Claims
- 1. In a semi-submersible vessel of the type comprising a platform, a plurality of columns extending downwardly from said platform and having sufficient buoyancy to substantially support the vessel and pontoons having inboard sections extending between said columns and outboard sections extending beyond said columns, the improvement comprising:
- means for producing a heave action for said vessel in response to waves encountered by said vessel which heave action is substantially out of phase with said waves when said vessel is in a working mode in which working mode said pontoons are submerged at a first depth suitable for carrying out normal drilling operations and said heave action is substantially in phase with said waves when said vessel is in a survival mode, in which survival mode said pontoons are raised to a second depth which is shallower than said first depth, so as to provide additional clearance of said platform above the surface while maintaining said pontoons substantially fully submerged,
- whereby when said vessel is operated in a survival mode, it will ride with said waves so as to obtain maximum clearance of said platform above said waves.
- 2. The apparatus according to claim 1 wherein said means for providing said heave action enables said vessel to operate substantially 180.degree. out of phase with said waves when said vessel is in said operating mode and substantially 0.degree. out of phase with said waves when said vessel is in said survival mode.
Parent Case Info
This application is a continuation of co-pending application Ser. No. 06/714,367, filed Mar. 21, 1985 now U.S. Pat. No. 4,909,174, issued Mar. 20, 1990, which was a continuation-in-part of application Ser. No. 06/525,827, filed Aug. 23, 1983 now abandoned.
US Referenced Citations (3)
Number |
Name |
Date |
Kind |
3160135 |
De Vries |
Dec 1964 |
|
3490406 |
O'Reilly et al. |
Jan 1970 |
|
4112864 |
Bergman |
Sep 1978 |
|
Continuations (1)
|
Number |
Date |
Country |
Parent |
714367 |
Mar 1985 |
|
Continuation in Parts (1)
|
Number |
Date |
Country |
Parent |
525827 |
Aug 1983 |
|