i6 



0.4 





... 











































/ 



• 























/ 























/ 























/ 



/ 





















o / 



/ 























p 





















S 



/ 























/ 























/ 



^ 























/. 























A 























/ 



& 























r 





















/ 



/ 























/ 

























0.04 

 Coble E 



0.12 

 sin t 



0.16 

 C 



n 



Figure 5 - Variation of ^ . . with sin<^ 



the data fairly well and no significant improvement of the fit can be made by 

 not passing the straight line through the origin. Considerable improvement in 

 the fit can be made only by use of a curvilinear representation. 



It is believed that the postulation of the sin term arose from the 

 neglect of the side force and the yawing of the cable. When the cable is in- 

 clined at a small angle to the stream the side force will be oriented so as 

 to have a large component upward. Hence. the cable will tow closer to the sur- 

 face of the water and the configuration of the cable in the vertical plane 

 will indicate an apparent increase in the normal force. 



It is hard to say how much of the deviation from the sine-squared 

 law could be due to systematic error in the measurement of the cable angles. 

 Some deviation from the sine-squared law is to be expected since this law is 

 supported by theory only for true cylindrical forms. It is the departure of 

 the stranded cable from true cylindrical form that is responsible for the ex- 

 istence of the side-force and it is not unreasonable to suppose that this de- 

 parture from cylindrical form will also affect the normal force. 



