A portable system to measure strip vibration at the nozzles level on continuous galvanizing lines is presented. It consists of three inductive sensors: two sensors are located near the strip edges and the last one is at the centre of the strip. This system has allowed reproducible results, provided the appropriate calibration procedure is used. The device has been successfully implemented on three lines of Arcelor. Considering the effect of strip tension and size, the frequency and amplitude measurements confirm the trends that can be expected from numerical modelling. Amplitude is always increased by the gas cooling power in the tower. Strip tension has a predictable effect on the frequency peaks; however its effect on amplitude is more ambiguous. Other observations have been made concerning the effects of pot roll bearings and roll intermesh.