Apparatus and method for enhancing buoyancy capacity of a spar

Abstract

The buoyancy capacity of a spar (i.e., a floating platform in deep waters) is enhanced using a modular can. The modular can includes a plurality of compartments releasably connectable (e.g., via bolts) to one another. The spar includes a spar deck and a hull surrounding a center well. The center well is partitioned by walls that form slots inside the hull. One of the slots is vacant. The vacant slot includes a compliant guide mounted to the walls. The modular can is assembled inside the vacant slot and progressively lowered into it so that the buoyancy can interfaces with the spar at the compliant guide. In use, the modular can supports the spar at the spar deck, the compliant guide, and/or a soft can coupled below the hull via a truss.

What is claimed is: 
     
         1 . A modular can for enhancing the buoyancy capacity of a spar, the modular can comprising:
 a plurality of compartments releasably connected to one another; and   means for coupling the buoyancy can to the spar.   
     
     
         2 . The modular can of  claim 1 , wherein the plurality of compartments comprise:
 at least one void compartment directly or indirectly connected to at least one an air-over-water compartment;   wherein the at least one void compartment comprises a top deck, a cylindrical inner shell connected below the top deck, and a bottom deck connected below the cylindrical inner shell;
 wherein the top deck comprises a top outer flange that extends beyond an outermost perimeter of the cylindrical inner shell, wherein the bottom deck comprises a bottom outer flange that extends beyond the outermost perimeter of the cylindrical inner shell; 
 wherein the top deck, the cylindrical inner shell, and the bottom deck form a close compartment that encloses a void space; and 
   wherein the at least one an air-over-water compartment comprises a top deck, a cylindrical inner shell connected below the top deck, a bottom deck connected below the cylindrical inner shell, and a watertight deck connected inside the cylindrical inner shell between the top deck and the bottom deck;
 wherein the top deck comprises a top outer flange that extends beyond an outermost perimeter of the cylindrical inner shell, wherein the bottom deck comprises a bottom outer flange that extends beyond the outermost perimeter of the cylindrical inner shell, wherein the watertight deck has a diameter that fits inside an innermost perimeter of the cylindrical inner shell; 
 wherein the top deck, the cylindrical inner shell, and the bottom deck form an open compartment that includes at least one top flooding hole located above the watertight deck and at least one bottom flooding hole located below the watertight deck, wherein the top flooding hole and the bottom flooding hole are configured to allow water to flow inside and air to flow outside of the at least one an air-over-water compartment to form a variable ballast. 
   
     
     
         3 . The modular can of  claim 2 , wherein the means for coupling the buoyancy can to the spar comprise a structural layer that surrounds the cylindrical inner shell of the at least one an air-over-water compartment and extends above and below the watertight deck of the at least one an air-over-water compartment. 
     
     
         4 . The modular can of  claim 2 , further comprising:
 an elastomer layer sized to fit between the top outer flange of the at least one void compartment and a stopper flange of a deck of the spar; and   a clamp configured to fasten the stopper flange of the deck of the spar, the elastomer layer, and the top outer flange of the at least one void compartment, together.   
     
     
         5 . The modular can of  claim 1 , wherein the plurality of compartments are bolted head to toe. 
     
     
         6 . A spar for use as a floating platform in deep waters, comprising:
 a spar deck;   a hull surrounding a center well, wherein the center well is partitioned by walls that form a plurality of slots, wherein at least one of the slots include a compliant guide mounted to some of the walls;   tanks surrounding the hull below the spar deck;   a truss located below the tanks and coupled to the tanks;   a soft tank located below the truss and coupled to the truss;   a modular can located in the at least one of the slots, the modular can including:
 a plurality of compartments releasably connected to one another; and 
 means for coupling the buoyancy can to the spar; 
   wherein the means for coupling the buoyancy can to the spar interface with the spar at the compliant guide; and   wherein, in use, the spar is supported by the modular can at one or more of the spar deck, the compliant guide, and the soft can, so that the buoyancy capacity of the spar is enhanced.   
     
     
         7 . The spar of  claim 6 , wherein the plurality of compartments comprise:
 at least one void compartment directly or indirectly connected to at least one an air-over-water compartment;   wherein the at least one void compartment comprises a top deck, a cylindrical inner shell connected below the top deck, and a bottom deck connected below the cylindrical inner shell;
 wherein the top deck comprises a top outer flange that extends beyond an outermost perimeter of the cylindrical inner shell, wherein the bottom deck comprises a bottom outer flange that extends beyond the outermost perimeter of the cylindrical inner shell; 
 wherein the top deck, the cylindrical inner shell, and the bottom deck form a close compartment that encloses a void space; and 
   wherein the at least one an air-over-water compartment comprises a top deck, a cylindrical inner shell connected below the top deck, a bottom deck connected below the cylindrical inner shell, and a watertight deck connected inside the cylindrical inner shell between the top deck and the bottom deck;
 wherein the top deck comprises a top outer flange that extends beyond an outermost perimeter of the cylindrical inner shell, wherein the bottom deck comprises a bottom outer flange that extends beyond the outermost perimeter of the cylindrical inner shell, wherein the watertight deck has a diameter that fits inside an innermost perimeter of the cylindrical inner shell; 
 wherein the top deck, the cylindrical inner shell, and the bottom deck form an open compartment that includes at least one top flooding hole located above the watertight deck and at least one bottom flooding hole located below the watertight deck, wherein the top flooding hole and the bottom flooding hole are configured to allow water to flow inside and air to flow outside of the at least one an air-over-water compartment to form a variable ballast. 
   
