Dispersion of waves ruins my required practical

We measured the speed of waves on water by lifting and dropping one end of a tray and timing the movement of a wave along the water. The wave was moving at around 30 cm/s. We then set a dripping tap to create waves of a particular frequency. This was of the order of 1 Hz. By the equation wave velocity = frequency x wavelength, the wavelength should be of the order of 30 cm. Look at the picture: That certainly doesn't seem to be the case. The problem appears to be that the equation might not apply in this example. Such waves are called capillary waves https://en.wikipedia.org/wiki/Capillary_wave The data about the waves given in the article seems to tie in. A dispersion relation is given which will need investigating but I need to work out how to calculate the surface tension.