Claims
- 1. A method of constructing a column stabilized semisubmersible variable draft vessel comprising the steps of:
- fabricating a pair of elongated hulls with each of said hulls having an oblong transverse cross section with a breadth greater than its height and having top and bottom substantially planar parallel surfaces extending substantially the entire length of each hull between bow and stern thereof; and disposing said hulls in substantially parallel spaced side-by-side relation with each of said hulls spaced from and lying on an opposite side of the longitudinal centerline of said vessel;
- fabricating a working platform and also means for supporting said platform in fixed spaced relation above said hulls a predetermined height and normally lying in a generally horizontal plane, said means including at least three pairs of upstanding columns connecting with said hulls and said platform, each of said columns being made with a substantially constant cross sectional area over the effective height of the column between the platform and associated hull;
- fabricating and disposing a plurality of longitudinally spaced structural truss means interconnecting and reinforcing the structural relationship of the hulls, platform and columns, with such truss means including substantially transversely extending members structurally interconnecting uppermost portions of the hulls;
- forming said vessel with said hulls, columns and related components so that the vessel is generally rectangular in plan with the length of said vessel along its longitudinal centerline and roll axis being at least plural times as great as the width of said vessel along its transverse centerline and pitch axis; locating at least three of said columns on each of said two hulls on opposite sides of the vessel's roll axis with pairs of such columns being located near opposite ends of each of said hulls on opposite sides of the vessel's pitch axis and at least another pair of said columns being located at an intermediate position on each of said hulls; and providing such columns with configurations and cross-sectional areas throughout effective height thereof and locating said columns at distances from the vessel's longitudinal roll axis and transverse pitch axis such that said columns will maintain the vessel's metacenter above the vessel's center of gravity for the high draft semisubmerged operating positions of the vessel and also such that said columns will provde righting moment about the longitudinal roll axis which is less than righting moment provided about said transverse pitch axis when the vessel is in semisubmerged column stabilized operating position;
- providing said hulls with ballast compartments, and providing means for ballasting said vessel when required to alter its draft between a low draft hull-supported floating condition in which the hulls have freeboard with said transversely extending members structurally interconnecting uppermost portions of the hulls being disposed above the mean waterline and a high draft semisubmerged column stabilized floating and operating condition in which the mean waterline is located along intermediate portion of said columns above said hulls and below the underside of said platform.
- 2. A method of constructing a vessel according to claim 1 further comprising: longitudinally dividing each of said hulls to provide at least two separate ballast compartments spaced transversely within each hull and transversely dividing each of said hulls to provide a plurality of separate ballast compartments spaced longitudinally within each hull.
- 3. A method of constructing a vessel according to claim 2 including forming each of said oblong hulls with a generally rectangular cross section between bow and stern thereof.
- 4. A method of constructing a vessel according to claim 3, including forming each of said columns with an oblong cross section having a dimension extending in the direction of the longitudinal vessel axis greater than the column's dimension extending transversely of the vessel, and locating the centroid of the cross section of each column on each hull outboardly of the longitudinal centerline of its associated hull.
- 5. A method of constructing a vessel according to claim 1 further comprising: providing as part of said means for ballasting the vessel means for ballasting the vessel to adjust its angle of heel about the vessel's roll axis when required during column stabilized semisubmerged operations.
- 6. A method of constructing a vessel according to claim 1, further comprising: providing as part of said means for ballasting the vessel means for ballasting the vessel to adjust its angle of trim about the vessel's pitch axis when required during column stabilized semisubmerged operations.
- 7. A method of constructing a vessel according to claim 1 further comprising: providing as part of said means for ballasting the vessel means for transferring ballast directly from one hull to the other hull to control heel of said vessel about its roll axis when required during semisubmerged column stabilized floating operations.
- 8. A method of constructing a vessel according to claim 1 including locating the centroid of the cross section of at least one column on each hull outboard of the longitudinal centerline of the associated hull.
- 9. A method of constructing a vessel according to claim 8 including locating the centroids of all of said columns outboard of the longitudinal centerline of the associated hull.
- 10. A method of constructing a vessel according to claim 9 wherein all of said columns have an elongated cross section with greater dimension extending in direction of the vessel's longitudinal axis.
