Vessel mooring system and method for its installation

A method of installing a mooring system in a vessel having a vertical well extending from the deck of the vessel to the bottom plates of the vessel comprising:

• connecting a lower bearing ring adjacent to the underside of said bottom plates said lower bearing ring circumscribing said well;
• placing a lower turret unit substantially within said lower bearing ring, said lower turret unit having an annular shape with a larger cross-sectional area, in a plane perpendicular to the longitudinal axis of said well, than said well, said lower turret unit rotatably mounted to said lower bearing ring for lateral guidance and prevention of uplift of said lower turret unit in a direction from said bottom plates to said deck;
• placing a middle turret unit substantially within said well;
• connecting said middle turret unit to said lower turret unit;
• connecting an upper bearing ring adjacent to the top of the deck, said upper bearing ring circumscribing said well;
• and
• connecting an upper turret unit to said middle turret unit, said upper turret unit having an annular shape with a larger cross-sectional area, in a plane perpendicular to the longitudinal axis of said well, than said well, said upper turret unit rotatably mounted to said upper bearing ring for lateral guidance thereof and for support of the weight of the assembly of said upper, middle and lower turret units;
• mounting a first continuous annular ring adjacent to the bottom plates of said deck, said first continuous annular ring circumscribing said well and having a bearing surface disposed in substantial concentric alignment to said well;
• installing a plurality of first bearing pads to the outer periphery of said lower turret unit said first bearing pads disposed substantially concentrically to said first continuous annular ring, thereby allowing said lower turret unit to rotate with respect to said lower bearing ring while being guided by said lower bearing ring due to the interaction of said first continuous annular ring and said first bearing pads;
• mounting a second continuous annular ring adjacent to said deck, said second continuous annular ring circumscribing said well and disposed in a plane substantially perpendicular to the longitudinal axis of said well;
• installing a plurality of second bearing pads adjacent to the lowermost surface of said upper turret unit, said second bearing pads disposed in a plane substantially parallel to said second continuous annular ring and in running contact therewith, thereby allowing the assembly of said upper, lower, and middle turret units to be supported from and rotate with respect to said deck;
• installing a third continuous annular ring secured adjacent said deck, said third continuous annular ring disposed in substantial concentric alignment to said well while circumscribing said well;
• installing a plurality of third bearing pads to said upper turret unit substantially concentrically to said third continuous annular ring, thereby providing lateral guidance to said upper turret unit due to the interaction of said third continuous bearing ring and said third bearing pads while allowing said upper turret unit to rotate with respect to said deck;
• installing a fourth continuous annular ring adjacent the bottom plates of said deck, said fourth ring disposed in a plane perpendicular to the longitudinal axis of said well and circumscribing said well;
• installing a plurality of fourth bearing pads adjacent to the topmost surface of said lower turret unit and in a plane substantially parallel to said fourth continuous annular ring, whereupon said lower turret unit is prevented from being uplifted in a direction from said bottom plates to said deck while rotating with respect to said first and fourth continuous annular rings;
• installing a plurality of chain pipes in said lower, middle, and upper turret units extending substantially in a direction parallel to the longitudinal axis of said well;
• installing at least one riser pipe substantially parallel to said chain pipes, said riser pipe extending from said upper turret unit to said lower turret unit;
• and
• wherein the step of connecting said upper turret unit further includes the step of:
• installing a plurality of chain drives on said upper turret unit each said chain drive adapted to pay out and reel in a chain through one of said chain pipes for securing the assembly of said upper, middle, and lower turret units to the subsea floor while allowing the vessel to rotate about said upper, middle, and lower turret units;
• securing a swivel joint onto said upper turret unit said swivel joint in fluid communication with said riser pipe;
• addition of a plurality of arcuate wear surfaces extending from substantially the top to substantially the bottom of said lower turret unit, each chain extending through a chain pipe and guided through said lower turret unit by contact with one of said arcuate wear surfaces;
• and
• installation of said upper turret unit further includes the steps of:
• installing a gear on said upper turret unit;
• installing a deck mounted motor driven gear to engage said gear on said upper turret unit thereby causing the vessel to weathervane about an anchored upper turret unit.

A vessel mooring system for newly constructed vessels and for retrofitting on existing vessels, said vessels having a deck, bottom plates, a well extending substantially vertically from said deck to said bottom plates below the vessel's water line comprising:

• a lower turret unit rotatably mounted below said bottom plates, said lower turret unit having an annular shape with a larger cross-sectional area in a plane substantially perpendicular to the longitudinal axis of said well, than said well;
• lower bearing means circumscribing said well and extending below said bottom plates for laterally guiding said lower turret unit and for counteracting uplift forces on said lower turret unit in a direction from said bottom plates toward said deck, said lower bearing means connected to said bottom plates of said vessel;
• a middle turret unit connected to the top of said lower turret unit and disposed substantially within said well, said middle turret unit having a substantially smaller cross-sectional area than the cross-sectional area of said lower turret unit in a plane perpendicular to the longitudinal axis of said well;
• the ratio of the opening of said well to the width of the deck adjacent said well being in the range of 1:5 to 1:10,
• an upper turret unit connected to said middle turret unit and disposed substantially above said deck of said vessel, said upper turret unit having an annular shape with a larger cross-sectional area in a plane perpendicular to the longitudinal axis of said well, than said well;
• and
• upper bearing means mounted to the top of said deck circumscribing said well for supporting the weight of the connected assembly of said upper, middle, and lower turret units above said deck and laterally guiding said upper turret unit;
• whereupon the vessel can be moored in seas having wave heights as great as ninety to one hundred feet.

