US3793974A

US3793974A - Marine transport

Info

Publication number: US3793974A
Application number: US00187537A
Authority: US
Inventors: J Bylo
Original assignee: Individual
Current assignee: Individual
Priority date: 1971-10-07
Filing date: 1971-10-07
Publication date: 1974-02-26
Anticipated expiration: 1991-02-26
Also published as: DE2248381C2; GB1402870A; JPS5699888A; DE2248381A1; JPS58481A; JPS4846080A; CA975705A

Abstract

An integrated marine transport system for joint or separate commercial and military uses in which a plurality of cargo containers, each sized to define the entire cargo carrying space of a vessel, are each separably mated with cooperatively configured vessels provided for moving the containers from port to port. The system also includes dock facilities configured to mate with the cargo containers and to receive and to discharge the containers directly from and to the vessels. The system also includes in-port vessels for transferring the containers from the port-to-port vessels to the docks. Also described is a novel docking arrangement useful in conjunction with the vessels and the cargo containers to provide port and cargo handling facilities in undeveloped areas.

Description

United States Patent [191 Bylo [ 1 Feb. 26, 1974 1 MARINE TRANSPORT [21] Appl. No.: 187,537

Related US. Application Data [63] Continuation-impart of Ser. No. 794,938, Jan. 29,

1969, abandoned.

[52] US. Cl 1l4/43.5, 114/72, 214/12 [51] Int. Cl B63b 35/44 [58] Field of Search.. ll4/43.5, 72, 77 R, 77 A, 73; 214/12, 14

[5 6] References Cited UNITED STATES PATENTS 3,139,197 6/1964 Bylo 214/12 3,508,514 4/1970 Vienna 114/77 R X 3,557,742 l/l97l Gainsley 114/77 R 3,556,036 l/l97l Wells 114/72 3,380,422 4/1968 Bachko 114/72 Primary ExaminerTrygve M. Blix Assistant ExaminerEdward R. Kazenske Attorney, Agent, or Firm-Christie, Parker & Hale V [57] ABSTRACT An integrated marine transport system for joint or separate commercial and military uses in which a plurality of cargo containers, each sized to define the entire cargo carrying space of a vessel, are each separably mated with cooperatively configured vessels provided for moving the containers from port to port. The system also includes dock facilities configured to mate with the cargo containers and to receive and to dis charge the containers directly from and to the vessels. The system also includes in-port vessels for transferring the containers from the port-to-port vessels to the docksv Also described is a novel docking arrangement useful in conjunction with the vessels and the cargo containers to provide port and cargo handling facilities in undeveloped areas.

23 Claims, 26 Drawing Figures PATENTED FEB28 I974 sum :03 of 1s 0 O O O Ennazsxsn sum 05 HF 1'5 m awn m PATENTED FEBZS I974 sum 08 or 15 PAIENTEDFEBZGIQM 3,793,974

SHEET 10UF15 PAIEIIIEIIIIBM 3.793.974

SHEET 11 0F IIIII 1111 QSQQE l I I I I I I I 1 I I I I I I PATENTEDFEBZSIQM 3,793,974

sum .12 0F15 PATENTED FEB 2 61574 mm m PATENTEB FEB2 6 i974 SHEET 150F151 MARINE TRANSPORT CROSS-REFERENCE TO RELATED APPLICATION This application is a continuation-in-part of copending application Ser. No. 794,938 filed Jan. 29, I969 now abandon.

FIELD OF THE INVENTION This invention relates to marine transport systems and to procedures and structures in furtherance thereof. More particularly, the invention relates to a marine transport system in which modularization of cargo holds, docks, and transport vessels is maximized, the cargo holds preferably defining the entire cargo carrying capacity of a given vessel in the system and being interchangeable between vessels.

