JPH04292292A - Ship, especially roll-on roll-off ship - Google Patents

Abstract

PURPOSE: To make improvements in the stability and safety of a ship against capsizal and suchlike without worsening the operational mechanism of a ro-ro cargo compartment by installing those of double sides, double decks andbulkhead decks, and sufficiently subdividing these double sides and double deckes in a dense manner, while installing each air escape in two cargo spaces. CONSTITUTION: In this roll-on/roll-off ship with double buoyant deckes, the hull is provided with a double hull side 2 passing an overall length of the hull, as terminated at a double bottom q and a main deck 3 stated by the rules, by way of example. It is also provided with a double bulkhead deck 4 with height corresponding to the height of deck stiffeners of an adequate single deck. In addition, the double hull side 2 is horizontally subdivided (5) by an outer plate of the bulkhead deck, and it is further subdivided (5) in the lateral direction by the horizontal bulkhead. Then, two vertical bulkheads are installed in the double bulkhead deck 4, and it is also subdivided (5) in the lateral direction at the same space as the double hull side. On the other hand, two holds 6 and 7 are provided with efficient air escape ports 8 and 9.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION The subject of the present invention is marine vessels, in particular of the roll-on roll-off type. The invention is applicable to shipbuilding, particularly to ships that do not have transverse watertight bulkheads in the cargo hold and meet requirements regarding the survivability of the ship in a damaged state. Cargo ships without transverse watertight bulkheads intended primarily for the carriage of roll-on/roll-off cargo are known. They usually have the following watertight compartments: double bottom, fore hold, stern hold, engine room and side tank. The bow and stern bulkheads and side tanks generally terminate on the primary deck above the deepest load waterline.

0002

To date, there has been no need for subdivisions for cargo roll-on roll-off vessels. This is because the bottom tanks of such ships are applied from a bottom loading material standpoint, and are often more for psychological reasons than for subdivision considerations. These can only protect the ship in case of shallow damage near the side tanks. Cargo and passenger ferry boats of the roll-on roll-off type that comply with the subdivision and breakage safety requirements contained in the 1974 SOLAS Convention are known. The bulkhead decks of ferries, which are usually closely subdivided by transverse bulkheads, are spaced below and extend from side to side. In such cases, side tanks are not applicable and much of the space below the bulkhead deck is used for cargo rather than for other purposes. For the remaining passenger roll-on roll-off vessels, below the bulkhead deck a vestibule of width B/5 is applied, which is relatively short and cross-joined to avoid asymmetric overflows.

The above solutions do not provide sufficient safety for passenger roll-on roll-off vessels in the event of a collision. On the contrary, these solutions appear to be extremely dangerous, as they do not protect the ferry from capsizing quickly if seawater enters onto the bulkhead deck. Good evidence for this was the overthrow of just two recent and most famous disasters, the 1982 European Gateway and the 1987 Herald of Free Enterprise.

[0004] In view of the new requirements for ship subdivisions based on probabilistic approaches, the subdivision index is a means to an end for ship safety in damaged conditions. The rules are 1992
Due to come into force as early as 2020, all dry cargo ships, including roll-on roll-off ships, will have to meet this requirement. Similar rules will be enforced on passenger vessels.

[0005] The new probabilistic rules require the same level of safety disregard as in the dry cargo ship type. That is, the new roll-on roll-off vessel must be significantly safer than the remaining dry cargo vessels and have the same subdivision index. For roll-on roll-off vessels of the invention in use, the value of the subdivision index is very low and often does not exceed a value of 0.1, if not at the limit. On the other hand, this index is higher than 0.5 compared to other cargo ships.

Within the currently applied concept of these watertight subdivisions, there is no possibility in any case to increase the index of roll-on roll-off marine subdivisions very significantly. This has occurred through a considerable increase in freeboard or through the application of movable transverse bulkheads in holds intended for roll-on roll-off cargo. Such a solution is clearly at odds with the basic operating mechanism.

