The paper presents a nonlinear technique for generating high and highest freak waves by using deterministic wave packets which are also embedded into irregular seas. First, the technique is developed for small water elevations with a linear description of the wave. Afterwards the method is extended to a nonlinear description based on the introduction of a “wave information” which includes the (linear) information of waves as Fourier Transforms. Combined with a modified wave celerity (information speed) the propagation of high waves can be developed by using Stokes higher order solutions or semi empirical expansion equations. As a result, the nonlinear wave contours, registrations and associated wave data are derived from the respective wave information. As the mentioned methods are not only used as a theoretical approach for describing steep wave trains a wide range of applications for generating high deterministic waves in model basins is presented. Thus extreme waves with heights of more than 3 m have been generated. This technique has also been adapted for the demands of computer controlled seakeeping tests. As both model and wave probe do not necessarily move at the same velocity, a time domain procedure is introduced for transforming the registration of the wave elevation from the wave probe posi-tion to the model position which leads, especially in astern and quartering seas, to extraordinary wave contours experienced by a moving vessel.

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