EP0091949A1 - Multi-tiered single-hulled barge-transport vessel for flotation loading, flotation stowage, and flotation unloading of very large riverine barges - Google Patents

Abstract

A boat (20) with a single hull (21) of shallow draft is intended for the floating loading and transport of large river barges. The boat (20), in one embodiment, has forward loading doors (45, 46), with a pair of sluice locks (55, 56) located after the doors (45, 46). for raising the barges to any one of a plurality of rows of barge holds (31-35) to provide floating storage in the holds. Most rows may consist of four slips (A-D), with side transfer passages (85) for moving barges between the inner and outer slips (A-D). In another embodiment, the boat (150) includes bow and stern loading doors (45, 46, 202, 203) and airlock locks (55, 56, 200, 201), the airlock locks at the front (55, 56) preferably serving a pair of inner holds B, C and the stern locks (200, 201) serving a pair of outer holds A, D, without the need for a lateral transfer between the inner and outer holds (A-D). The trim and trim of the boat (20, 150) are automatically controlled and maintained during floating loading and storage.

Description

MULTI-TIERED SINGLE-HULLED BARGE-TRANSPORT VESSEL FOR FLOTATION LOADING,FLOTATION STOWAGE, AND FLOTATION UNLOADING OF VERY LARGE RIVERINE BARGES Background of the Invention This invention relates to a multi-tier, barge carrying single-hull waterborne vessel. It is an improve ment over the vessel described, and claimed in our co pending patent application Serial No. 105,414, filed December 19, 1979. For many centuries materials have been transported by barges on rivers, lakes, canals, and inland waterway systems to ports near the river mouth, unloaded there from the barges, loaded on ocean-going vessels, sent to other ports across the sea, unloaded there, reloaded in many instances on barges, and shipped up another river system. As costs of loading and unloading cargo have risen higher and higher, containerization of cargoes has been introduced, but there has remained the necessity of unloading the barges at one port, placing the container and other cargo on a pier, and then loading from the pier into an ocean-going vessel, only to require the reverse procedure in the ports to which the cargo is carried by that vessel. All this adds considerably to the ultimate cost of the product concerned. The problem can be solved if the loaded barges themselves can be economically, safely, and efficiently transported across the ocean. Since they cannot undergo an ocean voyage directly in the water, the barges must be loaded aboard an ocean-going vessel. However, few vessels are capable of carrying a series of barges aboard, and the problem of loading barges on the vessels must be confronted. The barges are often very large, and cranes or elevators to lift them would be very expensive. In fact, large river barges are not designed to be lifted by cranes and their structure cannot withstand such treatment. Recent inventions such as disclosed in our U.S. Patent No. 3,913,512, issued October 21, 1975, have proposed flotation loading of barges and other cargo carrying containers aboard an ocean-going vessel. For a barge-carrying system to be practical, the ocean-going, barge-transporting vessel must be able to carry many barges. Our U.S. Patents Nos. 3,978,806, issued September 7, 1976 and 4,135,468, issued January 23, 1979 relate to a vessel having a plurality of longitudinal holds, side by side, either two or three parallel holds, each of which can take the full width of a barge and each of which can accommodate several barges in line or tandem. The problem of loading and unloading the vessel with barges was alleviated by mechanisms shown, for example, in our U.S. Patent No. 4,147,123, which issued April 3, 1979. More recently, our co-pending application, Serial No. 105,414, filed December 19, 1979, describes and claims a barge-transporting vessel for accommodating more than one tier of barges in a flotation loading and unloading system. The present invention is an improvement over that invention. Like that one, the present invention relates to the problem of how to provide for flotation loading and unloading of large riverine barges into and out from a series of different levels within the same ship and how to do so in a simple and economical manner. A problem that arises as soon as one attempts to load two or more tiers of barges into one vessel, is the problem of vessel draft. While there are ports which can accommodate drafts up to 75 or 80 feet, there are many ports with depths of less than 40 feet. A system restricted to voyages between deep-draft ports would not be economically practical. it is, therefore, an Object of the present invention to provide an efficient and simple system for loading barges into several tiers of holds in an ocean-going vessel even when the vessel is in a port restricting it to a relatively shallow draft. As will be seen, this object is attained by providing the barge-transporting vessel with an internal lock system somewhat analogous to canal locks. With such a vessel, it is also important to be able to minimize the total amount of water to be pumped in and out of the locks and holds and to keep the vessel properly stable and trimmed at all times. Hence, another object of the invention is to solve these problems as well, in a ship able to accept several tiers of barges by flotation loading and unloading. Other objects and advantages of the invention, and solutions to additional problems, will be seen in the following description.