[0007]

SUMMARY OF THE INVENTION The vessel of the invention has, over at least part of its length, a double side terminating in at least a primary continuous deck above the bulkhead deck, and has a double deck, at least a bulkhead deck. By the way, the double sides and deck are sufficiently densely subdivided into watertight compartments by watertight bulkheads, while the cargo hold has an effective air escape port ( air separator) is provided. The width of the double hull is preferably no greater than B/10, and the double hull is subdivided into deep tanks by transverse bulkheads;
The cargo hold has a constant width. The height of the double deck is preferably no greater than the height of the deck stiffener of the corresponding single deck. The double deck is subdivided horizontally and vertically by watertight bulkheads. The double bottom is preferably the minimum height required by regulation.

[0008]

[Effects of the Invention] There are two advantages of the present invention. I. From a design and operational point of view, the present invention makes it possible to obtain the high index of subdivisions required by the new subdivision regulations. That is, it makes it possible to build stable roll-on roll-off vessels without compromising a successful operational mechanism based on non-subdivided horizontal cargo holds. II. From a technical point of view: a) The invention does not reduce cargo space. With double deck,
A compartment below the deck not used for cargo, contained between the large deck stiffeners, may be used. Containment of the chamber by a relatively thin watertight shell in place of thick flanges on the deck stiffeners transforms this wasted space into a double buoyant deck of considerable volume. For this reason, the hitherto wide siding compartment below the bulkhead deck can be replaced by a relatively narrow double siding terminating in at least the primary deck above the bulkhead deck, thus improving the function of the cargo hold. b) The invention does not increase the weight of the ship, i.e. maintains the same dead weight. c) The invention improves overall ship power. d) Smooth ship sides facilitate cargo handling and segregation. The invention is illustrated in FIGS. 1 and 2. FIG. 1 shows a cross-sectional view of a roll-on roll-off vessel with double buoyant decks. The ship of figure 1 has a double bottom 1 of the minimum height stated by the regulations;
It has double sides 2 running the entire length of the ship, terminating in the main deck 3. The ship has a double bulkhead deck 4 of a height corresponding to the height of the deck stiffeners of an equivalent single deck. The double side is subdivided horizontally by the skin of the bulkhead deck and laterally by watertight bulkheads. The double bulkhead deck 4 has two vertical bulkheads and is subdivided horizontally into the same space as the double shipside. The holds 6 and 7 have effective air escape ports 8 and 9 located along the ship's sides. The corresponding relative tanks of the double bottom 2 are cross-connected or filled by the use of a ballast system. The ship of FIG. 2 has, in addition to the ship shown in FIG. 1, a double main deck 10. The double side 2 in this case remains the same width as the holds 6 and 7 in the case of the ship of FIG. 1, but is narrower. As a result, the ship is a little narrower than before.

[Brief explanation of drawings]

1 is a sectional view of a ship with double buoyant decks according to the invention; FIG.

FIG. 2 is a sectional view of a ship with double main decks according to the invention.

[Explanation of symbols]

1. Double bottom 2　Double ship side 3 Main deck 4,10 Double deck 5 Vertical and small divisions 6, 7 Ship hold (cargo room) 8, 9 Air escape port

Claims (4)

[Claims] 1. characterized in that it has, at least part of its length, a double side (2) terminating in a primary continuous deck above the bulkhead deck, and also has a double deck, at least a bulkhead deck (4), Vessels, especially of the roll-on roll-off type, having internal watertight compartments such as double-bottomed bow holds, stern holds and engine rooms. The double sides and double decks are sufficiently densely subdivided into watertight compartments, and the cargo compartments 6 and 7 have effective air vents 8 and 9 located in the side tops of these compartments. 2. The double side 2 has a suitable width not greater than B/10 and is divided into smaller compartments by bulkheads, while the cargo compartment (6, 7) has a constant width. The ship according to claim 1, characterized in that: 3. The double decks (4, 10) have a suitable height not greater than the height of the deck stiffeners of the corresponding single deck, and have longitudinal (5) and transverse subdivisions into watertight compartments. The ship according to claim 1, characterized in that: 4. Claim 1, characterized in that the double bottom 1 has a preferred height corresponding to the minimum height according to the regulations.
ships.