Abstract:
There is provided a sea going barge train or modular tanker vessel for ocean transportation of cargo, such as oil or other dry or liquid materials, consisting of a forward traction unit, a rear powered caboose unit and a series of modular units or barges interposed therebetween wherein the units are serially and flexibly interconnected by means of a universal type coupling which permits relative limited yaw, pitch and roll movement between units. The hull of each barge unit is substantially semi-cylindrically shaped so that the hull immersed section is circular and the barge units are detachably coupled to each other fore and aft and to the traction and caboose units at the circle center of the circle segment defined by the hull cross section so that hull continuity of the barge train is maintained as the barge units roll relative to each other. The universal type coupling employed to detachably couple the barge units to each other and to the forward traction unit and rear caboose unit consists of a male coupling shaft extending from a universal joint mounted at the fore or aft of a barge unit and a female socket, for receiving the male coupling shaft, mounted at the aft or fore of a mating barge unit.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention generally relates to a sea-going barge train. More particularly, the present invention relates to a barge train or modular tanker vessel for ocean transportation of cargo, such as oil or other dry or liquid materials, consisting of a forward traction unit, a rear powered caboose unit and a series of modular units or barges interposed therebetween wherein the units are flexibly interconnected by means of a universal type coupling. 
     2. Description of the Prior Art 
     At present, over the sea transport of oil from production sites to refineries or remote storage facilities is accomplished by means of specialized ocean going vessels such as tankers and super-tankers. Such tankers are large vessels designed to transport up to 400,000 tons of oil. Because of the size of such vessels they can only pass through channels and be accepted in harbors which are large enough and deep enough to accommodate such large vessels. Furthermore, large tankers, such as super-tankers, are too large to pass through such artificial waterways as the Panama Canal or the Suez Canal to thus take advantage of the economies such artifical waterways were designed and built to provide. As a result, such super-tankers are required to traverse many additional thousands of miles of ocean in order to deliver their cargos. 
     The construction of a modern super-tanker requires a dry dock facility of huge proportions and other specialized facilities and relatively few shipyards in the world have the capability of undertaking such a project. Also, because of the large investment required to construct and operate such large vessels, ownership of super-tankers is generally restricted to very large and wealthy multinational corporations. 
     SUMMARY OF THE INVENTION 
     It is, therefore, a primary object of the present invention to provide a novel tanker vessel for sea transportation of cargos such as oil which is less expensive to construct and operate than heretofore, requires a much smaller dry dock facility for construction than is required for present day tankers of comparable capacity, can be accommodated in channels and harbors which are much smaller and shallower than those required to accommodate present day tankers of comparable capacity, and can pass through artificial waterways such as the Panama and Suez Canals. 
     The above object, as well as others which will hereinafter become apparent, is accomplished in accordance with the present invention by the provision of a modular tanker vessel consisting of a forward traction unit, a rear powered caboose unit and a series of modular units or barges interposed therebetween wherein the units are serially and flexibly interconnected by means of a universal type coupling which permits relative limited yaw, pitch and roll movement between units. The hull of each barge unit is substantially semi-cylindrically shaped so that the hull inmersed section is circular and the barge units are detachably coupled to each other fore and aft and to the traction and caboose units at the circle center of the circle segment defined by the hull cross section so that hull continuity of the barge train is maintained as the barge units roll relative to each other. 
