Position data from an Argos-tracked buoy deployed in the southern Weddell Sea in the austral summer of 1986 are analysed to determine important time-scales of variation of sea-ice motion in the seasonal sea-ice zone. Quality control and pre-processing of raw buoy data are discussed. Processed position data are subjected to time- and frequency-domain analyses. These highlight the importance of diurnal and semi-diurnal periodicities in the buoy motion. These preferred periodicities are associated with tidal forcing rather than wind forcing or inertial oscillations. Periodograms of the longitudinal component of buoy motion indicate that the power of the 24 h tidal component drops dramatically around day 130 in 1986. The possible causes of this are discussed and it is concluded that internal resistance within the sea-ice field may have increased at that time.