Two-Dimensional Non-linear Dynamic Analysis of Cable Laying Operations

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 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 properly install and repair submarine cable systems. The results are presented as transfer functions and response spectra of cable dynamic tension for two different types of cable and several heading angles. The obtained responses make possible to determine order statistics of the cable lying process. The cable element angles, cable configuration and cable top force are presented for the case of ship under acceleration.