BACKGROUND OF THE INVENTION THE STATE OF THE ART At the present time, transport of cargo by water is, as a general rule, the most economical mode of transport available. In many instances, however, the cost differentials between sea and land transport, or between sea and air transport, in combination with the time differentials similarly involved, render land or air transport preferable to sea transport. If the cost of sea transport can be substantially reduced, the use of sea transport in preference to land or air transport would be increased to the advantage of the substantial maritime investment in the nation, as well as to the long term military advantage of the country.

The most significant single factor contributing to the total cost of transport of goods and materials by sea lies in cargo-handling expense. In break-bulk shipment of cargo by sea, wherein individual containers or small combinations or pallets of individual boxes, bags or other containers are loaded separately onto the transport vessel, manual handling of cargo occurs at many different points in the shipping process. In break-bulk shipment procedures, cargo is manually assembled and classified at a warehouse such as a manufacturers warehouse or cartage brokers warehouse. Next the cargo is transferred to surface transport vehicles, another cargo handling operation, for transport to a transit shed located in the dock area. Upon arrival of the vehicle at the transit shed, the cargo is again handled as it is transferred from the vehicle to storage locations in the transit shed. Subsequently, the cargo is transferred from the transit shed to dockside; in this process, the cargo is handled both upon removal from the transit shed and upon deposit at dockside. Still later, the cargo is removed from dockside to the cargo hold of the ship by the use of the cargo handling gear located either at dockside or upon the vessel; this procedure involves two additional cargo handling operations. Upon deposit of the cargo within the vessel, it is frequently moved within the vessel by stevedores since the cargo handling gear of a conventional shelterdeck vessel, for example, does not provide access to all cargo stowage locations of the vessel. Upon arrival of the vessel at its destination, 2 reverse cargo handling procedure is involved. Therefore, it is seen that approximately sixteen separate cargo handling procedures are involved in the marine transport of cargo from original source to ultimate destination. Each cargo handling operation involves manual labor performed with or without the assistance of mechanized cargo handling devices. It is well known that labor cost, rather than equipment cost, is the single most expensive item in any process performed practically anywhere in the world at the present time, particularly so in the United States.

In view of the above-described uneconomical characteristics of break-bulk cargo handling procedures, and in an effort to reduce the overall cost of marine transport, advances in the containerization of cargo have been realized in the United States as well as abroad. By these advances, the cargo handling process from manufacturers warehouse to ship and from ship to destination warehouse has been simplified by the elimination of the transit shed. In this process, cargo is transferred directly from the manufacturers warehouse, e.g., to dockside in a container which conventionally is the cargo van of a tractor-drawn cargo trailer (semi-truck trailer), the van being removable from its supporting wheels in the most advanced containerization operations presently in commercial use. These truck vans ultimately are loaded directly aboard the vessel, but in the interim between dispatch from the manufacturers warehouse and loading aboard ship or barge, the vans must be assembled in a staging area adjacent to dockside from which they are later moved to the vessel. According to current containerization practices, cargo handling procedures involving manual labor occur 14 times, as opposed to 16 times with break-bulk cargos, in transport of a given item of cargo from manufacturers warehouse or the like to destination warehouse. The basic practical advantage over break-bulk cargo handling techniques of containerization systems of the type described above is the reduction in the extent to which individual cargo packages are handled. That is, greater quantities of cargo are dealt with in each cargo handling operation with the result that handling costs per individual commercial unit of cargo are reduced to a greater extent than the reduction in the total number of cargo handling operations involved.

SUMMARY OF THE INVENTION This invention provides a unique and highly efficient marine transport system which takes utmost advantage of the structures and methods described in my prior U.S. Pat. Nos. 2,371,149 and 3,139,197 and 3,349,742, if desired.

