Tether Swim

TetherSwim is built for swimmers training with resistance cords, swim tethers, or endless pools. Traditional swim trackers can struggle with these sessions, giving you wildly inaccurate distances or ignoring your efforts altogether.

With TetherSwim, your distance is estimated intelligently based on your real stroke count, SWOLF, and previous swim history — all from your Apple Watch.

Features:

• Accurate distance estimates – Uses your stroke rate, efficiency, and past workouts to calculate real swim distance.

• Automatic SWOLF tracking – Measures your swim efficiency in tethered conditions.

• Calories, heart rate, and more – Full workout data, just like in regular pool swims.

• Exclude test swims – Keep your baselines clean by excluding warm-ups or experiments.

• Strava integration – Upload your tethered swim sessions directly.

• Water Lock mode – Automatically engages when you start, so your watch screen won’t go crazy mid-session.

Why I built it:

I’m a triathlete and DIY Ironman who trains in open water, pools, and with a tether when I can’t get to either. I’d been tricking my watch by setting the pool length to 200m and pretending to turn every few minutes — which worked until it didn’t. Once my watch stopped counting these “turns”, I wanted a better way to track my training without guesswork.

TetherSwim is the result — just me building a tool that I hope other tethered swimmers find useful. It’s not perfect, and I’d love feedback from other swimmers.

Please contact me for feedback below!