GB2080739A - A dockship - Google Patents

Abstract

A dockship with a large unobstructed hold (2) has a hatch opening (8) and hatch covers (9) which close the hatch opening (8). Hatch covers (9) are also used to form a removable portion (11) of the double bottom (12) of the ship. They may also be positioned at an intermediate height of the hold. <IMAGE>

Description

SPECIFICATION A dockship This invention relates to a dockship with a large unobstructed hold, the hatch opening of which is to be closed watertight with a series of hatch covers, which ship is arranged for the transport of heavy loads such as large prefabricated plant units which are to be loaded and unloaded by a gantry crane which is supported at its sides on the two high gangways and drivable therealong, or as an alternative, by rolling on and off through or over the stern by means of roll units.

The hatch covers are adapted to form a sturdy support deck in adjoining relation, whereas the loads are then to be stowed at two levels: on the hatch covers as deck load and under the hatch covers in the closed hold.

If, however, loads, stowed in the hold, are too high to permit to place the hatch covers thereon, the transport takes place with open hold. As main deck, i.e. uppermost entirely closed watertight deck, the hold deck is functioning then, which also forms the top of the double bottom and which, because of its low position, much restricts the maximum permitted draight afloat.

Therefore it is an advantage to construct the double bottom as high as possible so that the full loaded draught can be as large as possible. On the other hand, however, the dockship is not only destined for dry cargo, but should also be adapted to take so-called wet cargo aboard, such as bargers, which, with the ship trimmed down by the stern, and the hold floor, i.e. the double bottom tank top being submerged, should be permitted to float into and out of the hold, but when the double bottom is too high, this submersion is made very difficult.

The present invention tends to remove this difficulty and achieves it in that the upper double bottom portion is removable, whereby on the one hand when the hatch opening is closed watertight it is permitted to sail at a greater draught, and also when loading wet, this upper double bottom portion can be removed, whereas on the other hand, so as to increase the permitted draught when sailing with open hold, the double bottom is heightened by placing this upper portion thereon.

The preferred embodiment thereof is characterized in that the high box-shaped hatch covers can be nested on the hold deck, which thus form a watertight deck at a higher level, above the hold deck, so that the maximum permitted draught can be greater and the ship can be loaded deeper when afloat with open hold.

Additionally is further possible the use of the hatch covers as tweendeck in the hold, which can then function above this tweendeck for open stowage of loads, and is closed thereunder, and a watertight barrier around the hatch covers is provided in that at their periphery the hatch covers are provided with a compressible hollow seal.

The invention is described in more detail in the following specification with reference to the drawings in which illustrative embodiments of the invention are represented.

Figure 1 is a schematic side view of a dockship arranged for the transport of loads in a large, entirely unobstructed hold or as deck load on the hatch covers; Figure 2 is a corresponding plan view, with the hold closed by the hatch covers, in which when the hatch covers are removed, also open stowage of loads is contemplated; Figure 3 is a schematic transverse section of such a dockship, in which the hatch covers are selectively to be used to stow deck cargo thereon, or to be used as removable double bottom section on the dock floor, to increase the permitted draughtwhen afloat with open hold; and Figure 4 is a transverse section, corresponding with Figure 3, and showing the further possibility of having the hatch covers function as partition between a watertight closed lower loading hold and an open upper loading hold portion.

The dockship 1 as represented in the drawings has an open and unobstructed hold 2 in which by means of a gantry crane 4 which is drivable on the high gangways 3, cargo 5 is to be stowed. It is also possible to transport loads on deck, such as those indicated at 6 and 7 in Figure 1, on the hatch covers 9, arranged on the hatch opening 8 of the hold 2, which hatch covers have a sturdy box-shaped construction and form in adjoining relation a strong support deck.

The loads can be driven into and out of the hold 2 or on and off the deck through or over the stern, whereas by entirely opening the stern gate 10 which consists of an upper and lower part, the hold 2 can be flooded for wet loading and unloading of bargers, which is, however, not illustrated in the drawings.

