JPH08290796A - Catamaran with hydrofoil - Google Patents

Abstract

PURPOSE: To effectively float up a hull by reducing downward force acting on the surface of the hull to the utmost above a hydrofoil for supporting a part of hull weight during navigation. CONSTITUTION: A catamaran is equipped with a hydrofoil 21 under the ship's bottom through a strut 31 so as to support a part of hull weight during its navigation, and an angle β which a hull portion 11 including the attaching part of the hydrofoil 21 forms with a vertical line 10 to the surface of the hull is set up not more than about 20 degrees. As lift is generated on the hydrofoil 21 during the navigation, a negative pressure flow is thereby caused along the upper face of the hydrofoil 21, but since the angle βis small, downward force caused by the negative pressure toward the surface of the hull can be reduced to the utmost.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a catamaran, and more particularly to a catamaran equipped with hydrofoils for supporting a part of the weight of the hull during navigation.

[0002]

2. Description of the Related Art A conventional catamaran with hydrofoils is shown in FIG.
(Side view) and Fig. 9 (front view), there are hydrofoil 21, 22 mounted on the front and rear of the catamaran type hull 1 under the bottom of the ship via struts 31, 32. There is.

When the catamaran is sailing, the draft of the hull 1 can be reduced by the lift generated on the hydrofoils 21 and 22, so that the sailing can be carried out with less resistance. There is. The hydrofoil 21 and 22 include a hydrofoil 21 continuous in the lateral direction like the hydrofoil 21 shown in FIG. 9, and a hydrofoil 21 divided into right and left like the hydrofoil 21 shown in FIG.

[0004]

By the way, in the conventional catamaran with hydrofoil as described above, each hydrofoil 21,
Part of the weight of the hull is supported by the lift generated by 22 and the hull 1
The surface of the hull does not completely separate, but the draft surface of the hull changes from the draft surface 4 at rest to the average draft surface 5 during running. That is, a part of the weight of the hull is supported by the lift generated by each hydrofoil 21, 22, but the hull 1 is lifted by the wing and the water stopping surface 4
It floats from the surface but never completely rises above the surface of the water.

At this time, as the pressure on the upper surface of each hydrofoil 21, 22 decreases, the pressure in the water near the hydrofoil decreases. This pressure drop also affects the hull surfaces 11 and 12 in the vicinity of the hydrofoils 21 and 22, and a force that causes the hull 1 to sink is generated on the hull surfaces 11 and 12, and the hydrofoil lift force is increased. This will prevent the hull 1 from levitating.

The present invention is intended to solve such a problem, in which the downward force acting on the surface of the hull above the hydrofoil during sailing is reduced as much as possible to efficiently levitate the hull. It is an object of the present invention to provide a catamaran with hydrofoils whose propulsion performance is improved.

[0007]

In order to achieve the above object, the catamaran with hydrofoils of the present invention has hydrofoils under the bottom of the ship to support a part of the weight of the hull during navigation. The hull local portion including the mounting portion of is characterized in that the angle between the hull surface and the vertical line is set to about 20 degrees or less.

Further, the catamaran with hydrofoils of the present invention is characterized in that the length of the hull local portion in the lengthwise direction is set to about four times the chord length of the hydrofoils.

Furthermore, in the catamaran with hydrofoils of the present invention, the hull local portion has a length substantially the same as the chord length in front of the hydrofoils and at the rear of the hydrofoils. It is characterized by having a length approximately twice the chord length.

[0010]

In the catamaran with hydrofoil of the present invention described above, when a lift is generated by the hydrofoil during navigation, a downward force is exerted on the surface of a nearby hull due to the negative pressure generated along the upper surface of the hydrofoil. I try to work, but the hull local part including the attachment part of the hydrofoil,
Since the angle between the hull surface and the vertical line is set to about 20 degrees or less, which is significantly smaller than the conventional one, the downward force acting on the hull surface can be significantly reduced, and the hull can be sufficiently You will be able to surface and sail with less resistance.

Further, if the length of the local portion of the hull in the lengthwise direction is set to about four times the chord length of the hydrofoil, negative pressure generated along the upper surface of the hydrofoil exerts on the surface of the hull. The action of appropriately avoiding the influence is performed. further,
When the hull local portion has a length substantially equal to the chord length in front of the hydrofoil and approximately twice as long as the chord length behind the hydrofoil, The influence of the negative pressure generated along the upper surface of the hydrofoil on the hull surface,
The action of avoiding it more accurately is performed.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawings, a catamaran with a hydrofoil as an embodiment of the present invention will be described below. FIG. 1 is a side view thereof, FIG. 4 is an explanatory view showing how the hydrofoil is attached to the bow portion, FIG. 4 is a sectional view taken along the line AA of FIG. 1, and FIG.
It is sectional drawing which shows the modification of a ship body corresponding to.

As shown in FIGS. 1 and 2, this catamaran with hydrofoils also supports a part of the weight of the hull 1 at the time of navigation by means of struts 31 and 32 under the bottom of the ship to form a front hydrofoil 21 and a rear hydrofoil. Although the wing 22 is provided, in this embodiment, the hydrofoil 2 in particular is provided.
The hull local parts 11 and 12 including the mounting parts 1 and 22 are set so that the angle β formed by each hull surface and the vertical line 10 is about 20 degrees or less. The hull local parts 11, 12 are smoothly and continuously joined to the adjacent hull parts 1a, 1b, 1c.

