Figures of Merit 



A figure of merit is an index of quality of a system. It is here that the 

 operating parameters enter into the discussion. As an example, the rate of 

 lifting and lowering a load would form a basis for assigning a figure of merit 

 for the candidates. These factors are discussed only if it is suspected that they 

 will cause significant differences in the final cost/effectiveness evaluation. 



The magnitude and importance of the figures of merit in the system 

 evaluations are at best subjective judgments. Arbitrary standards will vary in 

 some logical manner with time, but they will also be assigned varying degrees 

 of importance by different groups or individuals at any given point in time. 

 In addition, technological breakthroughs or similar unforeseeable changes 

 produce new possibilities and invariably alter standards. Thus, it is apparent 

 that the heavy-lift system, the environment, and the ultimate mode of 

 operation are sufficiently complex and variable with time that the possibility 

 of optimization is out of the question. Therefore, the proposed method of 

 effectiveness evaluation is based on the objectives of currency and the 

 possibilities of systematic improvement. 



Accountable Factors 



Any factors which have or are suspected to have an influence on the 

 figures of merit must be considered. In this study, the most obvious and 

 important factors are the environmental conditions under which the system 

 must operate. Temperature extremes, currents, and ocean waves are 

 examples of the accountable factors which must be inputs for a realistic 

 evaluation. 



Other accountable factors given consideration in this report are the 

 critical logistic support considerations. Included here is the ability of the 

 lift system to receive loads from auxiliary support vessels while remaining 

 on station. 



In studies for which hard data are available, additional accountable 

 factors include personnel requirements, maintenance policies and require- 

 ments, and failure-rate data. These factors can enter the discussions in only 

 a general way, however, since there is very little experience on which to base 

 predictions. For some components there is the possibility of estimating and 

 extrapolating from related experience; for nonelectrical systems, however, 

 this information is hard to locate (if indeed there is any). 



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