Summary of the Invention The invention comprises a barge-carrying water- borne vessel having a hull with rigid supporting and hull reinforcing structure, a bow, a stern, and sidewalls pro viding a series of buoyancy compartments, including some special buoyancy compartments. The hull's hollow interior defines a series of tiers of barge holds, each extending most of the length of the vessel. There may be several such holds at each level. Flooding means enable placing water into each hold. A pair of bow gates are provided, one opening to each side to provide a frontal opening for flotation loading and unloading of barges. Aft of the bow gates are two special watertight gates or forward lock gates, one on each side, that also serve as part of the ship's collision bulkhead. Each of these can be swung upwardly to provide openings for flotation loading and unloading of the large barges. Aft of these gates and between them and the actual holds are twin deep loading passages or locks. At the aft end of each lock are watertight gates for each tier of holds. The hull interior is divided longitudinally by a centerline longitudinal bulkhead extending between respective tiers of holds and between the two locks, between the two special gates, and between the two bow gates. Each tier of holds except the bottom- most preferably has a plurality of holds on each side of the longitudinal bulkhead. Each hold preferably has barge-retention devices for holding each barge down against the bottom of the hold to prevent movement of the barges during the ocean voyage. In the lower holds these devices are made much stronger, so as to enable exchange of buoyancy between the vessel and each barge in the lower holds in the event of damage to the vessel's hull which results in flooding of the lower holds. This is an important factor for ship safety. Preferably, the vessel is provided with bargemoving means in its hollow interior. This may comprise a plurality of flow-creating means like those of our U.S. Patent No. 4,147,123, for causing flow of water to move barges in each hold in one direction during flotation loading and in the opposite direction during flotation unloading. Alternatively, a cable and winch system like that of U.S. Patents Nos. 3,913,512 and 3,978,806 may be used. There may be three, four or five tiers of barge holds. There may be a plurality of holds (preferably four) on each tier except the bottommost tier; preferably these are separated from each other on each level by longitudinal bulkheads, and in one form of the invention there are bulkhead openings between the inboard and outboard hold on each side of center for lateral transfer of barges. In another form of the invention, the outboard holds are loaded separately by means of gates and locks at the stern end of the vessel; in this form of the invention there is preferably no lateral movement of barges within the vessel. Hold flooding and draining means supply water to and remove it from each hold, as needed, when the respective aft lock gates are closed, for enabling flotation stowage of barges into desired positions in each hold. Similarly, lock supply and depletion means supply water to and remove it from each lock, separately, when all the lock gates are closed. In addition, when the loading is done exclusively through the bow gates, there may also be special buoyancy heel and trim tanks at the stern end of the vessel for heel and trim compensating for lock water weight, with pumping means for pumping seawater directly into and out from them. A water-circulation system is provided for filling or discharging water from the special buoyancy heel-and-trim tanks, in order to balance weight during operation of the internal lock system. The heel and trim tanks are not used when there is loading through stern locks as well as bow locks, for then balance can be achieved by the loading per se. In a preferred embodiment of the invention, each forward lock gate includes a stationary frame defining the gate opening, rectangular and smaller than the forward lock gate. This frame has a front face with gaskets thereon at the top, bottom, and each side, for leak-tight engagement with the forward lock gate. The frame also has a series of discrete wedges forward of the frame face and surrounding the gate opening; within the boundaries of these wedges lie the forward lock gate. The forward lock gate is rectangular and has an aft face which upon closure engages the gaskets on the face of the gate frame, and it also has a series of wedge-engaging members thereon for mating with and closing snugly against all of the wedges of the gate frame. In addition, the gate has retracting means for retracting these wedge-engaging members into marginal portions of the gate, so that the gate can be swung open. Preferably, hydraulically actuated dogging means on the forward lock gate enable the gate's wedge-engaging members to be forced against the wedges of the frame when the forward lock gate is closed, thereby forcing the aft face of the gate against the gaskets in a watertight sealable closure. This closure can withstand large hydraulic pressures exerted against either side of the forward lock gate. This dogging means and the wedge-engaging members include a gang bar actuator for each of the four edges of the gate, a series of dogs actuated by each gang bar, and a series of wedge bars, one for each dog. Preferably, the bow has a deck level or flat leading from each bow gate to the forward lock gate. This flat is generally on the same level as the bottom edge of the gate opening, and it has a well adjacent to the gate frame enabling the forward lock gate to extend below that bottom edge and also to accommodate the wedges at the bottom. The well can be eliminated if the flat is at a level slightly lower than the bottom of the gate opening. The flat is preferably at about the level of the tier directly above the bottommost tier, an appropriate level for flotation loading. The bottommost tier and the bottom of the locks lie below the level of the bow flat. In a preferred embodiment, a barge hold extends outboard of and parallel to each lock for substantially the full length thereof, and at each tier except the bottommost, being separated from the locks by watertight bulkheads. When there are stern gates there are two such gates, and they are preferably employed to load the two outboard holds of each tier, with the aid of locks, one for each side of the vessel. These gates may be of the type shown in our co-pending patent application Serial No. 105,414, filed December 19, 1979. The vessel of the invention also may include a series of depth gauges at port and starboard of the ship, and connected equipment for constant monitoring of trim, heel, and draft and shifting of ballast water to make corrections as needed. Pumps serving this system can be in constant operation during flotation loading and unloading, with automatic controlled valves opening and closing to direct the flow of water as required for trim, heel, and draft control, as well as hog and sag control during loading. A computer may be employed for monitoring theseconditions and responding by sending the appropriate signals. In this way the ship's attitude can be controlled to within very close tolerances. The same computer system may also be used for data recording, automatically taking a number or identifica tion code from the side of each barge, preferably by optical sensing means. There may also be included on the vessel a closed-circuit television system with cameras located in the loading passages, the locks, the holds, etc. to monitor the locks, the hold flooding, and the position of the gates and the gate latches, etc. All this may be monitored by a person in a central location, giving him a visual check on the physical movement of the barges, the barge identities and the conditions under which the barges are being loaded, locked, and stowed.

Brief Description of the Drawings In the drawings:

Fig. 1 is a schematic view in side elevation and partly in section of a vessel embodying the principles of the invention, showing a load of barges carried in five tiers of holds.

Fig. 2 is a top plan view of the uppermost (main) deck or tier of barge holds of the vessel of Fig. 1, as viewed along the line 2-2 of Fig. 1.

Fig. 3 is a view in horizontal section taken along the line 3-3 in Fig. 1, showing the second deck or tier of barge holds immediately below the top tier (main deck) of Fig. 2.

Fig. 4 is a similar view taken along the line 4-4 in Fig. 1 showing the third tier down (third deck), which is substantially identical to the fourth deck or tier. Fig. 5 is a similar view taken along the line 5-5 in Fig. 1 showing the bottommost tier, which is the fifth or tank top deck.

Fig. 6 is an enlarged fragmentary view in section of the vessel, as viewed along the line 6-6 in Fig. 4, showing barges in holds of the third or fourth tier or deck. Structural members above and below those holds are omitted from this view. Some barges are bulk loaded while others are container-loaded.

Fig. 7 is an enlarged fragmentary view in section of the vessel, taken along the line 7-7 in Fig. 3.

Fig. 8 is an enlarged fragmentary view in section of the vessel taken along the line 8-8 in Fig. 3.

Fig. 9 is an enlarged fragmentary view in side elevation and partly in section of one of the forward lock gates in its closed position.

Fig. 10 is an enlarged view in front elevation of the gate of Fig. 9, taken along the line 10-10 in Fig. 9.

Fig. 11 is a diagrammatic perspective view of the vessel of Fig. 1 showing the two locks located forward and the aft heel-and-trim tanks which are used in cooperation with each other.

Fig. 12 is a diagram of the barge lock pump and piping system.

Fig. 13 is a piping diagram for the heel and trim system.

Fig. 14 is a diagrammatic view in elevation of the vessel showing one flooding stage thereof. Fig. 15 is a view in section taken along the line 15-15 in Fig. 14.

Fig. 16 is a view in section taken along the line 16-16 in Fig. 14.

Fig. 17 is a schematic view in side elevation and partly in section of a modified form of vessel also embodying the principles of the invention, showing one barge in one of the forward locks.

Fig. 18 is a plan view of the uppermost deck or tier of barge holds of the vessel of Fig. 17.

Fig. 19 is a view in horizontal section taken along the line 19-19 in Fig. 17, showing the second deck or tier of barge holds of the ship of Fig. 17, which is substantially identical to the third deck or tier.

Fig. 20 is a view in horizontal section taken along the line 20-20 in Fig. 17, showing the fourth and lowest deck or tier of barge holds of the ship of Fig. 17.

Fig. 21 is a view in horizontal section taken along the line 21-21 in Fig. 17, showing the inner bottom level of the vessel, below the fourth deck.

Fig. 22 is an enlarged transverse view in section taken along the line 22-22 in Fig. 17 or Fig. 20.

Fig. 23 is a perspective view of this second form of vessel which is capable of loading barges through both bow and stem ends.

Fig. 24 is a partial perspective view showing the stern end of the vessel. Description of Some Preferred Embodiments The vessel shown generally in Figs. 1-6: Figs. 1-6 show a vessel 20 having a single hull or mono-hull 21 with sidewalls 22 and 23 comprising a series of port and starboard buoyancy tanks 24 and 25. There also is a series of bottom buoyancy tanks 26 and 27. The vessel 20 has a series of tiers of barge holds. For example, there may be five such tiers 31, 32, 33, 34, and 35. On each tier except the lowest tier 35 there are four holds A, B, C, and D with the two inboard holds B and C separated from each other by a watertight, longitudinal centerline bulkhead 40 which longitudinally bisects substantially the entire vessel. The lowest tier 35 has only two barge holds B and C, separated by the watertight, longitudinal centerline bulkhead 40. The upper deck or tier 31 need not be covered on top, as shown in Figs. 1 and 2. The vessel 20 is provided with two engine compartments 41 and 42, (Figs. 4 and 5), the engines driving two propellers 43, one on each side (see Fig. 1).

