This paper examines the appropriateness of the Fast Fourier Transform to the decomposition and representation of wave records taken at a fixed location. The prediction of wave behavior at any point on the sea surface should, theoretically, be realizable from this one record. The reality of this statement will be tested along with the use of harmonically generated wave records and the possible advantages of using non-harmonically generated records.
The goal of a short term deterministic prediction of wave behavior has been acknowledged for the past few years (EWEN, 2003; Salter, personal communication). For the wave energy industry a short term prediction would allow advanced control strategies for the maximum economical extraction of energy to be implemented. These control techniques (see Appendix B) are required in order to bring down the costs of electricity production and put offshore wave energy into the same costing bracket as other Renewables.
A few attempts have been made (Belmont et al, 1998; Zhang et al, 1999) to further this goal but they have left some doubts as to the range of their results. Belmont showed that a prediction on the order of 30 seconds ahead would be possible but, in producing his prediction results it appears that only 5 wave vectors were used to represent an omni-directional spectrum. Zhang went further in his prediction method by using real directional data and developing a directional hybrid wave model (DHWM) to produce an accurate prediction from a reference sensor to a point a few tens of meters distant. But, in his paper, he makes no mention as to whether this prediction was made in the time domain. Follow up work to this paper concerning prediction in time has not, to date, been found.