NaxCoO2 has an exceptional combination of thermoelectric properties, including low thermal conductivity, and it is currently under consideration for use in power recovery and as a solid state refrigerator. Our neutron Laue diffraction measurements reveal a kaleidoscope of superstructures as a function of composition. The ordering principle is the formation of multi-vacancy clusters that order long range. These clusters form rattling cages that can potentially disrupt thermal transport via phonons. We have grown a large, high quality single crystal of Na0.8CoO2 that has an ordered array of tri-vacancy clusters arranged in stripes. We propose to map out the full phonon dispersion using the rotation method on MERLIN. The aim of the project is to determine the effects of the rattling modes on the phonon dispersion, such as the creation of flat modes or gaps due to avoided crossings.