My prior U.S. Pat. Nos. 2,371,149 and 3,139,197 describe marine transport structures in which containerization of the cargo is maximized in that the vessel described in each of these patents features a cargo hold volume which is detachable as a unit from a selfpropelled buoyant base which is basically the machinery and non-cargo-carrying aspect of a marine vessel. These prior patents teach that the cargo hold unit may be transferred to or received from a suitable dock structure, configured to cooperate with the hold unit, merely by ballasting the vessel per se into and out of mating engagement with the cargo hold unit. In practical effect, then, the cargo hold unit functions much like a movable transit shed or warehouse, reference in this respect being had to the foregoing description of conventional break-bulk cargo handling techniques; it will be understood, however, that the cargo hold unit does not comply with the technical definition of a transit shed as concerns aisle spaces and the like. Therefore, in a complete routing of cargo pursuant to the system contemplated herein, cargo is handled once to transfer cargo from a manufacturera warehouse to a surface vehicle, a second time to transfer the cargo from the vehicle to the cargo hold unit, and twice again in the transfer of the cargo from the hold unit to a surface vehicle at the destination port and from the surface vehicle to the destination warehouse; in total, then, the present cargo handling system contemplates only four cargo handling operations in which manual effort is involved to any significant respect. In the system provided by this invention, handling costs attendant to transfer of a hold unit to or from the transit vessel involves minimum personnal and manual effort and is, therefore, insignificant in terms of contribution to the total cost of shipment of cargo by this system.

In addition to the foregoing direct cost saving advantages provided by this invention, additional advantages are obtained in that, by maximizing the volume of the container (the hold unit may be regarded as the ultimate container) to a degree far beyond that contemplated by existing containerization systems, the cost of the container per ton of cargo capacity is considerably lower than the corresponding cost associated with existing truck-type container modules. Further, inasmuch as the time involved in transferring the hold unit to a vessel like those described in the earlier two of my three above-mentioned patents is small, the vessel contemplated by this system is in productive motion from port to port for a considerably greater percentage of its useful life than is a container vessel of the type presently enjoying commercial exploitation.

The basic element or module of the present marine transport system is the ship-size container or cargo hold unit. The hold unit is standarized (i.e., modularized) in certain of its basic external dimensions and configurations, but its internal structure and remaining external features may be varied to accord with the specific requirements of particular commodities and cargo types. That is, while a cargo hold unit specifically tailored for use in shipping newsprint, for example, may appear externally to be essentially identical to a cargo hold unit tailored specifically for the transport of, say, bananas, internal cargo handling devices and environmental control facilities would be markedly different between these two basic containers. If desired, a cargo hold unit for use in a system of this invention may be constructed essentially as an automated warehouse for essentially automatic receipt and discharge of individual cargo units.

Further, the system contemplated by this invention permits variation in the design and outfitting of the vessels of the system to comply with the requirements of the ports between which they would normally operate, and also to conform to the particular sea-keeping criteria pertinent to the routes along which the particular vessels would normally be operated. In this regard, it is a feature of this invention that a given transit ship, especially where this invention serves commercial rather than military purposes, would run cyclically between two adjacent ports, say, from Los Angeles to San Francisco, California, and that a separate vessel would be operated on a shuttle route between San Francisco and Portland, Oregon, for example. In essence, then, the system of this invention contemplates that individual transit vessels would merely cycle back and forth between adjacent ports on a particular shipping route, whereas the cargo hold units may be moved serially along a greater route from port to port, picking up or discharging cargo in each port as desired. Such usage of a given transit vessel between only two specified ports has significant and substantial benefits in terms of shipboard operating personnel; ship crews may spend most of their nights ashore rather than aboard ship, thereby permitting a simplification of the crew facilities aboard the transit vessel and providing a substantial net reduction in operating cost to the ship owner.

Further, the system of this invention contemplates the use of specially designed in-port vessels suited for receiving a cargo hold unit from a transit dock facility located in an outer harbor, for example, to a working dock facility located at the inner harbor, at which location cargo is actually worked, i.e., taken from or placed in the individual cargo hold unit. The in-port transit vessel may have propulsion machinery designed to produce a highly maneuverable, but rather low speed vessel, whereas the port-to-port transit vessels may be designed and equipped for maximum speed and seakeeping ability, but only nominal maneuverability. The transfer dock facility which forms the interface between the port-to-port transit vessel and the in-port transfer vessel preferably is located at the outer harbor of a given port and is configured to permit economic usage thereof by both the transit vessel and the in-port vessel. The working dock facility at any given port need only be configured to mate with a particular in-port vessel and the standarized, molularly designed cargo units.

