JPH05338582A - Drift prevention device for hull - Google Patents

Abstract

PURPOSE:To prevent generation of drift of a hull at anchorage and going astern by simple constitution. CONSTITUTION:Fins 21 are provided on the ship's bottom in the vicinity of the bow. The fins 21 are arranged on symmetrical positions against the keel 22, and extended along the longitudinal direction of the hull 11. The ship's bottom 12 is upward inclined from the keel toward the chines 16, the fins 21 are provided nearly middle between the keel 22 and the chines 16, and projected from the bottom shell nearly perpendicularly. The bow receives resistance against drift due to the fins 21 at anchorage and going astern. Consequently, the hull 11 is not rotationally displaced centering around the stern due to a beam wind and the like at anchorage. Further, drift of the bow is not generated at going astern so as to promote steering effect.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lateral flow preventing device for a bow portion of a hull, and more particularly to a lateral flow preventing device for preventing lateral flow of the bow portion at the time of mooring and improving steering effect at the time of reverse travel.

[0002]

BACKGROUND OF THE INVENTION The stern of a hull is usually equipped with rudders, propellers,
Like the shaft bracket and the outer shell of the ship under the water line,
Although there is a portion of the stern that provides great resistance to lateral flow, there are few portions of the bow that are substantially resistant to lateral flow. Particularly, in the bow of a high-speed boat, only the inclined bottom shell plate is a portion that resists the lateral flow, and the resistance of the bottom shell plate to the lateral flow is small.

As disclosed in Japanese Patent Application Laid-Open No. 4-8696, the fins are always under the surface of the water so that the lateral flow of the bow can be prevented, and the fins are directed in a predetermined direction as necessary. Conventionally, a movable member has been known. Further, conventionally, as disclosed in Japanese Utility Model Laid-Open No. 1-180399, an anti-vibration plate formed by connecting two plate members in a T-shape protrudes from the bow of the bow and can be stored in the hull. It is known that it is configured as follows.

[0004]

If the bottom of the ship is not equipped with fins, etc., when the ship is moored or is navigating at a low speed, the stern does not easily flow sideways due to the large resistance to sideways flow, but the bow is crosswinded. Due to the effect of, a lateral flow easily occurs, and once a lateral flow occurs, it is difficult to stop. The lateral flow of the bow is a rotational movement of the hull around the stern, and is easily eliminated by starting forward steering or steering. However, there is a problem that it is difficult to stop the lateral flow of the bow by steering because the steering effect is extremely weak during reverse travel.

Therefore, if the configuration disclosed in each of the above publications is adopted, the fin disclosed in Japanese Patent Laid-Open No. 4-8696 has a problem that the structure is complicated because it has a movable mechanism. On the other hand, in the case of the damping plate disclosed in Japanese Utility Model Laid-Open No. 1-180399, since this damping plate has a movable mechanism for storing it in the hull, not only is the structure complicated, but also the ship bottom. There is a problem in that the strength of the hull is reduced because it has an opening at the bottom.

In view of the above problems, the present invention provides a lateral flow preventing device having a simple structure which can prevent lateral flow of the bow portion at the time of berthing and during reverse travel, and which does not reduce the strength of the hull. It was made for that purpose.

[0007]

The lateral flow preventing device for a hull according to the present invention is provided with a fin on the bottom of the ship near the bow, the fin projecting substantially vertically from the bottom plate of the hull and extending in the front-back direction of the hull. Is characterized by.

[0008]

The present invention will be described below with reference to the illustrated embodiments. 1 to 7 show a first embodiment of the present invention, in which the present invention is applied to a high speed boat. Further, in these drawings, only the hull 11 and the members provided on the bottom 12 are shown, and the upper structure is omitted. Incidentally, rudder 1
3, the propeller 14 and the shaft bracket 15 are shown only in FIGS. 1 and 3 and are omitted in the other figures. In addition, in FIG. 1, FIG. 2 and FIG.
Indicates the position of the water line on the hull 11.

