| 摘要 |
A system for controlling the draft of a DDF substructure, the substructure being adapted to support the upper end of at least one riser (120) extending from close to the seabed to above the sea surface, and having provision for moveable ballast to adjust its draft; the system comprising means to introduce ballast in order to keep the substructure at a stable draft with a suitable pitch rotational stiffness so that the allowable operational pitch angle is not exceeded with no risers installed, and means to expel ballast when a riser is connected up and tensioned, whereby, as the tension of the riser (or risers) tends to increase the draft of the substructure, removal of ballast counteracts this tendency, thus to ensure that the allowable operational pitch angle is not exceeded. |
