Vessel hull construction and method

A method for fabricating a major component of a double-hulled tanker, comprising:

• erecting from an upended to an upright orientation a vessel hull module for a double-walled tanker midbody, which module includes inner and outer hulls interconnected by longitudinal plates so as to define double-hull left, right and bottom walls each comprising a respective series of longitudinal cells, and a deck, bridging between said left and right walls, and transverse bulkhead means closing corresponding one ends of said cells and a corresponding one end of the space defined peripherally inwardly of said left, right and bottom walls and said deck, the opposite ends of said space being open, by:
• (a) providing a floating drydock section which is capable of being elevated and depressed in a body of water by pumping out and flooding ballast tanks thereof;
• (b) providing on said floating drydock a trunnion assembly including a support and trunnions journalling the support for pivotal movement about a substantially horizontal axis between a substantially horizontal first position, and a substantially vertical second position;
• (c) disposing said floating drydock in a body of water in a floating condition and disposing in the same body of water, adjacent said drydock, said module in an upended condition, floating with its closed end down;
• (d) depressing said drydock by flooding ballast tanks thereof and floating said upended module onto said support, with said support in said first, generally horizontal position, so that said upended module is supported on said support with said bottom wall and said deck of said upended module disposed on opposite sides of an imaginary vertical plane containing said axis of said trunnion assembly;
• (e) filling a heavier-than-air fluid medium into at least some of said cells of said bottom wall and pumping water out of the ballast tanks of said drydock section, so as to gradually elevate said drydock section and thereby cause said upended module on said support to rotate about said axis, with said support, until said support has said second, generally horizontal second position and said module is upright and rests on a support surface which is located adjacent to said support of said trunnion assembly,
• step (c) including:
• assembling said module on said floating drydock section from a plurality of hull and deck subassemblies and transverse bulkhead elements, while said floating drydock section is elevated in said body of water;
• depressing said elevated floating drydock and floating off thereof said upended module into said body of water;
• and
• installing additional structural elements in said upended module while said upended module is floating in said body of water;
• while said upended module is floating in said body of water, likewise successively assembling a plurality of like modules on said floating drydock and floating each off into said body of water as a respective upended module;
• steps (d) and (e) being successively conducted on each of said modules;
• (f) shifting along said support each upright module most recently subjected to step (e) along its own longitudinal axis away from said trunnion assembly before each respectively successive conduct of step (e);
• and
• (g) serially connecting all of said upright modules to one another end-to-end, thereby providing a tanker longitudinal midbody component.

A method for fabricating a double-hulled tanker, comprising:

• conducting the following series of steps to provide a bow-ended first longitudinal midbody component for said tanker:
• erecting from an upended to an upright orientation a vessel hull module for a double-walled tanker midbody, which module includes inner and outer hulls interconnected by longitudinal plates so as to define double-hull left, right and bottom walls each comprising a respective series of longitudinal cells, and a deck, bridging between said left and right walls, and transverse bulkhead means closing corresponding one ends of said cells and a corresponding one end of the space defined peripherally inwardly of said left, right and bottom walls and said deck, the opposite ends of said space being open, by:
• (a) providing a floating drydock section which is capable of being elevated and depressed in a body of water by pumping out and flooding ballast tanks thereof;
• (b) providing on said floating drydock a trunnion assembly including a support and trunnions journalling the support for pivotal movement about a substantially horizontal axis between a substantially horizontal first position, and a substantially vertical second position;
• (c) disposing said floating drydock in a body of water in a floating condition and disposing in the same body of water, adjacent said drydock, said module in an upended condition, floating with its closed end down;
• (d) depressing said drydock by flooding ballast tanks thereof and floating said upended module onto said support, with said support in said first, generally horizontal position, so that said upended module is supported on said support with said bottom wall and said deck of said upended module disposed on opposite sides of an imaginary vertical plane containing said axis of said trunnion assembly;
• (e) filling a heavier-than-air fluid medium into at least some of said cells of said bottom wall and pumping water out of the ballast tanks of said drydock section, so as to gradually elevate said drydock section and thereby cause said upended module on said support to rotate about said axis, with said support, until said support has said second, generally horizontal second position and said module is upright and rests on a support surface which is located adjacent to said support of said trunnion assembly,
• step (c) including:
• assembling said module on said floating drydock section from a plurality of hull and deck subassemblies and transverse bulkhead elements, while said floating drydock section is elevated in said body of water;
• depressing said elevated floating drydock and floating off thereof said upended module into said body of water;
• and
• installing additional structural elements in said upended module while said upended module is floating in said body of water;
• while said upended module is floating in said body of water, likewise successively assembling a plurality of like modules on said floating drydock and floating each off into said body of water as a respective upended module;
• steps (d) and (e) being successively conducted on each of said modules;
• (f) shifting along said support each upright module most recently subjected to step (e) along its own longitudinal axis away from said trunnion assembly before each respectively successive conduct of step (e);
• and
• (g) serially connecting all of said upright modules to one another end-to-end, thereby providing a tanker longitudinal midbody component;
• (h) providing a second said floating drydock section adjacent the first-described said floating drydock section;
• and
• as step (f) is conducted, shifting the respective upright module most recently subjected to step (e) from said support on said first-described floating drydock section, onto said second floating drydock section;
• step (g) being conducted on said second floating drydock section;
• at each instance while conducting step (g) that a respectively more recently assembled said upright module is connected end-to-end to a respectively previously assembled said upright module, the respective more recently assembled said upright module is supported on said first-described floating drydock section and the respective previously assembled said upright module is supported on said second floating drydock section, and the respective module ends to be connected to one another are disposed effectively between said first-described and second floating drydock modules;
• and, as part of said each instance, said first-described and second floating drydock modules are positionally adjusted relative to one another on said body of water for aligning the respective said module ends to be connected;
• (i) after step (h) has been completed, providing on said support of said first-described floating drydock section a tanker bow section having an end effectively disposed between said first-described and said second floating drydock sections in juxtaposition with an end of said tanker longitudinal midbody component;
• (j) connecting said end of said tanker longitudinal midbody to said end of said tanker bow section, to thereby provide a bow-ended tanker midbody component;
• and
• (k) depressing said first-described and second floating drydock sections and floating said bow-ended tanker midbody component therefrom onto said body of water;
• (1) repeating the series of steps (a)-(h) to provide a second tanker longitudinal midbody component;
• (m) after step (1) has been completed, providing on said support of said first-described floating drydock section a tanker stern section having an end effectively disposed between said first-described and said second floating drydock sections in juxtaposition with an end of said second tanker longitudinal midbody component;
• (n) connecting said end of said second tanker longitudinal midbody to said end of said tanker stern section, to thereby provide a respective stern-ended tanker midbody component;
• (o) depressing said first-described and second floating drydock sections and floating said stern-ended tanker midbody component therefrom onto said body of water;
• (p) maneuvering said bow-ended and stern-ended tanker midbody components and said first-described and second floating drydock sections so that one of said components is supported by said first-described floating drydock section and the other of said components is supported by said second floating drydock sections, with respective free ends of each juxtaposed effectively between said first-described and second floating drydock sections and said components in longitudinal alignment;
• (q) joining said free ends together to provide a double-hulled tanker;
• and
• (r) depressing said first-described and second floating drydock sections and floating said double-hulled tanker therefrom onto said body of water.