Page 39 - Practical Ship Design

10 Chapter I

being used to speed the process. If used at this early stage, some of the input is
likely to be tentative but one great joy of computer methods is the ease with which
calculations can be updated as better information becomes available. CAD methods
will generally be used when drawing the arrangement plan, the lines plan and other
plans, speeding this work enormously and greatly improving its quality. The fact
that scales can be changed during this process, with what started life as a 1/200
initial plan being transformed first to MOO and then to 1/50 enabling more and
more detail to be added, is a tremendous advantage. The scale change ability means
that even at a very early stage large-scale detailing can be used to investigate areas of
difficulty.
It is interesting to recall that initial design was one of the first subjects to be
attacked in the early days of computers. The method used at that time involved the
processing of multiple designs on a batch basis with the aim of identifying an
optimum solution from the resulting mass of designs. The process was not very
successful for two main reasons: the design processes used some algorithms of
doubtful accuracy and the criteria used to identify the optimum answer were
unsatisfactory.
An unfortunate side effect of the use of such computerised ship design programs
was the tendency this had of deflecting the designer from innovative thinking
about the design. No-one today would dispute that the biggest contribution to the
efficient transport of general cargo in recent years came, not from all the effort put
into optimising ship design using advanced computer methods, but from the lateral
thinking of the trucker who came up with the idea of making mixed general cargo
into an easily handled bulk cargo by putting it in standardised containers.

1.2.2 Expert systems

The modern approach to the use of computers for initial design makes use of an
expert system technique which almost certainly encourages innovative thinking
and is a trend which the author welcomes unreservedly. In the past when one of the
stalwarts of his design team was approaching retirement or leaving to take another
job, it had always to be a top priority to ensure that the departing expertise was
passed on to another member of the team. This was never easy but the advent of
computerised expert systems means that it is now possible to accumulate know-
how in an organised format as a standard routine.
Even more important, however, is the ability that an expert system has to make
use of the expertise of a large number of specialists enabling these to be consulted
at their convenience without any need for them to be present at the time when a
design is being prepared - usually in a hurry and when they may have other
commitments.