5.1 Introduction
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        From photographs and reports of ocean storms we conclude that storm waves are generally not regular or stable, that is, each individual wave does not retain its shape for very long. The wind forces cause the wave crest to steepen until a white cap forms and takes energy from the wave. Of ten two or more waves intersect forming a complex pattern of wave additions and subtractions. The occasional dangerous breaking wave is a product of a random combination of a wave steepened by wind forces and a second wave which adds energy to the first.

        In constructing a mathematical model it is obviously not feasible to consider the detailed interaction between a variety of boat types and a spectrum of wave types. However, it is possible to construct a generic model which permits us to study the significant engineering problems (as distinct from the scientific problems) associated with breaking wave capsizing.

The major engineering concerns are:

  1. Construction of a theoretical framework to assist in interpretation of model tests and full-scale events.
  2. Obtaining a working understanding of the relative importance of the factors involved in a breaking wave capsize.
  3. Developing the capability to predict loads on the boat and drogue system with sufficient accuracy to permit rational design of the equipment.

        Although this problem is extremely complex, the model tests show that much can be learned by the application of a relatively simple mathematical simulation. For this investigation the analysis was divided into two separate programs. First, a simulation of the boat and drogue in regular waves, and second, the boat and drogue being stuck by a breaking wave.