The bow gates 45 and 46, the collision bulkhead 50, and the locks 55 and 56. (Figs. 1 and 3-5) Two bow gates 45 and 46 are provided at and as part of the bow. Each gate 45, 46 lies on each side of the longitudinal centerline bulkhead 40 and opens outboard to their respective sides, providing passages 47 and 48 each having a bottom or flat 49. Aft of these bow gates 45 and 46 is a collision bulkhead 50. On opposite sides of the bulkhead 40 the collision bulkhead 50 is provided with a forward gate por tion 51, 52 that is hinged at its upper end 53. Each of thes forward gates 51 and 52 leads into a separate loading passage or lock 55 or 56 at the water level between the tier 33 and the next-to-lowest tier 34 of barge holds, and the flat 49 extends into these locks. The aft end of each lock 55 and 56 has a gate at each tier level. Hence, there are gates 57 and 58 at the level of the tier 31, gates 59 and 60 at the level of the tier 32, gates 61 and 62 at the level of the tier 33, gates 63 and 64 at the level of the tier 34, and gates 65 and and 66 at the level of the tier 35. Each loading passage or lock 55, 56 has a bottom deck 67 and vertical sidewalls 68 and 69, one of which, in each lock, is formed by the longitudinal bulkhead 40. Each loading passage 55, 56 is somewhat longer than the longest barge to be loaded, but not a great deal. Each will also act as a stowage compartment for four barges, in the manner described in our co-pending patent application Serial No. 214,412, filed December 8, 1980.

The fore lock gates 51 and 52 A problem which does not confront canal lock gates but applies to this vessel 20 is that of making all the lock gates watertight no matter from which side hydrostatic pres sure is exerted. This problem may be solved in the manner shown in Figs. 9 and 10. Each forward lock gate 51, 52 is provided with a gate frame 70 immediately adjacent the lock 55 or 56. The frame 70 defines an opening 71 that is slightly smaller than the gate 51 or 52, and the upper edge 72 of its lower margin 73 preferably is on a level with the flat or bottom 49. A well 74 in the flat 49 adjacent the gate frame 70 enables the gate 51 or 52 to swing up. Gaskets 75 surround the opening 71 on all four sides of the outer surface 76 of the frame 70, and hydrostatic pressure from the sea causes the closed gate 51 and 52 to seal against these gaskets 75 when sea water in the entrance passage 47 or 48 is higher than the level of water in the lock 55 or 56. The well 74 and also the remaining three sides around the periphery of the opening 71, are provided with a series of outer bearing wedges 77. Matching bearing wedges 78 on the gate 51 or 52 are used to dog the gate 51 or 52 against the gaskets 75. On each side of the gate 51 or 52 (Fig. 10), the bearing members 78 rotate about a pin 79 and are ganged to a rod 80 for hydraulic actuation by a cylinder 81. Thus, the dog wedges 78 can all be retracted for opening the gate 51 or 52 and can be brought to bear against the wedges 77 so as to force the closed gate 51 or 52 against the gaskets 75 to provide a watertight seal. The tiers 31-35 of barge stowage holds Each tier (31, 32, 33, 34) except the bottommost tier 35 has, as noted above, at least two outboard longitudinal holds A and D. These lie parallel to the inboard holds B and C, and each outboard hold A, D communicates with its adjacent inboard hold B, C, e.g., via a passage 85 having an arch 86 (Fig. 1). On each side of the vessel an outboard hold A, D extends beside and parallel to the adjacent lock 55, 56 for substantially the full length thereof, being separated from the lock 55 or 56 by a water- tight bulkhead 87. As noted, the bow floor 49 leading from the bow gates 45, 46 to the fore lock gates 51, 52 lies at generally the same level as the tier 34 directly above the bottommost tier 35 (see Figs. 1 and 9). The bottommost tier 35 and the bottoms 67 of the locks 55, 56 lie below the level of the bow floor 49.

Heel and Trim tanks 91 and 92 (see especially Figs. 11-16) In additions to the buoyancy tanks 24, 25, 26, 27, the vessel 20 of this embodiment has heel and trim tanks 91 and 92 at the stern. These cooperate with the locks 55 and 56 to keep the vessel 20 substantially on an even keel or no-trim condition during the flotation loading, stowage, and unloading of barges. Water transfer means for the heel and trim tanks 91 and 92 (shown in Fig. 13 and described below) transfer water from the tank 91 on one side of the stern to the other tank 92, and vice versa, according to the state of flooding of the locks 55 and 56, which are near the bow. Since the locks 55 and 56 are closer to the gravity center of the ship, both longitudinally and transversely, the tanks 91 and 92 are smaller than the locks 55 and 56, still enabling substantially full heel and trim control. Water transfer means (see Fig. 12) assist in transferring water from one lock 55, 56 to the other via a series of sluice gates 93, so that the locks 55, 56 can be (and are) operated out of phase with each other. Thus, one lock 55 can be flooded to the level for floating a barge in or out of the ship while the other lock 56 is flooded at a different level for transfer of a barge into or out from a hold, as will be described below.

The barge lock water flooding system (Fig. 12) Fig. 12 is a diagram showing an exemplary piping diagram for the locks 55 and 56. Each barge lock 55, 56 has a corresponding pump room 94, 95, each pump room having two pumps 96, 97, and each pump being driven, for example, by a 1000 BHP diesel engine 98. A suction header 100 is connected to all the pumps 96 and 97 and, at each end, to a sea chest 101 and 102. A discharge header 103 is also connected to all the pumps. Each lock 55, 56 has lock suction sumps 104 connected to the suction header 100 and flooding sumps 105 connected to the discharge header 103 and overboard discharge valves 103A. Each lock 55, 56 also has an equalizing sluice valve 106 at its forward gate 51, 52. The system thus enables rapid transfer of water from the sea chests 101 and 102 into either lock 55, 56, rapid gravity transfer of water from a lock 55 to the other lock 56 and vice versa via the sluice gates 93, rapid water level equalization through the sluice valves 106 when the locks have substantially reached the level of a flooded hold, and rapid draining of either lock 55, 56 through suction sumps. The lock pumps 96 and 97 may be of the impeller type to pump 14,000 cubic meters of water per hour to a maximum head of 25 meters in the lock 55 or 56. The suction and discharge headers 100 and 103 may be three meters by two meters in cross section. The sluice gates 93, of which there are typically four, may each have an area of four square meters; they may be of the guillotine type and of course they extend through the longitudinal centerline bulkhead 40. The heel and trim tanks flooding system (Fig. 13) As Fig. 13 shows, each heel and trim tank 91, 92 has its own dump valve 108, 109. A header 110 is connected through a valve 111 to the tank 91 and through a valve 112 to the tank 92. Pumps 113 and 114 are connected through respective valves 115 and 116 to the header 110 and through respective valves 117 and 118 to a sea chest 120 having double check valves 121 and 123, the latter of which is a check/stop valve as will be seen below. The systems of Figs. 12 and 13 are operated in synchronism with each other and in port/starboard opposition to one another, as will soon be seen. Each tank 91 or 92 may have a capacity of, for example, 9920 metric tons, while each lock 55 or 56 may have a capacity of 25,700 metric tons. Since the tanks 91 and 92 are at the stern and have a longer lever arm from the longitudinal center of the vessel 20, they can exert the same longitudinal moment -as the larger locks.

