## 4 Discussion
The inclusion of two trajectories over the same dry-land simulated slalom course, with a successful negotiation of all gates (Figure 1A), allows for quantification of the PNT solution and facilitates a comparison of athlete trajectories (Figure 2B). In this instance, even small positional changes across the entire course, as observed in the dry-land short and long trajectories, resulted in a significant difference of 10.5 m in the total distance travelled. Such a difference would have a substantial effect on performance, where a meaningful change is reported to be 0.4-0.6% [20]. The mean \(\pm\) SD total distance travelled using the PNT solution was found to be less than 1.5% for both the short (direct path) and long (less direct path) trajectories (Figure 3). This level of accuracy surpasses what has been reported in many team sport investigations [16,18,29]. These results suggest that the PNT solution could provide valuable information to coaches and athletes regarding overall performance. Furthermore, the narrow 95% CI for horizontal accuracy suggests that more specific segmental data could be obtained, as previously demonstrated through aerial analysis of single gate sections [3]. However, frequency distribution analysis (Figure 3) emphasises the importance for analysts to understand the integrity and continuity of PNT solutions, as well as how data are interpreted. Despite maintaining high numbers of satellites used (Figure 3A), and ideal PDOP and HDOP values (Figure 3C,D), the spread of data (0.10-0.45m) in the Hrms (Figure 3B) indicates the need for cautious interpretation. Future work should focus on using this to assess performance, along with developing and validating analysis systems that can provide coaches and athletes with invaluable information. As the data from the dry-land simulations provided positive results regarding the accuracy, precision, and functionality of the PNT solution in a controlled environment, testing on-water in a real-world uncontrolled situation took place (Figure 3B). In this instance, an even greater number of satellites were utilised (Figure 5A). While data were collected at a similar time of day, the dry land and on-water trials were performed on different days, which may mean there were less usable satellites available [30] or less signal obscuration at the receiver, or in this case, the athlete end [10], for the dry land trials. Even with much higher numbers of usable satellites in the on-water trial (Figure 6A), there were no significant differences between the horizontal accuracy (Hrms) of the dry-land verses the on-water trials. Importantly, while not significant, there was a definite trend of increased horizontal accuracy on-water (Figure 6B), which is supported by a significant decrease in the dilution of precision variables (Figure 6C,D). Even so, the use of dry-land simulation to test tracking devices in canoe slalom is warranted, and in this case, the PNT solution provided high levels of accuracy, availability, integrity, and service continuity. On-water testing likewise supports its use as a quantitative tracking tool, where future research needs to focus on the efficacy of DGNSS in canoe slalom along with methods of analysing segmental data. Conceptualization, P.W.M. and M.E.I. ; methodology, P.W.M. and M.E.I. ; software, P.W.M. and M.E.I. ; formal analysis, P.W.M. ; resources, P.W.M. and M.E.I. ; data curation, P.W.M. and D.C.; writing--original draft preparation, P.W.M. ; writing--review and editing, D.C. All authors have read and agreed to the published version of the manuscript. This research received no external funding. The study was conducted in accordance with the Declaration of Helsinki, and approved by the Massey University Ethics Committee (SOA 13/15). Informed Consent Statement: Informed consent was obtained from all subjects involved in the study. The raw data supporting the conclusions of this article will be made available by the authors on request. The authors declare no conflicts of interest.