The ship 1 is thus suited for universal use. Loads which are too large to go under the gantry crane 4, such as 7 in Figure 1, can be rolled on and off by means of special units, as described in Dutch patent application 7805807.

The hatch covers 9 are arranged as watertight tank sections, to be used for stabilisation purposes. For, the ship 1 has a great stability in view of the transport of heavy deck loads, such as complete plant units with a weight of hundreds of tons, and is in the absence of such high situated cargo too stiff, which is to be abolished by filling the hatch covers 9 which are arranged above the hold 2 with ballast water, whereby the ship 1 due to this high ballast, becomes less stiff, as described in Dutch patent application 7808836.

Also when loading heavy loads the stability of the ship 1 can be increased by placing hatch covers 9 as side tanks alongside outboard of the ship, whereby the beam of the ship is increased, which results in the desired increase in stability, as described in Dutch patent application 7703249.

The present invention tends to further increase the universal utility of such a dockship 1, particularly when afloat with open hold 2 in order to stow high loads therein, which do not go under the hatch covers 9 which are to be placed on the hatch opening 8, such as the high loads 5 which are represented in Figures 1 and 3.

Because in the absence of a continuous strength deck formed by the hatch covers 9 with the high gangways 3 above the hold 2, the hold deck 11 forming the top of the double bottom 12, is to be observed as uppermost continuous deck, due to this the permitted draught with open ship 1 is much restricted. The present invention tends to abolish this, and to thus come to a greater permitted draught, by removable constructing the upper portion of the double bottom, and aims particularly at the use of the hatch covers 9 for this removable portion of the double bottom 12 as indicated in Figure 1 with dotted lines.

As shown schematically in Figure 3, the hatch covers 9, as represented here by full lines on the hold bottom 11, are locked in nesting relation by means of suitable means, for instance retractable locking girders 13 as illustrated.

In Figure 3 the hatch covers 9 are shown with dotted lines on the hatch opening 8 above the hold 2, in which position they are rigidly supported as indicated at 14, so that heavy loads can be stowed thereon.

Figure 4 also shows the further possibilities of use of the hatch covers 9 to subdivide the hold therewith in lower loading holds such as 2a and 2b and an upper hold portion 2e to be held open. In orderto form a watertight barrier the hatch covers 9 are provided at their periphery with a hollow seal 15, which, when a hatch cover 9 is in its intended position, is compressed by wedges 16 or by means of pressurized fluid 17 which is introduced therein through suitable means, not shown.

Due to the sound watertight partition it is now possible to transport any desired freight 18, in the closed lower hold 2a, in bulk or as general cargo, and open freight as deck load in the open hold portion 2c which can be sheltered from the swash of overtaking green water by a deck trunk 19 which is removable constructed so as not to obstruct the deck surface when stowing loads on deck.

Finally it is remarked here that the invention is of course not restricted to the embodiments as represented here, but that still other embodiments are possible not going beyond the scope of the invention.

Claims (5)

1. A dockship with a large obstructed hold, the hatch opening of which is to be closed watertight with a series of hatch covers, which ship is arranged for the transport of heavy loads such as large prefabricated plant units which are to be loaded and unloaded by a gantry crane, which is supported at its sides on the two high gangways and drivable therealong, or as an alternative, by rolling on and off through or over the stern by means of roll units, characterized in that the uppermost double bottom portion is removable.

2. A dockship according to claim 1, characterized in that high box-shaped hatch covers (9) can be nested on the hold deck (11).

3. A dockship according to claim 2, characterized by the use of the hatch covers (9) as tweendeck in the hold (2), which can then function above this tweendeck for open stowage of loads (5, 6,7), and is closed thereunder.

4. A dockship according to claim 1, 2 or3, characterized in that at their periphery the hatch covers (9) are provided with a compressible hollow seal (15).

5. An arrangement, substantially as represented in the specification and/or the drawings.