Platform for afloat-condition drilling

Claim 1

A BUOYANT DRILLING RIG BASE FOR AFLOAT CONDITION DRILLING, COMPRISING, A HULL CONSTRUCTED OF HORIZONTALLY DISPOSED HOLLOW TUBULAR MEMBERS INTERCONNECTED TO DEFINE A GENERALLY V-SHAPE, A DECK HAVING A CONFIGURATION CORRESPONDING SUBSTANTIALLY TO THAT OF THE HULL, A WAVE-TRANSPARENT STRUCTURE SUPPORTING THE DECK FROM SAID HULL AND FORMING WITH SAID HULL MEMBERS BUOYANCY ELEMENTS HAVING DISPLACEMENT SUFFICIENT TO SUPPORT SAID BASE IN PARTIALLY SUBMERGED FLOATING POSITION IN A WATER BODY WITHOUT RIGID CONNECTION TO THE UNDERLYING LAND, SAID WAVE-TRANSPARENT STRUCTURE INCLUDING: (A) VERTICALLY DISPOSED HOLLOW END COLUMNS EXTENDING BETWEEN THE OUTER ENDS AND APEX PORTIONS OF THE HULL AND THE CORRESPONDING DECK PORTIONS, SAID END COLUMNS HAVING A RELATIVELY LARGE UNIFORM DIAMETER THROUGHOUT THEIR LENGTH; (B) A PLURALITY OF VERTICALLY DISPOSED HOLLOW INTERMEDIATE COLUMNS LATERALLY SPACED ALONG THE HULL MEMBERS BETWEEN SAID END COLUMNS, SAID INTERMEDIATE COLUMNS BEING OF SUBSTANTIALLY LESSER DIAMETER THAN SAID END COLUMNS; (C) SAID INTERMEDIATE COLUMNS HAVING ANNULAR ENLARGEMENTS OF SUBSTANTIALLY LESSER LENGTH THAN SAID INTERMEDIATE COLUMNS FORMING AUXILIARY BUOYANCY CHAMBERS POSITIONED ON THE COLUMNS AND HAVING THEIR OPPOSITE ENDS IN SUBSTANTIAL VERTICALLY SPACED RELATION TO BOTH THE HULL AND THE DECK AND LOCATED TO BE PARTIALLY SUBMERGED WHEN THE BASE IS SUBMERGED TO ITS WORKING LEVEL IN THE WATER BODY, SAID AUXILIARY BUOYANCY CHAMBERS HAVING COLLECTIVE TOTAL BUOYANCY TO PROVIDE TONS-PER-INCH IMMERSION SUFFICIENT TO PREVENT SUBSTANTIAL VERTICAL MOVEMENT OF THE BASE UNDER VARYING LIVE LOADS; (D) THE INTERMEDIATE COLUMN DISPOSED NEXT ADJACENT EACH OF SAID END COLUMNS HAVING A RELATIVELY LARGE UNIFORM DIAMETER SECTION EXTENDING UPWARDLY FROM SAID HULL MEMBERS TO ABOUT THE LEVEL OF THE UPPER ENDS OF SAID AUXILIARY BUOYANCY CHAMBERS ON THE OTHER INTERMEDIATE COLUMNS, AND HAVING A RELATIVELY SMALLER DIAMETER SECTION EXTENDING UPWARDLY FROM SAID LEVEL TO THE DECK; (E) THE SPACES BETWEEN THE SEVERAL COLUMNS BEING CLEAR OF ANY INTERVENING CROSS-BRACING TO PROVIDE MAXIMUM WAVE-TRANSPARENCY, AND MEANS FOR BALLASTING AND DEBALLASTING THE SEVERAL BUOYANCY ELEMENTS WHEREBY TO REGULATE THE EXTENT OF SUBMERGENCE OF SAID BASE IN THE WATER BODY.