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Chapter 2

Setting Design Requirements

2.1 STATING OBJECTIVES IN BROAD TERMS

It is most important that the objectives which a new design is to meet should be
stated in a way that does not rule out any possible solution. It is only too easy when
setting requirements to have a particular type of design in mind and write terms of
reference in a way that leads to a solution along these lines but excludes some other
equally good or better answer. Objectives should be set at their most desirable level
even if their attainment seems unlikely or impossible. This will stretch designers
and may cause them to come up with novel ideas that are ahead of any current
solution.
When setting objectives, it is wise to differentiate between qualities which are
essential and those which are only desirable and can be modified if the price of
their attainment is too expensive or turn out to be to the detriment of a higher rated
goal. It is debatable whether such relaxations in the statement of requirements
should be exposed to the designers at the outset or only be released to them when
the impossibility, or excessive cost of meeting the ideal requirements becomes
apparent. Concealing them will force maximum effort and good lateral thinking;
on the other hand, if this leads to the designers feeling that they have not been fully
trusted they may not give of their best.
A merchant ship’s requirements will usually originate in a transportation study
which examines the economic background to the projected service. The require-
ments for a warship will have been based on consideration of possible threats and
will usually have been preceded by many strategic studies.