- 11. A method of constructing a vessel according to claim 8 wherein said at least one column having its centroid outboard of the associated hull centerline is formed with an elongated cross section having a dimension extending in the direction of the longitudinal vessel axis greater than the column's transversely extending dimension.
- 12. A method of constructing a vessel according to claim 1 including forming each of said columns with an oblong cross section having a dimension extending in the direction of the vessel's longitudinal axis greater than the column's dimension extending transversely of the vessel and locating the centroid of the cross section of each such column on its associated hull outboard of the longitudinal centerline of such associated hull.
- 13. A method of constructing a vessel according to claim 1 including forming each of said hulls with a generally rectangular cross section between bow and stern thereof.
- 14. A method of constructing a vessel according to claim 1, so that said vessel has a length which is at least 2.5 times as great as its width.
- 15. A method of constructing a vessel according to claim 1 wherein at least one of the upper and lower ends of said columns is modified in cross section to provide mechanical connection between the columns and the platform.
- 16. A method of constructing a vessel according to claim 15, wherein each said modified column end includes a frustoconical section.
- 17. A method of constructing a column stabilized semisubmersible drilling vessel comprising constructing a vessel according to claim 1 and further comprising:
- providing a drilling rig on and carried by said work platform;
- providing means on said vessel for accommodating drilling equipment for conducting offshore drilling operations in column stabilized semisubmerged high draft condition;
- providing as part of said vessel ballast means means for ballasting the vessel to counteract change in its angle of trim caused when said drilling vessel is in said high draft column stabilized semisubmerged condition for drilling operations and is subjected to load change of such location and magnitude with respect to the pitch axis so that such latter ballast means provides when required a reduction of the vessel's angle of trim about its pitch axis during semisubmerged column stabilized drilling operations; and
- providing as part of said vessel ballast means means for ballasting the vessel to counteract its angle of heel caused when said vessel is in said high draft semisubmerged condition for drilling and is subjected to load change of such location and magnitude with respect to the roll axis so that such latter ballast means provides when required a reduction of the vessel's angle of heel about its roll axis during high draft semisubmerged column stabilized drilling operations.
- 18. A method of constructing a vessel as in claim 1 including locating the centroids of the water plane areas defined by the cross sections of the columns outboardly of the centerlines of the hulls an extended distance from the centerline of the vessel on opposite sides of the longitudinally extending roll axis to develop larger moments of inertia of the water plane area about the roll axis (than would otherwise be the case if the longitudinal centerlines of said hulls and their associated columns were coincident).
- 19. A method of constructing a vessel as claimed in claim 18, wherein said stabilizing columns are formed and located so that they have outboard portions thereof which extend transversely beyond the outboard sides of the respective hulls.
- 20. A method of constructing a vessel as in claim 1 wherein said transversely extending members are located with opposite end portions overlying top surfaces of said hulls and have their opposite ends connected to columns on each of said hulls near said hull top surfaces.
- 21. A method of constructing a vessel according to claim 20 further including securing opposite end portions of said transversely extending members to said top surfaces of said hulls.
