(see here for all the posts about using a diver’s bezel)
I previously wrote about things that you can do with a divers watch bezel. Since then I’ve figured out a few things.
It occurred to me that most of the techniques I spoke about in the previous post work best when you have a fully transferred minutes bezel (i.e. a marker on the bezel at every minute), like you find on just about all Seiko Divers, the Rolex DeepSea, newer Omega Planet Oceans, Omega Semaster 300Ms, Fortis divers, as well as many others. If you only have markers every five minutes after the first fifteen or twenty, you can still use those techniques, it’s just harder as you have to mentally interpolate to find the precise elapsed time, or to set the countdown start time.
With a non-transferred minutes track, for example, if you want to set things to twenty-eight minutes in the future, or specifically, at 60 minus 28, the 32 minutes position, first set the bezel location to thirty minutes (the first marker before the desired time) in the future and then turn the bezel two minutes more - or four clicks on a standard 120-click bezel (two clicks per minute).
Again, with a non-transferred minutes track, for figuring out elapsed times to the minute (or even thirty seconds) assuming we’re using the minutes hand, you’ll have to note where the closest five minute marker meets the minutes track on the watch face (or sometimes on the rehaut), and used the offset from there. For example, say the minute hand is pointing at somewhere between the thirty and thirty five minute markers. We could note where on the minutes track the thirty minute marker landed, then add the number of minutes between there and where the minute points to find the more precise elapsed time.
For any-style bezel, if you need to be able to suspend timing of an event, to be restarted at some later time, take the current moment on the bezel and line it up with the 12 marker on your face. If you’re measuring minutes, another way to think of it is set the arrow to negative however many minutes. Then when you want to start it up again, move the point of the bezel over the 12 to where the minute (or hour, or second, as appropriate) hand is pointing at.
If you’re measuring hours, there’s the problem of properly spotting the location of the hour hand against the bezel. There are a couple of ways to deal with this. One is you can spot the location by waiting until the second hand passes over the hour hand and use that - in the extreme case, hacking the movement to stop the seconds hand over the hour hand. Another way is to note that on a standard 120-click bezel, one click works out to six minutes (one hour spans five minutes, so each minute works out to 60 divided by 5, or 12 minutes, and since the click is every half minute, one click works out to 6 minutes). So if it’s say, eighteen after two, you can set the bezel to three clicks past two. The same technique can be used for spotting the elapsed time too.