Chryssostomtdts 
the study and that all considerations that can affect the final decision 
be introduced at that time. To be able to do so within the time and re- 
source limitations imposed in all real life problems the proposed ap- 
proach requires the development of suitable mathematical models that 
can be used at the different iteration cycles. The mathematical model 
to be used in the first iteration must be quick (speed is gained by sa- 
crificing the degree of detail) but of sufficient detail to permit the 
decision maker to select correctly from among the large number of 
alternatives that are being investigated. This selection usually invol- 
ves elimination of all infeasible alternatives. The mathematical model 
to be used in the second iteration must be sufficiently detailed and re- 
latively quick to permit the decision maker to select from the alter- 
natives that were not eliminated in the first iteration. This selection 
usually involves the elimination of all clearly inferior alternatives. 
The mathematical model to be used in the final iteration must be fully 
detailed in order to provide all the information necessary that will 
permit the decision maker to make the correct final decision. Fig. 1 
shows all the steps involved in the proposed design methodology. 
Seakeeping is a consideration that can affect the final deci- 
sion because it can affect the system's cost (profit) and feasibility to 
perform its mission, Therefore according to the method proposed 
above seakeeping considerations should be incorporated as early as 
possible in the design cycle. 
A procedure for incorporating seakeeping considerations in 
the design cycle is proposed in this study and is described in some 
detail in the sequel. 
II - FIRST ITERATION 
The mathematical model describing the system under inves- 
tigation during the first iteration of the proposed design methodology 
must have at least the following two attributes. First, it must be 
quick to enable its user to investigate the large number of alternatives 
called for by the proposed methodology and second, it must be accu- 
rate enough to allow its user to draw the correct conclusions from its 
results. The method that will permit us to construct the seakeeping 
part of the mathematical model to be used in the first iteration of the 
proposed design methodology is given in Reference 3. 
The highlights of this method are described below. 
II. 1. Method 
The notion of using standard series, see for example Ref. 4 
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