INTRODUCTION 



The work described herein was carried out as part of BuDocks Task No. 

 Y-F015-01-01-001, "Structures in Deep Ocean," which originated from the require- 

 ment of the Bureau to attain a deep ocean engineering capability in keeping with the 

 increased emphasis on the deep ocean as an operating environment for naval forces. 

 This report is the result of work performed under Task No. Y-F015-01 -01 -001(b), 

 "Mechanics of Raising and Lowering Heavy Loads in the Deep Ocean," 



The objectives of this work were to analyze and report on the results of 

 predictions of the forces in lines and the acceleration and displacements of loads of 

 various shapes during raising and lowering operations in the deep ocean. The study 

 is based on, and an extension of, a theoretical analysis by Arthur D. Little, Inc., 

 given in Project Trident Technical Report No. 1370863 of the Bureau of Ships, 

 entitled "Stress Analysis of Ship-Suspended Heavily Loaded Cables for Deep Under- 

 water Emplacements. " ' 



THEORY 



The problem considered in this report is that of a load suspended from a ship or 

 moored platform by means of a single cable, as shown in Figure 1.* The maximum depth 

 for such a lowering or raising operation is assumed to be on the order of 20, 000 feet. 



The requirements are (1) to analyze this problem so as to predict the cable and 

 the load dynamics, in particular the maximum dynamic stress induced in the cable as 

 a result of the motions of the suspension point, and (2) to provide a design procedure 

 for evaluating such stresses for a given load under specified conditions of sea-surface 

 oscillations. 



Solution of this problem is recognized to be difficult in view of the nonlinearitles 

 introduced in the damping due to drag forces of vertical oscillations of the load. A 

 simplified solution has been obtained by Arthur D. Little, Inc., as given in the Project 

 Trident report. A brief resume of the analysis presented in that report is given here, 

 details of which may be found in Appendix A. 



The equation of motion of an element of the cable initially located at a distance 

 X from the support point is given by 



(B.')2 ' '>■ (.x')2 



Figures 1 through 35 are presented immediately after the main body of text. 



