Method of transporting an elongate member

Abstract

The present invention provides a method for transporting an elongate member through water. The elongate member has a first end portion and a second end portion. The method comprises the steps of: adjusting the buoyancy of the elongate member to ensure that the elongate member is buoyant; providing at least one weight acting on each end portion of the elongate member; and transporting the elongate member through water in an inverted catenary configuration. The elongate member can be transported below the wave affected zone. The or each weight acting on each end portion of the elongate member can be detachably connected thereto. The elongate member can be transported by towing.

1 . A method for transporting an elongate member through water, the elongate member being positively buoyant and having a first end portion and a second end portion, the method comprising the steps of:
 providing at least one weight acting on each end portion of the elongate member; and   transporting the elongate member through water in an inverted catenary configuration.   
   
   
       2 . A method according to  claim 1 , wherein the water includes a wave affected zone, and the method includes the step of transporting the elongate member below the wave affected zone. 
   
   
       3 . A method according to  claim 1 , including detachably connecting the at least one weight acting on each end portion of the elongate member. 
   
   
       4 . A method according to  claim 1 , including the step of transporting the elongate member by towing. 
   
   
       5 . A method according to  claim 1 , including attaching the first end portion of the elongate member to a tow vessel via a towline. 
   
   
       6 . A method according to  claim 1 , including applying a back tension to the second end portion of the elongate member during transportation of the elongate member. 
   
   
       7 . A method according to  claim 1 , including attaching the second end portion of the elongate member to a second tow vessel via a second towline. 
   
   
       8 . A method according to  claim 1 , including attaching at least one weight in the region of each end portion of the elongate member. 
   
   
       9 . A method according to  claim 1 , including attaching at least one weight to a first towline coupling a first vessel to the first end portion and a second towline coupling a second vessel to the second end portion. 
   
   
       10 . A method according to  claim 9 , including damping the motion of the first and second tow vessels. 
   
   
       11 - 12 . (canceled) 
   
   
       13 . A method according to  claim 1 , including cladding at least a portion of an outer surface of the elongate member with a material that is both buoyant and insulating. 
   
   
       14 . A method according to  claim 9 , including coupling buoyancy to each towline in the region of the at least one weight such that in the event of towline breakage, the buoyancy is arranged to float. 
   
   
       15 . A method according to  claim 9 , including adjusting the depth at which the elongate member is transported by altering at least one of: the mass of the attached weights; the length of the towline(s); the buoyancy of the elongate member; and the tension applied during transportation of the towlines. 
   
   
       16 - 18 . (canceled) 
   
   
       19 . A method for transporting an elongate member through water, the elongate member having a first end portion and a second end portion and a central portion between the first and second end portions, the method comprising the steps of:
 adjusting the buoyancy of the elongate member to make it positively buoyant;   providing at least one weight acting on each end portion of the elongate member such that each end portion is less buoyant than the central portion; and   transporting the elongate member through water in an inverted catenary configuration, with the central portion disposed above each of the weighted end portions.   
   
   
       20 . A method as claimed in  claim 19  wherein the elongate member is transported through seawater above a seabed, and all the weights on the elongate member are supported in the water by the positive buoyancy of the elongate member such that they are free from the seabed and do not engage with it during the transportation of the elongate member. 
   
   
       21 . A method of towing an elongate member through water, the elongate member having a first end portion and a second end portion and a central portion between the first and second end portions, the method comprising the steps of:
 providing a towline, a vessel and at least one weight;   adjusting the buoyancy of the elongate member to make it positively buoyant;   attaching the towline to the vessel;   coupling one of the end portions of the elongate member to the towline;   attaching at least one weight to the towline acting between the vessel and the end portion;   submerging the elongate member in water;   providing at least one weight acting on each end portion of the elongate member such that each end portion is less buoyant than the central portion; and   moving the vessels and towing the elongate member through water in an inverted catenary configuration, with the central portion disposed above each of the weighted end portions; and damping the movement of the vessel from the end portion of the elongate member by ensuring that the elongate member has a greater buoyancy than the at least one weight.   
   
   
       22 . A method as claimed in  claim 21  wherein the elongate member is towed through seawater above a seabed, and all the weights on the elongate member are supported in the water by the positive buoyancy of the elongate member such that they are free from the seabed and do not engage with it during the transportation of the elongate member.