GB2123354A - Barge carrying vessel - Google Patents

Abstract

A semi-submersible, barge carrying coaster has a flat-bottomed hull, a main deck accessible from the sides and, in one embodiment, from the stern, selectively variable water ballast means whereby the draught of the vessel may be varied to allow barges 26 to be floated on or floated off the deck, retractable/extendible stanchions 28 for retaining the barges laterally of the coaster and pressure means 37 urged against the ends of the barges to restrain the barges longitudinally of the coaster. The stanchions 28 run in longitudinal gulleys 27 and have screwed- down gripping pieces pressing on the barges. <IMAGE>

Description

SPECIFICATION Improved vessel This invention relates to an improved vessel for carrying one or more barges and to a method of loading barges onto, or unloading barges from, such a vessel. The term 'barge' as used herein is intended to be construed broadly as meaning any floatable freight container or support, for example, a flatbottomed freight boat or a floatable cargo hold.

Ships which carry flat-bottomed freight barges are well known, particularly in the United States. The ships are used to transport a plurality of such laden barges to the entrance of an inland waterway where the ship can travel no farther and then the barges are unloaded so that the cargo moves to its final destination by barge. The barges are known as lash barges or shipborne barges and there are several accepted standards. As an example of accepted barge standards there is a published British Standard and International Standard for the barges, namely British Standard Marine Series ISO 41751979. The Standard lays down the barge dimensions and dimensions of the principal construction elements of the barges.There is also now a draft standard for a half lash barge which is the same length as a lash barge but half the width making it more suitable for British waterways which tend to be narrower than U.S. and continental waterways.

At present the lash barges are unloaded or handled aboard the mother vessel by special ship crane, by elevator or by a system based on the floating dock principle. For example Page 39 of the magazine "Seatrade" of January 1981 shows a vessel with a lifting gantry; page 46 of the magazine "Fairplay" of 16 April 1981 shows a semisubmersible barge carrier which has a float-on-floatoff capacity for a first layer of barges from the stern and then a lift-on-lift-off capacity for a second layer of barges.

Semi-submersible vessels are also known general ly for example, May 1982 issue of "Ocean Industry" shows a semi-submersible vessel used for carrying two drilling rigs where the rigs were floated into position over the deck, the ship deballasted to lift the rigs dry and then the rigs welded to the deck.

According to the present invention a vessel for carrying one or more barges (as hereinbefore defined) comprises a barge deck open to both sides of the vessel for receiving the or each barge, selectively variable water ballast means whereby the draught of the vessel may be varied between greater and lesser draught levels to allow a barge to be loaded or unloaded by floating the barge on, or off, the barge deck, and means for retaining the or each barge on the deck of the vessel during transport.

Preferably there are twelve water ballast tanks, the water content of which may be varied to alter the draught of the vessel. In one embodiment the barge deck is dimensioned to receive four lighter aboard Coaster flat-bottomed freight barges (LAC); in another embodiment eight barges may be carried.

Alternatively the vessel may receive a single float able cargo hold or, in the second embodiment, a larger barge with four smaller barges.

In the preferred, second embodiment access to the deck is also available over one end of the vessel, suitably the stern.

The means for retaining the or each barge during transport may be retractable stanchions retained in gulleys formed within the deck.

The invention also includes a method of loading or unloading a barge carrying vessel including a barge deck having open sides, water ballast means, and barge retaining means the method comprising; selectively controlling the water ballast means whereby the draught of the vessel is varied between a lesser, normal draught level for transport and a greater, submerged draught level in which a barge, as hereinbefore defined, may be floated onto, or off, the barge deck from the side of the vessel, and, respectively, retaining or releasing the barge by means of releasable retaining means.

The water ballast means preferably includes twelve water ballast tanks the water content of which may be controlled by one or more pumps.

The invention will now be described by way of example with reference to accompanying drawings in which: Figure 1 is a side elevation of a first embodiment of vessel in accordance with the present invention; Figure 2 is a perspective view showing loading of a vessel in accordance with Figure 1; Figure 3 is a side elevation of a second embodiment of vessel in accordance with the present invention; Figure 4 is a top plan view of a laden main deck of the vessel of Figure 3 with the superstructure sections broken away; Figure 5 is a diagrammatic sectional plan view below the main deck; Figure 6 is a cross-sectional view on 6-6 in Figure 4; Figure 7shows the method of securing a LAC barge partly broken away; Figure 8 shows the method of securing a LAC barge and a larger NED Barge; and Figure 9 is an enlarged side elevational view of the means for securing the barges longitudinally of the vessel.

