APPENDIX III 



ADDITIONAL PERFORMANCE CONSIDERATIONS 



PREVIOUS ANALYSES 



In order to perform the analysis prerequisite to the 

 design of the cable-towed oceanographic instrumentation 

 system, it was necessary to make specific assumptions re- 

 garding the nature of the hydrodynamic loads imposed on the 

 faired cable and to estimate the value of the resiataaace 

 coefficient. In the analysis reported in (1) ^ it was 

 recognized that the expression for the dependence of the 

 hydrodynamic loads on the cable angle, as given by Whicker 

 (4) , is probably more nearly correct than that given by 

 Eames (5). Earaes ' formulation was selected for this appli- 

 cation, however, since its use results in a conservative 

 estimate of the geometry of the cable catenary and over- 

 statement of the tension. A value of 0.2 was selected for 

 the resistance coefficient on the basis of the best experi- 

 mental data available at that time. 



On the basis of the foregoing, and the simplifying 

 assumption that the cable angle at the depressor, with 

 respect to the horizontal, would be nearly 90 degrees, the 

 results of the preliminary design study indicated that with 

 a depressor downforce of 4,450 pounds and a length of 6,200 

 feet of faired cable, a maximum depth of 5,000 feet could be 

 obtained at a towing speed of 7% knots. 



III. 2 