A vessel mooring system for a vessel having a deck, bottom plates, a well extending substantially vertically from said deck to said bottom plates below the vessel's water line comprising:

• a lower turret unit rotatably mounted below said bottom plates, said lower turret unit having an annular shape with a larger cross-sectional area in a plane substantially perpendicular to the longitudinal axis of said well, than said well;
• lower bearing means circumscribing said well and extending below said bottom plates for laterally guiding said lower turret unit and for counteracting uplift forces on said lower turret unit in a direction from said bottom plates toward said deck, said lower bearing means connected to said bottom plates of said vessel;
• a middle turret unit connected to the top of said lower turret unit and disposed substantially within said well, said middle turret unit having a substantially smaller cross-sectional area than the cross-sectional area of said lower turret unit in a plane perpendicular to the longitudinal axis of said well;
• an upper turret unit connected to said middle turret unit and disposed substantially above said deck of said vessel, said upper turret unit having an annular shape with a large cross-sectional area in a plane perpendicular to the longitudinal axis of said well, than said well;
• and
• upper bearing means mounted to the top of said deck circumscribing said well for supporting the weight of the connected assembly of said upper, middle, and lower turret units above said deck and laterally guiding said upper turret unit;
• mooring means extending through said upper, middle and lower turret units for anchoring said vessel to the bottom of a body of water;
• said lower bearing means further comprises:
• a first continuous annular ring mounted adjacent the bottom plates of said deck, said first continuous annular ring circumscribing said well and having a bearing surface disposed in substantial concentric alignment to said well;
• said lower turret unit further comprises:
• a plurality of first bearing pads mounted to the outer periphery of said lower turret unit said first bearing pads disposed substantially concentrically to said first continuous annular ring, thereby allowing said lower turret unit to rotate with respect to said lower bearing means while being guided by said lower bearing means due to the interaction of said first continuous annular ring and said first bearing pads;
• said upper bearing means further comprises:
• a second continuous annular ring adjacent said deck, said second continuous annular ring circumscribing said well and disposed in a plane substantially perpendicular to the longitudinal axis of said well;
• said upper turret unit further comprises:
• a plurality of second bearing pads mounted adjacent to the lowermost surface of said upper turret unit, said second bearing pads disposed in a plane substantially parallel to said second continuous annular ring and in running contact therewith, thereby allowing the assembly of said upper, lower, and middle turret units to be supported from and rotate with respect to said deck;
• said upper bearing means further comprises:
• a third continuous annular ring secured adjacent said deck, said third continuous annular ring disposed in substantial concentric alignment to said well while circumscribing said well;
• said upper turret unit further comprises:
• a plurality of third bearing pads mounted to said upper turret unit substantially concentrically to said third continuous annular ring, thereby providing lateral guidance to said upper turret unit due to the interaction of said third continuous annular ring and said third bearing pads while allowing said upper turret unit to rotate with respect to said deck;
• said lower bearing means further comprises:
• a fourth continuous annular ring adjacent the bottom plates, said fourth ring disposed in a plane perpendicular to the longitudinal axis of said well and circumscribing said well;
• said lower turret unit further comprises:
• a plurality of fourth bearing pads adjacent to the topmost surface of said lower turret unit and in a plane substantially parallel to said fourth continuous annular ring, whereupon said lower turret unit is prevented from being uplifted in a direction from said bottom plates to said deck while rotating with respect to said first and fourth continuous annular rings;
• a plurality of chain pipes in said lower, middle, and upper turret units extending substantially in a direction parallel to the longitudinal axis of said well;
• at least one riser pipe substantially parallel to said chain pipes, said riser pipe extending from said upper turret unit to said lower turret unit;
• and
• a plurality of chain drives on said upper turret unit each said chain drive adapted to pay out and reel in a chain through one of said chain pipes for securing the assembly of said upper, middle, and lower turret units to the subsea floor while allowing the vessel to rotate about said upper, middle, and lower turret units;
• a swivel joint mounted to said upper turret unit said swivel joint in fluid communication with said riser pipe;
• said lower turret unit further comprises:
• arcuate wear surfaces extending from substantially the top to substantially the bottom of said lower turret unit, each chain extending through a chain pipe and guided through said lower turret unit by contact with one of said arcuate wear surfaces;
• said upper turret unit further comprising, a first gear;
• and
• a second gear secured to said deck and operably connected to said first gear for weathervaning the vessel when said assembly of said upper, middle and lower turret units is anchored to the subsea floor.