  We investigate applicability of the Hasselmann kinetic equation to the
spectrum of surface gravity waves at different levels of nonlinearity in the
system, which is measured as average steepness. It is shown that even in the
case of relatively high average steepness, when Phillips spectrum is present in
the system, the spectral lines are still very narrow, at least in the region of
direct cascade spectrum. It allows us to state that even in the case of
Phillips spectrum the kinetic equation can be applied to the description of the
ensembles of ocean waves.

Atmospheric and Oceanic Physics;Chaotic Dynamics;Computational Physics