JPS5989286A - Double-shaft type shallow draft ship - Google Patents

Abstract

PURPOSE:To smooth the flow toward a propeller by forming the undersurface of the bottom of a batock flow type ship at its stern part, viewed in a single hull section, below the undersurface of bottom situated near the propeller shaft and by supporting the portion of propeller shaft which is situated outside the hull with a bracket. CONSTITUTION:At the stern 1, a pair of propeller shafts 2a, on the right and left, are installed in a position aside from the center of the max. half width of the hull toward both hull sides, and in the central part a bottom surface 5 of batock flow type is formed. A tunnel-shaped bottom recess is provided between the propeller shaft 2a and this batock flow type bottom surface 5, which is formed below the bottom surface near the propeller shaft 2a viewed in a single hull section. Thus the flow toward propeller is smoothed even though the construction is widened toward the stern, while the merit of bi-shaft type shallow draft is allowed to remain, to assure reduction of hull resistance, propeller cavitation and hull vibration.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a shallow draft ship having a pair of left and right propeller shafts at the stern.

Generally, when designing a ship with a shallow draft and sufficient dead weight, the ratio of the ship's width to the draft becomes very large, making it difficult for water to flow smoothly into the propeller. In order to improve this, two-shaft shallow draft ships were developed as shown in Figure 1 (stern side view), Figure 2 (stern plan view), and Figure 3 (stern front view). ing.

In this type of two-shaft shallow draft ship, a tunnel-shaped bottom recess 4 is formed near each propeller axis between the propeller axes of both propellers 2 in the stern part 1, and a butt-flow type ship bottom is formed between the left and right bottom recesses 4. A surface 5 is formed.

A rudder 3 is provided behind each propeller 2.

By the way, in the case of such a two-shaft shallow draft ship, when the degree of enlargement of the stern section increases, turbulence occurs in the flow in the bottom recess 4, and furthermore, flow separation occurs, resulting in an increase in hull resistance and propeller cavitation. There is also a problem that it causes an increase in vibration.

The present invention aims to solve these problems by increasing the flow along the bottom surface of the ship inside the propeller shaft, making it easier to flow, and thereby preventing an increase in hull resistance. The purpose is to provide a two-shaft shallow draft ship with

Therefore, the twin-shaft shallow draft ship of the present invention is provided with a pair of left and right propeller shafts arranged at the ship's side in the stern part, and a buttock flow type bottom surface is provided in the center between the two propeller shafts. A buttock flow type ship bottom surface is formed below the ship bottom surface in the vicinity of the propeller shaft in the same hull cross section, and the outboard portion of the propeller shaft is supported by the ship body by a shaft bracket.

Hereinafter, embodiments of the present invention will be explained with reference to the drawings.
4 and 5 show a two-shaft shallow draft boat as a first embodiment of the present invention, FIG. 4 being a side view of the stern portion thereof, and FIG. 5 being a front view of the stern portion thereof.

In the stern part 1, propeller shafts 2a of a pair of left and right propellers 2 are arranged near the ship side from the center of the maximum half width of the hull, and a buttock flow type ship bottom surface 5 is provided in the center between both propeller shafts 2a. It is provided.

A tunnel-shaped bottom recess 4 is formed between the propeller shaft 2a and the buttock flow type ship bottom 5 at the bottom of the ship near the propeller shaft 2a.

In this way, the buttock flow type ship bottom 5 is formed below the ship bottom near the propeller shaft 2a in the same hull cross section.

In the above-described hull, in the present invention, in particular, the outboard portion of the propeller shaft 2a is supported by the shaft bracket 14 on the hull. Note that the reference numeral 3 in FIG. 4 indicates a rudder.

With the above configuration, while taking advantage of the advantages of a two-shaft shallow draft ship, it is possible to smooth the flow to the propeller 2 even if the stern section is enlarged, thereby reducing hull resistance, propeller cavitation, and hull vibration. This results in a reduction in energy consumption.

6 and 7 show a two-shaft shallow draft boat as a second embodiment of the present invention, FIG. 6 being a side view of the stern portion thereof, and FIG. 7 being a front view of the stern portion thereof.

In this second embodiment, compared to the first embodiment described above,
A skeg 15 is provided below the shaft bracket 14, which improves the directional stability of the hull, but other points are the same as in the first embodiment. be.

Further, FIG. 8 is a front view of the stern section showing a two-shaft shallow draft boat as a third embodiment of the present invention. The recess 4 is omitted.

However, a buttock 70 type ship bottom 5 is provided in the center between the left and right propeller shafts 2a, and this buttock flow type ship bottom 5 is larger than the ship bottom near the propeller shaft 2a in the same hull cross section. formed below.

The outboard portion of the propeller shaft 2a is supported on the hull by a shaft bracket 14.

Therefore, as in the case of each of the above-mentioned embodiments, it is possible to make the flow to the propeller smooth despite the enlargement of the stern part, and this has the effect of reducing hull resistance, propeller cavitation, and hull vibration. is obtained.

Furthermore, in this third embodiment, the shaft bracket 14
A skeg 15 is provided below the skeg 15 to improve the directional stability of the hull as in the case of the second embodiment described above.

As described in detail above, according to the present invention, a pair of left and right propeller shafts are provided in the stern portion of the ship, which are disposed closer to the ship side.
A buttock flow type bottom surface is provided in the center between both propeller shafts, and the buttock flow type bottom surface is formed lower than the bottom surface near the propeller shaft in the same hull cross section, and It has a simple structure in which the outboard part of the boat is supported on the hull by a shaft bracket.
It is possible to significantly improve the performance as a two-shaft shallow draft ship, and there is an advantage that the above-mentioned performance can be sufficiently maintained even when the stern section is enlarged.

[Brief explanation of the drawing]

Figures 1 to 3 show a conventional twin-shaft shallow draft ship.
The figure is a side view of the stern part, FIG. 2 is a plan view of the stern part, and FIG. 3 is a front view of the stern part. It indicates a ship and is the fourth
FIG. 5 is a front view of the stern, FIG. 6 is a front view of the stern, FIGS. Its stern side view, No. 7
This figure is a front view of the stern part thereof, and FIG. 8 is a front view of the stern part showing a two-shaft shallow draft boat as a third embodiment of the present invention. 1...Stern part, 2...Propeller, 2a...Propeller shaft,
3. Rudder, 4. Bottom recess, 5. Baton Kutsurou type bottom surface, 14. Shaft placket, 15. Skeg. Sub-Agent Patent Attorney Yoshihiko Iinuma Figure 1 Figure 2 Figure 3 Figure I Figure 4 Figure 5 Figure 6 Figure 7 Figure 2Q Figure 8

Claims (1)

[Claims] The stern section has a pair of left and right propeller shafts placed closer to the ship's side, and a buttock flow type bottom surface is provided in the center between the two propeller shafts, and the buttock flow type bottom surface is located near the propeller shafts in the same hull cross section. A two-shaft shallow draft ship, characterized in that the propeller shaft is formed below the bottom surface of the ship, and an outboard portion of the propeller shaft is supported on the hull by a shaft bracket.