In Figures 1 and 2 of the drawings there is shown a vessel 1 for carrying a plurality of flat-bottomed freight barges 2 (Figure 2), or alternatively a single floatable cargo hold 3 (Figure 1). The vessel has a control bridge 4 and storage and accommodation space at the stern, and a barge deck 5 between the stern and the bow of the vessel. Disposed below the control bridge 4 and the storage and accommodation space is the engine room for the engine and propellor power assembly generally denoted 6.

The barges 2 are locked into position by end locking means and removable side posts as will be explained in detail in connection with the second embodiment. The barge deck is arranged to receive four LAC barges 2 and disposed below the barge deck 5 are a plurality of water ballast tanks dotted as 7, the water content of which may be controlled by means of one or more pumps provided (not shown).

In use the vessel 1 carries the laden LAC barges 2 or floatable cargo holds as far as the depth of water and width of waterway will allow; the normal draught required by the vessel being indicated by the line 8. Once the vessel 1 can travel no further the water ballast tanks 7 are filled with water until the draught of the vessel reaches a submerged draught level indicated by line 9. Once in this position the barges 2 or cargo hold 2 is released and floated off from the side. Loading of the barges 2 aboard the vessel 1 works in reverse as illustrated in Figure 2.

Thus, the vessel 1 is maintained in the submerged position, the barges 2 are floated onto the barge deck 5 by means of a tug 10, the barges are then locked into position, and the water ballast tanks 7 are evacuated to bring the draught level back to line 8.

This arrangement provides a very much simpler vessel than previously available since no crane unit is required. Moreover, the vessel is capable of three different functions: (i) it may carry a number of LAO barges as particularly described, or (ii) it may act as a normal coaster with a single floatable cargo hold, or (iii) it may act as an offshore carrier for large objects due to its large, long and strengthened barge deck.

In the second embodiment there is shown a vessel 20 having a main deck 21, a control bridge and accommodation unit 22 at the bow and laterally spaced funnel sections 23 at the stern. Disposed in the stern is an engine room 24 and below deck the vessel 20 is provided with a plurality, suitably twelve as illustrated, water ballast tanks 25 the water content of which may be controlled by means of one or more pumps provided in the engine room 24.

The vessel 20 has access to the main deck 21 from either side or from the stern and is adapted to receive eight LAC barges 26 as shown or four LAC barges 26 and a NED barge 36 (being a barge equivalent in capacity to four LAC barges 26).

In order to secure the barges in position the main deck 21 is provided with longitudinally extending gulleys 27 which are disposed at each side of, and between, the desired location positions for the barges 26 and house a plurality of retaining stanchions 28 (Figures 7 and 8). The stanchions 28 are pivotally mounted within their respective gulleys 27 as at 29 and may be raised to an upright position by winch means 30 on the funnel sections 23: a stop (not shown) being provided to hold the stanchions at the upright position. Each stanchion 28 carries a securing clamp 31 at its upper end which, by manipulation of handle 32 may be screwed down into locking engagement over a flange 33 on the barge. If a NED barge 36 is to be secured, as show in Figure 8 then spacer pieces 34 may be provided with a larger securing clamp 35.

In order to secure the LAC barges 26 or NED barge 36 longitudinally of the vessel 20 vertically extending pressure members 37 may be provided at each side and at each end (Figure 9). The pressure members 37 are movably supported upon pivot arms 38 and, are urged against the barge ends by hydraulic cylinder means 39 moving downwardly and outwardly relative the superstructure 22 (as shown by the dotted lines) where it is retained laterally by a U-shaped guide 46. Once the barges 26,36 are in position, the barges 26 on the stern section of the vessl 20 may be retained by lines or additional retractable stanchions 28.

At the stern the two rear barges are retained laterally by pressure members 37 on the funnel sections 23 as shown in Figures 3 and 4. A two-wire bridle is then secured around the back of the two rear barges to hold the barges in position. Alternatively, telescopic retractable stanchions may be provided at the rear to prevent displacement. The ends of the barges abut one another or, if desired, wooden or elastomeric rubbing pieces are disposed between.

