A cover exhibiting a plasticized construction for use with an elongated and inner perimeter defined opening associated with a transportable barge, said cover comprising: a body constructed from a plurality of assembleable cover sections extending in both widthwise and lengthwise fashion relative to an edge defining the open perimeter of the barge, said plurality of cover sections including first and second end sections (10, 26) and intermediately defined and alternating female and male sections (12, 14, 16, 18, 20, 22, 24) arranged in joint abutting fashion, said male cover sections each exhibiting first extending edges along each of opposite ends, alternating female cover sections each exhibiting second extending edges which locate and engage said male extending edges; a plurality of perimeter edge locations brackets defined alongside edge locations of each cover section and including at least one of opposing pairs of lifting eyes and locking pins and adapted for either securing said cover section upon the barge perimeter defining edge or for lifting the cover section off of the bargee and at least one door subassembly (48, 50) traversable over an opening defined in at least one cover section and exhibiting a four point locking and sealing arrangement in a closed position, a pivot handle connected to said door and, upon rotating upwardly, unseating said door from a perimeter edge of the cover in an upwardly displacing and opening position to permit said door to be transported away from the opening for accessing a cargo carrying interior associated with the barge, characterized in that said door subassembly further comprises a first remote end located pair of legs pivotally secured to an underside of the cover section in cooperation with a second handle end actuated pair of pivotal legs, a roller (100, 102) supported at a remote end of each pivotal leg, wherein a pair of inner located and width extending cables extends between opposite and inwardly facing end locations of said door, said cables seating through a pair of doorway perimeter secured and pivotal eye brackets such that said eye brackets guide and restrain said cables all along the range of opening and closing of said door. a body constructed from a plurality of assembleable cover sections extending in both widthwise and lengthwise fashion relative to an edge defining the open perimeter of the barge, said plurality of cover sections including first and second end sections (10, 26) and intermediately defined and alternating female and male sections (12, 14, 16, 18, 20, 22, 24) arranged in joint abutting fashion, said male cover sections each exhibiting first extending edges along each of opposite ends, alternating female cover sections each exhibiting second extending edges which locate and engage said male extending edges; a plurality of perimeter edge locations brackets defined alongside edge locations of each cover section and including at least one of opposing pairs of lifting eyes and locking pins and adapted for either securing said cover section upon the barge perimeter defining edge or for lifting the cover section off of the bargee and at least one door subassembly (48, 50) traversable over an opening defined in at least one cover section and exhibiting a four point locking and sealing arrangement in a closed position, a pivot handle connected to said door and, upon rotating upwardly, unseating said door from a perimeter edge of the cover in an upwardly displacing and opening position to permit said door to be transported away from the opening for accessing a cargo carrying interior associated with the barge, characterized in that said door subassembly further comprises a first remote end located pair of legs pivotally secured to an underside of the cover section in cooperation with a second handle end actuated pair of pivotal legs, a roller (100, 102) supported at a remote end of each pivotal leg, wherein a pair of inner located and width extending cables extends between opposite and inwardly facing end locations of said door, said cables seating through a pair of doorway perimeter secured and pivotal eye brackets such that said eye brackets guide and restrain said cables all along the range of opening and closing of said door.