Dynamics and Kinematics of the Laying and Recovery of Submarine Cable

This paper is an attempt to formulate a comprehensive theory with which the forces and motions of a submarine cable can be determined in typical laying and recovery situations. In addition to the f undamental case of a cable being laid or recovered with a ship sailing on a perfectly calm sea over a horizontal bottom, the effects of ship motion, varying bottom depth, ocean cross currents, and the problem of cable laying control are considered. Most of the results reduce to simple formulas and graphs. Their application is illustrated by examples. TABLE OF CONTENTS I. Introduction II. Basic Assumptions I I I . Two-Dimensional Stationary Model 3.1 General 3.2 Normal Drag Force and the Cable Angle a 3.3 Tangential D r a g Force 3.4 Sinking Velocities and Their Relationship to D r a g Forces 3.5 General Solution of the Stationary Two-Dimensional Model 3.6 Approximate Solution for Cable Laying 3.7 Approximate Solution for Cable Recovery 3.8 Shea's Alternative Recovery Procedure IV. Effects of Ship Motions. 4.1 Tensions Caused by Ship Motions V. Deviations from a Horizontal Bottom 5.1 Kinematics of Laying Over a Bottom of Varying D e p t h 5.2 Time-Wise Variation of the Mean Tension in Laying Over a Bottom of Varying D e p t h 5.3 Residual Suspensions VI. Cable Laying Control 6.1 General 6.2 Accuracy of the Piano Wire Technique VII. Three-Dimensional Stationary Model 7.1 General 7.2 P e r t u r b a t i o n Solution for a Uniform Cross-Current Appendix A. Discussion of the Two-Dimensional Stationary Configuration for Zero Bottom Tension Appendix B.