Spar hull belly strake design and installation method

Abstract

A spar hull for a floating vessel can include a hard tank having a belly portion, a fixed strake coupled to the outer surface of the tank and a folding strake coupled to the belly portion of the tank, the folding strake having one or more strake panels and one or more support frames. A method for installing folding belly strakes on a spar hull may include providing a floating spar hull having a hard tank with a belly side, rotating the spar so that the belly side is in a first workable position, coupling at least one folding strake to the belly side of the spar, and coupling the strake in a folded position for transport. The method may include positioning the spar hull offshore in a transport position, upending the spar hull, unfolding the strake, fixing the strake in the unfolded position and installing the spar hull.

1 . A method for installing belly strakes on a spar hull for floating vessels, comprising:
 providing a floating spar hull comprising a hard tank having a belly side, the spar being towable in a horizontal position;   rotating the spar hull so that the belly side is in a first workable position;   coupling at least one folding strake to the belly side of the spar hull;   coupling the strake in a folded position; and   rotating the spar hull to a second position for transport.   
   
   
       2 . The method of  claim 1 , further comprising transporting the spar hull to a work pit prior to rotating the spar to the first workable position and wherein rotating the spar hull to a second position includes rotating the spar hull to a position for wet tow. 
   
   
       3 . The method of  claim 1 , wherein the at least one strake comprises a strake support frame and one or more strake panels and wherein coupling the folding strake to the belly side of the spar hull further comprises:
 fitting the support frame and one or more panels to the hard tank; and   removing one or more of the supports or panels for transport.   
   
   
       4 . The method of  claim 3 , further comprising transporting the spar to a location for operations and coupling the one or more removed supports or panels to the spar hull. 
   
   
       5 . The method of  claim 4 , further comprising unfolding one or more support frames and fixing the one or more supports frames in the unfolded position. 
   
   
       6 . The method of  claim 1 , further comprising installing the spar hull for offshore oil and gas operations, comprising:
 positioning the spar hull offshore in a transport position wherein the strake remains in the folded position;   upending the spar hull;   unfolding the strake;   fixing the strake in the unfolded position; and   positioning the spar hull in the installed position.   
   
   
       7 . The method of  claim 6 , wherein unfolding the strake further comprises unfolding support frames and unfolding strake panels. 
   
   
       8 . A spar hull for a floating vessel, comprising:
 a hard tank having an outer surface, wherein the outer surface has a belly portion;   a first fixed strake coupled to a first portion of the outer surface of the tank, wherein the first portion does not include the belly portion;   a second folding strake coupled to the belly portion of the outer surface of the tank, the folding strake having one or more strake panels and one or more support frames.   
   
   
       9 . The spar hull of  claim 8 , wherein the one or more strake panels and the one or more support frames are rotatably coupled to the belly portion of the outer surface. 
   
   
       10 . The spar hull of  claim 9 , further comprising a locking structure adapted to locks the one or more strake panels, the one or more support frames, or a combination thereof in one or more folded or unfolded positions relative to the outer surface of the tank. 
   
   
       11 . The spar hull of  claim 10 , wherein the locking structure includes a nut and bolt. 
   
   
       12 . A folding strake for a floating spar, comprising:
 a strake panel configured to be coupled to the side of the spar and having an unfolded and at least one folded position;   a support frame configured to be coupled to the side of the spar and having an unfolded and at least one folded position; and   wherein the support frame is configured to support the strake panel when the frame and panel are in the unfolded positions.   
   
   
       13 . A method of installing a spar hull for offshore oil and gas operations, comprising:
 providing a spar hull having belly strake, wherein at least a portion of the belly strake has folded and unfolded positions;   fixing the strake in the folded position;   positioning the spar hull offshore in a transport position wherein the strake remains in the folded position;   upending the spar hull;   unfolding the strake;   fixing the strake in the unfolded position; and   positioning the spar hull in the installed position.   
   
   
       14 . The method of  claim 13 , wherein unfolding the strake further comprises unfolding support frames and unfolding strake panels.