FIG. 1 shows a state in which the hull 11 is anchored in plain water. In this state, the chine 16
Although it is located above the level water surface WL at the bow, it is inclined downward toward the stern, and is located below the level water surface WL at the stern. That is, ship side skin 1
A part 17a of the ship 7 is located below the level water surface WL at the stern, and a part 17a of the ship side outer plate 17 and the rudder 1
3, the propeller 14 and the shaft bracket 15 have a large resistance to the lateral flow of the stern.

As shown in FIG. 2, a pair of fins 21 are provided on the bottom 12 near the bow. The fin 21 is disposed at a target position with the keel 22 as a center, and extends substantially in the front-rear direction of the hull, that is, along the keel 22. As shown in FIG. 4, the ship bottom 12 is inclined upward from the keel 22 toward the chine 16, and the fin 2
The reference numeral 1 is provided between the keel 22 and the chine 16 and projects outward substantially orthogonal to the bottom shell plate. The fins 21 are provided slightly below the water line, and are below the water surface WL when the hull 11 is anchored or at a low speed, but as will be described later, when the hull 11 is trimmed by the trim of the hull 11. It is exposed above the water surface WL.

FIG. 6 shows an example of a structure for attaching the fins 21 to the bottom 12 of the ship. In this example, fin 2
1 is integrally formed from a flexible member such as synthetic rubber, and is composed of a mounting portion 23 to the ship bottom 12, a main body portion 24, and a head portion 25. The mounting portion 23 extends perpendicularly to the body portion 24, and the head portion 25 is formed on the opposite side of the body portion 24 from the mounting portion 23 and is thicker than the body portion 24. Mounting part 23
Is embedded in a recess 26 formed in the ship bottom 12 and fixed to the ship bottom 12 with, for example, an adhesive or a bolt. The head portion 25 of the fin 21 has an effect of increasing the lateral flow resistance generated in the fin 21.

Next, the operation of the apparatus of this embodiment will be described. When the hull 11 is moored in plain water, the fins 21 are located below the water surface, as shown in FIGS. 1, 2 and 4. Therefore, for example, when the hull 11 receives a cross wind, the rudder 13 and the propeller 1 are arranged at the stern in the lateral flow.
4, shaft bracket 15, ship side outer plate 17 under the water line
a and the like become resistance, and the fin 21 becomes resistance at the bow. Therefore, resistance to lateral flow is generated at the stern and the bow, and the conventional hull 1
The rotational movement around the stern 1 can be reduced. Also, when the hull 11 is moving forward at a very low speed, the same action prevents the lateral flow.

When the vehicle is moving backward, the fins 21 resist the lateral flow at the bow, so that the lateral flow of the bow is suppressed, and therefore the steering effect is promoted and the hull 11 can be moved backward in a desired direction. This action is shown in FIG.
The water flow F is
₂ hits the fins 21 slightly obliquely or in parallel, but when steered, because the resistance of the fins 21 prevents the bow from flowing laterally, the hull 11 can turn in a desired direction.

On the other hand, when the hull 11 is moving forward at a speed equal to or higher than a predetermined value, the bow is lifted above the water surface WL by trimming as shown in FIG. 3, and the fins 21 are exposed above the water surface WL. Therefore, the fins 21 do not resist the forward movement. Note that, in FIG. 3, reference numeral WA indicates a ship wake surface, and reference numeral WF indicates a bow wave front.

Next, referring to FIG. 5, the hull 11 is slanted 45
The operation of the present embodiment in a state where the vehicle is moving forward with a follow-up wave will be described. The lateral flow velocity of the bow of the hull in FIG. 5 is the same as the water flow F ₁ in FIG. 6, and the direction is opposite. Reference numeral WT indicates a wavefront.

In the navigation state as shown in FIG. 5, there is a possibility of causing so-called broaching. That is, the hull 1
1 changes the direction orthogonal to the traveling direction of the wave, and is likely to receive a transverse wave. This phenomenon is more likely to occur when the bow has a greater resistance to lateral flow. However, since broaching may cause capsizing, it is preferable to control so that the traveling direction of the hull 11 does not change when sailing with a diagonal follow wave. That is, it is preferable that the bow portion is in a state in which lateral flow is easy.