Operation of the heel and trim tanks 91 and 92 in cooperation with the locks 55 and 56 Figs. 14-16 illustrate one state of the system, showing how the loading of the tanks 91 and 92, diagonally opposite the loading of locks 55, 56, is used to balance the heel and trim moments caused by lock filling and thereby to stabilize the vessel 20. These views show the loading of the second deck 32, with lock filling and water levels appropriate for loading that deck, but the general principles apply to the loading of all of the decks. The following summary illustrates this operation, beginning with loading of the top deck 31, even though Figs. 14-16 show water levels for loading the second deck 32 only. Values are given to illustrate the operation, but not to limit the invention to these actual values. Assuming the ship 20 to be substantially as described above, it has, when empty of barges a displacement of 75,000 metric tons and a draft of four meters. The passages 47 and 48, together with the locks 55 and 56, are flooded to levels equal to the vessel's exterior draft. Then the bow gates 45 and 46 and the lock gates 51 and 52 are opened; and with the locks 55 and 56 flooded, a barge may be floated into the lock 55. Then the forward lock gate 51 is closed, and the level in the lock 55 is raised, thus hydraulically lifting up its barge to the uppermost tier 31 (main deck --see also Figs. 1 and 2), which has also been flooded. The lock 56 is still flooded only at about the level of the tier 34. There will then be 20,700 metric tons of water in the lock 55 and 6,700 metric tons in the lock 56. To balance this, both for heel and trim, the heel and trim tank 92 will be fully loaded with 8000 metric tons of water, while the heel and trim tank 91 is empty. The flooded decks at the tier 31 hold 33,560 metric tons of water. While the first barge is being loaded through the main deck gate 57 into the tier 31, a second barge is being loaded through the gate 52 into the lock 56. The gates 57 and 52 are closed, and water is transferred from the lock 55 into the lock 56 to raise the second barge to the tier level 31 while the water in the lock 55 is lowered to the tier level 34. Simultaneously and continuously, water is transferred from the heel and trim tank 92 into the tank 91 to maintain heel and trim at zero values. The gates 58 and 51 are opened substantially simultaneously so that the second barge can be floated into the tier 31 while a third barge is being loaded into the lock 55. This alternation continues until the uppermost tier 31 is loaded and also one barge is stowed on the normally retracted support members 130 and 131 (Fig. 2) at the uppermost level of each lock 55, 56. Then the tier 32 (see Figs. 14 to 16, illustrating water levels for loading the tier 32) is loaded with similar alternation, and a barge is stowed on the members 130, 131 at that level in each lock 55, 56. Next the tier 33 is similarly loaded and a barge stowed in each lock. Then the tier 34 is loaded by direct flotation thereinto. Next the lowermost (fifth deck) tier 35 is loaded, and finally a barge is stowed preferably on the support members 130 and 131 at the level 34. The alternation system is used for each tier except for the tier 35, and the heel and trim tanks 91 and 92 are used as required to give the needed balance of moments. Trim and heel is very critical during flotation stowage. If the very long vessel, with its long holds nearly the length of the vessel, should vary from horizontality by even a slight angle in the longitudinal direction, the depth of the water near the ends of a hold could change by several feet. This would be excessive, since efficient design requires that the holds be of as little height as practical for the barges being handled and they should be flooded to the least depth practical. Proper clearances cannot be maintained if the water depth shifts significantly during flotation stowage. In general, the larger the vessel, the more critical trim and heel will be. To closely maintain proper trim and heel, as well as vessel draft, there is provided a system for constantly monitoring these conditions during loading, locking and flotation stowage of barges. Depth gauges G are positioned on the vessel's hull at strategic locations, such as illustrated in Fig. 11, for providing signals corresponding to the ship's depth at each location. As indicated, the gauges G, which may be pressure gauges, preferably number at least three on each of the port and starboard sides of the vessel. There may also be depth gauges G in the locks 55 and 56, in the trim and heel tanks 91 and 92, and at each end of each of the holds (see Fig. 15), for monitoring the volume of water therein. A computer 122 (Figs. 11 and 13) is connected to all the depth gauges G, constantly monitoring the depth at each location and producing precise data as to the trim, heel, and draft of the vessel. As indicated in Fig. 13, the computer 122 preferably is also connected to the system for flooding and draining the trim and heel tanks to operate the pumps 113, 114 and the various valves for controlling the ballasting in the tanks 91 and 92. Thus, the computer 122 is connected to the dump valves 108 and 109 to control deballasting of water from either tank 91 or 92; to the valves 111 and 112 to control pumping of water into the tank 91 or 92; and to the check/ stop valve 123 for controlling the pumping in of sea water through the sea chest 120. The pumps 113 and 114 preferably are run continually during loading and stowage, and if so, the computer 122 is also connected to a valve 124 in a conduit 125 which enables the pumps to recirculate sea water when the valve 124 is open and the valves 111, 112, and 123 are closed. With this system, trim and heel of the vessel can be precisely controlled. For example, on a vessel of the size shown in the drawings, trim (longitudinal horizontality) can be controlled within tolerances of three inches, well below the approximate maximum of one foot that can be tolerated. Heel (transverse horizontality) can be controlled to within tolerances of one inch, well below the approximate maximum variance of three inches. The depth gauges G are of the time-interval averaging type, so that the relatively small waves and other surface disturbances which might be encountered in port do not adversely affect the ability closely to control trim and heel. As mentioned above, the computer 122 may also be used for recording data relative to each barge loaded into the vessel. Reading devices of a well-known type, preferably optical sensing devices (not shown) may be located in the loading passages 47 and 48 and in the holds for automatically reading a number or identification code from the side of each barge. There may also be included on the vessel a closed- circuit television system including a monitor 127 (Figs. 1 and 14), in a location such as the bridge. Cameras C, as partially indicated in Fig. 1, are positioned in the loading passages, and locks, and at least the forward portion of each hold to provide a visual check as to what barges are entering the ship and being locked and stowed, what the flood condition and water level is in the locks and in each hold, and the positions of the gates and of the gate latches. The cameras C are all connected to the television monitor 127. An operator or supervisor monitoring the television monitor 127 can also have the automatic barge-identification data at hand, and with this equipment can check on the physical movements of the barges, the barge identities, and the conditions under which the barges are being loaded, locked, and stowed.

