2. METHOD
For each design displacement and each design speed, we have a five parameter optimisation problem; specifically, we need to find the optimum length and draft as well as three shape parameters. The computer program GODZILLA (Lazauskas 1996) was used to find these optimum parameters. The program contains a variety of hill-climbing routines to assist in the search process, however for the highly multimodal objective function we are considering in the present study, the program's nonlinear components are essential. These include genetic algorithm techniques, and a number of other heuristics that can broadly be described as Artificial Life methods.
In order to exhibit the effects of displacement, we carried out the optimisations at three fixed (dimensional) displacements for each class: 0.080, 0.090, and 0.100 tonnes for K1 kayaks, 0.155, 0.170 and 0.195 tonnes for K2 kayaks, and 0.300, 0.335, and 0.380 tonnes for K4 kayaks.
For each of these displacements, optima were sought at 10 volumetric Froude numbers, Fnv = 1.6,1.7, ...,2.5., making 90 design problems in total. Each design problem was run with at least three different initial populations, and a minimum of 8000 resistance evaluations were performed during each run.