In the present system, therefore, it is seen that the cargo hold unit is the basic module involved, and that the transit vessels, in-port vessels, and the transfer dock and the working dock facilities are all cooperatively structured and arranged to cooperate with the cargo hold unit but may otherwise be varied in structure, proportions and arrangement to meet the peculiar limitations imposed by their own environment and specific use.

GENERAL RESUME OF CLAIMS Generally speaking, in terms of a marine transport system, this invention comprises a plurality of modular cargo hold units of standardized lower configuration and dimension. At least some of the hold units are buoyant when loaded and have hatches provided through the top thereof; cargo handling equipment of substantially conventional arrangement is located adjacent the hatches and is operable for working cargo in the hold unit through the hatches. Some of the hold units, including those with top hatches, have closable access means laterally into them; these access means are openable for working cargo in the units through the access means. The system also includes a self-propelled vessel for moving cargo hold units between a plurality of ports served by the system. The vessels are configured to interchangeably mate with the hold units, to support the hold units, and to secure the hold units from shifting relative to the vessels. In at least one port served by the system, there is provided dock means for supporting a hold unit independently of a vessel for working of cargo in the unit through the access means.

This invention also provides vessels arranged for moving hold units within a given port facility between a cargo-working dock and a transfer dock at which the between-port vessels may pick up and deposit hold units; according to the invention, the transfer docks preferably are located in the outer areas of the port and are arranged for buoyantly receiving and discharging hold units.

This invention further involves specific improvements in transfer dock structures, transfer vessels, and in working dock arrangements. This invention also provides improvements in the structure of portable docks particularly suited for military applications of this system. It is a feature of the basic commercial system described above that is is compatible with military logistics and transport requirements to the end that the same cargo hold units useful in commercial marine transport systems are useful in an improved military cargo transport system which is also a part of this invention.

DESCRIPTION OF THE DRAWINGS The above-mentioned and other features of this invention are more fully set forth in the following detailed description of preferred embodiments of the invention, which description is presented with reference to the accompanying drawings, wherein:

FIG. 1 illustrates, relative to the United States, a commercial marine transport system according to this invention;

FIG. 2 is an enlarged illustration of the portion of FIG. 1 which pertains to the West Coast of the United States;

FIG. 3 is an elevation view of a port-to-port transit vessel for use in the system depicted in FIGS. 1 and 2;

FIG. 4 is an elevation view of an in-port transfer vessel suited for use in the system of FIGS. 1 and 2;

FIG. 5 is an elevation view of the vessel shown in FIG. 4 illustrating another stage in the operation of such vessel;

FIG. 6 is a fragmentary cross-sectional elevation view of the vessel shown in FIGS. 4 and 5;

FIG. 7 is an elevation view of another in-port vessel useful in the transport system illustrated in FIGS. 1 and FIG. 8 is an end elevation view of a transfer dock facility for use in the system according to this invention;

FIG. 9 is an elevation view of a working dock facility according to this invention;

FIG. 10 is a side elevation view of a portable working dock facility according to this invention;

FIG. 11 is a cross-sectional elevation view taken along line 11-11 of FIG. 10;

FIG. 12 is an enlarged fragmentary plan view taken along line 12-12 of FIG. 10;

FIG. 13 is an elevation view of the dock of FIG. 10 installed adjacent an unimproved beach or the like;

FIG. 14 is an end elevation view of the structure shown in FIG. 13 showing a cargo hold unit engaged with the dock;

FIG. 15 is a top plan view of a transit vessel, fitted with a cargo hold unit, towing a pair of portable working dock structures FIG. 16 illustrates a military transport and logistical support system according to this invention;

FIG. 17 is a perspective view of a military transit vessel and a pair of cargo hold units specifically suited for military application;

