to earlier measurements for taut cables and cylinders. These results and their corresponding values of 

 ks are listed in Table C3, and they agree quite well with the measurements shown in Fig. C6. 



Table C3 



Flat-Sag Cable Results for Added Mass and Damping 



Double Armor Steel (DAS) Cable 



Natural frequency 



Added mass 



Hydrodynamic 



Vibration 



Reduced fluid 



in water, /„/Hz 



coefficient, Q^ 



decrement, 8 



Reynolds number, Re^ 



damping, k^ 



5.2 (29)* 



2.48 



0.21 



1920 



2.16 



4.65 (52) 



2.40 



0.07 



1720 



0.71 



4.24 (69) 



1.14 



0.08 



1570 



0.73 



3.93 (90) 



1.06 



0.07 



1450 



0.56 



3.83 (100) 



1.06 



0.09 



1420 



0.72 



4.02 (187) 



1.10 



0.05 



1485 



0.41 



'Tension in pounds (1 pound = 4.45 Newtons) 



Sarpkaya (C6) discusses an alternate method for calculating the added mass and damping 

 coefficients from force coefficients measured in periodic flows of water over stationary cylinders. How- 

 ever, care should be taken in interpreting these force coefficients because the added mass coefficient 

 Cam is not equal to the inertia coefficient C^h or C^i as measured in a periodic flow of water. There is 

 an additional pressure gradient generated by the acceleration of the fluid in the latter case which pro- 

 duces the so-called Froude-Krylov force. Under potential flow or ideal fluid conditions C„,/, or C^, is 

 unity plus C^^. 



References 



CI. J.H. Pattison, "Measurement Technique to Obtain Strumming Characteristics of Model Mooring 

 Cables in Uniform Currents," David W. Taylor Naval Ship Research and Development Center 

 Report SPD 766-01, April 1977. 



146 



