Hull structure of a multi-hulled ship

Abstract

To provide a hull structure of a multihull ship capable of preventing the mixture of the shaking due to a long period wave and the shaking due to a short natural period wave.SOLUTION: A hull structure according to one embodiment of the present invention comprises: a first hull; a second hull arranged in parallel to the first hull; and a fin arranged to be protruded toward the opposite direction of the first hull in a lower part of the second hull.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] One embodiment of the present invention relates to the hull structure of a multi-hull ship having a plurality of hulls.

Background Art

[0002] Patent Document 1 discloses a multi-hull ship having a main hull and side hulls. The roll of a ship (oscillation in the roll direction) becomes very large when the period of the wave and the natural period of the ship's roll coincide. The natural period of the ship's roll becomes shorter as the width of the hull increases. However, when the width of the hull increases, the propulsion resistance increases. Therefore, a multi-hull ship such as that of Patent Document 1 is characterized in that the side hulls widen the width of the ship to shorten the natural period of the ship's roll and suppress an increase in propulsion resistance. As a result, a multi-hull ship such as that of Patent Document 1 can shorten the natural period of the ship's roll to be shorter than the period of the wave while ensuring the stability of the ship, and can reduce the roll.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, the period of the wave is not constant, and there are waves with long periods and waves with short periods. A multi-hull ship such as that of Patent Document 1 can shorten the natural period of the roll, but in order to respond to long-period waves, there may be a mixture of rolling due to long-period waves and rolling with a short natural period. long

[0005] Therefore, an object of one embodiment of the present invention is to provide a hull structure of a multi-hull ship that prevents the mixture of rolling due to long-period waves and rolling with a short natural period.

Means for Solving the Problems

[0006] A hull structure according to one embodiment of this invention is characterized by comprising: a first hull; a second hull arranged parallel to the first hull; and a fin positioned at the lower part of the second hull, projecting toward the direction opposite to the first hull.

[0007] The hull structure of this embodiment is a multi-hulled vessel having multiple hulls. At least one of the hulls constituting the multi-hulled vessel (the second hull) is equipped with a fin that protrudes in the opposite direction to the other hulls (the first hull). The fin suppresses rolling motion and reduces the short-period oscillations of the hull. As a result, the hull structure of this embodiment prevents the coexistence of oscillations caused by long-period waves and oscillations with short natural periods.

[0008] Furthermore, it is preferable that the fin is positioned at the lowest part of the first hull.

[0009] This allows the hull structure of this embodiment to enhance the effect of the fins.

[0010] Furthermore, it is preferable that the fins protrude in a direction perpendicular to the direction toward the lower part of the second hull.

[0011] This allows the hull structure of this embodiment to enhance the effect of the fins.

[0012] Furthermore, the fins are aligned along the height direction of the second hull. Ta It is preferable that the shape is short in the direction and long along the longitudinal direction of the second hull.

[0013] As a result, the hull structure of this embodiment can suppress propulsion resistance.

[0014] The hull structure of this embodiment may include a skeg positioned at the bottom of the first hull.

[0015] As a result, the hull structure of the present embodiment can further reduce the rolling motion in the roll direction by the skeg, and can improve the straight-running performance.

[0016] Note that it is preferable that the width of the second hull is narrower than the width of the first hull.

[0017] The hull structure of the present embodiment can reduce the force received from the waves by making the second hull smaller.

[0018] The second hull may have a relatively narrow lower part and a relatively wide upper part disposed above the draft.

[0019] The hull structure of the present embodiment increases the restoring force during inclination by enlarging the upper part disposed above the draft.

[0020] Further, the upper part may have a shape in which the width further expands as it moves away from the draft.

[0021] The hull structure of the present embodiment can significantly increase the resistance due to buoyancy by further widening the hull width as it moves away from the draft, and can keep the inclination angle in the roll direction within a specified range.

[0022] Note that the second hull may include a first side hull and a second side hull disposed sandwiching the first hull, and the fins may include a first fin disposed on the first side hull and a second fin disposed on the second side hull.

Brief Description of the Drawings

[0023] [Figure 1] It is a plan view of the triple hull ship [1]. [Figure 2] It is a left side view of the triple hull ship [1]. [Figure 3] It is a front view of the triple hull ship [1]. [Figure 4] It is a diagram showing the relationship between the wave period and the mixing ratio of rolling. [Figure 5] It is a plan view showing an example in which fins 20A and 20B are arranged at positions separated from side hulls 2A and 2B. [Figure 6] It is a plan view showing an example in which fins 20A and 20B are divided into a plurality.

Embodiments for Carrying out the Invention

[0024] FIG. 1 is a plan view of a trimaran 1 having the hull structure of the present embodiment. FIG. 2 is a left side view of the trimaran 1, and FIG. 3 is a front view of the trimaran 1. In the present embodiment, the traveling direction of the ship is referred to as the Y direction, the right direction among the directions orthogonal to the Y direction is referred to as the X direction, and the vertically upward direction is referred to as the Z direction.

