JP2817096B2 - Ship bottom structure - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ship having a structure in which the bottom serves as a sliding surface for propulsion, and more particularly to a bottom structure of such a ship.

[0002]

2. Description of the Related Art Wave propulsion resistance is one of the propulsion resistances of ships. The wave resistance of a ship occurs near the waterline (especially near the bow and stern). Further, the wave-making resistance has such a property that the wave-making resistance increases in a quadratic curve with respect to the main engine output as the traveling speed of the ship increases. That is, in a ship running in a submerged state, no matter how high the propulsion engine outputs, there is a limit to the ship speed because the wave-making resistance increases accordingly.

[0003] As a countermeasure against the wave-making resistance, for example, the following various devices have been devised. In submerged ships, the bow is made spherical to suppress the generation of bow waves, and the stern is provided with a spherical bulge (so-called balbasstern) to reduce stern waves. The hull shape itself is made slender (the so-called hull coefficient is reduced) to reduce waves. In a small boat such as a motorboat, by reducing the weight of the hull and increasing the output of the engine, the hull slides on the water surface to reduce wave-making resistance. The hull itself was raised above the water surface, such as a submarine, or underwater, such as a hydrofoil, hovercraft, techno super liner, etc., to eliminate (or minimize) the generation of waves by the hull. There are also things.

In a small boat (for example, a small fishing boat), the depth of submersion (the draft depth at the stern) is relatively shallow due to its light weight. Therefore, in a conventional small boat, the propulsion shaft extends obliquely downward in the stern direction so that the propulsion device (screw) is submerged to a predetermined depth. By the way, when the axis of the propulsion device is directed obliquely downward as described above, the water stream lines are uneven at the upper and lower portions of the propulsion device.

[0005]

However, each of the above-mentioned conventional countermeasures (-) has the following drawbacks.

[0006] In the above measures, the bow and stern are merely spherical, so that the bow wave and the stern wave can be somewhat reduced, respectively.
Since the ship runs in the submerged state, a large wave resistance still occurs. Therefore, even if the engine has a high output, there is a limit to the boat speed.

In the above measures, since the boat is elongated, the wave-making resistance is reduced, but the rolling becomes large during running or when the boat is stopped, and the riding comfort and workability on the boat are deteriorated.

[0008] Although the above measures can achieve high speed by sliding the bottom of the boat on the water surface, they can be applied only to small boats such as motor boats, and the types of boats are limited. Further, in the case where the bottom of the ship slides on the water surface, the skid becomes severe and the traveling performance deteriorates.

According to the above measures, the production cost is extremely high, and there is a great economical problem when applied to general ships.

[0010] In addition, many measures other than those described above have been attempted as countermeasures against wave-making resistance, but at present, the effect of reducing wave-making resistance has not been significantly improved.

If the axis of the propulsion device is directed obliquely downward, as in a conventional small boat (for example, a small fishing boat), the water stream lines become uneven at the upper and lower portions of the propulsion device, resulting in poor propulsion efficiency. Problem.

SUMMARY OF THE INVENTION In view of the above problems, the present invention has been made to improve the propulsion efficiency of a hull by reducing the wave-making resistance during traveling of a ship of a type in which the bottom of the ship glides on the water surface, thereby improving the water surface glide speed higher than before. It is an object of the present invention to provide a bottom structure of a marine vessel that can achieve the above-mentioned requirements and can improve the riding comfort and running performance of the marine vessel.

[0013]

The present invention has the following structure as means for solving the above-mentioned problems.

[0014] The present invention is directed to a ship in which the bottom slides on the water surface when the ship is running. In the bottom structure of the ship according to the present invention, an overhanging portion is provided at the bottom of the hull, protruding downward from the bottom of the hull, and has an interior of a watertight structure. The main engine is installed. Further, in the present invention, the remaining portion of the ship bottom excluding the overhanging portion is formed in a planar shape. The overhang is preferably provided in the vicinity of the center of the bottom of the ship, and a flat state portion may be formed on each side of the overhang at the bottom of the ship.

In the ship of the present invention, when it floats on the water, the overhang provided on the bottom of the ship is completely submerged below the water surface. In addition, the vacant space in the overhang portion has an acting force for lifting the ship and also serves as a space for installing the main engine. still,
In a small boat, it is possible to increase the volume of the space in the overhang portion to such an extent that the drafts at the bow and stern can be set to almost “0”.

Further, in the bottom structure of a ship according to the present invention, a propulsion shaft from the main engine is extended from a rear portion of the overhang portion in parallel with the bottom of the ship, and a propulsion device (screw) is provided at the tip of the propulsion shaft.
Is installed. Even when the hull is relatively shallow, such as a small boat, the propulsion shaft extends parallel to the bottom of the ship by providing an overhang and installing the main engine in the overhang as described in the present application. It is possible to do.