- 22. A method of constructing a column stabilized semisubmersible variable draft vessel comprising the steps of:
- fabricating a pair of elongated hulls with each of said hulls having an oblong transverse cross section with a breadth greater than its height and having top and bottom substantially planar parallel surfaces extending substantially the entire length of each hull between bow and stern thereof; and disposing said hulls in substantially parallel spaced side-by-side relation with each of said hulls spaced from and lying on an opposite side of the longitudinal centerline of said vessel;
- fabricating a working platform and also means for supporting said platform in fixed spaced relation above said hulls a predetermined height and normally lying in a generally horizontal plane, said means including at least two pairs of upstanding columns connecting with said hulls near opposite ends thereof and also with said platform, each of said columns being made with a substantially constant cross sectional area over the effective height of the column between the platform and associated hull;
- fabricating and disposing a plurality of longitudinally spaced structural truss means interconnecting and reinforcing the structural relationship of the hulls, platform and columns, with such truss means including substantially transversely extending members structurally interconnecting uppermost portions of the hulls;
- forming said vessel with said hulls, columns and related components so that the vessel is generally rectangular in plan with the length of said vessel along its longitudinal centerline and roll axis being substantially greater than the width of said vessel along its transverse centerline and pitch axis; locating at least three of said columns on each of said two hulls on opposite sides of the vessel's roll axis with one of said two aforesaid pairs of columns located near opposite ends of each of said hulls and being disposed on opposite sides of the vessel's pitch axis and at least another pair of columns being located at an intermediate position on each of said hulls; and providing such columns with configurations and cross-sectional areas throughout effective height thereof and locating said columns at distances from the vessel's longitudinal roll axis and transverse pitch axis such that said columns will maintain the vessel's metacenter above the vessel's center of gravity for the high draft semisubmerged operating positions of the vessel and also such that said columns will provide righting moment about the longitudinal roll axis which is less than righting moment provided about said transverse pitch axis when the vessel is in semisubmerged column stabilized operating position;
- providing said hulls with ballast compartments, and providing means for ballasting said vessel when required to alter its draft between a low draft hull-supported floating condition in which the hulls have freeboard with said transversely extending members structurally interconnecting uppermost portions of the hulls being disposed above the mean waterline and a high draft semisubmerged column stabilized floating and operating condition in which the mean waterline is located along intermediate portion of said columns above said hulls and below the underside of said platform.
- 23. A method of constructing a vessel according to claim 22 further comprising: longitudinally dividing each of said hulls to provide at least two separate ballast compartments spaced transversely within each hull and transversely dividing each of said hulls to provide a plurality of separate ballast compartments spaced longitudinally within each hull.
- 24. A method of constructing a vessel according to claim 23 further comprising: providing as part of said means for ballasting the vessel ballast means for adjusting the vessel's angle of trim about its pitch axis when required during column stabilized semisubmerged operations.
- 25. A method of constructing a column stabilized semisubmersible drilling vessel comprising constructing a vessel according to claim 24 and further comprising:
- providing a drilling rig on and carried by said work platform; and
- providing means on said vessel for accommodating drilling equipment for conducting offshore drilling operations in column stabilized semisubmerged high draft condition.
- 26. A method of constructing a vessel according to claim 23 including forming each of said oblong hulls with a generally rectangular cross section between bow and stern thereof.
- 27. A method of constructing a vessel according to claim 26, including forming each of said columns with an oblong cross section having a dimension extending in the direction of the longitudinal vessel axis greater than the column's dimension extending transversely of the vessel, and locating the centroid of the cross section of each column on each hull outboardly of the longitudinal centerline of its associated hull.
- 28. A method of constructing a vessel according to claim 22 further comprising: providing as part of said means for ballasting the vessel ballast means for adjusting the vessel's angle of heel about its roll axis when required during column stabilized semisubmerged operations.
- 29. A method of constructing a vessel according to claim 22 further comprising: providing as part of said means for ballasting the vessel means for transferring ballast directly from one hull to the other hull to control heel of said vessel about its roll axis when required during semisubmerged column stabilized floating operations.
- 30. A method of constructing a vessel according to claim 22 including locating the centroid of the cross section of at least one column on each hull outboard of the longitudinal centerline of the associated hull.
- 31. A method of constructing a vessel according to claim 30 including locating the centroids of all of said columns outboard of the longitudinal centerline of the associated hull.
- 32. A method of constructing a vessel according to claim 31 wherein all of said columns have an elongated cross section with greater dimension extending in direction of the vessel's longitudinal axis.
- 33. A method of constructing a vessel as claimed in claim 32, wherein said stabilizing columns are formed and located so that they have outboard portions thereof which extend transversely beyond the outboard sides of the respective hulls.
- 34. A method of constructing a vessel according to claim 30 wherein said at least one column having its centroid outboard of the associated hull centerline is formed with an elongated cross section having a dimension extending in the direction of the longitudinal vessel axis greater than the column's transversely extending dimension.
- 35. A method of constructing a vessel according to claim 22 including forming each of said oblong hulls with a generally rectangular cross section between bow and stern thereof.
- 36. A method of constructing a vessel according to claim 31, including forming and assembling said hulls, columns and related components so that the vessel has a length-to-width ratio of at least 2.0 to 1.
