Q: What is the difference between a diver's watch bezel that moves 60 times and one that moves 120 times?
Why do watches have different numbers of notches?
A: It depends on whether you want accuracy or sturdiness when displaying.
One thing watch enthusiasts often talk about is the clicking feel of the rotating bezel on a diver's watch. Essentially, almost all diver's watches (including non-ISO-certified diver-style sports watches) have notches on the rotating bezel. The reason is to ensure the display of the rotating bezel is correct.
What's important about a rotating bezel is ease of maintenance, durability, and high display accuracy, rather than feel. Most commonly, there are 60 notches. In contrast, some high-end diver's watches have as many as 120 notches. Bezels with fewer notches are said to be less prone to malfunction and less susceptible to damage from shocks, as they have a certain amount of play. For this reason, even professional diver's watches often choose to use rotating bezels with fewer notches. However, some inexpensive diver's watches have display misalignment on their rotating bezels.
The 120-notch bezel has a great feel.
On the other hand, smaller notches provide a more precise feel and also improve the accuracy of the rotating bezel's display. However, the mechanism becomes more complex, which can lead to more malfunctions than a watch with fewer notches. A good example of a watch that combines many notches with ease of maintenance is Seiko's high-end diver's watch. Its rotating bezel successfully achieves a simple structure and accurate display.
Photograph by Masanori Yoshie
http://www.webchronos.net/features/36498/