FIG. 18 is a perspective view of another multi-cargo hold unit transport vessel especially suited for military use in combination with cargo hold units of the type suited for commercial use as contemplated by FIG. 3;

FIG. 19 is a cross-sectional elevation view taken along line 1919 of FIG. 18;

FIG. 20 is aschematic diagram of a manufacturing and marketing system incorporating the marine transport system illustrated in FIGS. 1 and 2, for example;

FIG. 21 illustrates, relative to the western part of the United States and Canada, another commercial marine transport system;

FIG. 22 is a perspective view of a port facility for the transport system represented in FIG. 21;

FIG. 23 is a perspective view of another port facility for the system represented in FIG. 21;

FIGS. 24 and 25 are a schematic elevation view showing two different stages in the hold unit discharge process for the port facility shown in FIG. 23; and

FIG. 26 is a perspective view of a military weapons platform arranged for movement by a vessel according to this invention.

DESCRIPTION OF THE ILLSTRATED EMBODIMENTS FIG. 1 illustrates the general functioning of a commercial marine transport system 10 serving the West Coast 11 and the East Coast 12 of the United States. As will be made clear from the following description, this system is not restricted to service of coastal ports, nor is it restricted only to commercial service. The system also may service inland areas via rivers, and it may be combined with military transport systems operating according to similar principles as set forth in the following description. With reference to the West Coast of the United States, reference numerals 1 3-19 designate, respectively, the following ports relative to which system 10 is described in detail:

13 San Diego, California 14 Long Beach-Los Angeles, California 15 Greater San Francisco Bay Area, California 16 Astoria-Portland, Oregon l7 Seattle, Washington and Vancouver, B. C.

18 Juneau, Alaska 19 Seward-Anchorage, Alaska It will be understood that more or less ports on the West Coast of the United States may be included in system 10 as desired, the ports listed above having been identified merely for the purposes of example.

As suggested above, system 10 includes a plurality of port-to-port transit vessels 20 (see FIG. 3) which cooperate with a greater plurality of modular, i.e., generally dimensionally and functionally standardized, cargo hold units 22 (see FIGS. 3 and 9). The system also includes, in each port comprehended by the system, at least one and preferably several working dock facilities, a transfer dock facility, and an in-port transfer vessel. At least as many transit vessels 20 are provided as there are shipping runs between adjacent ports. That is, FIG. 1 illustrates a transport system comprehending a total of twenty-two ports which correlate to twenty-one adjacent pairs of ports. Additional transit vessels may be required on shipping runs where cargo traffic is particularly heavy, or on runs where the distance between adjacent ports is large, as on the shipping run via Panama Canal 23 between San Diego 13 and Corpus Christi, Texas 24.

Cargo hold units 22 of system 10 are all standardized as to selected external dimensions, arrangements and configuration. Each hold unit defines a structural shell 25 (see FIG. 9) which encloses a cargo space 26. The

cargo space is horizontally subdivided by internal decks.

27 within the shell, and closable access openings 28 (FIG. 3), sized to admit fork-lift trucks 29 or the like, are provided to the decks from the exterior of the shell. Because certain of their external features are standardized, the hold units are modular in design.

Each hold unit defines means which cooperate with a transit vessel to secure the hold unit in place on the transit vessel during ocean passage of the vessel. As shown in FIG. 9, such means includes a rib 30 which depends from the lower extent of the hold unit, and which cooperates in a correspondingly controured recess 31 (FIG. 3, and see also FIG. 19) within the deck of the transit vessel which supports the hold unit when the hold unit and the vessel are mated. The interior of the rib defines a portion of cargo space 26.

The cargo hold units are made as large as possible. Preferably the hold units have capacity to receive at least 5,000 tons of average density cargo. The transit vessels are sized to be large enough to receive and support at least one cargo hold unit (see FIG. 3), to provide sufficient ballast capacity 32 that the vessel may be buoyantly raised and lowered into and out of engagement with a loaded cargo hold unit as described below, to provide suitable accommodations 33 for operating personnel, and to provide space for propulsive machinery 34 and ballast pumps 35. It is preferred that the majority of the transit vessels present in system be like vessel (FIG. 3), namely, a carrier for a single hold unit which, when mated with the vessel, defines the entire cargo carrying capacity of the vessel. The cargo hold unit, therefore, will be seen to resemble a movable cargo warehouse.

