The measured and predicted values of Q„, show considerable deviation at small RCy, but reasonable 

 agreement is exhibited at Rev = 2000 and above. However, the predicted curve is valid only as a guide 

 since most of the simplifying assumptions under which it was derived are not applicable to large ampli- 

 tude vibrations of marine cables. 



The hydrodynamic damping is considered in the form 



^s = y (-^ + Qm)8 = y 



Ia 



fn 



8. 



(C5) 



The values of k^ measured by vibrating the cables listed in Table C2 in still water are plotted in Fig. C6. 

 The parameter k^ usually termed the reduced damping, commonly appears in the study of flow-induced 

 oscillations of cables and structures (C2) and is related to the linear damping coefficient c by 



c = pD^fks. (C6) 



In either form the total damping is the sum of the structural and hydrodynamic damping contributions. 



For taut cable conditions, however, the structural contribution is very small and the results in Fig. C6 



are essentially equal to the fluid contribution to the total damping. The same dependence of the added 



mass and fluid damping on the vibration Reynolds number was obtained by Chen, Wambsganss and 



Jendrejczyk (C4) and by Skop, Ramberg and Ferer (C5) during experiments conducted with vibrating 



cylinders in water. 



Table C2 



Cable Added Mass and Damping; 



Legend for the Data in Figures C5 and C6 



Cable type and specifications 



Fig. C5 



Fig. C6 



3/32 inch (2.4 mm) steel wire cable, three modes: 



D A A 



0,(1,« 



3/32 inch (2.4 mm) hydrophone cable 





A 



1/4 inch (6.4 mm) steel wire, two modes: 



■ 



Da 



3/8 inch (9.5 mm) jacketed kevlar fiber: 







X 



7/16 inch (11.1 mm) polyester fiber: 





-t- 



0.6 inch (15.5 mm) Double Armor Steel cable: 



t 



t 



0.6 inch (15.5 mm) Uniline cable: 



f> 



F^ 



0.6 inch (15.5 mm) Seacon cable: 



<J 



<d 



144 



