For analysing performance in alpine ski racing, an accurate estimation of the skier’s centre of mass trajectory and speed is indispensable. However, the sole use of low-cost GNSS might not be accurate enough to detect meaningful differences. The aim of this study was to introduce a new system that can improve the accuracy of a low-cost GNSS to an acceptable level. To this end, the data obtained by low-cost GNSS was fused with data form inertial sensors and position information of permanent magnets buried into the snow surface along the ski track. This fusion improved the system’s accuracy from 2m to 0.5m. Despite the added sensing technologies, the system remained simple and was easy to use. Further improvements are possible and a technical validation of the system could be a major aim for the future.