A count-up bezel is a rotating ring on a watch case that shows how long a diver has been under water. It counts elapsed time from the moment it is set. Without one, a diver could misjudge how long they have been submerged. Most count-up bezels meet the ISO standards for dive watches.
How do you use a count-up bezel?
At the start of a descent, the diver turns the bezel until its arrow, or pip, sits over the minute hand. As the dive goes on, the minute hand moves away from the pip and along the scale on the bezel. On returning to the surface, the diver reads the elapsed time from the point where the minute hand now sits. The bezel marks a moment that has already passed, not one still to come. It turns in one direction only.
Not to be confused with
A countdown bezel works the other way round. Its 60-minute scale runs counterclockwise, so it counts down towards an end point instead of up from a start. It points to a moment in the future, while a count-up bezel marks one that has already gone. A countdown bezel also lacks the one-way action of a count-up bezel. A chronograph is different again, because it needs an end point.
Where it comes from
The Blancpain Fifty Fathoms of 1953 is described as the first modern dive watch with a one-way rotating bezel that carried a diving scale. Blancpain’s CEO, Jean-Jacques Fiechter, made a rotating bezel for timing dives one of his criteria for the watch. Its bezel had a lock. The wearer had to press it down with three fingers before it would turn, because an accidental turn could put the diver in danger.
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