In this embodiment, as described above, the fin 21 is used.
Is formed of a flexible member, so that when it receives a strong water flow, it largely bends in the opposite direction of the water flow as shown in FIG. Therefore, the fins 21 substantially reduce the eddy resistance, and the resistance of the fins 21 against the lateral flow becomes very small. Therefore, as shown in FIG. 5, the bow portion of the hull 11 laterally flows toward the wave bottom WB on the inclined surface of the wave, which prevents the hull 11 from turning in the direction of receiving the transverse wave, and Safety in navigation is secured.

FIGS. 8 and 9 show a second embodiment. This embodiment has a construction in which the fins 21 do not have a great resistance when the hull 11 is traveling at high speed in the waves. .. That is, as shown in FIG. 8, the distance between the pair of fins 21 is wider toward the stern side and is not parallel to the keel 22 as in the first embodiment. The reference numerals are the same as those in FIGS. 7 and 5, respectively.

When the hull 11 is moving forward in the waves at a speed equal to or higher than a predetermined value, the bow wave WF flows diagonally rearward from the keel 22 in front of the fins 21 to the left and right. A part of the water flow F ₃ around the fins 21 at this time hits the fins 21 at the attack angle α each time the bow bottom hits the waves.
In this case, the water flow F ₃ that hits the fin 21 is high speed,
And the frequency is high. Therefore, the fin 21 repeatedly bends outwards each time, and such a phenomenon is not preferable in terms of strength of the fin 21.

Therefore, in order to reduce the amount of bending of the fins 21 as much as possible, the attack angle α is set to a small value of about 30 °. In the case of the second embodiment, the effect of preventing the lateral flow of the bow by hitting the fins 21 with the water flow F ₂ during reverse travel is as follows.
It is effective as in the case of the first embodiment.

FIG. 10 shows a third embodiment. In this embodiment, contrary to the second embodiment, the distance between the pair of fins 21 is narrower toward the bow side. With the configuration of the third embodiment, the same effect as that of the first embodiment can be obtained.

[0022]

As described above, according to the present invention, with a simple structure, it is possible to prevent the lateral flow at the time of berthing and at the time of backward movement, and further, it is possible to obtain the effect that the hull strength is not lowered.

[Brief description of drawings]

FIG. 1 is a side view showing a first embodiment of the present invention and showing a state of mooring in plain water.

FIG. 2 is a plan view showing a state in which the hull shown in FIG. 1 is viewed from the bottom of the ship.

FIG. 3 is a side view showing a state in which the hull shown in FIG. 1 is moving forward at high speed.

FIG. 4 is a diagram showing a state as viewed along line IV-IV in FIG. 1.

FIG. 5 is a diagram showing a state in which the hull shown in FIG.

FIG. 6 is a view showing how fins are attached to the bottom of a ship.

FIG. 7 is a diagram for explaining the action of the fins in the first embodiment.

FIG. 8 is a diagram showing a state in which the hull including the apparatus of the second embodiment is viewed from the bottom of the ship.

FIG. 9 is a view of the state at the moment when waves hit the fins of the hull provided with the apparatus of the second embodiment, as viewed from the bow side.

FIG. 10 is a view showing a state in which the hull including the apparatus of the third embodiment is viewed from the bottom of the ship.

[Explanation of symbols]

 11 hull 12 ship bottom 21 fins

Claims (3)

[Claims] 1. A lateral flow preventing device for a hull, characterized in that fins projecting in a substantially orthogonal direction from the outer plate of the bottom and extending in a substantially front-back direction of the hull are provided on the bottom of the ship near the bow. 2. When the hull moves forward at a speed equal to or higher than a predetermined value,
The lateral flow preventing device for a hull according to claim 1, wherein the fin is exposed on the water surface by trimming the hull. 3. The fin is formed of a flexible member, and when the flow velocity of the water flow near the bow bottom of the bow is relatively high, the fin is bent so that eddy resistance is not substantially generated. The lateral flow preventing device for a hull according to claim 1.