- 37. A method of constructing a vessel according to claim 36 so that said vessel has a length which is at least 2.5 times as great as its width.
- 38. A method of constructing a vessel according to claim 22 wherein at least one of the upper and lower ends of said columns is modified in cross section to provide mechanical connection between the columns and the platform.
- 39. A method of constructing a vessel according to claim 38 wherein each said modified column end includes a frustoconical section.
- 40. A method of constructing a vessel as in claim 22 wherein said transversely extending members are located with opposite end portions overlying top surfaces of said hulls and have their opposite ends connected to columns on each of said hulls near said hull top surfaces.
- 41. A method of constructing a vessel according to claim 40 further including securing opposite end portions of said transversely extending members to said top surfaces of said hulls.
- 42. A method of constructing a vessel as in claim 22, wherein the vessel is provided with six column including three columns on each hull, with one middle pair of columns located adjacent the vessel's transverse pitch axis and with two other pairs of columns located on opposite sides of the vessel pitch axis in generally symmetrical relation thereto near opposite ends of the associated hulls.
- 43. A method of constructing a vessel as in claim 22 wherein: the vessel is provided with a total odd number of pairs of columns and the middle pair of columns is located adjacent the vessel's pitch axis, with the remaining pairs of columns being disposed in equal numbers on opposite sides of the vessel pitch axis and including two pairs of columns located near opposite ends of said hulls.
- 44. A method of constructing a vessel as in claim 22 wherein: the vessel has a total even number of pairs of columns and the middle two pairs of columns are located on opposite sides of and near the transverse pitch axis; the remaining pairs of said columns being located outwardly of said middle pairs of columns and including two pairs of end columns on the hulls near opposite ends of said hulls.
- 45. A method of constructing a column stabilized semisubmersible variable draft vessel comprising the steps of:
- fabricating a pair of elongated hulls with each of said hulls having a substantially rectangular cross section with a breadth greater than its height extending between bow and stern of the hull; and disposing said hulls in substantially parallel spaced side-by-side relation with each of said hulls spaced from and lying on an opposite side of the longitudinal centerline of said vessel;
- fabricating a working platform and also means for supporting said platform in fixed spaced relation above said hulls a predetermined height and normally lying in a generally horizontal plane, said means including at least two pairs of upstanding columns connecting with said hulls near opposite ends thereof and also with said platform, each of said columns being made with a substantially constant cross sectional area over the effective height of the column between the platform and associated hull;
- fabricating and disposing a plurality of longitudinally spaced structural truss means interconnecting and reinforcing the structural relationship of the hulls, platform and columns, with such truss means including substantially transversely extending members structurally interconnecting uppermost portions of the hulls;
- forming said vessel with said hulls, columns and related components so that the vessel is generally rectangular in plan view with the length of said vessel along its longitudinal centerline and roll axis being substantially greater than the width of said vessel along its transverse centerline and pitch axis; locating at least three of said columns on each of said two hulls on opposite sides of the vessel's roll axis with one of said two aforesaid pairs of columns located near opposite ends of each of said hulls and being disposed on opposite sides of the vessel's pitch axis and at least another pair of columns being located at an intermediate position on each of said hulls; and providing such columns with configurations and cross-sectional areas throughout effective height thereof and locating said columns at distances from the vessel's longitudinal roll axis and transverse pitch axis such that said columns will maintain the vessel's metacenter above the vessel's center of gravity for the high draft semisubmerged operating positions of the vessel and also such that said columns will provide righting moment about the longitudinal roll axis which is less than righting moment provided about said transverse pitch axis when the vessel is in semisubmerged column stabilized operating position;
- providing said hulls with ballast compartments, and providing means for ballasting said vessel when required to alter its draft between a low draft hull-supported floating condition in which the hulls have freeboard with said transversely extending members structurally interconnecting uppermost portions of the hulls being disposed above the mean waterline and a high draft semisubmerged column stabilized floating and operating condition in which the mean waterline is located along intermediate portion of said columns above said hulls and below the underside of said platform;
- longitudinally dividing each of said hulls to provide at least two separate ballast compartments spaced transversely within each hull and transversely dividing each of said hulls to provide a plurality of separate ballast compartments spaced longitudinally within each hull;
- providing as part of said means for ballasting the vessel ballast means for adjusting the vessel's angle of heel about its roll axis when required during column stabilized semisubmerged operations; and also providing as part of said means for ballasting the vessel ballast means for adjusting the vessel's angle of trim about its pitch axis when required during column stabilized semisubmerged operations.
