  We report on a Raman scattering study on the superconducting cobaltite
$Na_xCoO_2\cdot yH_2O$ as function of Na content and hydration (x$\approx$1/3,
3/4 and y$\approx$0, 2/3, 4/3). The observed phonon scattering and scattering
continua are analyzed in terms of lattice strain due to the structural misfit
and disorder. Hydration, due to the intercalation of one or two $H_2O$ layers,
releases a part of this strain. Our Raman data suggest a connection between
disorder on the partly occupied Na sites, the split off of the $a_{1g}$ level
from the other $t_{2g}$ states of $Co^{4+}$ and superconductivity.

Strongly Correlated Electrons;Superconductivity