With a growing range of floating tidal energy converters being developed, tested and deployed the SURFTEC project aimed to measure and model the motion of this type of device. Part of this work included the design and development of a relatively low cost data logging and motion sensing system, deployed on a test device at two sites between 2017 and 2020. Approximately 8000 hours of data were recorded, with concurrent recording of flow data using an ADV as well as GPS position information and motion data from redundant IMUs. This paper illustrates the capability of the system by showing the results of processing the recorded data through a Kalman filter model to recover position and heading of the device, continuing from previously published results. This allows for better understanding of the platform’s response to flow conditions and consequently improved input for models of mooring and structural loads. The lessons learned regarding the design and deployment of this data logging system are also discussed.