It will be understood from the following text that this invention also comprehends, in the context of a commercial transport system, port-to-port transit vessels capable of receiving a plurality of modular cargo hold units 22. Such multi-unit transit vessels may be used to advantage in servicing the San Diego to Corpus Christi segment of system 10, or the Seattle to Juneau segment of the system where the distance between adjacent ports greatly exceeds the distance between adjacent pairs of ports elsewhere in the system. FIG. 18 illustratesa multi-unit transit vessel 130 which may be used to advantage in system 10.

Each transit vessel, consistent with the requirement that it be standarized to mate with the modular cargo hold units, preferably is adapted specifically to the particular route along which it operates in system 10. Thus, the transit vessel which operates between, say, Los Angeles 14 and San Francisco 15 may possess different propulsion and maneuvering equipment, hull form, and personnel accommodations than the transit vessel which operates between, say, Boston 37 and Portland, Maine 38 in view of the different average sea and weather conditions and the peculiarities, such as effective water depth, of the harbors serviced.

Referring still to FIGS. 1 and 2, and also to FIG. 9, each port serviced by system 10 includes at least one working dock facility 40, and it is preferred that each port be equipped with a plurality of such dock facilities. Preferably, the working dock facilities are located in an inner harbor area where surface vehicles may have ready access to the dock facilities; a working dock facility may constitute a portion of a manufacturing operation located within the port area. The term working dock facility is used to describe a dock structure where cargo is worked (loaded or unloaded) relative to a cargo hold unit engaged with and supported by the dock structure.

Working clock 40, shown in FIG. 9 defines a vessel slip 41 between two parallel piling arrays 42. The pilings 43 in each array are all vertical and are driven into harbor bottom 44 to have their upper ends located well above water surface 45. The pilings of each array preferably are arranged in two rows of pilings disposed parallel to the length of slip 41, which rows in each array are spaced apart a distance greater than the width of a ballastable buoyant unit 46 located between the rows. Each buoyant unit carries a plurality. of rollers 47 which cooperate with the opposed faces of the pilings in the two rows of the corresponding array for maintaining the buoyant unit in place between the pilings and for guiding the buoyant unit in vertical movement along the pilings. The buoyant units are caused to move vertically in the dock structure by operation of ballast pumps 48 located in each unit, which pumps are operable to cause water to be pumped into or out of the units. If desired, each buoyant unit 46 may be defined by a midship vessel bottom section according to the disclosures of my prior U.S. Pat. No. 3,349,742; such a practice enables maximum possible standardization of the structures used in system 10 and thereby results in minimum cost to install and operate the system.

Piling arrays 42 are spaced sufficiently far apart that slip 41 is wide enough to accommodate a vessel, possibly a port-to-port transit vessel 20 but preferably an inport transfer vessel 49 described below, which carries a cargo hold unit 22. An access deck 50 is supported by the upper ends of the pilings in each array, and preferably both decks 50 of the dock structure are located in a common plane. The access decks are sufficiently strong that they can support fork-lift trucks 29 and such other vehicles and equipment as may be used to work cargo in a hold unit engaged with the dock structure. It is preferred that the opposing edges 51 of the access decks be spaced apart a distance which is only slightly greater than the width of cargo hold unit 22.

