JPS5975885A - Double axis shallow draft vessel - Google Patents

Abstract

PURPOSE:To smooth flow at the stern thus to reduce hull resistance by forming such that the center line of recessed section at the bottom of a double axis shallow draft vessel formed with buttock flow type bottom face between left and right recess at the bottom will open outward in rear direction. CONSTITUTION:In a double axis shallow draft vessel formed with a buttock flow type bottom face 5 between left and right recess 4 in the bottom at the stern section, said recess 4 will enlarge rearwardly where the axis is formed approximately in parallel with a propeller shaft 6 with outwardly opening angle (a). Since the tunnel-shaped recess 4 will widen rearwardly to smooth flow to the propeller 2, disturbance and separation of flow is reduced to reduce hull resistance, propeller cavitation and vibration of hull while remaining advantage of wide vessel where load weight under shallow draft can be increased.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a twin-stern, two-shaft, shallow-draft ship which has an increased width and a two-axle, two-rudder configuration in order to increase the payload with a shallow draft.

BACKGROUND ART Conventionally, two-shaft shallow draft ships shown in FIGS. 1 to 8 have been developed, and research is underway to put them into practical use.

Figure 1 is a side view of the stern, and Figure 2 is a bottom view of the stern.

FIG. 8 is a rear view of the stern with the rudder removed.

In these figures, 01 is the hull, 02 is the propeller, 03 is the rudder, 04 is the four tunnel-shaped bottom parts, and 05 is the buttock flow type bottom surface.

This type of twin-stern shallow draft ship has four tunnel-shaped bottom parts 04 near each propeller shaft between both propeller shafts at the stern.
It is characterized by forming a buttock flow type hull surface 05 between the left and right four hull bottom parts 04.

However, in conventional vessels of this type, when the degree of enlargement of the stern section increases, the flow in the tunnel-shaped hull recess 04 inside the propeller shaft becomes turbulent, and the flow also separates, increasing the hull resistance and causing the propeller cavity ( - has the disadvantage of causing increased vibration and vibration.

In order to eliminate such drawbacks of the conventional art, the present invention provides a two-shaft shallow-draft ship with a propeller shaft that speeds up the flow in the hull recess on the inside of the propeller shaft and makes it easier to flow. In a two-shaft shallow draft ship, in which a tunnel-like bottom recess is formed near each propeller axis between the two, and a buttock flow type bottom surface is formed between the left and right four bottom parts, The patent states that the b line is formed with an outward opening angle toward the rear.

The ship of the present invention will be explained with reference to the following nine drawings. Figure 4 is a bottom view of an embodiment of the two-shaft shallow draft ship of the present invention, and Figure 5 is a rear view with the rudder removed. In each case, only one side is shown.

■ is the hull, 2 is a propeller attached to the rear end of the propeller shaft 6, which is opened outward toward the rear at an angle α with the center line of the hull, and 8 is attached to the rear of propeller 2. The rudder 4 is a tunnel-shaped bottom recess formed near the propeller shafts 6, which are provided in a pair on the left and right, and substantially parallel to the propeller shafts 6.

As can be seen from FIG. 5, the bottom recess 4 is enlarged as it moves rearward from the bottom of the ship, and its center axis is formed with an outward opening angle toward the rear as described above.

Reference numeral 5 denotes a buttock flow type bottom surface formed between the bottom recesses 4 provided on the left and right sides. .

In this way, the two-shaft shallow draft ship of the present invention has a propeller shaft 6
The tunnel-shaped bottom recess 4 is formed on the rear floor by arranging the bottom recess with an outward opening angle α towards the rear and forming the bottom recess approximately parallel to the propeller axis with an opening angle outward towards the rear. As the flow to the propeller becomes smoother, there is less turbulence in the flow.

In addition, it is possible to reduce flow separation, and while taking advantage of the advantages of this type of ship shape, it is possible to reduce hull resistance, propeller cavity, and hull vibration.

As described above in detail, the two-shaft shallow draft boat of the present invention has a bottom recess defined in the claims that is formed substantially parallel to the propeller axis and is arranged with an outward opening angle toward the rear. This has the advantage of smoothing the flow in the tunnel-like bottom recess and increasing the speed of inflow into the propeller, eliminating or alleviating the drawbacks of this type of ship. In the above embodiments, a shallow draft ship was described; however, the present invention is not limited to such ships, but is also effective for tankers, bulk carriers, and the like.

[Brief explanation of the drawing]

Figures 1 to 3 show the stern of a conventional two-shaft shallow draft ship, with Figure 1 being a side view, Figure 2 being a bottom view, and Figure 8 showing the stern with the rudder removed. FIG. 4 and 5 are views showing the stern of the twin-shaft shallow draft boat of the present invention, and FIG. 4 is a bottom view. FIG. 5 is a rear view. l, 01...Hull, 2.02...Propeller, 8.0
8... Rudder 4.04... Bottom recess, 5.05... Buttock flow type bottom surface, 6... Propeller axis. Procedural amendment (voluntary) January 1980 Commissioner of the Japan Patent Office Mr. Indication of the case 1984 Patent application No. 184993 Name of the invention Two-shaft shallow draft boat Relationship with the amended case Patent applicant address 2-5-1 Marunouchi, Chiyoma-ku, Tokyo Name (6211) Mitsubishi Heavy Industries, Ltd. Agent (1) On page 4, line 19, ``reduction'' is corrected to ``reduction.'' (2) On page 5, lines 9 to 12, the phrase ``The above embodiment is an effective one.'' was replaced with ``The shallow draft ship described in the above embodiment is a tanker. It is widely applied in bulk carriers, etc.”.

Claims (1)

[Claims] A pair of left and right propeller shafts are arranged near the stern of the ship, and tunnel-shaped bottom recesses are formed between the propeller shafts near the respective propeller shafts, and a buttock flow type ship bottom surface is provided between the left and right bottom recesses. What is claimed is: 1. A twin-shaft shallow-draft ship, characterized in that the center line of the bottom concave portion is formed with an outward opening angle toward the rear.