     The universal type coupling employed to detachably couple the barge units to each other and to the forward traction unit and rear caboose unit consists of a male coupling shaft extending from a universal joint, such as a cardan or Hook joint or the ball of a ball and socket joint mounted at the fore (or aft) of a barge unit and a female socket, for receiving the male coupling shaft, mounted at the aft (or fore) of a mating barge unit. The universal joint of the male mating barge unit is mounted at the center of the circle defined by the hull cross section while the female socket of the female mating barge unit is also mounted, in its final locked position, at the center of the circle defined by the hull cross section. The female socket is carried by a housing adapted for vertical movement on the female mating barge unit so that the female socket can be vertically aligned with the male coupling shaft of the male mating barge during the coupling operation, where there is a difference in draft between the barges to be coupled. Furthermore, the female socket housing permits rotational movement of the female socket about vertical and horizontal axes during coupling of the mating barge units preceding the final locked position of the female socket to further promote the coupling operation. By repositioning the female socket housing so that the female socket is positioned at the center of the circle defined by the barge hull cross section and locking the female socket in its final locket position, following the coupling operation, the respective hulls of the mating barge units are aligned for hull continuity. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Other objects and features of the present invention will become apparent from the following detailed description considered in connection with the accompanying drawings, in which: 
     FIG. 1 is a broken side elevational view of a sea-going barge train according to the present invention; 
     FIG. 2 is a perspective view of the female mating barge unit end according to the present invention; 
     FIG. 3 is a perspective view of the male mating barge unit end according to the present invention; 
     FIG. 4 is a perspective elevational view of the female coupling mechanism; 
     FIG. 5 is an exploded view of the female coupling mechanism of FIG. 4; 
     FIG. 6 is an exploded view of the male coupling mechanism; 
     FIGS. 7 to  10  are schematic side elevational views of the male and female coupling mechanisms showing the sequence of the coupling operation; and 
     FIG. 11 is a cross-sectional side elevational view of the bumper employed between barge units. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Now turning to the drawings, there is shown in FIG. 1 a sea-going barge train according to the present invention, generally designated  10 . Barge train  10 , consists of a forward traction unit, designated  12 , a rear powered caboose unit, designated  14 , and a series of modular units or barges, designated  16 . There can be a relatively large number of barge units  16  in each barge train  10  which are serially coupled together and to forward traction unit  12  and rear powered caboose  14  by means of universal type coupling  18 . Universal type coupling  18 , which will hereinbelow be described in detail, permits relative limited yaw, pitch and roll movement between the various units which thereby dramatically reduces dynamic torsional and bending stresses in the barge train hull due to wave action. 
     Each barge unit  16  is designed to have a draft of about forty feet and a beam of one hundred feet thereby permitting the barge units to pass through the Panama Canal (which is one hundred ten feet wide) and to be acceptable in almost all harbors and channels. As clearly seen in FIGS. 2 and 3, barge unit  16  has a hull  20  of substantially semi-circular cross section, so that the hull immersed section is circular, which minimizes the ratio of the ratio of skin area to displacement thereby minimizing the frictional resistance of hull  20  as it passes through the water. FIG. 2 shows the end of barge unit  16  on which the female coupling mechanism, designated  22 , of coupling  18  is mounted. FIG. 3 shows the end of barge unit  16  on which the male coupling mechanism, designated  24 , of coupling  18  is mounted. As clearly seen, the female socket  26  of female coupling mechanism  22  and the male coupling shaft  28  of male coupling mechanism  24  are located at the circle center of the circle segment defined by the cross section of hull  20 . 
     The forward traction unit  12  has a conventionally shaped bow  30  which merges at the mid and aft portions thereof to a hull  32  having the shape and dimensions of hull  20  of towed barge units  16 . At the rear or aft portion of traction unit  12 , the appropriate female or male coupling mechanism,  22  or  24 , is provided for coupling the traction unit to the first of the serially coupled barge units  16 . As with barge units  16 , the location of the coupling mechanism, female or male as the case may be, is at the circle center of the circle segment defined by the cross section of hull  32 . Traction unit  12  houses the propulsion machinery (not shown) for turning screw propellers  34  for propelling barge train  10 . 
     The rear powered caboose unit  14  has a hull  36  with the same semi-circular cross sectional shape and dimension as hull  20  of barge unit  16  which merges into a streamlined shape at the end  38  of the unit. As in the case of forward traction unit  12 , the front portion of caboose unit  14  is provided with the appropriate female or male coupling mechanism,  22  or  24 , for coupling to the last of the serially coupled barge units  16 . The location of this female or male coupling mechanism is also at the circle center of the circle segment defined by the cross section of hull  36 . Caboose unit  14  houses propulsion machinery (not shown) and can be used to assist in braking barge train  10  when required. Powered caboose unit  14  can also be used as a tug for delivering individual barge units  16  into or out of harbors thereby obviating the necessity for the entire barge train  10  to enter into harbors which may be too small or shallow to accommodate large ships. 
