JPS6140596B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for reducing resistance experienced by a ship during navigation, and particularly to a device for reducing resistance to a ship's hull suitable for use in a high-speed ship.

Conventional hull resistance reducing devices include those shown in Figures 1 and 2. Figure 1 is a side view of the device;
FIG. 2 is a sectional view taken along the line - in FIG. 1, and FIG. 3 is a plan view showing a state in which a ship equipped with the above device is turning.

In Figures 1 to 3, 1 is the main hull, 2 is the rudder, 3 is the propeller, 4 is the stern bossing, 5 is the propeller shaft, 6 is the propeller cap, 7 is the upper rudder support member, 8 is the rudder stem, 9 is a protrusion for reducing hull resistance;
9a and 9a' are the outer plates of the protrusion 9, 9b and 9b' are reinforcement members for the protrusion, 10 is the load water line, 10a is an arbitrary water line, 11 is the rear end of the main hull on the load water line, and 12 is the center of the hull Line, 13 is the turning trajectory of the ship,
14 is the water flow at the stern, 15a is the upper stun frame, 15b is the lower stun frame, l is the amount of protrusion,
O indicates the center point of the ship, and P indicates the turning center of the ship.

As shown in FIGS. 1 and 2, a protrusion 9 is provided behind the rear end 11 of the main hull 1 above the load waterline 10, with a part of the protrusion 9 positioned above the load waterline 10, and the rest of the protrusion 9 positioned above the load waterline 10. It is known that by locating it below 10, waves generated from the stern of the main hull 1 and waves generated from the protrusion 9 can interfere with each other, thereby reducing hull resistance.

However, if the protrusion 9 is removed from the main hull 1 in this way,
If the protrusion is made to protrude further rearward than the rear end 11 by a protrusion amount l, not only will this cause problems during berthing and unberthing work, but waves will collide with this protrusion 9, causing excessive stress to the connection with the main hull 1. This may cause damage.

In addition, as shown in Fig. 3, when the ship turns, the stern water flow 14 flowing outside the turning circle
Since it collides with the protrusion 9, it similarly generates excessive stress at the connection part with the main hull 1, which has the disadvantage of causing damage.

Furthermore, general ships do not always sail only at the loaded waterline 10, and the waterline changes depending on the loading situation, so the buoyancy of the protrusion 9 changes due to such changes in the waterline, and the weight of the protrusion 9 changes. If the buoyancy becomes too large compared to the buoyancy, there is a problem in that excessive stress is generated at the connection between the protrusion 9 and the main hull 1.

Furthermore, as a result of providing the protrusion 9 behind the rudder 2 that has the effect of blocking the water flow 14 at the stern when turning, the directional stability of the ship becomes excessive, resulting in a decrease in maneuverability (deterioration of rudder effectiveness). This also causes the problem that it becomes difficult for the ship to turn even if the ship is steered.

The present invention attempts to solve the above-mentioned problems in conventional hull resistance reduction devices, and aims to balance the weight and buoyancy of the protrusion regardless of changes in the draft, so that the main body of the protrusion is Avoid creating excessive stress at the connection with the hull,
It is an object of the present invention to provide a device capable of preventing damage.

For this reason, the hull resistance reducing device of the present invention is provided with a hull resistance reducing protrusion that protrudes rearward from the rear end of the main hull at the load waterline at the stern, and reduces the weight and buoyancy of the protrusion within the working draft range. In order to maintain approximately equal balance, a ballast water tank is provided inside the protrusion, and the ballast water tank is also provided with a water filling mechanism.

Hereinafter, a hull resistance reducing device as an embodiment of the present invention will be explained with reference to the drawings. Fig. 4 is a side view thereof, and Fig. 5 is a horizontal sectional view taken along the - line in Fig. 4. The same reference numerals as those described above indicate substantially similar parts, and reference numeral 16 indicates a seawater tank, 17a indicates an upper conduit, and 17b indicates a lower conduit.

As shown in Figures 4 and 5, at the stern, ballast water is stored inside a protrusion 9, which is a wave-dissipating object for reducing hull resistance and which protrudes fixedly rearward from the rear end 11 at the load waterline 10 of the main hull 1. A seawater tank 16 as a tank is installed, and this seawater tank 1
A conduit 17a as an air vent means is led from the upper part of the seawater tank 16 to the top of the protrusion 9, and a conduit 17b as a water intake means is led from the lower part of the seawater tank 16 to the bottom water intake port of the protrusion 9.