The vessel of Figs. 17-24 Figs. 17 to 24 show a modified form of vessel 150 capable of more rapid loading and not requiring lateral transfer of barges. The key here is that the vessel 150 employs both forward and aft loading. The vessel 150 has a single hull or mono-hull 151 with sidewalls 152 and 153. The hull defines a series of port and starboard buoyancy tanks 154 and 155 and center (bottom) buoyancy tanks 156 (Fig. 21), port and starboard coal bunkers 157 and 158 (Figs. 19 and 20), and port and starboard bow and stern heel and trim tanks 161, 162, 163, and 164. The vessel 150 has a series of tiers of barge holds. For example, there may be four such tiers 171, 172, 173, and 174. On each tier there are four holds A, B, C, and D with the two inboard holds B and C separated from each other by a longitudinal centerline bulkhead 175 which longitudinally bisects substantially the entire vessel. The bulkhead 175 is hollow to provide useful space including accommodation for passages 176 and 177 leading from the machinery space 178 to carry the engine exhaust fluids up to the vessel's funnels 180 and 181. The machinery space 178 is preferably provided with two engines, each driving a propeller. As in the vessel 20, the vessel 150 is provided with two bow gates 45 and 46 at and as part of the bow. These may be identical to those previously described, as are the collision bulkhead 50, the forward lock gates 51, 52 and the forward locks 55, 56, so that the same reference numerals are used here. Again, one gate 45, 46 lies on each side of the bulkhead 175 and opens out to the side, providing two passages 47 and 48 each with its bottom or flat 49. Aft of these bow gates 45 and 46 is the collision bulkhead 50 with its forward gate portions 51 and 52 hinged at their upper ends 53. Each of these forward gates 51 and 52 leads into the separate loading passage or lock 55 or 56 at the water level of the lowest tier 174, and the flat 49 extends into these locks. The aft end of each lock 55 and 56 has a gate at each tier level. Hence, there are gates 191 and 192 at the level of the tier 171, gates 193 and 194 at the level of the tier 172, gates 195 and 196 at the level of the tier 173, and gates 197 and 198 at the level of the tier 174. Each loading passage or lock 55, 56 has its bottom deck 67 and vertical sidewalls 68 and 69, one of which, in each lock, is formed by the longitudinal bulkhead 175. Each loading passage 55, 56 is somewhat longer than the longest barge to be loaded, but not a great deal, and each also acts as a stowage compartment for three barges, in the manner described in our co-pending patent application Serial No. 214,412, filed December 8, 1980. Portions of the tanks deck 199 level of the vessel, shown in Fig. 21, are used for lock pump rooms. Thus, the spaces 184 and 185 indicated in Fig. 21 contain port and starboard, bow and stern lock pumping equipment, respectively.

The stern gates The locks 55 and 56 in the vessel 150 are used only for loading the two inboard holds B and C of each tier of holds 171, 172, 173 and 174. In the vessel 150 there is no lateral movement of barges, as there was in the vessel 20 described earlier. Instead, the outboard holds A and D of all tiers 171, 172, 173 and 174 are loaded by means of two stern locks 200 and 201 respectively in line with the outboard holds A and D. The stern locks 200 and 201 have respective stern gates 202 and 203 that are raised and lowered vertically with the aid of respective gate towers 204 and 205. To preserve good hull lines (see Figs. 18, 19 and 24), the gates 202 and 203 are somewhat forward of the actual end of the stern so that there are inlet passages 206 and 207 provided with bottoms 208 and 209. The locks 200 and 201 have forward gates at each tier. There are gates 211 and 212 for the tier 171, gates 213 and 214 for the tier 172, gates 215 and 216 for the tier 173, and gates 217 and 218 for the tier 174. The stern gates 202 and 203 may be like those shown in our copending application Serial No. 105,414, filed December 19, 1979. The forward gates 211 through 218 may be like those shown in our copending application Serial No. 105,414, filed December 19, 1979. Three tiers of barges may be stowed in the stern locks 200 and 201, as shown in our copending patent application Serial No. 214,212, filed December 8, 1980. Since the vessel 150 is usually loaded simul taneously at both bow and stern, loading (and also unloading) can be done more than twice as fast as in the vessel 20, for no time is taken up by lateral shifts of barges.

Balance and controls A large vessel of this kind requires special controls during loading and unloading. Once loaded, the vessel can cross the ocean in the usual manner, but while it is loading and unloading, the flow of water into and out from the holds and locks and loading passages can set up significant stresses. These stresses can seriously damage the ship -- possibly even split her in two. Moreover, the level trim of the vessel is very critical during flotation loading, locking, and stowage, as discussed above in connection with the vessel 20, because of relatively close tolerances in the height of the holds, and their extreme length. Therefore, there must be positive controls for draft, trim, and heel or list. The tolerances of these are very small -- a difference in draft and in trim of only about three to twelve inches can be tolerated, anything over that is dangerous; in other words the bow and stern can vary from each other in draft only by a maximum of about one foot for safety to be preserved. For heel or list, a variation of onl about one to three inches across the bow can be tolerated. All this calls for a precision control system, such as that illustrated in connection with the vessel 20, in Figs 1, 11 and.13. The system employs depth gauges G in each lock in each end of each hold, and in each ballast tank. See, for example, the gauges G indicated in Figs. 19 and 21 for the vessel 150. Each gauge G is connected to a central control station 220 (Fig. 17) where data from the gauges is prefer able fed to a compHiter. The pumps serving the system are operating all the time during loading and unloading of the vessel, with bypass provided in place of stopping the pumps, as described above for the vessel 20, with reference to Fig. 13. These pumps and their by-pass valves are preferably all controlled by the same computer, as outlined above. The computer, from this information, calculates the needed trim and heel and draft corrections and actuates the pump valves for accomplishing this within the critical tolerances. Closed circuit television is employed, as described above for the vessel 20, for visual check on the locks, loading passages, lock gates, hold flooding conditions, etc. This system is indicated schematically in Fig. 1 for the vessel 20, and the system for the vessel 150, not specifically shown in Figs. 17-24, would be similar. It can also include automatic barge identification reading devices, as described in connection with the vessel 20. The vessels 20 and 150 of this invention are designed to retain approximately three meters of water depth in each hold during loading and stowage, and therefore each hold floor and most bulkheads must be of heavy plate sufficient structurally to withstand this loading. A benefit of this is that the entire vessel is strengthened, particularly in longitudinal bending strength. The vessel is thus efficiently designed to meet hogging and sagging stresses developed by bending moments from large weights of water at its ends, from the locks, trim and heel tanks. Hog and sag stresses during loading can be considerable without overstressing the vessel longitudinally, and transverse strength is also enhanced by the design of the vessel. However, to insure against overstressing, provision is made for delivering ballast water to and removing it from the port, starboard and center buoyancy tanks 154, 155 arid 156 (Fig. 21) as required to reduce these stresses, via the central control station 220. Figs. 23 and 24 show in perspective the vessel 150 during bow and stern loading operations. As indicated, a barge 221 is loaded into the bow, through the starboard side loading passage 48, at the same time another barge 222 is loaded into the stern, at the port side. These two barges 221 and 222 will then be raised to the appropriate respective hold in the locks 56 and 200, respectively, so that the loading on the vessel due to lock filing will be roughly balanced. Precision control of trim, heel and draft during this operation is achieved as described above with draft-measuring gauges, trim, heel and draft tanks, and ballast transfer pumping and valve operation. Also as described above, locks of each respective pai 55, 56 (bow) or 200, 201 (stern) preferably are filled and drained in opposition to one another, so that water can be transferred from one lock to the adjacent lock in alternating fashion and the total water load on the ship will be kept as low as possible. Thus, when the locks 56 and 200 are filling the locks 55 and 201 are draining, and vice versa. To those skilled in the art to which this invention relates, many changes in construction and widely differing embodiments and applications of the invention will suggest themselves without departing from the spirit and scope of the invention. The disclosures and the description herein are purely illustrative and are not intended to be in any sense limiting.