Each buoyant unit 46 carries means which are engageable with a cargo hold unit to support the hold unit above water surface 45 upon removal from slip 41 of the vessel which conveyed the hold unit to the working dock facility. As shown in FIG. 9, each buoyant unit 46 carries a plurality of retractable beams 53 which are disposed transversely of the length of slip 41. The beams are movably mounted to the upper extent of each buoyant unit for movement between (1) a retracted position in which the adjacent ends 54 of the beams are disposed outwardly of access deck edges 51 from the slip, and (2) an extended position in which (a) the beams extend in cantilever fashion inwardly of the slip and (b) ends 54 of opposing beams are spaced apart a distance less than the width of a cargo hold unit but greater than the maximum width of the depending rib 30 of a cargo hold unit. In their extended position, the beams are arranged for supporting a cargo hold unit by engagement with the downwardly open marginal flange-like surfaces 55 of the hold unit outwardly of and parallel to rib 30. Suitable bearings 56 are disposed between the beams and the buoyant units to movably support the beams on the buoyant units.

Pilings 43 need have only sufficient strength to support access decks 50 and to withstand whatever lateral loads may be imposed upon the pilings by the buoyant

Claims

1. A marine transport system comprising a plurality of modular cargo hold units of standardized lower configuration and dimension, each of the hold units having longitudinal and end sides, at least some of the hold units being buoyant when loaded, said some hold units having the interior thereof subdivided longitudinally into a plurality of hold spaces and vertically by a plurality of decks, said some hold units having hatches provided through the top thereof to the hold spaces and cargohandling equipment of substantially conventional arrangement adjacent the hatches operable for working cargo into and out of essentially the entire internal volume of the unit through the hatches, at least those hold units with hatches having closable side access means laterally there into in association with a plurality of the decks thereof and openable for working cargo into and out of the internal volume of the unit therethrough, a self-propelled vessel for moving cargo hold units between a plurality of ports served by the system and configured to interchangeably mate with the hold units for supporting the same and for securing a hold unit supported thereby from shifting relative thereto, and dock means in at least one port served by the system for supporting a hold unit independently of the vessel for working of cargo in the unit through the access means, the vessel including ballasting means operable for altering the draft of the vessel between a shallow draft state wherein the vessel is operable for supporting a hold unit and for moving the same between ports in the system and a deep draft state wherein the hold unit, where the hold unit is one of said some hoLd units, is floatable free of the vessel at a dock for the working of cargo to and from the hold unit through the top hatches thereof by use of said cargo-handling equipment, the ballasting means also being operable to implement transfer of a hold unit between the vessel and said dock means.

2. A marine transport system according to claim 1 wherein each hold unit is sized relative to the vessel when loaded and mated with the vessel to consume a substantial fraction of the load-carrying capacity of the vessel.

3. A marine transport system according to claim 1 including at least one cargo hold unit having only closable access means laterally thereinto.

4. A marine transport system according to claim 1 wherein the access means are provided at an end of at least some of the hold units.

5. A marine transport system according to claim 1 wherein the dock means includes means for adjusting the position thereat of a received cargo hold unit.

6. A marine transport system comprising, in combination, a plurality of elongate multi-deck modular cargo hold units of standardized lower configuration and dimension, a self-propelled vessel for moving cargo hold units between ports served by the system and configured to interchangeably mate with the hold units for supporting the same and for securing a hold unit supported thereby from shifting relative thereto, dock means in each port served by the system for supporting a cargo hold unit independently of the vessel, means cooperating between the vessel and the dock means for buoyantly transferring a hold unit to and from the dock means, and means operable for adjusting the positional relation of a cargo hold unit relative to the dock means in the absence of a supportive vessel and including variable buoyancy means, means defined by the dock means for guiding the variable buoyancy means vertically, and retractable means carried by the variable buoyancy means for engaging and supporting a cargo hold unit.

7. A system according to claim 6 wherein the dock means defines a slip for receiving a vessel, the variable buoyancy means extends longitudinally along opposite sides of the slip, and the retractable means are mounted for movement laterally of the length of the slip.

8. A system according to claim 7 including an access deck supported by the variable buoyancy means guide means and disposed along at least one side of the slip for supporting cargo working personnel and equipment, the variable buoyancy means being configured and arranged for adjusting the draft thereof while supporting a cargo hold unit an amount at least equal to the spacing between the uppermost and the lowermost of the cargo hold unit decks.

