Liuhua 11-1 under tow from Scotland to Singapore

Project Summary

A Sedco 700-class semi-submersible drilling rig was to be moved from its lay-up location in Scotland to Singapore to be converted into the Liuhua 11-1 Floating Production System vessel (FPS).

Argonautics Marine Engineering was hired by Reading & Bates Development Company to compare the various transport options: wet tow or dry transport. For the dry transport option, stability and motion response analyses of the potential carriers, and a detailed structural analysis of the rig were performed. Safety aspects and commercial implications of each option were addressed.

Within the boundary conditions, the wet tow turned out to be the more favorable option, see also photograph above. The rig departed Scotland in April 1994 and was safely delivered to the FELS shipyard in Singapore.

Scope of Work

The project scope included:

• Modeling of the heavy-lift vessels for the hydrodynamic analysis;

• Modeling of the drilling rig for the structural analysis;

• Feasibility study of dry transport with respect to stability, ship motions and rig strength;

• Optimization of cribbing support of rig floaters;

• Calculation of the wet tow resistance and wet tow motions of the rig;

• Comparisons of wet tow versus dry transport with respect to safety;

• Comparisons of wet tow versus dry transport with respect to schedule and cost.

Acknowledgement

Photograph courtesy of Matthews-Daniel Company.