Within the context of wave energy conversion, this paper investigates the practice of using wave (frequency) spectra to characterise wind waves. In particular, this paper looks at the major shortfall of the wave spectrum - its lack of information provision on the temporal variability of the wave activity. Finally, the issue of different spectral shapes with the same seaway summary statistics (i.e. Hs, the significant wave height, and Tz, the mean zero crossing wave period) is investigated. Measured wave data recorded off the West Coast of Ireland provides the basis for this analysis, with the wavelet transform providing the primary analysis tool.