Break-Bulk Cargo Handling
Conventional ships have on-board crane systems to assist in the loading and unloading of cargo. Due to the limited reach of such crane systems, after a ship is docked, there is a relatively fixed embarkation/debarkation area on the dock defined by the reach of the ship's crane.
The shipping of break bulk goods such as cocoa beans from third world nations to the United States provides an example of the conventional shipping process. The cocoa beans are grown abroad, harvested and packed into 150 pound sacks. The sacks are transported to the dock area where they are placed on pallets having lifting slings attached, commonly referred to as a sling and/or sling load of cocoa beans. A typical sling of cocoa beans contains 30-35 sacks.
The slings of cargo are arranged in groups adjacent to each other, the number of slings per group preferably equalling the capacity of the on-board crane which the ship employs. In view of the low labor cost in third world countries, it is not unusual to have the entire preparation operation done by manual labor. Accordingly, when the empty ship docks to pick up a load of cocoa beans, appropriate groups of slings of cocoa beans are in place on the dock to be loaded onto the ship by the ship's crane.
Typically, for a ship with a large capacity crane, only one or two groups of slings can be positioned on the dock in the embarkation area for the ship. As the ship's crane lifts the first group of slings and transfers the group into the ship's cargo hold, more slings of cocoa beans are assembled in the space vacated by the first group. The loading process continues until a desired number of sling groups are aboard the ship. As the groups of slings are placed in the hold of the ship, the groupings of slings remain intact to facilitate off-loading without any unnecessary handling.
Once loaded, the ship departs and sails to its destination such as a port in the U.S. When the ship docks, crews of stevedores stand ready to assist in the off-loading of the cocoa beans. The off-loading commences with the ship's crane being utilized to transfer the groups of slings of cocoa beans-from the ship's hold to the dock within the debarkation area defined by the reach of the ship's crane. Once the first group of slings of cocoa beans are in the debarkation area, they must be moved before subsequent sling groups of cocoa beans can be unloaded from the ship's hold.
Conventionally, stevedores employ forklifts to remove the slings from the debarkation area of the dock to a storage area, such as a warehouse. As soon as the slings are released from the crane, forklift operations commence. This method of ship unloading has been employed for many years and has been a reasonably satisfactory method of unloading break bulk goods such as cocoa beans from a ship. Over the years, the capacity of ship cranes has gradually increased. At one time ship crane capacity was on the order of the 6-8 slings. That capacity has increased with newer cranes having the capacity of 10, 12 or 14 sling loads. Currently, the fourteen sling capacity crane is the largest crane used in commercial shipping of cocoa beans.
The holds of cargo vessels have been designed to haul either bulk cargoes when the hold is free from obstructions, or for general cargoes in holds provided with tween decks to support multiple tiers of cargo, such as palletized cargo or containers of cargo. Also, some vessels have been adapted for mixed cargoes by providing a conventional tween decks in the upper portion of the hold with the lower portion being left unobstructed for the hauling of dry bulk cargo. However, need exists for a cargo vessel that can be rapidly converted from the handling of dry bulk cargo to the handling of general cargo by the use of mechanisms contained aboard the vessel. When converted for the hauling of dry bulk cargo, it is desirable that the hold be substantially free of structural supports and other obstructions. Also, it is desirable that the tween deck structure utilized for the storage of general cargo be adjustable so that the height between the tween deck structures can be changed to accommodate various types and sizes of cargo and cargo containers, and that this structure be able to accommodate pallets of the maximum size and weight that can be loaded outside of the vessel and then placed aboard so as to provide high cargo handling efficiency.
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 broker's 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, a 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 US.
In view of the 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 U.S. as well as abroad. By these advances, the cargo handling process from manufacturer's 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 manufacturer's 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 manufacturer's 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 fourteen times, as opposed to sixteen times with break-bulk cargos, in transport of a given item of cargo from manufacturer's 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 that the reduction in the total number of cargo handling operations involved.
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