5. CONCLUSION
We have found optimum ships for minimum total drag over a large range of
speeds and displacements. Results were obtained both with and without
form drag corrections, and for monohulls, catamarans and trimarans.
Although the net contribution of form drag is small, it can nevertheless
be important in determining the optimum. The optimum ships tend to be
longer and have a lower wave resistance relative to viscous resistance than
conventional ships. The genetic algorithm tool GODZILLA has proved useful
in searching for the global minimum in the presence of two or more local
minima, and will be essential in extended work involving shape variations
and other constraints. Optimum (long) monohulls are always better than
optimum catamarans or trimarans of the same total displacement, from the
point of view of total calm-water drag alone, unless there are restrictions
on the ship geometry.
ACKNOWLEDGEMENTS
This work was supported by the Australian Research Council.
Back to Title Page
Previous Section
Next Section