DYNAMIC TENSION OF MARINE CABLES DURING LAYING OPERATIONS IN IRREGULAR WAVES

A numerical approach for predicting motion and tension of marine cables during laying operations in a rough sea is presented. The solution methodology consists of dividing the cable into straight elements, which must satisfy equilibrium equation and compatibility relations. The system of obtained nonlinear differential equations is solved by Runge-Kutta method, taking explicitly into account the effect of regular and/or irregular waves. Illustrative applications of the method are given for a cable-lying ship of approximately 100 m length, designed to install and repair submarine cable systems. The results are presented as transfer function and response spectrum of cable dynamic tension for two different types of cable, several ship velocity-heading combinations. The obtained responses make it possible to determine order statistics of the cable lying process.