Loadout Of Auger Deck And Hull-Deck Mating Operations
Authors: Kenney J.J. , Knoll D.A. , Brooks Al , Crimmins D.M. , Wilkinson Gordon , Danos J.H. 
Published: October 2008

Loadout of the 24,000 ton Auger deck and the subsequent open ocean joining of the deck to the 20,000 ton floating hull (hereafter referred to as the mating operation), posed interesting technical and operational challenges. The knowledge gained through technical analyses was incorporated into detailed procedures which led to both operations being successful. Some of the actual responses varied from the theoretical solutions, but remained acceptable.

Introduction

The deck was 1oaded onto McDermott's Intermac 650 material barge in the transverse direction which meant that large loads needed to be transferred over relatively short distances. This led to the development of an allowable displacement "envelope". This envelope related the land based deck elevation(s) to the floating material barge elevation. A barge ballast plan, a straightforward dimensional control plan to measure the actual displacements, a program to process the surveying information and formalized channels of communication were all included in the detailed procedure. These procedures were used to monitor the operation and ensured that the actual relative vertical displacements were within the tight tolerances of an allowable "envelope".

The deck was mated to the floating hull in 240 feet of water in the unprotected Gulf of Mexico during hurricane season. Many analyses were performed to verify the acceptability of the mating concept and to detail the actual operations plan. The motions of both components were studied to ensure that adequate cent rolled separation between the two floating bodies would occur; thus, preventing damage to the deck, hull and the material barge. Hydraulic cylinders were selected as the control led release mechanism in lieu of using explosives which was the original proposal. Temporary ballast, power and mooring systems were developed for the hull to make the operation efficient and secure. Detailed offshore procedure manuals were developed which described the deck, hull and barge(s) preparations; on-site positioning of the marine spread consisting of the hull and two attendant derrick barges; a step by step rigging plan for the actual float-in; ballast operations and mooring system operations and severe weather contingency planning due to hurricanes.

Loadout Analyses: Models and Techniques

The deck was fabricated by McDermott Incorporated in Amelia, Louisiana and was erected on top of a temporary support frame referred to as the cribbage. The 985 ton cribbage was approximately 32 feet high and provided the proper elevation for mating. The cribbage was a space frame consisting of four main truss rows which supported the main truss rows of the deck. The cribbage was supported by four, pile supported, land based skidways. Four mooring dolphins were installed in the canal to support the skidways extending into the canal. To maintain the proper elevation during loadout, the canal needed to be deepened. Since bringing the barge up against the bulkhead would have required dredging at the bulkhead, thereby compromising its integrity, the Contractor chose the option of using mooring dolphins in the quay as opposed to reconstructing the bulkheads.