Tap each band as people launch and land, what the colours and sounds mean, and how the count copes with no signal.
Tallying is the roll call. A phone at the launch point set to OUT, and one where people come ashore set to IN, or one phone switched between the two.
Keep tapping. Scans are saved on the phone and upload in order when the signal comes back, keeping the time each one was actually taken. The bar at the top says how many are waiting.
While a phone is offline it only knows its own scans, so other screens can be behind until it catches up. If the safety lead needs to make a decision during an outage, use the paper count.
Tap the screen once: browsers block sound until the screen has been touched. The sound button is at the top right.
Band will not read? Mark that person out or in by hand on the tally board. See The tally board.