     The hull under water transverse section, designated  40 , of barge train  10  in FIG. 1, always remains circular as the individual units roll relative to each other so that hydraulic continuity of hull section  40  is maintained. This maintenance of the circular shape of hull under water transverse section  40  is a direct result of the shapes of hulls  20 ,  32 , and  36  of the individual units of barge train  10 , the universal type couplings  18  and the locations thereof. 
     Universal type coupling  18 , as indicated above, consists of a female coupling mechanism  22  mounted at the female mating end of a barge unit  16  and a male coupling mechanism  24  mounted at the male mating end of a barge unit  16 . Complementary female and male coupling mechanisms,  22  and  24 , are also mounted at the connecting ends of traction unit  12  and caboose unit  14 . As clearly seen in FIGS. 4 and 5, female coupling mechanism  22  includes female socket  26 , female socket housing  42 , carriage housing  44 , lock collar  46 , pulley  48  and female socket vertical guide  50 . Female socket  26  has a cylindrically shaped barrel portion  52  for receiving therein shaft  28  of male coupling mechanism  24  with a tapered funnel shaped forward portion  54  for facilitating coupling between female socket  26  and shaft  28 . Vertically extending bearing shafts  56  and  58  extend from the top and bottom of barrel portion  52  and engage with top and bottom bearing sockets  60  and  62  in female socket housing  42  for securing female socket  26  therein and permitting pivotal movement of female socket  26  in the horizontal plane. Housing  42  is also provided with a pair of horizontally extending opposing bearing shafts, designated  64 , which engage with bearing sockets  66  in the opposing sidewalls  68  of carriage housing  44  thereby permitting pivotal movement of housing  42  and female socket  26  in the vertical plane. This arrangement permits substantially universal type movement of female socket  26  in order to facilitate coupling with male coupling shaft  28 , which will be explained more fully hereinafter. Carriage housing  44 , which in addition to sidewalls  68  includes top, intermediate and bottom walls  70 ,  81  and  72 , is provided with vertical guide rails  74  which are received in vertical tracks  76  of vertical guide  50 . Vertical guide  50  is fixedly mounted to the female mating end of a barge unit  16 , traction unit  12  or caboose unit  14 . This structure permits vertical movement and positioning of female socket  26  in order to additionally facilitate the coupling procedure as more fully explained hereinafter. Guillotine type lock collar  46  is vertically movable and adapted to engage recess  78  of shaft  28  of male coupling mechanism  24  to prevent withdrawal of shaft  28  following the coupling operation. Engagement of lock collar  46  also restricts rotation in the horizontal plane and clockwise rotation in the vertical plane of female socket  26 . Additional restriction of rotation of female socket  26  in the vertical plane is provided by vertically movable set screw  80  which is guided through aligned openings in top wall  70  and intermediate wall  81  of carriage housing  44  to move into engagement with the top of socket housing  92  following the coupling operation. Pulley  48  guides cable  82  which is threaded through barrel portion  52  of female socket  26  and is attached to the tip  84  of male coupling shaft  28  during the coupling operation. Cable  82  is operated by a winch (not shown) mounted on the deck of barge unit  16  and serves to guide shaft  28  into barrel portion  52  of female socket  26  and to pull barge  16  housing the male coupling mechanism  24  into coupling engagement with barge  16  housing the female coupling mechanism  22 . 
     Male coupling mechanism  24  includes a universal joint, such as a cardan or Hook universal joint or preferably a ball and socket joint as shown in FIG.  6 . The male coupling mechanism  24  shown in FIG. 6 includes a ball  86  from which shaft  28  extends and socket  88  fixedly mounted to the male mating end of barge unit  16  at the circle center of the circle segment defined by the cross section of hull  20  of barge unit  16 . Ball  86  is captured in socket  88  to form a ball and socket with shaft  28  extending through opening  90  at the forward end of socket  88 . 