Further, the mounting positions of the hydrofoils 21, 22 and the hull local part
The relationship with 11 and 12 is set as shown in FIG.
That is, the hull local portion 11 has a length substantially equal to the chord length C of the hydrofoil 21 in front of the hydrofoil 21 and approximately twice the chord length C behind the hydrofoil 21. The length of the hull local portion 11 is approximately four times the chord length. In addition, the code | symbol 4 in FIGS. 1-3 shows a stationary draft surface, and the code | symbol 5 has shown the average draft surface at the time of navigation.

In the above-mentioned hydrofoil catamaran of the present embodiment,
When generating lift on the hydrofoils 21, 22 during navigation,
Due to the negative pressure generated along the upper surface of 21, 22, a downward force tends to act on the surface of the nearby hull, but the hull local parts 11, 12 including the mounting parts of the hydrofoils 21, 22 are Vertical line
Since the angle β formed with 10 is set to about 20 degrees or less, which is significantly smaller than the conventional one, it is possible to significantly reduce the downward force acting on the surface of the hull, and thus the hull 1 is sufficiently levitated. You will be able to sail with less resistance.

That is, in the conventional hull shape of the catamaran with hydrofoils, the vertical line 10 and the hull surface have a relatively large angle β as shown in FIG. Although the integrated pressure value in the up-down direction has a large downward value, in this embodiment, the angle β is set to 20 degrees or less as described above, so that the downward force acting on the surface of the hull can be reduced.

FIG. 6 shows the relationship between the angle β of the hull surface and the downward force (F _z ) of the pressure integral acting on the hull surface, and FIG. 7 shows the hull surface portions 11 and 12 on the hull surface. The distribution map of the acting pressure (P) in the ship front-back direction is shown.

In this embodiment, in particular, in consideration of the pressure distribution shown in FIG. 7, the chord length C of the hydrofoils is located in front of the hydrofoils 21, 22 in the ship length direction as shown in FIG. The hydrofoil
Behind 21 and 22, the angle β between the vertical line 10 below the static draft surface 4 and the hull surface is approximately 20 within a range of approximately C × 2 of approximately C × 2.
By setting the pressure to be less than or equal to the degree, the downward force (F _z ) of the pressure integration can be significantly reduced.

In this embodiment, the hydrofoil blades 21, 22 are attached to the hull local portions 11, 12 having a length approximately four times the chord length C, but the hydrofoil blades 21, 22 are attached. As long as the position is within the hull local parts 11 and 12, better effects can be sufficiently obtained as compared with the conventional case. Moreover, even if the angle β formed by the surface of the hull below the draft surface with the vertical line during sailing is set to 20 degrees or less over the entire length of the hull as shown in FIG. 5, the above-mentioned effects cannot be obtained. Needless to say.

[0020]

As described in detail above, according to the catamaran with hydrofoil of the present invention, the following effects can be obtained. (1) When a hydrofoil is lifted during navigation, a downward force tends to act on the surface of the nearby hull due to the negative pressure generated along the upper surface of the hydrofoil, including the mounting part of the hydrofoil. Since the hull local part sets the angle between the hull surface and the vertical line to about 20 degrees or less, which is significantly smaller than the conventional one,
The downward force acting on the surface of the hull can be significantly reduced, which allows the hull to float sufficiently and sail with less resistance. (2) If the length of the hull local portion in the lengthwise direction is set to be about four times the chord length of the hydrofoil, the negative pressure generated along the upper surface of the hydrofoil will affect the hull surface. It can be avoided appropriately. (3) The hull local portion has a length substantially equal to the chord length in front of the hydrofoil and approximately twice the chord length behind the hydrofoil. The influence of the negative pressure generated along the upper surface of the hydrofoil on the surface of the hull can be more accurately avoided.

[Brief description of drawings]

FIG. 1 is a side view of a catamaran with hydrofoils as an embodiment of the present invention.

2 is a cross-sectional view of essential parts of the catamaran with hydrofoils of FIG. 1 at a hydrofoil mounting position.

FIG. 3 is an explanatory view showing how the hydrofoils are attached to the bow of the catamaran with hydrofoils of FIG.

FIG. 4 is a sectional view taken along the line AA of FIG.

FIG. 5 is a cross-sectional view showing a modified example of the hull corresponding to FIG.

FIG. 6 is a graph showing the relationship between the angle of the hull surface and the vertical downward force of the pressure integral acting on the hull surface.

FIG. 7 is a distribution diagram in the longitudinal direction of the hull of the pressure acting on the hull surface at the hull local portion including the hydrofoil mounting portion.

FIG. 8 is a side view of a conventional catamaran with hydrofoils.

9 is a front view of the catamaran with hydrofoils of FIG. 8. FIG.

FIG. 10 is a front view showing a modified example of a catamaran with hydrofoils corresponding to FIG. 9.

[Explanation of symbols]

 1 Hull 4 Stationary Draft Surface 5 Average Draft Surface during Running 10 Vertical Line 11, 12 Hull Local 21 Front Hydrofoil 22 Rear Hydrofoil 31, 32 Strut C Chord Length β Hull Surface Angle

Claims (3)

[Claims] 1. An angle formed between a hull surface and a vertical line by a hull local portion including a mounting portion of the hydrofoil, in which a hydrofoil is provided under the bottom of a catamaran to support a part of the weight of the hull during navigation. A catamaran with hydrofoils, characterized by being set to about 20 degrees or less. 2. The catamaran with hydrofoil according to claim 1, wherein the length of the hull local portion in the lengthwise direction is set to about four times the chord length of the hydrofoil. A catamaran with hydrofoils. 3. The catamaran with hydrofoils according to claim 2, wherein the hull local portion has a length substantially equal to the chord length in front of the hydrofoils and behind the hydrofoils. A catamaran with hydrofoil, characterized in that it has a length approximately twice as long as the chord length.