assumptions associated with the structure and with 

 hydrodynamic loading criteria and because of errors 

 inherent in the computational techniques and 

 machines. Therefore, to provide full confidence in a 

 program it should be validated by comparing pre- 

 dicted results with precise experimental data. How- 

 ever, because little experimental data exists to 

 validate programs, only a few of the programs for the 

 simple mooring types have been validated. 



Assumptions. The assumptions vary from pro- 

 gram to program but basically center on the method 

 used to model the structure and on the simplifica- 

 tions used in the calculation and application of the 

 hydrodynamic loading forces. 



Remarks. A brief summary of program charac- 

 teristics and capabilities are presented, and the availa- 

 bility of program listings is indicated. 



Survey Results 



All the programs presented in Table 1 are 

 operational. It should be mentioned that some of the 

 dynamic programs use a steady-state program to 

 establish a starting point for dynamic analysis. The 

 entries in Table 1 based on Reference 16 by Patton 

 and on References 37 and 38 by Goodman and 

 Sargent are examples of static programs which are 

 extracted from a dynamic program. 



DYNAMIC ANALYSIS 



In this section computer programs for the 

 dynamic analysis of moored cable systems are pre- 

 sented. These programs try to simulate the dynamic 

 response of various moored structures under the 

 action of time-dependent forces other than those pro- 

 duced by vortex shedding. Table 2 presents the pro- 

 grams and attempts to update and complement the 

 surveys presented in References 1 through 3. 



Terminology of Table 2 



Each of the descriptive terms found in Table 2 

 are briefly discussed below. 



Program Dimensionality. As with the 

 steady-state programs, the dynamic programs may be 

 one-, two- or three-dimensional. The two programs in 

 Table 2 that are one-dimensional examine the behav- 

 ior of a mooring system along the cable a.xis. The 

 remaining programs are concerned with tensions and 

 displacement of the system in a plane or in space. The 

 authors of several of the two-dimensional programs 

 feel that extension to the third dimension would not 

 require large amounts of reprogramming. To simulate 

 the ocean environment, particularly near the surface, 

 three-dimensional analysis is many times a necessity 

 because of nonplanar wind, wave, and current forces. 



Mooring Type. Again the reader is referred to 

 Figure 1 for definitions of the terms used to describe 

 mooring-system types. Most of the programs listed in 

 Table 2 are for the single-point mooring. 



Solution Method. A variety of solution methods 

 are used in the dynamic programs. Reference 3 gives 

 an excellent summary of the methods with their 

 merits and demerits. 



System Excitation. The environmental factors 

 which produce the dynamic system response are sum- 

 marized here. The excitation sources are related to 

 wave, wind, or current. 



System Damping. The forces generated by 

 mooring systems which oppose the dynamic response 

 of the systems are called damping forces. Damping is 

 generally hydrodynamic- or cable-related but mav be 

 assumed to be a function of the geometry or mass of 

 the system. An excellent presentation of the Voight 

 and Maxwell linear-damping models for cables is given 

 in Reference 4U. 



Properties of Cables. The assumptions associ- 

 ated with the cables are summarized here, in most 

 cases all forces and mass are assumed to be concen- 

 trated at discrete points along the cable. The cables 

 are assumed either to be completely flexible and 

 elastic or to be made up of a series of springs or rigid 

 segments interconnected with springs. 



Status of Program. Information on whether the 

 program is operational or proprietary is given. 