[0025] The trimaran 1 is an example of a multi-hull ship. The trimaran 1 includes a main hull 10 which is an example of a first hull, and side hulls 2A and 2B which are examples of second hulls.

[0026] The main hull 10 is the main hull of the trimaran 1. The main hull 10 includes various compartments such as a passenger compartment, a cargo compartment, a power compartment, or a compartment for arranging sensors and the like (not shown). The main hull 10 is long in the direction parallel to the Y direction (front-rear direction) and short in the direction parallel to the X direction (width direction). The main hull 10 is designed in a shape that does not have an excessive restoring force and ensures a degree of resilience that does not cause capsizing.

[0027] The main hull 10 has a skeg 50 at the bottom of the hull. The skeg 50 is arranged at the rear part of the main hull 10. The length (width) of the skeg 50 in the direction parallel to the X direction is short, and the length (front-rear length) in the direction parallel to the Y direction is long. With such a shape, the skeg 50 reduces the rolling (side-to-side rolling) in the roll direction. In addition, since the skeg 50 is arranged at the rear part of the main hull 10, it also reduces the yawing and improves the straight running performance. However, the skeg 50 is not an essential configuration in the present invention.

[0028] Side hulls 2A and 2B are arranged parallel to the main hull 10. Side hull 2A is located on the right side of the main hull 10. Side hull 2B is located on the left side of the main hull 10. Both side hulls 2A and 2B are connected to the main hull 10. In this embodiment, side hulls 2A and 2B are connected to the top of the main hull 10 at the top of the hull, as an example, but the connection configuration of the main hull 10, side hulls 2A and 2B is not limited to this example.

[0029] Side hulls 2A and 2B are connected aft of the main hull 10 in a plan view. This allows the trimaran 1 to reduce yaw motion and improve straight-line stability.

[0030] The side hulls 2A and 2B, like the main hull 10, are long in the longitudinal direction and short in the width direction. More specifically, the longitudinal length of the side hulls 2A and 2B is shorter than the longitudinal length of the main hull 10. Also, the width of the side hulls 2A and 2B is narrower than the width of the main hull 10. As an example, in this embodiment, the longitudinal length of the side hulls 2A and 2B is equal to the distance between the center position of the main hull 10 and the center positions of the side hulls 2A and 2B.

[0031] As a result, the trimaran 1 reduces the force exerted on the side hulls 2A and 2B by waves, and also suppresses the propulsion resistance of the side hulls 2A and 2B. The longitudinal length and width of the side hulls 2A and 2B are designed to meet the requirements stipulated in the regulations for ship stability.

[0032] The trimaran 1 exhibits behavior similar to that of a wider main hull 10 in terms of rolling motion (swaying in the roll direction) due to the side hulls 2A and 2B. The trimaran 1 widens the width of the ship by the side hulls 2A and 2B, shortening the natural period of the ship's rolling motion and reducing propulsion resistance. As a result, the trimaran 1 can ensure ship stability while shortening the natural period of its rolling motion to the period of the waves, thereby reducing rolling motion.

[0033] Furthermore, the trimaran 1 of this embodiment is equipped with fins 20A and fins 20B at the lower part of the side hulls 2A and 2B. Fins 20A and fins 20B each protrude in the direction opposite to the main hull 10.

[0034] Fins 20A and 20B are short in the direction parallel to the Z direction (height direction) and long along the front-to-back direction. This reduces the thrust drag of fins 20A and 20B. Also, fins 20A and 20B are, Y The ends of the directional shaft are tapered. This further reduces propulsion resistance. However, Y It is not essential that the ends of the direction be tapered.

[0035] Fins 20A and 20B suppress the rolling motion of the trimaran 1 and reduce the short-period oscillations of the hull. As a result, the hull structure of the trimaran 1 in this embodiment prevents a mixture of oscillations caused by long-period waves and oscillations with short natural periods.

[0036] Figure 4 shows the relationship between wave period and the proportion of rolling motion. The horizontal axis of the graph in Figure 4 represents the ratio of wave period to the ship's natural period (natural period of rolling motion). The vertical axis of the graph in Figure 4 represents the proportion of rolling motion due to waves and rolling motion due to the ship's natural period.

[0037] The "with outer fins" and "with outer fins (double area)" shown in the figure correspond to the data for fins 20A and 20B in this embodiment. Figure 4 shows the data for "without fins" as a reference example. The "with inner and outer fins" data is also a reference example. "With inner and outer fins" refers to the data for fins that have portions that protrude not only in the direction opposite to the main hull, but also in the direction toward the main hull.

[0038] The period of a wave is not constant, long Waves and short-period waves exist. As shown in Figure 4, in a hull structure without fins, the longer the wave period, the more the oscillations caused by long-period waves and oscillations caused by short-period waves coexist.

