Conversion of the Ocean Clipper to DPS-3 classification

The Texas A&M Ocean Engineering senior design project for 1999 was to design the upgrade of Diamond Offshore´s dynamically positioned drillship, Ocean Clipper, from a DPS-1 classed vessel to a DPS-2 and DPS-3 classed vessel. The objective of this paper is to describe the results of this design. A dynamically positioned drillship has the capability to maintain a fixed position and heading in any environment up to the maximum design environment. The Dynamic Positioning System (DPS) classification status (DPS-1, DPS-2, and DPS3) defines the redundancy necessary to withstand specified failures on the drilling vessel while maintaining station. During drilling operations, failures such as the loss of an electrical bus, generator, engine, or thruster are considered. In addition, the complete loss of a compartment, including its contents, due to fire or flood while maintaining station in the maximum design environment is evaluated. Four environments are considered for the operation of the upgraded Ocean Clipper. These environments are the Gulf of Mexico, the North Sea, the South China Sea, and West Africa. The modifications suggested for the Ocean Clipper to operate under a DPS-3 classification differed for each environment. For the West Africa environment, the recommended modifications are the addition of a third electrical bus, the division of the SCR room into three compartments, the separation of the transformer room and air conditioning (AC) condensers, the addition of a door and back-up differential global positioning systems (DGPS) in the dynamic positioning (DP) room, and the addition of another thruster control system. These modifications are also recommended for operation in each of the other environments as well other modifications specific to the environment