The main deck 21 is strengthened to take the weight of the barges to be carried and the vessel 20, as a whole, is designed in such a way that she can go aground fully laden without suffering structural damage: thus the vessel 20 is flat-bottomed (see Figure 6) with the drive propellors 42 disposed above bottom level (Figure 3).

In use the barges 26 are floated-on or floated-off from the stern and or the sides of the vessel 20 by altering the draught as appropriate between the upper and lower draught levels, indicated by lines 40 and 41 respectively in Figure 3: the stanchions 28 and pressure members 37 being readily extended or retracted as desired.

The present invention therefore provides a semisubmersible vessel capable of being submerged below its normal draught level so that, in use, one or more barges, as hereinbefore defined, may be floated onto, or off, a deck of the vessel: the barges being floated from the side of the vessel and/or floated from the stern end. Thus the vessel of the present invention is unique in that an alteration takes place on her loadline conditions.

The preferred vessel is a coaster of about 2,200 tons deadweight, which by means of 12 large ballast tanks can submerge herself sufficiently for eight LAC barges to be taken on board. The whole operation of submerging, taking the barges on board, securing and deballasting only takes a few hours.

As explained above the vessel 20 can carry one larger NED barge 36 instead of four small barges 26, i.e. a combination of one large plus four small ones instead of eight. As the barges have no bow or bridge and greatly reduced length and draught and in particular almost no height as opposed to the vessel, the barges can be floated-off so that very small ports and creeks can be penetrated for commercial traffic.

Notwithstanding the vessel's 20 barge carrying capacity the vessel, without carrying any barges, may carry large and heavy structures for the oil related industries. Moreover, the ballast tanks, if desired, could be used for the carriage of non-toxic/ non hazardous liquids.

The loading and off-loading of the barges 26,36 by floating on or off on either side of the ship and also over the stern is particularly convenient when encountering a strong tide. Moreover the stern loading may be alternatively used for shore loading if the vessel 20 is to carry cargo other than barges.

Preferably the vessel 20 has two main engines which gives the extra safety that if one engine fails, the speed of the vessel will only be affected by about ten per cent.

Claims (8)

1. A vessel for carrying one more barges (as hereinbefore defined) comprising a barge deck open to both sides of the vessel for receiving the or each barge, selectively variable water ballast means whereby the draught of the vessel may be varied between greater and lesser draught levels to allow a barge to be loaded or unloaded by floating the barge on, or off, the barge deck, and means for retaining the or each barge on the deck of the vessel during transport.

2. A vessel according to claim 1 wherein the deck is also open to one end.

3. A vessel according to claim 2 wherein the deck is accessible over the stern.

4. A vessel according to any one of the preceding claims wherein the means for retaining the or each barge during transport comprises a plurality of retractable stranchions retained within gulleys formed within the deck, and a plurality of pressure members movable against the or each side barge by pressure cylinder means.

5. A vessel according to any one of the preceding claims wherein the water ballast means comprises twelve water ballast tanks distributed throughout the length of the vessel.

6. A semi-sumbersible, barge-carrying coaster comprisng a flat-bottomed hull, a main deck accessible from the sides and from the stern, selectively variable water ballast means whereby the draught of the vessel may be varied between greater and lesser draught levels to allow a barge to be loaded or unloaded by floating the barge on, or off, the barge deck, and retractable/extendible retaining means for retaining the or each barge on the deck of the vessel during transport.

7. A coaster according to claim 6 wherein the retaining means comprises a plurality of stanchions retained within recesses within the deck during loading and extendible to lock a barge in position laterally, and a plurality of pressure members movable against the end of a barge to restrain the barge longitudinally.

8. A method of loading or unloading a barge carrying vessel including a barge deck having open sides, water ballast means, and barge retaining means, the method comprising: selectivelycontroll- ing the water ballast means whereby the draught of the vessel is varied between a lesser, normal draught level for transport, and a greater, submerged draught level in which a barge, as hereinbefore defined, may be floated onto, or off, the barge deck from the side of the vessel, and, respectively, retaining or releasing the barge by means of releasable retaining means.