JPH0120119B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a semi-submersible catamaran, and more particularly to a semi-submersible catamaran that can make its wake distribution as uniform as possible and reduce underwater noise caused by propellers. be.

Conventionally, in a general semi-submersible catamaran, as shown in FIG. By using the wake of the propeller, the straight rudder pressure increases, which is effective in terms of maneuverability.

However, in order to minimize the noise caused by underwater propeller noise, which is required in recent years for ships, etc., it is necessary to minimize the non-uniformity of the wake on the propeller disk surface caused by wakes such as struts. . Therefore, it is necessary to place the rear end of the strut 2 sufficiently far from the propeller 4 to make the wake more uniform. If the wake distribution in the case of the conventional semi-submerged catamaran shown in FIG. By protruding into an elongated and axially symmetrical valve shape, it is possible to achieve a uniform wake distribution in the propeller radial direction as shown in Fig. 2-B. Under such a good wake distribution, the wake of the propeller 4 is almost constant all around the same radius, so there are fewer changes in the operating state due to the rotation of the propeller blades, and lift fluctuations, etc. is sufficiently small, and compared to the case of the wake distribution shown in FIG. 2-A, cavitation is less likely to occur, and therefore propeller vibration and noise are also smaller.

However, in this case, as described above, although the wake distribution is improved, there is a problem in that the arrangement of the rudder device 1 shown in FIG. 1 becomes difficult. Therefore, it is realistic to place the rudder ahead of the propeller, but
In this case, as with the strut, the rudder must be placed sufficiently away from the propeller disk surface so as not to impair the uniformity of the wake.

However, if the rudder is disposed below the submerged body, the maximum shear will be even greater in semi-submerged catamarans, which tend to have deep water even under normal circumstances, which is undesirable from the viewpoint of the water depth of the port.

Therefore, the present invention simultaneously provides sufficient rudder force for maneuvering the vessel during high-speed cruising and low underwater noise performance by arranging the retractable rudder device at a position that does not impair the uniform wake distribution as described above. This was done for the purpose of providing a fleet of semi-submersible catamarans. A major feature of semi-submersible catamarans is that when cruising at low speed, in shallow water, the rudder can be retracted and the ship can be fully maneuvered using the difference in thrust between the propellers on both sides. there is no problem.

That is, the semi-submersible catamaran of the present invention is a semi-submersible catamaran equipped with a propeller at the rear end of the submerged body provided at the lower part of the strut, in which the rear end of the submerged body is attached to the strut. Extending to the rear end of the strut to a position where turbulence of the water flow due to the strut almost disappears, and protruding from the rear end of the strut in an elongated and axisymmetric bulb shape,
It is constructed by providing a rudder device which can protrude from the bottom of the submerged body and can be retracted into the submerged body at a position forward of the rear end of the strut.

An embodiment of the present invention will be described below with reference to the drawings. Fig. 3 is a side view of essential parts of a semi-submersible catamaran according to an embodiment of the present invention, and Fig. 4 is a submerged body of Fig. 3. FIG. 3 is a plan cross-sectional view of main parts.

First, this semi-submersible catamaran is equipped with a propeller 4 at the rear end of the submerged body 3 provided at the bottom of the strut 2. The bulb has an elongated, axially symmetrical shape such as a torpedo shape that protrudes a distance E from the part.
This allows the rear end of the strut 2 and the propeller 4 to be positioned sufficiently apart.

Note that it is effective to make the distance E as long as possible in order to form the ideal uniform wake distribution shown in Fig. 2-B, but the length of the semi-submersible catamaran, It is desirable to make a decision by taking into account major factors such as swamping, the speed of the ship being used, structural problems, and other factors.

Next, in this semi-submersible catamaran, the rudder device 5
, strut 2 as shown in Figures 3 and 4.
It is disposed at a position forward of the rear end of the submerged body 3 so as to be able to protrude from the bottom of the submerged body 3 and to be retractable into the submerged body 3.

This rudder device 5 has two parts in the submerged body 3 shown in FIG.
A transmission shaft 7 connecting the main engine 6 and the propeller 4
It can be stored in the storage space 8 provided in the middle, but the principle is that it can be used with a stabilizer that has the same function as the conventionally widely used fin stabilizer, and its operation can also be hydraulic or mechanical. You can use any method such as
Furthermore, any method of retracting and protruding the rudder device 5 may be used.

As mentioned above, in the semi-submersible catamaran of the present invention, the rudder device 5 is provided forward of the rear end of the strut 2. However, if the rudder device 5 is installed forward of the rear end of the strut 2 If it is placed between the strut 2 and the propeller 4 and above the submerged body, the wake of the strut 2 will make steering difficult, and noise and vibration will occur due to vortices and bubbles generated on the free surface during steering, which is undesirable. It is known.

In addition, when sailing at low speeds or in places with shallow water lines such as in ports, the rudder device 5 can be retracted and the ship can be sufficiently maneuvered by the thrust difference between the left and right propellers 4 of the twin hull without using the rudder. Can only be used in deep locations.

Therefore, in the semi-submersible catamaran of the present invention, the rear end of the submerged body equipped with a propeller is located sufficiently far from the rear end of the strut, so that most of the turbulence in the water flow caused by the strut is avoided. The propeller operates at the position where it disappeared. In other words, it is possible to make the wake distribution uniform, reduce underwater noise caused by propeller noise, and reduce the occurrence of cavitation.Furthermore, as mentioned above, while making the wake distribution uniform, it is possible to maintain sufficient rudder area for maneuvering. This makes it possible to install a rudder device with

[Brief explanation of drawings]

Figure 1 is a side view of the main parts of a conventional semi-submersible catamaran.
Figure 2-A is a wake distribution diagram for the semi-submersible catamaran shown in Figure 1, Figure 2-B is an improved wake distribution diagram, and Figure 3 is a wake distribution diagram for the half-submerged catamaran in the embodiment of the present invention. FIG. 4 is a side view of the main parts of the submersible catamaran, and FIG. 4 is a plan sectional view of the main parts of the submersible body shown in FIG. 2... Strut, 3... Submerged body, 4... Propeller, 5... Rudder device.

Claims (1)

[Claims] 1. In a semi-submerged catamaran equipped with a propeller at the rear end of a submerged body provided at the bottom of a strut, the rear end of the submerged body is the rear end of the strut, and the water flow by the strut is The strut extends to a position where turbulence almost disappears, and is formed to protrude from the rear end of the strut into an elongated, axisymmetric valve shape, and can protrude from the bottom of the submerged body at a position forward of the rear end of the strut. 1. A semi-submersible catamaran, characterized in that it is equipped with a rudder device that can be retracted into the submerged body.