Air and seawater enter and exit the seawater tank 16 through these conduits 17a and 17b, respectively.
The inner diameter of each conduit 17a, 17b is not very large, so seawater flows into the seawater tank 1 very rapidly.
6. It is designed so that no water can flow into or out of the tank.

The shape and capacity of the seawater tank 16 are as follows:
It is determined so that the weight of the protrusion 9 (including the seawater in the seawater tank 16) and the buoyancy of the protrusion 9 can be equally balanced within the range of the working draft.

When the waterline 10a changes, water is immediately injected into the seawater tank 16 or drained from the seawater tank 16 through the lower conduit 17b, and the weight and buoyancy of the protruding object 9 are adjusted regardless of the draft within the working draft range. Balance automatically. As a result, excessive stress is not generated at the connection between the protrusion 9 and the main hull 1, and therefore no damage is caused to this portion.

Note that the inner diameters of the conduits 17a and 17b are not very large, and seawater is not rapidly injected and discharged, so that the seawater in the seawater tank 16 can withstand sudden draft changes such as hull movement in waves. does not follow. Therefore, the weight of the protrusion 16 (including the seawater in the seawater tank 16) will balance the average buoyancy.

In the above-mentioned embodiment, the water intake means 17 is used as a water injection and drainage mechanism for the seawater tank 16 as a ballast water tank.
b and air venting means 17a are provided,
As shown in FIG. 4 by the two-dot chain line, this water supply and drainage mechanism connects the seawater tank 16 to the seawater tank 16 through a pipe 17c.
A ballast water pump 17p may also be connected.

In this case, for example, the ballast water pump 17p is automatically started and stopped based on a signal from a sensor that detects the stern draft.
The effect is to balance the weight and buoyancy almost equally.

Therefore, as in the case of the above embodiment, there is an advantage that the connection portion of the protrusion 9 to the main hull 1 can be strongly protected.

As described in detail above, according to the hull resistance reduction device of the present invention, a protrusion within the range of the working draft is installed inside the protrusion as a wave-dissipating object that protrudes rearward from the rear end of the main hull at the load waterline. This extremely simple configuration includes a ballast water tank with a water filling mechanism that balances the weight and buoyancy of the projector, making it possible to prevent the occurrence of excessive stress near the base of protrusions, which has been a problem in the past, and improve strength. , resulting in significant improvements.

[Brief explanation of the drawing]

Figure 1 is a stern side view showing a conventional hull resistance reduction device, Figure 2 is a horizontal sectional view taken along the - line in Figure 1, and Figure 3 is a plan view showing a turning state of a vessel equipped with a hull resistance reduction device. 4 and 5 show a hull resistance reducing device as an embodiment of the present invention, FIG. 4 is a side view thereof, and FIG.
FIG. 3 is a horizontal cross-sectional view along the line. 1... Main hull, 2... Rudder, 3... Propeller, 4
... Stern botting, 5 ... Propeller shaft, 6 ...
Propeller cap, 7... Upper rudder support member, 8...
...Rudder handle, 9...Protrusion for reducing hull resistance (wave-dissipating object), 9a, 9a'...Outer plate of protrusion, 9b, 9
b'... Reinforcement member for protrusions, 10... Full load waterline,
10a...Arbitrary waterline, 11...Aft end of main hull on load waterline, 12...Hull centerline, 1
3... Ship's turning trajectory, 14... Water flow at the stern, 15
a... Upper stun frame, 15b... Lower stun frame, 16... Seawater tank, 17a... Conduit as air venting means, 17b... Conduit as water intake means, l... Projection amount, O... Center point of the hull ,
P...The turning center of the ship.

Claims (1)

[Scope of Claims] 1. A hull resistance reducing protrusion is provided at the stern of the ship that protrudes rearward from the rear end of the main hull at the load waterline, and the weight and buoyancy of the protrusion are approximately equally balanced within the working draft range. A hull resistance reduction device characterized in that a ballast water tank is provided inside the protrusion, and a water injection and drainage mechanism is provided in the ballast water tank. 2. Claims in which the above-mentioned water injection and drainage mechanism is constituted by a water intake means communicating from the lower part of the ballast water tank to the bottom water intake of the protrusion, and an air vent means provided at the upper part of the ballast water tank. The hull resistance reduction device according to paragraph 1. 3. The hull according to claim 1, wherein the water injection and drainage mechanism includes a ballast water pump provided in the main hull, and piping that communicates from the pump to the ballast water tank. Resistance reduction device.