Annual surfer performance statistics.

1 Statistics based on one year of data collected by the same surfer of an intermediate level according to the Hutt et al. [60] surfer skill rating scale.
2 Uncertainty (±) was computed based on a sensitivity analysis of fixed parameters used in the GPS processing, with the following parameters varied: the minimum moving speed (fixed at 0.5 ms−1) varied between 0.2–1.0 ms−1, at 0.2 ms−1 intervals; the pre-processing high speed filter (fixed at 15.3 ms−1) varied between 10–18 ms−1, at 2 ms−1 intervals; the minimum duration of a classified wave (fixed at 4s) varied between 3–6 s, at 1s intervals; and the duration the surfer was allowed to fall below the threshold velocity and outside the permissible directions (fixed at 8s) varied between 6–10 s, at 1s intervals. For each sensitivity run, one parameter was varied while keeping others fixed at their default value. In total 17 sensitivity runs were conducted and for each of the surfer performance variables, standard deviations were computed based on the 17 runs and are provided as ± values in the table.
Annual surfer performance statistics.