Prove

Two places show progress, and both show only measured numbers — nothing generated.

The athlete's Progress page

/athlete/progress (also on the iPhone):

• Your focus areas — the themes the coach has tagged across guided reviews, each moving from working on it to improving to resolved. The card appears once a review is tagged.
• This month · last month — Sessions filmed, Waves ridden (from the watch when it was worn, otherwise estimated from video — the source is labelled), Top speed (GPS, watch only) and Focus areas resolved.
• Coach notes — the running count.
• Session frequency (last 12 weeks) and a Coach feedback timeline.

The page is for viewing; drills live under Drills (/athlete/drills).

Apple Watch data

When an athlete records a surf on the Apple Watch, the recording hands off to their iPhone and uploads to Surflink. It appears under Manage → Wearable Sessions (/wearable) for the coach, on the linked training session's Watch data card, and on the synced clip's insights.

What is captured

• GPS — speed, distance and the track (the map and per-wave speeds).
• Motion at up to 100 Hz — gravity-separated acceleration, rotation and orientation, which power pop-up, turn, G-force and airtime detection.
• Heart rate and calories — effort, heart-rate zones, recovery and a training-load score.
• Environment — relative altitude and, on Ultra, best-effort water temperature.

The full raw signal is retained, so detectors can be re-run on old sessions as they improve.

The wearable session page

/wearable/[id] shows the GPS map with a linked speed / heart-rate chart (selecting a wave cross-highlights map, chart and timeline), a per-wave breakdown (speed, duration, peak G, turns, airtime, pop-up time, with a motion chart per wave), an effort panel (zones, recovery, training load, paddle / ride / rest split, cadence, calories) and coaching takeaways — rule-based pointers computed from the session's metrics, not written by a model.

Every session wears a confidence tier: Trust (validated against labels or strong signal), Estimated (heuristic detection, no ground truth yet) or Beta / GPS-only (indicative only). Absolute speed and distance are always GPS-bound; motion events get more accurate as labels accrue.

Ground-truth labels

On the session timeline a coach can confirm, edit or add ride starts and ends, pop-ups and turns. Labels are stored as ground truth, used to measure detector precision and recall, and used to tune thresholds — globally and per athlete. Re-run the detectors on an old session to backfill it.

Trends, imports and deletion

The Trends view on /wearable rolls sessions into charts (waves per session, top speed, ride time, calories, training load, paddle efficiency) with a per-athlete filter. A GPX import brings in a session recorded elsewhere. Only coaches and admins can delete a wearable session (the trash on a card, or Delete on the session page); linked footage is unaffected.

How the watch, the phone and the footage line up

The training session is the hub. The athlete's iPhone pushes the day's schedule to the watch, so Start Surf on the watch picks the scheduled session (or Freestyle) and the recording carries the athlete and session from the first sample — even fully offline. Footage filmed while the watch is live is bound to that watch session at capture; clips from other cameras are aligned afterwards by cross-correlating the watch's speed with the pose-derived speed from the video. See Apple Apps.