As in the present invention, the water line shape shown in FIG. 3 (a) is made acute at the forward part of the bow, so that the waves colliding with the bow collapse at the front part of the bow during navigation. The reflected wave becomes smaller and the wave resistance decreases.

The increase in wave resistance at the bow of the present invention was examined by a model test, and the result is shown in FIG. 4 in comparison with the increase in wave resistance at the conventional bow. In FIG. 4, the horizontal axis represents the dimensionless amount of the wavelength λ of the incident wave by the ship length L, and the vertical axis represents the amount of increase in wave resistance. Solid line in the figure
(a) shows the case of the bow of the present invention, and the dotted line (b) shows the case of the conventional bow.

As is apparent from FIG. 4, in the case of the bow of the present invention, the amount of increase in wave resistance is smaller than that of the conventional bow.
20-30% could be reduced.

[0027]

As described above, according to the present invention,
Even in the case of a large vessel such as a tanker or a bulk carrier, the ratio of width to length of which is relatively large, wave resistance during navigation can be reduced appropriately.
In addition, there is provided an industrially useful effect in which the bow portion becomes long and the entry into the port of the port with respect to the entire length of the hull does not occur, and the increase in the weight of the steel material does not reduce the loading weight.

[Brief description of the drawings]

FIG. 1 is a schematic side view showing one embodiment of a bow of the present invention.

FIG. 2 is a schematic front view of a bow of FIG. 1;

FIG. 3 is a plan view showing a water line shape of a bow of FIG. 1;

FIG. 4 is a graph showing an increase in resistance in waves.

FIG. 5 is a schematic side view of a conventional bow.

FIG. 6 is a schematic side view showing a prior art bow.

FIG. 7 is a schematic front view showing a bow of the prior art.

[Explanation of symbols]

 Reference Signs List 1 hull 2 bow 2a inclined lower surface of bow 3 sphere 4 wavefront height from flat water surface 5 perpendicular to bow

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B63B 1/06 B63B 1/10 B63B 1/18 B63B 1/40 B63B 3/46

Claims (1)

(57) [Claims] 1. A bow portion above a draft line of a hull is formed so as to slope upward from a lower portion as viewed from a side and protrude forward, and a cross-sectional shape of the forwardly protruding bow portion is formed. Is a downward wedge shape, 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 30 ° to 120 °. Within range, and
A tanker or a rosette, wherein the fore part has a shape in which a forward end portion is cut off from a position at a maximum height where a wave surface of the bow-shaped inclined lower surface protruding from the draft line comes from the draft line. Bow shape of a large vessel such as a cargo ship .