JPH0299487A - Lateral stabilizing device for small water plane type single hull ship - Google Patents

Abstract

PURPOSE:To improve lateral stability during low speed running as excellent intrinsic high speed performance is ensured by a method wherein the width of a ship bottom is rapidly spread in an inverted truncated chevron-shape, and a ballast tank in which water is capable of being injected and drained is provided to a low ship hull. CONSTITUTION:In a small water plane type single hull ship (SWASH) 1, the width of a water plane during high speed sailing is decreased, as a result of setting to G1>=M1, wherein G1 is a center of gravity and M1 is metacenter, being made, a ship is deficient in lateral stability during low speed sailing. In this case, a coupling part between upper and lower ship hulls 1a and (ovoid) 1b is formed in an inverted truncated chevron-shape in cross section as seen from lower part to an upper part, and the width of a ship is increased rapidly toward the upper part so that a water plane is increased rapidly. A ballast tank 4 is provided to the central part of the lower ship hull 1b, and ballast is injected in the ballast tank 4 so that a draft is raised to a given position LW2 during low speed sailing.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention is applicable to small waterline monohull vessels (Small, 1ilat).
This is related to er-plane Area Single Hull (hereinafter referred to as 5WASH).

(Prior Art) In the 5WASH as shown in FIG. 3, the connecting portion 1c between the upper hull 1a and the lower hull 1b is very narrow at 11, so the hull resistance is small and it is suitable for a high-speed boat. However, because the waterline is narrow, it lacks stability, especially against rolling motion. For this reason, attitude stabilizing devices such as fins a and rudders attached to both sides of the lower hull 1b are essential. However, although this device is effective when traveling at high speeds, its control power is weak when the ship is traveling at low speeds or when the ship is stopped.

That is, the attitude stabilizing devices such as the fins a become almost ineffective when the ship is at low speed or when the ship is stopped because the force acting on the fins a decreases in proportion to the square of the acceleration.

Stabilization by injecting ballast water is also used, but this is normally done for the purpose of lowering the center of gravity of ships.
It is not intended to increase the waterline surface.

(Problems to be Solved by the Invention) It is an object of the present invention to provide a device that enables lateral stability during low-speed navigation in a 5WASH suitable for a high-speed boat.

(Means for solving problems by invention) By reducing the width of the water line surface at high speed, G, ≧Mx
(Gi: Center of Gravity, M: Metacenter) As a result, in ships lacking lateral stability at low speeds, the inside of the ship is rapidly expanded in an inverted eight-shape cross section so that the water line rapidly increases at low speeds. In addition, a ballast tank that can be filled with water was installed in the center of the lower hull.

At low speeds, water is injected into the ballast tank, and at high speeds, water is drained to raise and lower the water line.

(Example) An explanation will be given based on FIGS. 1 and 2. 1 is 5 according to the present invention
The WASH s La is the upper hull, lb is the lower hull (ovoid) with a circular cross section, 2 is the fin fixed to the side of the lower hull 1b, and 3 is the propeller attached to the rear end of the lower hull 1b. be. Reference numeral 4 denotes a ballast tank provided in the center of the lower hull tb, into which seawater is injected by a pump (not shown) at low speeds to lower the stanchion and increase the water line area.

Now, the connection part between the lower hull 1b and the upper hull 1a is the second
As shown in the figure, the lower part is the narrowest, and the cross section is formed in an inverted eight shape from there toward the upper hull 1a.

Therefore, when normally sailing at high speed, the water line should be located at the F part of the connecting part 1c to reduce the hull resistance, and when it crosses this 1J narrow part, it suddenly The width is wider. That is, at low speeds, ballast is poured into the ballast tank 4 so that the water line rises to the position LW in FIG.

(Function) a) During high-speed sailing: When all the seawater in the ballast tank 4 is drained and the ship's own weight is reduced, the ship floats to the surface, so the submerged surface area of the ship becomes smaller, viscous resistance becomes smaller, and the water line area becomes smaller. In addition to reducing wave-making resistance, the hull resistance is also significantly reduced, making it possible to travel at high speeds. In this state, the water line becomes low as LWi in Figure 2, and the metacenter M
4 will also be lower. However, in this case, a wing stabilizer such as fin stabilizer 2 is used to control the ship's attitude.

b) When sailing at low speed: When the ship's speed drops below a certain speed in a port area or when berthed, the ballast tank 4
Since the stabilizing effect in the empty state is no longer effective, seawater is poured into the ballast tank 4 at the center of the ship to raise the ship's water line from LW□ to LW2. As a result, the width of the water line increases as shown in Figure 2, so the horizontal metacenter M
3 rises from M to M2, and the ship's center of gravity moves from Go to 0.
2, which increases lateral stability.

(Effects) For ships that lack lateral stability at low speeds, the connection between the upper and lower hulls can be rapidly expanded upwards in an upside-down shape, and water can be poured into the center of the lower hull. A ballast tank is installed, so at high speeds the fin stabilizer effectively stabilizes the vehicle, and at low speeds the water line is raised to lower the center of gravity.

By raising the metacenter M, lateral stability can now be achieved.

[Brief explanation of drawings]

FIG. 1 is a front view of 5WASH to which the present invention is applied. Figure 2 is a sectional view taken along the line ■-■ in Figure 1. Figure 3 shows the ship wall seen from the same position as Figure 2 of the known 5WASI. In the figure: a Fin I S W A S Hla
Upper hull 1b Lower hull lc Connection part 2 Fin 3 Propeller 4 Ballast tank Above Applicant: Sumitomo Heavy Industries, Ltd. Sub-agent Patent attorney Isamu Ohashi Figure 2 Figure 3

Claims (1)

[Claims] By reducing the width of the water line surface at high speed, G_1≧M_1 (G_1: center of gravity, M_1: metacenter)
As a result, in ships that lack lateral stability at low speeds, the width of the ship can be rapidly expanded upwards in an inverted eight-shaped cross section so that the water line rapidly increases at low speeds, and water can be poured into the center of the lower hull. A lateral stabilization device for a small waterline monohull ship characterized by the installation of a ballast tank.