     
     
         8 . The spar of  claim 7 , wherein the means for coupling the buoyancy can to the spar comprise a structural layer that surrounds the cylindrical inner shell of the at least one an air-over-water compartment and extends above and below the watertight deck of the at least one an air-over-water compartment. 
     
     
         9 . The spar of  claim 7 , further comprising:
 an elastomer layer sized to fit between the top outer flange of the at least one void compartment and a stopper flange of the spar deck; and   a clamp configured to fasten the stopper flange of the spar deck, the elastomer layer, and the top outer flange of the at least one void compartment, together.   
     
     
         10 . The spar of  claim 6 , wherein the plurality of compartments are bolted head to toe. 
     
     
         11 . The spar of  claim 10 , further comprising locking dogs located on the spar deck around the at least one slot, the locking dock having an extended configuration wherein the locking dogs are capable of retaining the modular can in or above the at least one slot, and a retracted configuration wherein the locking dogs allow the modular can to be lowered into the at least one slot. 
     
     
         12 . A method of enhancing a buoyancy capacity of a spar, the spar including a spar deck, a hull surrounding a center well, wherein the center well is partitioned by walls that form a plurality of slots inside the hull, wherein at least one of the slots include a compliant guide mounted to some of the walls, the spar further including tanks surrounding the hull below the spar deck, a truss located below the tanks and coupled to the tanks, and a soft tank located below the truss and coupled to the truss, the method comprising:
 providing a modular can, the modular can including:
 a plurality of compartments releasably connected to one another; and 
 means for coupling the buoyancy can to the spar; 
   placing the modular can in the at least one of the slots;   interfacing the means for coupling the buoyancy can to the spar with the spar at the compliant guide; and   using the modular can to support the spar at one or more of the spar deck, the compliant guide, and the soft can.   
     
     
         13 . The method of  claim 12 , wherein the plurality of compartments comprise:
 at least one void compartment directly or indirectly connected to at least one an air-over-water compartment;   wherein the at least one void compartment comprises a top deck, a cylindrical inner shell connected below the top deck, and a bottom deck connected below the cylindrical inner shell;
 wherein the top deck comprises a top outer flange that extends beyond an outermost perimeter of the cylindrical inner shell, wherein the bottom deck comprises a bottom outer flange that extends beyond the outermost perimeter of the cylindrical inner shell; 
 wherein the top deck, the cylindrical inner shell, and the bottom deck form a close compartment that encloses a void space; and 
   wherein the at least one an air-over-water compartment comprises a top deck, a cylindrical inner shell connected below the top deck, a bottom deck connected below the cylindrical inner shell, and a watertight deck connected inside the cylindrical inner shell between the top deck and the bottom deck;
 wherein the top deck comprises a top outer flange that extends beyond an outermost perimeter of the cylindrical inner shell, wherein the bottom deck comprises a bottom outer flange that extends beyond the outermost perimeter of the cylindrical inner shell, wherein the watertight deck has a diameter that fits inside an innermost perimeter of the cylindrical inner shell; 
 wherein the top deck, the cylindrical inner shell, and the bottom deck form an open compartment that includes at least one top flooding hole located above the watertight deck and at least one bottom flooding hole located below the watertight deck, wherein the top flooding hole and the bottom flooding hole are configured to allow water to flow inside and air to flow outside of the at least one an air-over-water compartment to form a variable ballast. 
   
     
     
         14 . The method of  claim 13 , wherein the means for coupling the buoyancy can to the spar comprise a structural layer that surrounds the cylindrical inner shell of the at least one an air-over-water compartment and extends above and below the watertight deck of the at least one an air-over-water compartment. 
     
     
         15 . The method of  claim 13 , further comprising:
 providing an elastomer layer sized to fit between the top outer flange of the at least one void compartment and a stopper flange of the spar deck; and   providing a clamp; and   fastening the stopper flange of the spar deck, the elastomer layer, and the top outer flange of the at least one void compartment, together.   
     
     
         16 . The method of  claim 12 , comprising bolting the plurality of compartments head to toe. 
     
     
         17 . The method of  claim 16 , further comprising:
 hoisting a first of the plurality of compartments in or above the at least one of the slots;   extending locking dogs located on the spar deck around the at least one slot to retain the first of the plurality of compartments in or above the at least one of the slots;   hoisting a second of the plurality of compartments on top of the first of the plurality of compartments;   bolting the second of the plurality of compartments to the first of the plurality of compartments;   retracting locking dogs the locking dogs to allow the first of the plurality of compartments and the second of the plurality of compartments to be lowered into the at least one slot.