     The coupling of female coupling mechanism  22  with male coupling mechanism  24  is shown in FIGS. 7 to  10  wherein initially female socket  26  is free to rotate in both the horizontal and vertical planes as shown in FIG. 7, in order to align the same with shaft  28  of male coupling mechanism  24 . Cable  82  is then attached to male coupling shaft  28  and the vertical position of female socket  26  is adjusted in the direction of arrow “A” by mechanism  92 , such as an adjustment screw or hydraulic ram, which causes carriage housing  44  to move verticaly in female socket vertical guide  50 , so that the position of female socket  26  is substantially horizontally aligned with male coupling mechanism  24 , as shown in FIG.  8 . By thus horizontally aligning female socket  26  with male coupling mechanism  24 , allowance is made for any difference in draft between the barge units being coupled. At this time the winch (not shown) associated with female coupling mechanism  22  is operated to take up cable  82  and and draw barge unit  16 , on which male coupling mechanism  24  is mounted, towards barge unit  16  on which female coupling mechanism  22  is mounted, until male coupling shaft  28  enters into barrel portion  52  of female socket  26 , as shown in FIG.  9 . At this point the two barge units are substantially longitudinally aligned so that lock collar  46  may be lowered in the direction of arrow “B” by mechanism  94 , such as an adjustment screw or hydraulic ram, to engage recess  78  of male coupling shaft  28  and lock the same to prevent withdrawal from female socket  26 . Movable set screw  80  is then vertically adjusted to abut against the top of female socket housing  42  to prevent rotation thereof, as well as female socket  26 , in the vertical plane. In the final stage of the coupling operation shown in FIG. 10, mechanism  92  is operated to adjust the vertical position of carriage housing  44  in the direction of arrow “C” to return female socket  26  to its final position at the circle center of the circle segment defined by the cross section of hull  20  of barge unit  16 . Thus, the circle centers of the circle segments defined by the cross sections of the respective hulls  20  of the coupled barge units  16  are axially aligned. In the event the newly connected barge unit is empty it will ride high in the water and must be ballasted by a transfer of cargo, such as oil, from the other barge units of barge train  10  and/or water ballast in its ballast tanks, assuming the barge units have a double hull construction. 
     As clearly seen in FIG. 3, a pair of bumpers  96  are provided at the lateral outer edges on one end, preferably the front end, of barge unit  16  and exert a predetermined pressure on the mated barge unit  16 . The purpose of bumpers  96  is basically fourfold; first, to cushion impact during the coupling operation; two, to impart a limited lateral rigidity to barge train  10 , giving the train a tendency to self align, particularly when at rest; three, to absorb shocks between adjacent barge units  16  in the event the turning radius of barge train  10  exceeds the lower design radius limit; and four, to provide yawing stability to the barge train  10  which is subject to longitudinal compression when in the trough of a wave. The bumper must also be retractable an amount sufficient to prevent interference during the coupling operation. A suitable bumper design is shown in FIG. 11 wherein the bumper housing  98  is mounted in the wall  100  of the end of barge unit  16  and is adapted to slidingly receive the shaft  102  of bumper  96 . Bumper shaft  102  rests on spring  104  which provides sufficient bias to bumper  96  to accomplish the purposes set forth above. Of course, other biasing means may be used in place of spring  104 , such as hydraulic means, etc. To permit retraction of bumper  96  during the coupling operation a cam  106  and cam follower  108  operate on spring  104 . In normal operation, the high point or lobe  110  of cam  106  engages follower  108  to extend spring  104  and hence bumper  96  to its fully extended position. When it is desired to retract bumper  96 , cam  106  is rotated in the direction of arrow “D” so that the low point  112  of cam  106  engages cam follower  108  permitting bumper  106  to be retracted the amount necessary to allow the coupling operation to be performed. 
     In the event the small gap between successive barge units  16  causes an unacceptable turbulent drag on barge train  10 , the gap can be closed by means of a cowling  114 , a broken away portion of which is shown in FIG. 2, or a flexible filler. The addition of cowling  114  serves to maintain hydraulic continuity between adjacent barge units  16  and between forward traction unit  12  and adjacent barge unit  16 . 
     A feasibility study performed with respect to the barge train according to the present invention comparing it to a conventional tanker of 139,200 metric tons shows that the barge train will require 46% less hull steel than the conventional tanker. This demonstrates a very large savings in construction costs over the costs for a conventional tanker. 
     It is to be understood that the foregoing general and detailed descriptions are explanatory of the present invention and are not to be construed as restrictive of the scope of the following claims.