The Neptune Spar hull sections stowed on the Mighty Servant 3

Project Summary

For the dry transport of the 12,700 T Oryx Energy Neptune Spar hull from Pori, Finland, to the U.S. Gulf, the Dockwise semi-submersible, heavy-lift vessel Mighty Servant 3 was selected. Because of the total length of the Spar hull (215 m), a stowage configuration based on two side-by-side sections was proposed, see also following photograph, courtesy of Aker Rauma Offshore.

The two 22 meter diameter cylinders have different stiffnesses relative to the stiffness of the hull of the transport vessel. The still water and wave deflections of the ship hull and its interaction with the Spar hull sections were studied. Recommendations for shaping of the wooden cribbing were made to minimize the bending stresses in the Spar hull sections. Early 1997, the Spar hull sections were safely delivered to the hull mating site.

Scope of Work

The project scope included:

• Modeling of the heavy-lift ship hull girder;

• Structural modeling of the longest of the two Spar hull sections;

• Determination of the most realistic worst case wave profile for the transport;

• Calculation of ship hull deflection in hogging and sagging conditions;

• Showing effect of cribbing shaping on the Spar section's internal stresses.

Acknowledgement

Photograph courtesy of Aker Rauma Offshore.