Further, in the bottom structure of the ship according to the present invention, the overhang portion has a streamline shape that is long in the bow and stern directions when viewed from below.

In the ship of the present invention, the draft at the bow and stern becomes shallow due to the buoyancy of the space inside the overhang, and the remaining portion excluding the overhang at the bottom of the ship is formed flat. When the ship is run, the bottom of the ship slides on the water surface. Therefore, the wave-making resistance due to the hull (particularly the bow and stern) is reduced, the propulsion efficiency of the ship is improved, and the speed can be further increased. Further, since the entire projecting portion is submerged, no wave is generated by the projecting portion, and the wave creating resistance is not increased by the projecting portion.

Further, even when the bottom of the boat slides on the water surface when the boat is running as described above, the hull does not skid because the overhang portion remains submerged. Further, if the shape of the overhang is streamlined, the resistance of the overhang during traveling of the boat can be reduced even if the overhang is submerged. Further, when the main engine is installed in the space of the overhang portion, the center of gravity of the whole ship is lowered, and the stability can be improved.

When the propulsion shaft from the main engine is extended in parallel with the bottom of the ship and a propulsion device (screw) is attached to the tip of the propulsion shaft, the water flow lines at the top and bottom of the propulsion device become uniform. Propeller efficiency is improved.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIGS. 1 to 3, a preferred embodiment of the present invention will be described. A relatively small vessel such as a fishing boat is used as the illustrated vessel. still,
In the case of a fishing boat, FRP is preferably used as the material of the hull 1.

The ship shown in FIGS. 1 to 3 has a wide bottom 13 for its length. Further, the ship bottom 13 is formed to be relatively flat.

In this bottom structure of a ship, a projecting portion 2 projecting downward is formed substantially at the center of the bottom 13 of the ship. The overhang portion 2 is formed in a streamline shape that is long in a direction connecting the bow 11 and the stern 12 when viewed from below. The overhang 2 is formed in a container shape by closing the lower end of a teardrop-shaped annular side wall 21 with a bottom wall 20.

In the overhang portion 2, a space 22 having a considerably large volume is provided.
Are formed. The main unit 3 for driving the propulsion unit is installed in the space 22.

Incidentally, it is preferable that the overhang portion 2 is designed so as to minimize the resistance of the overhang 2 in water during traveling with the installation space for the main engine 3 secured. The resistance in water of a streamlined object such as the overhang 2 having a streamlined shape when viewed from the bottom has a correlation with the flow velocity, using the ratio between the maximum width and the length of the object (the overhang 2) as a parameter. Has been elucidated by hydrodynamics. Therefore, if the minimum width of the overhang 2 required for the installation of the main machine 3 is determined, the length of the overhang 2 corresponding to the minimum resistance in water with respect to the design speed is obtained. or,
The depth of the overhang 2 is determined by the required gap between the propulsion device 5 and the ship bottom 13. In addition, the empty space 22 in the overhang portion 2
Has an acting force to float the ship when the ship floats on the water, and preferably has a volume (drainage weight) that allows the bottom 13 to float near the water surface in a small boat.

In this embodiment, the overhang portion 2 is formed separately from the hull 1 by, for example, a steel plate, and is attached to the hull 1 with screws or the like while maintaining a watertight structure. In another embodiment, the overhang 2 may be integrally formed with the hull 1 by, for example, FRP.

On the bottom 13 of the ship, a flat portion having a considerable area remains in the remaining portion except the overhang portion 2. In the ship of the present application, the remaining portion of the ship bottom 13 serves as a water surface for running.

In the bottom structure of the ship, the propulsion shaft 4 from the main engine 3 extends from the rear of the overhang portion 2 in parallel with the bottom 13 of the ship, and a propulsion device (screw) is attached to the tip of the propulsion shaft 4. 5 is attached. Even when the depth of submersion of the hull 1 is relatively shallow as in a small boat, the propulsion can be achieved by providing the overhang 2 and installing the main engine in the space 22 in the overhang 2 as in the present application. The shaft 4 can be extended in parallel with the ship bottom 13.

In this embodiment, the bow 1 of the overhang 2
A watertight partition 23 is provided on one side, and the inside of the watertight partition 23 is used as an active fish tank 24. The overhang portion 2 is submerged in its entire height range, and a live fish tank 24 can be formed by providing a water passage in the watertight partition wall 23.

[0030] In the illustrated vessels, when floated on water, the buoyancy acts by space 22 in the projecting portion 2, it is possible to levitate to the vicinity of the waterline showing the ship bottom 13, for example by reference numeral L _1. Then, when the actual traveling ship, the ship bottom 13 (becomes waterline is, for example, the code L ₂ position) will be planing on the water surface, wave drag due to the hull 1 becomes small. At this time, in the illustrated ship, since the bottom 13 has a relatively large area and the bottom 13 is formed in a flat state, the sliding property during traveling becomes good, and the wave-making resistance is further reduced. .

