LapPacer for Apple Watch

LapPacer runs standalone on Apple Watch — no iPhone required. Prop it up poolside as a visible pace display, or wear it and let it record your swim as a real workout in the Health app.

Setup

• Lengths — the total number of pool lengths for the whole set.
• Segments — splits the lengths into that many equal repeats. The counter resets to 0 at the start of each segment. Lengths must always be evenly divisible by the segment count, so the app automatically snaps both values to valid combinations as you adjust them.
• Minutes / Seconds — the total time for the entire set, split evenly across all segments.
• Countdown (sec) — how long the "Get Ready" countdown runs before the length counter starts. Set it to 0 to skip the countdown entirely.
• Pool Length — your pool's length, used both for pacing and recorded as the lap length on the workout saved to Health.
• Units — Yards or Meters, matching how your pool is measured.
• Water Lock on Start — when On, the watch automatically enables Water Lock once your set begins. Off by default.
• Stop on Water Unlock — when On (and Water Lock on Start is also On), turning the Digital Crown to disable Water Lock mid-swim immediately stops the current set, the same as a long-press. Off by default.

Tap any +/− button to adjust a value.

Starting a Set

Tap Start. Your settings are saved on the watch and loaded automatically next time. The "Get Ready" countdown appears in yellow, giving you time to get in position. Once it reaches zero, the length counter begins climbing, timed to reach each segment's target exactly when that segment's share of the total time elapses.

Reading the Display

The current length shows as a large whole number, colored on a green → yellow → red sweep as you approach the next length — a glance tells you whether you're ahead, on pace, or behind.

• Length just started — green
• Halfway through the length — yellow
• Length about to turn over — red

The display doesn't auto-rotate — Apple Watch has no orientation sensor for this. Tap the number to rotate it 90° at a time, to match however you've turned your wrist or propped the watch poolside.

Stopping a Set

Press and hold the display for about a second to stop the current set and return to Setup. There's no on-screen reset button while a set is running — this keeps the whole screen dedicated to the pace number. A reset button does appear on the finished screen after a set completes normally.

Finishing

When the final segment completes, the display shows the total lengths completed and the total time for the set, both in green.

Recording Your Swim in Health

Starting a set begins a real pool-swim workout session, recorded to the Health app under the name LapPacer (not the generic "Pool Swim") — using your configured pool length and units for the recorded lap distance. This also keeps the display awake during your set, the same privilege the native Workout app gets. Ending a set — whether it finishes normally or you stop it early — saves the workout.

Water Lock

If you turn on Water Lock on Start, the watch locks its touchscreen against accidental water taps once your set begins, showing the system's Water Lock screen. To unlock it (and stop ignoring your touches again), turn the Digital Crown — this also ejects water from the speaker, same as it does for the native Workout app.

Always On Display

On Apple Watch Series 5 and later with Always On Display enabled in Settings, the pace display stays dimly visible even when your wrist is down or the watch is sitting stationary. Apple Watch Series 4 does not support this — its screen will sleep normally when not actively raised or touched.