Seakeeping Constderattons in a Total Destgn Methodology 
c) Eliminate all infeasible designs. 
d) Evaluate the optimization criterion for all feasible de- 
signs, and 
e) Select the alternative that is feasible and satisfies the 
problem objective. 
The part of the mathematical model that is directly related 
to the seakeeping considerations will now be described in some detail. 
The other elements of the mathematical model can be found described 
in the literature dealing with the subject of preliminary ship design 
optimization, see for example Reference [5] , and therefore will not 
be repeated here. 
Description of the Environment 
The environment in which the system under investigation is 
to operate must be described in order to permit the evaluation of the 
system's seakeeping qualities. Given the route of operation sucha 
description can be obtained from the information given in Reference 
[6] . The complete environment description would require the cons- 
truction of a frequency histogram as a function of significant wave 
height, average period, direction,time and geographical location. 
For the present study the environment description was sim- 
plified to a frequency histogram which is a function of the significant 
wave height and geographical location only, and the spectrum des- 
cribing such seaways (fully developed, long crested) is given by : 
o* (w ) = aa me exp ( - ae 
cF 
where a = 0.0081 23 fe /aet=] 
and B= 0324 ay feet] 
In addition only head seas were considered in this study. 
The simplifications adopted in this study are not considered 
unrealistic. In the route chosen for investigation (New York-Rotterdam) 
head seas were predominantly encountered at least 50% of the time 
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