## 2 Materials and Methods  
The primary objective of this study was to evaluate the positional accuracy, availability, integrity, and service continuity of the PNT solution. Therefore, the focus was primarily on assessing the performance of the device rather than analysing specific test protocols or athlete performances [22]. Additionally, because of an inability to precisely follow a set trajectory through slalom gates of a known distance, it was decided to perform multiple (\(n=25\)) runs over two different trajectories during a dry-land simulation. These trajectories, namely the short or more direct path, and long or less direct path, were chosen to simulate performer variability (Figure 1A) typical of slalom canoeing [22]. This was then followed by an assessment of the device's performance during an uncontrolled on-water slalom for real-world comparisons (Figure 1B). This sample size was based on previous research [22] conducted in a similar context, where aerial video tracking showed significant differences but remained practically useful for canoe slalom. Using these data, a priori statistics were generated (G*power V 3.1.9.7, Heinrich-Heine University, Dusseldorf, Germany) for \(t\)-tests of the mean differences between two dependent matched means. Calculations were based on an equivalence or non-inferiority test rather than a traditional hypothesis test. It was decided that a difference of 1.0 \(\pm\) 0.5 m in trajectory was acceptable, resulting in a required sample size of \(n=6\). However, considering the sample size used in previous studies [22], our need for increased reliability, and the potential for greater variability in real-world settings, a sample size \(n=25\) was chosen. For all data collection, one DGNSS device (Arrow 100 GNSS receiver, Eos Positioning Systems, Inc.(r), (Eos), Montreal, CA, USA) was used in combination with one experienced (35 years national/international experience) male kayaker in accordance with the University Human Ethics Committee. Figure 1: (**A**) Dry-land simulated slalom course with marked trajectories (obtained from the Arrow 100 and proceed with ArcGIS Pro) for one trial, labelled as short (\(-\)) more direct, and long (\(-\)) less direct, for validation purposes, and (**B**) real-world on-water flatwater slalom course used. The GNSS receiver was positioned on the participant's canoeing helmet, over the frontal-sagittal border of the parietal and frontal bones of the skull, to minimise satellite reception impediment [11], but also because international federation rules [1] stipulate the head must pass through the gate-line. As such, placement on the boat would likely augment any discrepancy or misrepresentation of athlete trajectory, limiting data value. The PNT solution utilised in this study made use of SBAS SouthPAN (Satellite-Based Augmentation System South Pacific) in combination with all available GNSS constellation channels, including GPS, GLONASS, Galileo, Beidou, and QZSS. The device could receive differential corrections through NTRIP (Networked Transport of RTCM via Internet Protocol) GNSS data obtained from PositioNZ base station(s). Specifically, the differential corrections were sourced from the mount point DNVK00 NZL0. The mount station was located approximately 41 km from the location of both trials. Prior, unpublished data showed that this distance for these venues did not affect the accuracy, availability, integrity, and continuity of the PNT solution outside the optimal range required (Table 1). GNSS signals and measurement extraction were processed via EOS Pro Tools application (Eos Positioning Systems, Inc.(r), (Eos), Montreal, CA, USA) using propriety algorithms. This application provided UTC Time, Longitude, Latitude, Height above sea level, Speed, Hrms, Vrms, 3 Drms, Satellites in view, satellites used, PDOP, VDOP, HDOP, and differential age throughout the study. For real-time data logging, EOS pro Tools connected via a third-party mobile iOS app called ArcGIS QuickCapture (ESRI, Redlands, CA, USA).