JP7316415B1 - Deck stringer structure for multi-deck ships - Google Patents

Abstract

A deck stringer structure for a multi-deck ship capable of maintaining the maximum waterline as originally planned even when the specifications of the ship are changed. In a multi-deck ship (S), a thickened deck stringer (20) is used as a deck stringer for attaching a freeboard deck (7) to a ship's side outer plate (2). Since the freeboard fb can be determined with reference to the upper surface of the thickened deck stringer 20, the load line WL can be raised as a result. Further, since the thickened deck stringers 20 are part of the longitudinal direction of the ship, it is possible to minimize the reduction in the maximum cargo load with a minimum increase in hull weight. [Selection drawing] Fig. 1

Description

The present invention relates to a deck stringer structure for multi-deck ships. More particularly, the present invention relates to a deck stringer structure for multideck ships such as RORO ships (Roll-on/Roll-off ships) and PCTC ships (Pure Car and Truck Carrier ships).

The freeboard of a ship is an indicator of stability by ensuring the reserve buoyancy of the ship, and the greater the freeboard, the higher the stability. The freeboard of an ordinary ship is the vertical distance from the top of the upper deck to the load line at midship length.
The maximum amount of cargo that can be loaded on a ship is limited by the ship's structural strength and hull shape so that the ship can sail with sufficient reserve buoyancy.
In multi-deck ships such as RORO ships, even if the standard of freeboard is not the upper deck but the lower deck, it is possible to have a through deck to communicate between the engine room and the collision bulkhead and in the lateral direction. The deck that is continuous with the hull is sometimes called the freeboard deck.

Freeboard, the vertical distance above a ship's load line, is a safety indicator and also affects a ship's gross tonnage.
Gross tonnage refers to the figure obtained by multiplying the index indicating the size of a ship stipulated in Article 4 of the "Law on Tonnage Measurement of Ships" by the coefficient stipulated in Article 5, Paragraph 2 of the same law, and the number of tons. It is attached. In short, it is an index that expresses the volume of a ship, not its weight, and since this gross tonnage affects the port entry tax and registration tax of a ship, which deck among multiple decks should be the freeboard deck is a matter of balance with the gross tonnage. determined by taking into account

In the multi-deck ship (RORO ship) of Patent Document 1, two layers of decks 111 and 118 are provided between an upper deck 112 and a ship bottom 104 as shown in FIG. 111 is the freeboard deck. Also, the load waterline WL is positioned between the upper deck 111 and the lower deck 118 . In this ship the freeboard fb is the vertical distance between the deck 111 and the load line WL.
In the prior art of FIG. 4, reference numeral 121 is a horizontal partition. Each deck 112, 111, 118 extends transversely through the transverse bulkhead 121 and is joined to the side shell plating (which extends vertically).

As shown in Non-Patent Document 1, the deck and the side shell plating are joined together via deck stringers. As shown in FIG. 5, the deck stringer 10 is a row of steel plates closest to the ship's side and is attached to the ship's side shell plate 2 by welding or the like. The freeboard deck 7 is joined to the deck stringer 10 by welding or the like.

By the way, the design and construction of a ship is carried out based on the initial plan, but if the freeboard becomes larger than expected due to a later specification change, the originally planned maximum waterline may remain low. . A low maximum waterline is disadvantageous to ship owners as the maximum cargo capacity remains low.

JP 2016-124467 A

"Nautical and Naval Architecture" 118 pages March 10, 2003 11th Edition Published by Takeo Nohara Kaibundo Publishing Co., Ltd.

SUMMARY OF THE INVENTION In view of the above circumstances, an object of the present invention is to provide a deck stringer structure for a multi-deck ship that can maintain the maximum waterline as originally planned even if the ship specifications are changed.

A deck stringer structure for a multi-deck ship according to the first invention is a deck stringer for attaching a freeboard deck to a side shell plate of a multi-deck ship. It is characterized by using a deck stringer.
A deck stringer structure for a multi-deck ship according to a second invention is characterized in that, in the first invention, the thickened deck stringers are formed over a predetermined length in the longitudinal direction from the center point in the longitudinal direction.
A deck stringer structure for a multi-deck ship according to a third aspect of the invention is characterized in that, in the second aspect, the thickened deck stringer has an upper surface at a connection portion with the freeboard deck formed into an inclined surface that descends inward in the ship width direction. It is characterized by

According to the first invention, since the freeboard can be determined with reference to the upper surface of the thickened deck stringer, the full load waterline can be raised as a result. Also, since the thickened deck stringers are part of the longitudinal direction of the ship, it is possible to minimize the reduction in maximum cargo capacity with a minimum increase in hull weight.
According to the second invention, since the thickened deck stringers are provided across the longitudinal center of the hull, the effect of raising the full load waterline is maximized.
According to the third invention, since the upper surface of the junction between the thickened deck stringer and the freeboard deck is a slanted surface, inconveniences such as damage to the tires of the loaded automobile hitting the corners do not occur.

1 is a cross-sectional view of a main part showing a deck stringer structure according to an embodiment of the present invention; FIG. Figure 2 is a partial plan view of the deck stringer structure shown in Figure 1; BRIEF DESCRIPTION OF THE DRAWINGS It is a longitudinal cross-sectional view of the multi-deck ship which concerns on one Embodiment of this invention. 1 is a longitudinal sectional view of a main part of a ship described in Patent Literature 1; FIG. 1 is a perspective view showing an example of a deck stringer described in Non-Patent Document 1; FIG.