[0039] In contrast, Figure 4 shows that the "with outer fins" and "with outer fins (double the area)" configurations reduce the coexistence of oscillations caused by long-period waves and oscillations caused by short-period waves. Furthermore, as can be seen from the results in Figure 4, the larger the fin area, the greater the effect in preventing the coexistence of oscillations caused by long-period waves and oscillations caused by short-period waves. However, the larger the area, the greater the waterline... D The width of the lower part becomes larger. Therefore, the fin area should be set appropriately considering the desired effect.

[0040] Furthermore, as shown in Figure 4 as an example, the configuration with "inner and outer fins" actually increases the mixture of oscillations caused by long-period waves and oscillations caused by short-period waves. Therefore, it is clear that it is important for the fins to protrude in the direction opposite to the main hull.

[0041] Fins 20A and 20B are most effective at suppressing roll oscillation when positioned at the very bottom of side hulls 2A and 2B. However, it is not essential that fins 20A and 20B are positioned at the very bottom of side hulls 2A and 2B. They only need to be positioned at the bottom of side hulls 2A and 2B. Of course, the lower fins 20A and 20B are positioned, the greater their effect in suppressing roll oscillation.

[0042] Furthermore, fins 20A and 20B can achieve the greatest effect in suppressing rolling oscillation when they protrude perpendicular to the downward direction (i.e., parallel to the X direction). However, it is not essential that fins 20A and 20B protrude parallel to the X direction. Fins 20A and 20B may protrude at an angle from the X direction. Of course, the closer fins 20A and 20B protrude to the direction parallel to the X direction, the greater their effect in suppressing rolling oscillation.

[0043] As shown in Figure 3, the side hulls 2A and 2B of this embodiment have a relatively narrow lower section and a relatively wide upper section positioned above the waterline. The larger upper section positioned above the waterline of the side hulls 2A and 2B increases the righting force when tilted.

[0044] Furthermore, as shown in Figure 3, the upper parts of the side hulls 2A and 2B in this embodiment, which are positioned above the waterline, have a shape that widens further as they move away from the waterline. This allows the side hulls 2A and 2B to significantly increase buoyancy resistance when the roll angle becomes large, and to keep the roll angle within a specified range.

[0045] In this embodiment, a trimaran is shown as an example of a multi-hulled vessel, but the hull structure of the present invention can also be applied to catamarans and multi-hulled vessels having even more hulls.

[0046] It should be noted that the present invention is not limited to the embodiments described above, and various modifications are possible within the scope of the claims. Forms obtained by appropriately combining the technical means disclosed in the embodiments are also included in the technical scope of the present invention.

[0047] For example, Figure 5 is a plan view showing an example where fins 20A and fins 20B are positioned away from side hulls 2A and 2B. As shown in Figure 5, fins 20A and fins 20B do not need to be directly attached to side hulls 2A and 2B, but may be attached at a distance from side hulls 2A and 2B via supports or the like. In this case, the length of the moment arm in the roll direction becomes even longer, which further increases the effect of reducing oscillation in the roll direction.

[0048] Figure 6 is a plan view showing an example where fins 20A and 20B are divided into multiple parts. As shown in Figure 6, fins 20A and 20B may be divided into multiple parts along the Y direction. In this case as well, fins 20A and 20B can achieve the same effect as fins 20A and 20B shown in Figure 1. [Explanation of Symbols]

[0049] 1: Trimaran 2A: Side Hull 2B: Side Hull 10: Mainhull 20A: Fin 20B: Fin 50: Skeg

Claims

1. The first hull and, A second hull is arranged parallel to the first hull, A fin is positioned at the lower part of the second hull, projecting only in the direction opposite to the first hull with respect to the position of the second hull, A multi-hulled ship structure equipped with [a specific feature].

2. A hull structure according to claim 1, The fin is located at the lowest part of the second hull. The hull structure of a multi-hulled ship.

3. A hull structure according to claim 1 or claim 2, The fin protrudes in a direction perpendicular to the direction toward the lower part of the second hull. The hull structure of a multi-hulled ship.

4. A hull structure according to any one of claims 1 to 3, The fin has a shape that is short in the direction along the height of the second hull and long in the direction along the fore-aft of the second hull. The hull structure of a multi-hulled ship.

5. A hull structure according to any one of claims 1 to 4, The first hull is equipped with a skeg positioned at the bottom of the hull, The hull structure of a multi-hulled ship.

6. A hull structure according to any one of claims 1 to 5, The width of the second hull is narrower than the width of the first hull. The hull structure of a multi-hulled ship.

7. A hull structure according to any one of claims 1 to 6, The second hull has a relatively narrow lower section and a relatively wider upper section located above the draft. The hull structure of a multi-hulled ship.

8. A hull structure according to claim 7, The upper part has a shape in which the width further widens as it moves away from the waterline. The hull structure of a multi-hulled ship.

9. A hull structure according to any one of claims 1 to 8, The second hull includes a first side hull and a second side hull positioned on either side of the first hull, The fin includes a first fin positioned on the first side hull and a second fin positioned on the second side hull. The hull structure of a multi-hulled ship.

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