When the ship is running, the entire overhang portion 2 remains submerged, but no wave resistance is generated by the overhang portion 2 when submerged in water. In addition, when the overhang portion 2 runs in a submerged state, resistance occurs in the overhang portion 2 portion,
Since the overhang portion 2 is formed in a streamlined manner, the resistance due to the overhang portion can be reduced.

Also, since the overhang 2 remains submerged when the ship is running, the overhang 2 functions as a center keel for a large boat or a skeg for a small fishing boat. Therefore, even when the bottom 13 slides on the water surface as described above, the hull 1 does not slide, and the traveling performance is improved. Further, in this ship, since the main engine 3 is installed in the space 22 of the overhang portion 2, the center of gravity of the whole ship is lowered, and the stability can be improved.

In this ship, the propulsion shaft 4 from the main engine 3
Is extended in parallel with the ship bottom 13 and a propulsion device (screw) 5 is attached to the tip of the propulsion shaft 4.
The upper and lower water flow lines become uniform, and the efficiency of the propulsion unit is improved.

In the above embodiment, a small boat such as a fishing boat is employed as a ship, but in other embodiments, the present invention can be applied to a medium or large boat.

[0035]

The bottom structure of a ship according to the present invention has the following effects.

(1) Overhang 2 having drainage function (buoyancy)
Is projected below the ship bottom 13, so that the drafts of the bow 11 and the stern 12 can be made shallower in a drainage type ship. Therefore, in the ship of the present application, the wave-making resistance during traveling is smaller than that of the conventional ship-shaped ship, and the propulsion efficiency is improved.

(2) Since the remaining portion of the bottom 13 excluding the overhang portion 2 is formed in a flat shape, the slidability of the marine vessel whose bottom 13 slides on the water surface becomes even better (wave resistance is reduced). And the propulsion efficiency is further improved.

(3) The improvement in propulsion efficiency described in the above (2) enables an increase in boat speed, and enables a small boat to gliding with a smaller engine output than a conventional gliding boat. Further, the synergistic effect of the glide performance of the flat bottom 13 and the speed of the boat due to the improvement of the propulsion efficiency makes it possible to increase the speed of the boat more than before.

(4) The overhang portion 2 serves as a center keel or a skeg at the bottom of the ship, so that even if the bottom 13 slides on the water surface as described above,
The hull 1 does not skid, and the traveling performance is improved. In addition, since the boat bottom 13 can be formed to have a wide width, the roll is reduced and the riding comfort is improved.

(5) Since the main engine 3 is installed in the space 22 of the overhang portion 2, the center of gravity of the whole ship is lowered, and the stability can be improved.

(6) As in claim 2 of the present application, the overhang 2 is made to protrude below the bottom 13 of the ship, and the main engine 3 is inserted into the overhang 2.
When the propulsion shaft 4 from the main engine 3 is extended in parallel with the ship bottom 13 and the propulsion device (screw) 5 is attached to the tip of the propulsion shaft 4, the upper and lower propulsion devices 5 The streamline becomes uniform, and the propulsor efficiency is improved.

(7) As in the third aspect of the present invention,
When formed in a streamlined shape when viewed from the bottom, even when the overhang portion 2 runs in a submerged state, the resistance due to the overhang portion 2 can be reduced, and the propulsion force does not decrease so much.

[Brief description of the drawings]

FIG. 1 is a side view of a ship provided with a bottom structure according to an embodiment of the present invention.

FIG. 2 is a bottom view of FIG.

FIG. 3 is a sectional view taken along the line III-III of FIG. 1;

[Explanation of symbols]

1 is a hull, 2 is an overhang, 3 is a main engine, 4 is a propulsion shaft, 5 is a propulsion device, 11 is a bow, 12 is a stern, 13 is a ship bottom, 21 is a side wall, and 22 is a void.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) B63B 1/18 B63B 1/40 B63B 1/12

Claims (3)

(57) [Claims] When the ship is running, the bottom (13) is on the water surface.
In vessels, such as sliding, the bottom of the hull (1), before
Serial ship bottom (13) from projecting downward and inside the cavity of the watertight (22) and the projecting portion provided with a (2), propeller driven overhung portion cavity (2) (22) A main engine (3) for the ship, and
A bottom structure for a ship, characterized in that the remaining part except the overhang (2) is formed in a plane . 2. A propulsion shaft (4) from the main engine (3) extends from the rear of the overhang portion (2) in parallel with the ship bottom (13), and is propelled to the tip of the propulsion shaft (4). The bottom structure of a ship according to claim 1, wherein a vessel (5) is mounted. 3. The overhang portion (2) is provided with a bow and
3. The bottom structure of a marine vessel according to claim 1, wherein the marine vessel has a streamline shape that is long in a stern direction.