Deep Water Offshore Apparatus And Assembly Method

Abstract

A truss type spar that eliminates the need for the more complex and critical attachment of the buoyant hull to the truss section at a fabrication site/yard that is remote from the fabrication yard where the buoyant hull and truss sections were originally built. The buoyant hull and initial truss sections are constructed at the fabrication yard of choice, joined together, and transported to a dock or fabrication yard (a second location) that is as close as possible to the final offshore installation site. Transport of such completed structures, either separately or together, is normally done on a heavy lift vessel to reduce transport time and prevent damage to the buoyant hull and truss sections. Once at the fabrication yard/dock, the joined buoyant hull and initial truss section are floated off the heavy lift vessel and the draft adjusted to a position suitable for joining additional truss sections. One or more additional truss sections can be attached to the initial section, and the completed buoyant hull and truss is then towed to the final offshore installation site.

1 . A truss spar type structure, comprising:
 a. a buoyant hull section;   b. an initial truss section attached to the buoyant hull section at a fabrication yard on land before transport from the fabrication yard, with the size of the attached buoyant hull and initial truss section capable of being transported on a heavy lift vessel; and   c. at least one additional truss section attached to the main truss section at a different location from the original fabrication yard for the buoyant hull and main truss sections.   
     
     
         2 . The truss spar type structure of  claim 1 , wherein each additional truss section is shorter than the main truss section. 
     
     
         3 . A method for assembling a truss spar type structure, comprising the steps:
 a. constructing a buoyant hull section;   b. constructing an initial truss section;   c. joining the initial truss section to the buoyant hull section, with the joined buoyant hull section and initial truss section capable of being transported on a heavy lift vessel;   d. transporting the joined buoyant hull and truss sections on a heavy lift vessel to a second location; and   e. attaching at least one additional truss section to the main truss section.