9. A system according to claim 7 including means supported by the guide means releasably engageable with a cargo hold unit for supporting a hold unit engaged thereby relative to the dock means independently of the retractable means.

10. A system according to claim 9 wherein the releasably engageable means are arranged for disengagement from a cargo hold unit only upon removal of essentially all load therefrom.

11. A system according to claim 7 wherein the variable buoyancy means comprises an elongate ballastable pontoon disposed adjacent to and parallel to each side of the slip.

12. A system according to claim 11 including ballasting means operable for ballasting each pontoon independently of the other for independent variation of the buoyancy of each pontoon.

13. A system according to claim 12 wherein the pontoons and the ballasting means are cooperatively arranged for adjusting the trim and heel characteristics of each pontoon independently of the other pontoon.

14. A system according to claim 11 wherein each pontoon is essentially identical in external configuration and dimension to that portion of the vessel which is mateable with a cargo hold unit.

15. A system according to claim 14 wherein each pontoon has a length essentially equal to the length of a cargo hold unit and has a U-shaped transverse cross-sectional configuration.

16. A system according to claim 6 wherein the said vessel is a transit vessel operable essentially only for moving cargo hold units between ports served by the system, and including, in each port served by the system, second dock means in each port independent of the first dock means for receiving a cargo hold unit from the transit vessel, for transferring a cargo hold unit to the transit vessel, and for supporting a cargo hold unit independently of the transit vessel, and a transfer vessel in each port served by the system for moving cargo hold units between the first and second dock means of the port.

17. A system according to claim 16 wherein each transfer vessel is configured and arranged for cooperation with the cargo hold units and the first and second dock means for supporting a single cargo hold unit and for receiving from and discharging to the first and second dock means a cargo hold unit.

18. A system according to claim 17 wherein each transfer vessel includes a buoyant hull and means for raising and lowering a cargo hold unit relative to the hull.

19. A system according to claim 17 wherein the transfer vessel includes means for buoyantly raising and lowering a cargo hold unit relative to the hull thereof.

20. A system according to claim 19 wherein the hull of the transfer vessel defines two longitudinal ballast tank spaces along the opposite sides thereof and means for filling and emptying said tanks of water ballast, float means disposed in each tank, the float means in each tank having buoyancy when essentially fully submerged at least equal to one-half the weight of a loaded cargo hold unit, and means carried by the float means for movement therewith relative to the hull extending through the hull for engaging a cargo hold unit in supporting relation.

21. A system according to claim 20 wherein the transfer vessel and the first dock means in each port are cooperatively arranged so that the float means of the transfer vessel are elevatable relative to the vessel hull while supporting a loaded cargo hold unit a distance at least adequate to enable insertion of the retractable means between the hull and the hold unit for transfer of the weight of the hold unit from the vessel to the retractable means.

22. A system according to claim 20 wherein the float means comprises an elongate float member in each ballast tank and aligned with the length of the tank, the means carried by the float means comprises a plurality of vertical pillars supported on each float member at spaced locations therealong and extending through the vessel hull above the float member, and means releasably engageable between the pillars and the hull for securing the pillars from movement vertically relative to the hull.

23. A marine transport system comprising, in combination, a plurality of elongate multi-deck modular cargo hold units of standardized lower configuration and dimension, a self-propelled vessel for moving cargo hold units between ports served by the system and configured to interchangeably mate with the hold units for supporting the same and for securing a hold unit supported thereby from shifting relative thereto, each cargo hold unit defining a depending rib disposed centrally of the width thereof and extending longitudinally thereof, the vessel defining a longitudinal well extending forwardly of the hull thereof from a transom stern for a distance at least equal to the length of a cargo hold unit, the well having a bottom surface configured to mate with the hold unit rib, and a closable gate in the vessel transom in alignment with the portion of the well surface mateable with a hold unit rib, dock means in each port served by the system for supporting a cargo hold unit independently of the vessel, and means cooperating between the vessel and the dock means for buoyantly transferring a hold unit to and from the dock means.