DYNAMICS AND KINEMATICS OF SUBMARINE CABLE 



1163 



7000 



4000 



TIME 



15 20 



N MINUTES 



Fig. 21 

 pended. 



Variation of tension with time when cable No. 2 is completely sus- 



On the other hand, in the case of a frictionless bottom, the removal of 

 the supporting water drag forces would cause the cable to seek a catenary 

 equilibrium position on the low side of the crest. But in doing this, the 

 cable would drag itself over the crest, with an accompanying increase in 

 shipboard tension. 



Thus for the case of a bottom rise steeper than the cable inclination 

 (a < 7) either an increase or a decrease of tension with time is possible, 

 depending on the nature of the bottom. 



5.3 Residual Suspensions 



If the cable is not paid out rapidly enough, or if the ship speed is ex- 

 cessive, the cable will be left with residual suspensions after it has been 

 laid. To get an idea of the possible magnitudes of the tensions accom- 

 panying these suspensions, we consider here some numerical examples 

 pertaining to cable No. 2. As before, we assume for definiteness the ex- 

 treme case of a bottom rough enough to prevent movement of the cable. 



In Fig. 22 is shown the profile of a 85 fathom (210 feet) increase in 

 depth with a maximum slope of 45°. This profile was obtained from 