Claims

CLAIMS : 1. A single-hulled, deadweight-activated, multi tiered, relatively shallow-draft, barge-carrying, waterborne vessel into which very large riverine barges can be loaded and conveyed to their stowage position by flotation and from which they can be unloaded by flotation, including in combination: a single hull with rigid supporting and hull reinforcing structure, a bow, a stern, and sidewalls providing a series of buoyancy compartments, said hull having a hollow enclosed interior defining a series of tiers of barge holds, one above the other, each hold having a bottom and extending most of the length of said vessel, a bow gate comprising part of the bow of said vessel and having two portions mounted on vertical pivot axes, one opening to each side of the vessel, for flotation loading and unloading therethrough, longitudinally extending vertical bulkhead means bisecting the vessel, including the bow, said gate portions swinging away from the vertical bulkhead upon when opened, a collision bulkhead aft of said bow gate having as a portion thereof a forward lock gate on each side of said longitudinal bulkhead, each swinging upwardly on horizontal pivots in a forward sweeping arc and including means for effecting watertight sealing when closed, no matter which side of said forward lock gate the hydrostatic loading comes from, a pair of loading passage locks inside said hull, each extending aft from said collision bulkhead, said forward lock gates defining the forward end of said locks, a series of generally vertically aligned water- tight aft lock gates for said locks in said tiers of holds, each of which, when open, enables transfer by flotation between said loading passage lock and a respective hold, opening and closing means for opening and closing each said gate so as to enable flotation loading and unloading into and from each lock on each end thereof, hold flooding and draining means for supplying water to and removing it from the holds, separately, when all said lock gates are closed, for enabling flotation stowage of barges into desired positions in each said hold, and lock supply and depletion means for supplying water to and removing it from each said lock, separately, when all said lock gates are closed.

2. The vessel of claim 1 wherein each said fore lock gate comprises: a stationary frame defining the gate opening as a rectangle that is smaller than said forward lock gate, said frame having a front face with gasket means thereon at the top, bottom, and each side, for engagement with said forward lock gate to render said forward lock gate water- tight when closed, said frame: also having a series of discrete wedges forward of said face frame, on at least the bottom and sides of said gate opening, within the boundaries of which said forward lock gate lies, said forward lock gate being rectangular and having an aft face which upon closure engages said gasket means against the face of said gate frame, and having a series of wedge-engaging members thereon for mating with and engaging against all of said wedges of said gate frame in camming relationship, retracting means for retracting said forward lock gate's wedge-engaging members, for enabling said forward lock gate to be swung open, hydraulically actuated dogging means on said forward lock gate for forcing said gate's wedge-engaging members against said wedges of said frame when the forward lock gate is closed, thereby to force said aft face against said gasket means in a watertight sealable closure to withstand large hydraulic pressures exerted against either side of said forward lock gate, opening means for swinging said forward lock gate upwardly about its horizontal pivot when that gate's wedge-engaging means are retracted.

3. The vessel of claim 2, wherein said dogging means and said wedge-engaging members include a gang bar actuator for each edge of the gate, on which wedges are located, a series of dogs actuated by each said gang bar, and a series of wedge bars, one for each said dog.

4. The vessel of claim 2 wherein said bow has a flat leading from said bow gate to said forward lock gate, substantially on the same level as the bottom edge of said gate opening, and a well in said flat adjacent to said gate frame enabling said forward lock gate to extend below said bottom edge and accommodating the wedges at the bottom.

5. The vessel of any of claims 1 to 4 having four said holds per tier, two on each side of said longitudinally extending vertical bulkhead means, one inboard said hold and one outboard said hold, said loading passage locks being aligned respectively with said inboard holds, a pair of stern loading locks, one aligned with each said outboard hold, a stern gate for each said stern lock dividing said lock from the sea, and a hold gate for each said stern lock at each tier connecting said stern lock to its said outboard hold, said hold gates and said stern gate defining the ends of said stern locks, whereby said vessel can be simultaneously loaded from both ends and simultaneously unloaded from both ends and the lock operation can be synchronized to keep the vessel in trim.

6. The vessel of claim 5 having a heel tank on both port and starboard sides of the vessel and adjacent to both the bow and the stern.

7. The vessel of claim 5 wherein said longitudinally extending bulkhead is hollow vertically and accommodates conduits connecting the exhaust from the vessel's engines with exhaust funnels.

8. The vessel of claim 7 wherein each said lock has barge stowage means at most of said tiers.

9. The vessel of claim 1 wherein said buoyancy compartments include a pair of heel-and-trim tanks at the stern for keeping the vessel substantially horizontal and planar during the flotation loading, stowage and unloading of barges and avoiding substantial list, and water transfer means for said heel-and-trim tanks so that water can be transferred from the tank on one side of said stern to the other tank according to the state of flooding of the locks near the bow.

10. The vessel of claim 9 wherein said longitudinally extending bulkhead means includes a plurality of sluice gate means for connecting each lock to the other and for isolating the locks from each other, and water transfer means for actuating said sluice gates to transfer water from one lock to the other, so that the locks can be operated out of phase with each other, so that one lock can be flooded to the level for floating a barge in or out while the other is flooded at a different level for transfer into or out from a hold.

11. The vessel of claim 1 wherein each tier has two inboard longitudinal holds, adjacent each other on opposite sides of said bulkhead, each opening via a said aft lock gate into a said lock, and each tier except the bottommost also has at least two outboard longitudinal holds parallel to said inboard holds and communicating with them laterally so that barges can be transferred laterally between each outboard hold and its associated inboard hold.

12. The vessel of claim 11 wherein at each tier except the bottommost, on each side of the vessel, an outboard hold extends beside and parallel to said lock for substantially the full length thereof, being separated from said lock by watertight bulkhead means.

13. The vessel of claim 12 wherein said bow has a flat leading from said bow gates to said forward lock gates, at generally the same level as the tier directly above said bottommost tier, said bottommost tier and the bottom of said locks lying below the level of said bow flat.

