Through-hull mooring system

Abstract

A mooring system for floating platform that includes a hawspipe positioned below the sea level when the platform is ballasted for normal operations. The system also includes an outer fairlead that guides a mooring line from the floating platform to an anchoring point on the seabed. The outer fairlead is positioned relative to the floating platform's center of gravity and center of buoyancy. The outer fairlead is also positioned to be above the deballasted waterline.

1 . A floating platform comprising:
 a mono-column hull with a moonpool extending therethrough;   a winch supported by said mono-column hull;   a hawspipe with an inner end open to the moonpool and an outer end open to the exterior of said mono-column hull, wherein the outer end of said hawspipe is below the operational waterline of said mono-column hull;   an outer fairlead positioned relative to the outer end of said hawspipe; and   a mooring line extending from said winch and through said hawspipe and said outer fairlead.   
   
   
       2 . The floating platform of  claim 1 , wherein said outer fairlead is below the center of gravity of said mono-column hull. 
   
   
       3 . The floating platform of  claim 1 , wherein the outer end of said hawspipe is below the depth of an ice flow when said mono-column hull is ballasted for drilling operations. 
   
   
       4 . The floating platform of  claim 3 , wherein the outer end of said hawspipe is above the waterline when said mono-column hull is deballasted. 
   
   
       5 . The floating platform of  claim 4 , wherein said outer fairlead is positioned adjacent to the outer end of said hawspipe and said mooring line extends from said outer fairlead to an anchoring position without crossing any other fairleads. 
   
   
       6 . The floating platform of  claim 1 , wherein said mono-column hull includes ballast tanks below said hawspipe. 
   
   
       7 . The floating platform of  claim 1 , wherein said mono-column hull includes an ice flow zone and a ballasting zone and wherein the outer end of said hawspipe is in the ballasting zone. 
   
   
       8 . The floating platform of  claim 7 , wherein said mooring line extends through the moonpool in the ice flow zone of said mono-column hull. 
   
   
       9 . The floating platform of  claim 8 , wherein the inner end of said hawspipe is positioned adjacent the ice flow zone and the ballasting zone of said mono-column hull. 
   
   
       10 . A floating platform comprising:
 a ballasted hull with a channel extending therethrough, wherein said ballasted hull has an operational waterline when ballasted for drilling operations and a deballasted waterline;   a hawspipe connecting the channel of said ballasted hull with the outside of said ballasted hull;   a winch supported by said ballasted hull;   an inner fairlead connected to said ballasted hull and operationally aligned with said winch; and   an outer fairlead connected to said ballasted hull and positioned between the operational waterline and the deballasted waterline of said ballasted hull; wherein said inner fairlead and said outer fairlead are in operable alignment with said hawspipe.   
   
   
       11 . The floating platform of  claim 10  wherein the channel extending through said ballasted hull is a moonpool. 
   
   
       12 . The floating platform of  claim 10 , wherein said outer fairlead transfers mooring forces to said ballasted hull as close to the center of gravity as possible. 
   
   
       13 . The floating platform of  claim 10 , wherein said outer fairlead is positioned below the depth of ice when said ballasted hull in a ballasted for drilling operations. 
   
   
       14 . The floating platform of  claim 10 , wherein said ballasted hull further comprises:
 an ice flow section shaped to minimize the force from ice flowing past said floating platform; and   a ballasted section below said ice flow section, wherein said ballasted section is below the ice when the floating platform is ballasted for drilling operations.   
   
   
       15 . The floating platform of  claim 14 , a portion of said hawspipe is above the center of buoyancy of said floating platform when ballasted for normal drilling operations. 
   
   
       16 . The floating platform of  claim 15 , further comprising a second ballasted hull with a channel extending therethrough, wherein said second ballasted hull has an operational waterline when ballasted for drilling operations and an deballasted waterline;
 a second hawspipe connecting the channel of said second ballasted hull with the outside of said second ballasted hull;   a second winch supported by said second ballasted hull;   an second inner fairlead connected to said second ballasted hull and longitudinally aligned with said second winch; and   a second outer fairlead connected to said second ballasted hull and positioned between the ballasted waterline and the un-ballasted waterline of said second ballasted hull; wherein said second inner fairlead and said second outer fairlead are in operable alignment with said second hawspipe.   
   
   
       17 . A mooring system comprising;
 a mono-column hull and a moonpool extending therethrough, said mono-column hull having a deballasted waterline and a range of operational waterlines above the deballasted waterline;   a mooring winch supported by said mono-column hull;   an inner fairlead positioned in the moonpool of said mono-column hull;   a hawspipe between the moonpool and the exterior of said mono-column hull; wherein said hawspipe opens to the exterior of said mono-column hull above the deballasted waterline; and   an outer fairlead connected to the exterior of said mono-column hull adjacent to said hawspipe.   
   
   
       18 . The mooring system of  claim 17 , wherein said mooring winch is cantilevered over the moonpool of said mono-column hull. 
   
   
       19 . The mooring system of  claim 17 , wherein said inner and outer fairleads are operationally aligned with said hawspipe. 
   
   
       20 . The mooring system of  claim 17 , wherein said mono-column hull has a center of gravity and a deballasted center of buoyancy, and wherein said hawspipe exits said mono-column hull above the deballasted center of buoyancy. 
   
   
       21 . The mooring system of  claim 20 , wherein said mono-column hull has a deballasted waterline, and wherein said hawspipe exits said mono-column hull above the deballasted waterline. 
   
   
       22 . The mooring system of  claim 21 , wherein said mono-column hull include an ice-flow zone; and wherein said hawspipe exits said mono-column hull below said ice-flow zone. 
   
   
       23 . The mooring system of  claim 22 , wherein said mono-column hull further includes ballasting tanks positioned below said hawspipe.