Training sets send swimmers off on staggered 5–10 second intervals: the 1st swimmer in every lane leaves the wall together, then the 2nd swimmers, then the 3rd. One wall clock can't time them all — this page gives each send-off its own start.
Tap Start as the 1st swimmers in each lane leave the wall — then again as the 2nd, 3rd, … go. Only the next send-off's Start is enabled, and the first Start launches the shared clock at the top.
Tap a lane's Stop as that swimmer finishes; their time freezes in place. Clear resets everything (it asks first once times exist). The screen stays awake while you're timing.
Brainzie Poolside