14. The vessel of claim 1 wherein each said lock has barge stowage means at most of said tiers.

15. A single-hulled, deadweight-activated, multi-tiered, relatively shallow-draft, barge-carrying, waterborne vessel for flotation loading, flotation stowage, and flotation unloading of very large riverine barges, including in combination: a single hull with rigid supporting and hullreinforcing structure, a bow, a stern, and sidewalls providing a series of buoyancy compartments, said hull having a hollow enclosed interior defining a series of tiers of barge holds, one above the other and comprising a lowest tier, an open-top uppermost tier, and a plurality of intermediate tiers, each hold having a bottom extending most of the length of said vessel, a bow gate comprising part of the bow of said vessel and having two portions mounted on vertical pivots, one opening to each side of the vessel, for flotation loading and unloading therethrough, a central longitudinally extending vertical bulkhead bisecting the bow and away from which the gate portions open, bisecting the hull and all except the uppermost tier of holds, a collision bulkhead aft of said bow gate having as a lower portion thereof a forward lock gate on each side of said longitudinal bulkhead, each swinging upwardly on horizontal pivots in a forward sweeping arc and including means for effecting watertight sealing when closed, no matter which side of said forward lock gate the hydrostatic loading comes from, a pair of loading locks inside said hull on opposite sides of the central bulkhead, each extending aft from said collision bulkhead and from one said forward lock gate, which defines the forward end thereof, so that one lock is used for flotation loading of the port side of said vessel and the other lock is used for flotation loading of the starboard side of said vessel, a series of generally vertically aligned aft lock gates for said locks in said tiers of holds, each of which, when open, enables transfer of barges by flotation between said loading lock and its respective hold tier, at least each tier except the lowest having a plurality of holds on each side of said central bulkhead, opening and closing means for opening and closing each said gate so as to enable flotation loading and unloading into and from each lock at each end thereof, hold flooding and draining means for supplying water to and removing it from the holds, separately, when all said lock gates are closed, for enabling flotation stowage of barges into desired positions in each said hold, and lock supply and depletion means for supplying water to and removing it from each said lock, separately, when all said lock gates are closed.

16. The vessel of claim 15, wherein said tiers having a plurality of holds on each side of the central bulkhead include a pair of inner holds each aligned with a lock, and an outer hold outboard at each inner hold, with a transfer passage for barge transfer between the inner and outer holds.

17. The vessel of claim 15, wherein each tier includes a pair of inner holds each aligned with one of said loading locks, and an outer hold outboard of each inner hold, and the vessel further including a pair of stern loading locks, one aligned in the each outboard hold, a stern gate for each said stern lock dividing said lock from the sea, and a hold gate for each said stern lock at each tier connecting said stern lock to its said outboard hold, said hold gates and said stern gate defining the ends of said stern locks, whereby said vessel can be simultaneously loaded from both ends and simultaneously unloaded from both ends and the lock operation can be synchronized to keep the vessel in trim.

18. The vessel of claim 17, wherein each tier has four holds, two inboard and two outboard.

19. A single-hulled, multi-tiered, relatively shallow-draft, barge-carrying, waterborne vessel into which very large riverine barges can be loaded and conveyed to their stowage position by flotation and from which they can be unloaded by flotation, including in combination: a single hull with rigid supporting and hullreinforcing structure, a bow, a stern, and sidewalls providing a series of buoyancy compartments, a series of tiers of barge holds in the hull, each hold having a bottom and extending through most of the length of the vessel; a pair of bow gates in the bow of the vessel, comprising port and starboard gates openable outwardly for flotation loading and unloading of barges therethrough; longitudinally extending vertical bulkhead means bisecting the vessel; a transverse bulkhead aft of the bow gates, including port and starboard watertight forward lock gates adjacent to the longitudinal bulkhead on either side; a pair of loading locks, one aft of each forward lock gate and adjacent thereto, each lock extending in height from the lowest tier of holds to the uppermost tier of holds; watertight gate means for the holds, at the aft end of the locks; lock supply and depletion means for supplying water to and removing it from each lock, separately; hold flooding and draining means for supplying water to and removing it from the holds to enable flotation stowage of barges into desired positions in the holds; and port and starboard heel-and-trim tanks at the stern, for closely maintaining the vessel at its normal horizontality during loading, stowage and unloading of barges, with water transfer means associated with the heel- and-trim tanks for supplying water to them individually and for transferring water between them, from port to starboard and vice versa, according to and in counter- balance to the state of flooding of the locks.

20. The vessel of claim 19 wherein the distance of the heel-and-trim tanks aft of the vessel's center of gravity is greater than the distance of the locks forward of the vessel's center of gravity, so that bow weight of the ship due to lock filling can be balanced by a relatively small volume of water in the heel-and-trim tanks.

21. The vessel of claim 19, wherein the lateral distance of each heel-and-trim tank out from the vessel's center of gravity is greater than the lateral distance of each lock out from the vessel's center of gravity, so that the trim of the ship due to filling of one lock higher than the other can be balanced by a relatively small volume of water in a heel-and-trim tank.

22. The vessel of claim 19, further including a plurality of depth gauges positioned at port and star board of the vessel to monitor the depth of the vessel in the water at numerous points, so that the state of trim and heel can be determined, and means connected to the depth gauges and to the water transfer means associated with the heel-and-trim tanks, for constantly monitoring and correcting heel, trim and draft during loading and flotation stowage of barges, to maintain the vessel's holds in proper horizontal condition and to maintain proper draft of the vessel.

23. A method for flotation loading, stowing and unloading of barges in a single-hulled, multi-tiered relatively shallow-draft, barge-carrying waterborne vessel, comprising: (a) opening the bow of the vessel via bow gates positioned along the waterline; (b) opening a lock gate and flooding one of a pair of port and starboard loading locks aft of the bow gates; (c) floating a first barge into the flooded lock; (d) closing the lock gate and raising the level of water in the barge-containing lock to the uppermost tier of holds, while balancing the lock filling by filling one of a pair of port and starboard heel-and-trim tanks at the stern of the vessel, diagonally opposed to the position of the lock being filled; (e) flooding the uppermost tier holds adjacent to the barge-containing lock; (f) stowing the first barge in a hold of the uppermost tier; (g) while stowing the first barge, loading a second barge into the other lock, opposite said one lock, with the other lock level at water line, and closing the lock gate for the other lock; (h) transferring water from the one lock to the other lock to lower the one lock's water level and raise the other lock's water level and raise the second barge to the uppermost tier; (i) while transferring water from the one lock to the other, transferring water from said one heel-and- trim tank to the other, keeping the vessel substantially in horizontal heel and trim; (j) stowing the second barge in a flooded hold on the upper tier; (k) opening the one lock gate with its water level substantially at water line and loading a third barge into the one lock; (1) transferring water from said other lock back to the one lock to lower the level in the other lock and raise the level and the third barge in the one lock, while transferring water from said other heel-and-trim tank back to the one heel-and-trim tank; (m) repeating these steps and continuing the process of loading the uppermost tier with alternation of locks until that tier is fully loaded, and while constantly trimming the vessel via said heel-and-trim tanks to maintain the horizontality of the vessel during barge loading and stowage; and (n) repeating the same alternating-lock loading process with respect to the next tier below the uppermost tier, and for all tiers not generally at the ship's water line .

24. The method of claim 23, further including the steps of stowing a barge in each lock at the level of each tier of holds above the lowermost tier, on retractable support members.