Next, embodiments of the present invention will be described with reference to the drawings.
FIG. 3 shows a vertical cross section at the center in the longitudinal direction of the multi-deck ship S according to one embodiment of the present invention. 1 is the upper deck, 2 is the side shell plate, and 3 is the bottom of the ship. An upper structure 4 such as a cabin is provided on the upper surface of the upper deck 1 .
Three layers of decks 5, 6 and 7 are provided between the upper deck 1 and the bottom 3 of the ship. 5 is the second deck, 6 is the third deck, and 7 is the fourth deck. 8 is a tank top.

In the multideck ship S of FIG. 3, the freeboard fb is calculated as the vertical distance between the freeboard deck 7 and the load line WL.
Strictly speaking, the freeboard fb is measured with the upper surface of the freeboard deck 7 as a reference. As shown in FIG. 5, the deck stringer 10 based on the initial plan of design and construction serves to connect the freeboard deck 7 to the ship's side shell plate 2, and the measurement of the freeboard fb is based on its upper surface 10a.

The present invention features the use of thickened deck stringers 20 to accommodate specification changes after initial planning.
As shown in FIG. 1, this thickened deck stringer 20 has a plate thickness that increases upward. Then, the thickened deck stringer 20 is attached by removing the deck stringer 10 to which it was originally attached. The attachment is made by welding the thickened deck stringers 20 to the side shell 2 and the freeboard deck 7 is welded to the end faces of the thickened deck stringers 20 .

The thickened deck stringer 20 is preferably made of a single steel plate from the viewpoint of ensuring strength. However, even if a steel plate for increasing the thickness is joined to the upper surface of the deck stringer 10 originally used by welding or the like, it is included in the thickened deck stringer 20 of the present invention as long as the welding strength is sufficient.

The upper surface of the connection of the thickened deck stringer 20 to the freeboard deck 7 is formed into an inclined surface 23 . The inclined surface 23 is a slope that descends inward in the width direction of the ship.
If the inclined surface 23 is provided in this way, when the multi-deck ship is a car carrier, troubles such as damage to the tires of cars traveling in the hold by hitting corners do not occur.

Any values can be selected for the thickness of the thickened deck stringer 20 and the width in the ship width direction.
In the embodiment of FIG. 1, the thickness of the thickened deck stringer 2 is approximately 36 mm, but is not limited to this dimension. In addition, the width w of the ship width method is about 1200 mm, but it is not limited to this size, and any size can be adopted according to the width of the hull.

The thickened deck stringer 20 straddles the longitudinal midpoint of the hull (on many cargo ships, the midship midship length between the fore and aft perpendiculars, also called midship ms). Only the necessary length is provided in the front and rear so that
Depending on the length of the ship, the length L forming the thickened deck stringers 20 can be chosen arbitrarily. In the embodiment of FIG. 2, the length is 20 m in total and 10 m forward from the midship ms, but the length is not limited to this, and it is a matter of course that any size can be adopted according to the length of the hull.

In the multi-deck ship S to which the present invention is applied, the deck stringers 10 are initially designed with a single steel plate shown in FIG.
However, if the freeboard fb becomes larger than originally planned due to specification changes during design and construction, thickened deck stringers 20 are used.

The thickness of the thickened deck stringer 20 may be determined according to the vertical distance to which the load line WL is desired to be raised.
Once the thickness is determined, the width w and length L of the thickened deck stringer 20 can be determined according to the size of the multi-deck ship S.

The thickened deck stringer 20 of this embodiment has the following effects.
(1) The freeboard fb can be determined with the upper surface of the thickened deck stringer 20 as a reference. In this case, the load line WL can be raised compared to the freeboard fb' based on the upper surface of the deck stringer 10 originally planned.
(2) Since the intensifying deck stringers 20 are part of the longitudinal direction of the ship, the increase in hull weight can be minimized and the reduction in maximum cargo capacity can be minimized.
(3) Since the thickened deck stringers 20 are provided across the longitudinal center of the hull (midship ms), the effect of raising the load line WL is maximized.
(4) Since the upper surface of the junction between the thickened deck stringer 20 and the freeboard deck 7 is an inclined surface 23, the tires of the loaded vehicle are not damaged by contact with the corners.

Although the illustrated embodiment is a RORO ship, the present invention can be applied to other ships as long as they are multi-deck ships.

1 upper deck 2 side shell plate 3 bottom 4 superstructure 7 freeboard deck 10 deck stringer 20 thickened deck stringer 23 slope

Claims (3)

In multi-deck ships,
A deck stringer structure for a multi-deck ship, characterized in that thickened deck stringers are used as the deck stringers for attaching the freeboard deck to the side shell plates, the thickness of which is increased upward in a part of the ship in the longitudinal direction. 2. A deck stringer structure for a multi-deck ship according to claim 1, wherein said thickened deck stringers are formed over a predetermined length in the fore-and-aft direction with a center point in the longitudinal direction as a boundary. 3. The deck stringer structure for a multi-deck ship according to claim 2, wherein the thickened deck stringer has an upper surface at a connection portion with the freeboard deck formed as an inclined surface that descends inward in the width direction of the ship.