COMPIT 2010 in Gubbio - TUHH

quired); installation, training and maintenance costs; and interest on loans (or opportunity cost on
bound capital).
During formal training, the costs for each user include: the appropriate fraction of the cost of the
trainer; the operating costs of the CAD system used for training; opportunity costs since the trainees
cannot work productively during the training period. Where users are self-taught, the costs arise due
to low user productivity during the training period. Training time and costs are frequently underestimated.
Amounts suggested by vendors and other users are generally too low. In many cases several
man-months are needed for staff to become fully productive using the new software. The disparity in
the training costs of different systems (due to, often considerable, differences in user-friendliness,
technical support and quality of training) may significantly outweigh the differences in the licence
fees alone. Cheap software frequently turns out to be expensive if all costs (including training and opportunity
costs) are considered.
3.1.4.2. Economic Benefits of CFD
The value of computer technologies can be classified according to time, quality and cost aspects. The
main benefits of CFD in these respects are, according to Bertram (1993):
• Problems solved more quickly than when using conventional approaches, due to better (direct)
insight into design aspects. CFD analyses of ship hulls and appendages before final
model testing are now standard practice in ship design. CFD can also help with much faster
trouble shooting in cases where problems are found. For example: hydrodynamically excited
vibrations as described by Menzel et al. (2008).
• Improved designs through detailed analysis and / or formal optimisation, e.g. Hochkirch and
Bertram (2009).
• The speed of CFD now allows its applications during preliminary design. The use of CFD
early in the design phase reduces the potential risk associated with the development of new
ships. This is especially important when exploring niche markets for unconventional ships
where the design cannot be based on previous experience, e.g. Ziegler et al. (2006).
• CFD does not significantly reduce the cost of the actual design process, but it improves quality
and helps with the early detection of design flaws and this can lead to significant cost savings.
Within the first weeks of design, 40% to 60% of the total ship production cost is determined,
Johnson (1990). The costs of design modifications increase by orders of magnitudes
the further into the project they are made; ideally no fundamental modifications should be
made after the conceptual design phase. Achieving this goal can be greatly facilitated by the
use of CFD. If CFD is employed consistently to determine the final hull form at an earlier
stage, numerous decisions that influence the production costs can be made earlier in the design
process, thus reducing the risk of expensive design modifications being necessary later in
the project. This is especially important in the context of modern workflow methodologies
(e.g. concurrent engineering and lean production).
When assessing the economic benefits of CFD, merely considering cost aspects will therefore lead to
incorrect strategic decisions. We can assess the benefits of CAD by using an analogy with another
computer technology: CIM (Computer-Integrated Manufacturing), aptly put by Dietrich (1988):
“In other words, when taking CIM decisions, the question of ‘What will we save in
the short term?’ is not the right one to ask. The real issue is rather ‘How will our operational
situation develop if we do not introduce CIM?’ ”
3.2. Secondary Phase: Assessment and Decision
Areas suitable for the application of CAD (and / or CFD) may be selected considering:
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