25. A single-hulled, multi-tiered, relatively shallow-draft, barge-carrying, waterborne vessel into which very large riverine barges can be loaded and con veyed to their stowage position by flotation and from which they can be unloaded by flotation, including in combination: a single hull with rigid supporting and hull reinforcing structure, a bow, a stern, and sidewalls pro viding a series of buoyancy compartments; a series of tiers of barge holds in the hull; each hold having a bottom and extending through most of the length of the vessel, at least most of the tiers having four holds, two inboard and two outboard; a pair of bow gates in the bow of the vessel, comprising port and starboard gates openable outwardly for flotation loading and unloading of barges therethrough; a transverse bulkhead aft of the bow gates, including port and starboard watertight forward lock gates; a pair of forward loading locks, one aft of each forward lock gate and adjacent thereto, each lock extending in height from the lowest inboard holds to the uppermost tier of holds, and aligned generally with the inboard holds of the tiers; watertight gate means for the inboard holds, at the aft end of the forward locks; a pair of stern gates in the stern of the vessel, for flotation loading and unloading of barges therethrough, port and starboard aft loading locks forward of the stern gates and aligned with the outboard holds of the tiers, each extending in height from the lowest outboard holds to the uppermost tier of holds; watertight aft gate means for the outboard holds, at the forward end of the aft loading locks; lock supply and depletion means for supplying. water to and removing it from each lock, separately; hold flooding and draining means for supplying water to and removing it from the holds to enable flotation stowage of barges into desired positions in the holds; and port and starboard heel-and-trim tanks at the bow and the stern, for closely maintaining the vessel at its normal horizontality during loading, stowage and unloading of barges, with water transfer means associated with the heel-and-trim tanks for supplying water to them individually and for transferring water between them, from port to starboard and vice versa, according to and in counter- balance to the state of flooding of the locks.

26. The vessel of claim 25, further including a plurality of depth gauges positioned at port and starboard of the vessel to monitor the depth of the vessel in the water at numerous points, so that the state of trim and heel can be determined, and means connected to the depth gauges and to the water transfer means associated with the heel-and-trim tanks, for constantly monitoring and correcting heel, trim and draft during loading and flotation stowage of barges, to maintain the vessel's holds in proper horizontal condition and to maintain proper draft of the vessel.

27. The vessel of claim 19 or claim 25, further including closed circuit television cameras positioned in the vessel to monitor loading, locking and stowage of barges, and a television monitor connected to the cameras and located at an observation station so that the progress of loading, locking and stowing vessels, as well as the flood condition of loading passages, locks and holds and the positions of gates can be observed from the observation station.

28. The vessel of claim 19 or claim 25 wherein the bottoms of the holds and the bulkheads are formed of heavy metal plate sufficient to withstand the weight of about three meters of water in, each hold, whereby the vessel is very strong in longitudinal bending strength and can withstand considerable end loadings without a damaging degree of hog occuring in the vessel.

29. A single-hulled, deadweight-activated, multi-tiered, relatively shallow-draft, barge-carrying, waterborne vessel into which very large riverine barges can be loaded and conveyed to their stowage position by flotation and from which they can be unloaded by flotation, including in combination: a single hull with rigid supporting and hull reinforcing structure, a bow, a stern, and sidewalls providing a series of buoyancy compartments, said hull having a hollow enclosed interior defining a series of tiers of barge holds, one above the other, each hold having a bottom and extending most of the length of the vessel, a bow gate comprising part of the bow of the vessel, for flotation loading and unloading therethrough; a pair of outboard stern gates at the stern of the vessel; bow lock means aft of the bow gate and stern lock means forward of the stern gates, for raising and lowering barges to and from respective holds of the multiple tiers for flotation stowage and unloading of barges to and from the holds; watertight gates associated with the lock means and the holds; hold flooding and draining means for supplying water to and removing it from the holds, for enabling flotation stowage of barges into desired positions in each hold, and for enabling unloading of barges; said bow lock means being associated with certain vertically aligned holds and said stern lock means being associated with other vertically aligned holds; and heel-and-trim control means including heel-and- trim ballast tanks, depth sensors at various locations along the hull, and pump means for transferring water to and from the ballast tanks, for closely controlling heel and trim during flotation loading and stowage; whereby the vessel may be loaded from both ends simultaneously, with the weight of bow and stern locking at least partially balancing.

30. The vessel of claim 29, including four holds on substantially every tier, with two inboard bow locks and two outboard stern locks.

31. The vessel of claim 29 or 30, further including closed circuit television cameras positioned in the vessel to monitor loading, locking and stowage of barges, and a television monitor connected to the cameras and located at an observation station so that the progress of loading, locking and stowing vessels, as well as the flood condition of loading passages, locks and holds and the positions of gates can be observed from the observation station.

32. A method for flotation loading, stowing and unloading of barges in a single-hulled, multi-tiered, relatively shallow-draft, barge-carrying waterborne vessel, comprising: (a) opening the bow of the vessel via bow gates positioned along the waterline; (b) opening the stern of the vessel via one of a pair of stern gates positioned along the waterline; (c) opening an inboard, bow lock gate and flooding one of a pair of port and starboard inboard loading locks aft of the bow gates; (d) flooding one of a pair of outboard, stern loading locks forward of the stern gates, the stern lock flooded being diagonally opposite the bow lock being flooded; (e) floating first and second barges into the respective flooded locks; (f) closing the lock gates and raising the level of water in the barge-containing locks simultaneously to the uppermost tier of holds, while closely maintaining the heel and trim of the vessel by controlling water volume in pairs of port and starboard bow and stern heel-and-trim tanks; (g) flooding the uppermost tier holds adjacent to the barge-containing locks; (h) stowing the first and second barges in holds of the uppermost tier; (i) while stoxvάng the first and second barges, loading third and fourth barges into the other two locks, opposite the first-flooded locks and diagonally opposite each other, with the lock levels of said other two locks being at water line, and closing the gates for said other two locks; (j) at the bow locks and at the stern locks, separately, transferring water from one lock to the other to lower the one lock's water level and raise the other lock's water level and to raise the third and fourth barges to the uppermost tier; (k) while transferring water from one lock to the other at both bow and stern, closely maintaining the heel and trim of the vessel by continuing to regulate water volume of the heel-and-trim tanks; (1) stowing the third and fourth barges in respective flooded holds on the upper tier; (m) opening the gates for the diagonally opposed locks whose water level has been lowered, with the water levels substantially at water line, and loading fifth and sixth barges into these locks; (n) transferring water from the two filled locks back to the other locks to lower and raise the lock levels, respectively, while continuing to closely maintain proper heel and trim; (o) repeating these steps and continuing the process of loading the holds of the uppermost tier with alternation of locks until that tier is fully loaded, and while constantly trimming the vessel via said heel-and-trim tanks to maintain the horizontality of the vessel during barge loading and stowage; and (p) repeating the same alternating-lock loading process with respect to the next tier below the uppermost tier, and for all tiers not generally at the ship's water line.

33. The method of claim 32, further including the steps of stowing a barge in each lock at the level of each tier of holds above the lowermost tier, on retractable support members.

34. The method of claim 32, further including visually monitoring the loading, locking and flotation stowage of barges through the use of a closed-circuit television system including cameras positioned at various locations in the vessel and a television monitor positioned at an observation station.