ESV Iolair testing its firefighting equipment

Project Summary

In September 1995, the BP Emergency Standby Vessel Iolair was purchased by Reading & Bates, for conversion into a Workover/Well Intervention Vessel. The Iolair is a self-propelled, twin hull, six column stabilized, semi-submersible type vessel. 

The proposed conversion included removal of some of the top structures, removal of the fire-fighting systems, closing of the dive tube and wave surge tank and the addition of a large derrick set and well stimulation equipment. These changes significantly affect the vessel's center of gravity as well as its wind area. The converted vessel had to meet the 1990 Department of Energy's Fourth Edition guidelines and the Lloyd's Register of Shipping requirements. Argonautics Marine Engineering was hired to assist with the stability analysis of the vessel.

Scope of Work

The project scope included:

• Modeling of the hydrodynamic part of the semi-submersible vessel;

• Modeling of the wind areas of the vessel;

• Intact stability analysis of the vessel before and after conversion using StabCAD;

• Damaged stability analysis of the vessel before and after conversion using StabCAD;

• Establishing the new allowable KG curve and resulting deck load capability;

• Comparison of various sponson configurations to improve stability/deck load capability.

Acknowledgement

Photograph courtesy of Reading & Bates Development Company.