III. THE EFFECT OF OCEAN CURRENTS 



Due to the frictional forces on the cable, a current will bend the 

 cable as shown in Figure 2. (Such frictional forces will also act on the array 

 and vessel if they are within the current.) Of interest here are three quanti- 

 ties: the additional stresses in the cable, the offset (D) from the target, and 

 the horizontal force (F) which must be exerted by the vessel in order to remain 

 stationary against the current. 



This problem can be solved very accurately by balancing the compo- 

 nents of the various forces acting on an infinitesimal element of the cable. The 

 results for all pertinent variables can be expressed in terms of integrals which 

 have been tabulated (David Taylor Model Basin Report 687 and its Supplement). 

 However, if the net vertical force (gravity minus buoyancy) is much larger than 

 the horizontal frictional forces due to the current, bending of the cable will be 

 very small, and the following simple analysis can be applied. 



SURFACE 



CURRENT V 



^ 



X = 



+ x 



X = X 



ARRAY 



X=L 



FIGURE 2 BENDING OF THE CABLE BY A 

 HORIZONTAL CURRENT 



Arthur m.ILittlcJnf. 