- 46. A method of constructing a vessel according to claim 45 further comprising: providing as part of said means for ballasting the vessel means for transferring ballast directly from one hull to the other hull to control heel of said vessel about its roll axis when required during semisubmerged column stabilized floating operations.
- 47. A method of constructing a vessel according to claim 45 including locating the centroid of the cross section of at least one column on each hull outboard of the longitudinal centerline of the associated hull.
- 48. A method of constructing a vessel according to claim 47 including locating the centroids of all of said columns outboard of the longitudinal centerline of the associated hull.
- 49. A method of constructing a vessel according to claim 47 wherein said at least one column having its centroid outboard of the associated hull centerline is formed with an elongated cross section having a dimension extending in the direction of the longitudinal vessel axis greater than the column's transversely extending dimension.
- 50. A method of constructing a vessel according to claim 48 wherein all of said columns are formed with an elongated cross section having a greater dimension extending in direction of the vessel's longitudinal axis.
- 51. A method of constructing a vessel as claimed in claim 50, wherein said stabilizing columns are formed and located so that they have outboard portions thereof which extend transversely beyond the outboard sides of the respective hulls.
- 52. A method of constructing a vessel according to claim 45, including forming and assembling said hulls, columns and related components so that the vessel has a length-to-width ratio of at least 2.0 to 1.
- 53. A method of constructing a vessel according to claim 52 so that said vessel has a length which is at least 2.5 times as great as its width.
- 54. A method of constructing a vessel according to claim 45 wherein at least one of the upper and lower ends of said columns is modified in cross section to provide mechanical connection between the columns and the platform.
- 55. A method of constructing a vessel according to claim 54, wherein each said modified column end includes a frustoconical section.
- 56. A method of constructing a column stabilized semisubmersible drilling vessel comprising constructing a vessel according to claim 45 and further comprising:
- providing a drilling rig on and carried by said work platform; and
- providing means on said vessel for accommodating drilling equipment for conducting offshore drilling operations in column stabilized semisubmerged high draft condition.
- 57. A method of constructing a vessel as in claim 45 wherein said transversely extending members are located with opposite end portions overlying top surfaces of said hulls and have their opposite ends connected to columns on each of said hulls near said hull top surfaces.
- 58. A method of constructing a vessel according to claim 57 further including securing opposite end portions of said transversely extending members to said top surfaces of said hulls.
Parent Case Info
This application is a divisional of application Ser. No. 708,133, filed July 23, 1976 issued as U.S. Pat. No. 4,091,760 on May 30, 1978; said application Ser. No. 708,133 in turn being a continuation of application Ser. No. 529,061 filed Dec. 3, 1974 (abandoned) which in turn is a continuation of Ser. No. 177,219 filed Sept. 2, 1971 (abandoned); said application Ser. No. 177,219 being a division of application Ser. No. 766,662 filed Sept. 4, 1968 issued as U.S. Pat. No. 3,616,773 on Nov. 1971, with said Ser. No. 766,662 being a continuation-in-part of application Ser. No. 666,395 filed Sept. 8, 1967 (abandoned); said U.S. Pat. No. 3,616,773 being reissued as U.S. Pat. No. RE. 29,167 on Apr. 5, 1977 from applications referred to in said reissue patent.
US Referenced Citations (1)
Number |
Name |
Date |
Kind |
RE29167 |
Lloyd |
Apr 1977 |
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Divisions (2)
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Number |
Date |
Country |
Parent |
708133 |
Jul 1976 |
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Parent |
766662 |
Sep 1968 |
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Continuations (2)
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Number |
Date |
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Parent |
529061 |
Dec 1974 |
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Parent |
177219 |
Sep 1971 |
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Continuation in Parts (1)
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Number |
Date |
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Parent |
666395 |
Sep 1967 |
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