Abstract: Shrouded towers for supporting adjustably cantilevered work platforms for performing external surface work on ship hulls (such as abrading and painting) are modularized for sake of economy and efficient utilization, including shifting of modules using techniques and equipment currently used for shifting shipping containers. Supply and recovery line connections between support barge-mounted equipment, floating drydock and work platform-mounted work applicators is facilitated by fixed installation of some portions and the provision of flexible connectors between these portions. Alternative adjustable cantilevering structures are disclosed for mounting the work platforms to the vertically movable trolleys. Preferably, rotating wheels rather than compressed air, are used to propel the abrasive grit against the hull surface, and abrasive supply systems having degrees of automated recovery of spent grit are disclosed.

Abstract: Dry, particulate abrasive for use in abrasive blast cleaning of a ship hull is supplied to blasting pots from abrasive supply hopper assemblies lifted into place from a recycling station. Spent abrasive, with debris, is collected and placed on a conveyor belt extending parallel to the keel blocks, for conveying the collected material to the recycling station. There, the collected material is processed to remove undersized and foreign material from the reuseable abrasive grit. The latter is loaded into supply hopper assemblies, which are crane-lifted back into supplying relation with respective blasting pots. By preference, the abrasive blasting work takes place from elevatable, curtain-enclosed platforms supported on a drydock floor, the blasting pots are located on the drydock wing wall, the abrasive grit is ferromagnetic and recovered from the drydock floor partly with the aid of a magnetic abrasive pick-up unit, and the recycling station is located on a barge moored at an end of the drydock.

Abstract: The fixtures in which curved and reinforced flat plates are held while being welded, cleaned, coated and cured include fixedly mounted exterior towers and interior towers removably mounted on rollable bogies (i.e., rail cars or carriages) for ease of transport through a succession of work stations. Subcomponents fabricated on respective bogies are weldingly joined to form module subassemblies after coupling and maneuvering the respective bogies to align the subcomponents (i.e., units). A transverse bulkhead is supported on fluid cushion pallets beside the bogie-supporting rails, so that the transverse bulkhead can be positioned for welding of each subassembly thereto, to provide each respective double-walled vessel hull midbody module.

Abstract: For fabricating a double-hulled tanker, or a major component of one including at least part of longitudinal midbody, a floating drydock is used which has two independently elevatable-depressible sections. The midbody part is made of individual modules, each of which is fabricated in an upended orientation. The upended modules are successively floated onto a tilting assembly on one drydock section, tilted over and serially added to a growing midbody on the other drydock section. The two drydock sections are pumped out and flooded as the process progresses for shifting the positioning of the growing midbody and modules. Other parts, including a bow and stern are added, to provide a complete vessel.

Abstract: For cleaning and/or painting the exterior of a ship hull while the ship is in dry dock, one or more staging devices are provided. Each includes a metal framework tower supporting a vertically movable elevator assembly that comprises a trolley, from which a variably laterally projecting platform is supported on articulated, cantilevered arms. Adjustable, non-porous shrouds enclose a volume of space between the outside of the tower and an increment of one side of the exterior of the ship hull, from above, fore, aft and outside. Cleaning and painting operations are conducted from the platform on the hull increment, and debris is removed from the dry-dock deck area enclosed by the shroud, after which the device is moved by crane, typically twenty feet (6.1 m), towards the ship's bow or stern. The shrouds are then adjusted so that a further hull increment can be worked on. The trolley and extension-retraction of the platform support arms are operated by electrohydraulic winch and hydraulic cylinders, respectively.

Abstract: An improved curved-plate, double-hull tanker construction is provided, having reduced or eliminated transverse reinforcing structure in its midbody, except for bulkheads. The hull, though double, can compare in weight to conventional single hulls, despite being entirely made of mild steel plate. It is made of significantly fewer pieces, with a reduction in welding footage. More of the steel is used in the form of plate, rather than more expensive shapes. Improved productivity is possible, resulting from standardization of parts, less scrap, greater use of jigs and fixtures, automated welding, blast-cleaning and painting, so that not so much staging is needed, the work environment can be safer, and the product can be produced at a lower unit labor cost. Preferably, cathodic epoxy painting is used for durability and reduction in problems due to blast cleaning, solvent evaporation and generation of refuse.

Abstract: The parallel midbody for the hull of a tanker is fabricated of modules, each made of double-walled longitudinal subassemblies welded to one another and to a bulkhead. The subassemblies are made of outer cylindrically curved plates welded edge to edge, and inner cylindrically curved plates welded edge to edge. Longitudinal rib plates are extended between and are welded into joints between curved plates in the inner and outer hulls. The curved plates are convex towards the exterior of the vessel. At respective transitions between the bottom and sides, the inner and outer hulls have bilge radii which approximate in size the radii of curvature of others of the plates including ones both adjacent to and remote from the bottom-to-side transitions. A fixture for facilitating welding of the T-joints of the subassemblies is provided. The subassemblies and modules are fabricated in an up-ended orientation.