How To Use The Bezel On A Dive Watch

Dive watches are one of the most popular types of watches. However, most of us only use the dive watches as “desk divers”. They are not actually used for diving for most owners of diving watches. Nonetheless, diving watches are fascinating and can be used for much more than just diving.

The dive watch bezel is used for divers to time the remaining oxygen in their oxygen tanks. The timing allows the diver to dive and have oxygen for the decompression during the ascent. However, a dive watch can be used to time eggs, barbecue, etc.

Throughout this post, you will learn how to use the bezel on a dive watch, even if you are a “desk diver”.

How Does A Dive Watch Bezel Work?

The dive watch was first made by Blancpain, closely followed by Rolex’s well-known Submariner. Blancpain made their watch to fit the requirements from the French military elite combat divers. While water resistance watches had been a thing for many years before the first diver, they where no watches made for active water use.

The water-resistance and bezel were what made the watch a true diver essential. The water-resistance made sure the watch would function correctly, even submerged in water for longer periods of time. The bezel was made to measure the time remaining in the water. While it is a misconception that the diver can calculate how much oxygen is remaining in their tanks, the individual diver know approximately how long time it takes to empty an oxygen tank. The duration of the oxygen tank is based on the fitness and fatigue of the diver.

There are different types of bezels in terms of the rotation. There are unidirectional and bidirectional bezels. The most common on a dive watch is a unidirectional bezel. The unidirectional bezel will typically be rotating counterclockwise. The counterclockwise movement has to do with the safety of the diver.

For example: Imagine that you zeroed your descent time at the 15-minute mark. You have been underwater for some time and want to look at how long you have been underwater, yet, now, the bezel is zeroed at the 25-minute mark. If you have forgot the bezel was zeroed at the 15-minute mark (because it is a set-and-forget feature), you would be playing with your own life as you now extend the dive with 10 minutes. This can happen if your wrist bumps into something and turn the bezel. If the bezel is turned counterclockwise, you will only decrease the dive length and, therefore, not endanger yourself.

The unidirectional is what you typically will find on a GMT watch. This is where the bezel will turn both ways. However, if you are going to use the watch for diving, this is a terrible idea, as described above.

Omega Seamaster 300M Professional
Omega Seamaster 300M Professional

So how does the bezel work? When looking at a diving watch, there is a zero marker. The zero marker is placed at the minute hand at descent. For example, when looking at the Omega Seamaster 300M Professional, the zero marker should be located at the 8-minute mark based on the clocks current position. The diver then knows how long he or she has been underwater. The diver can then easily calculate the time used underwater. Therefore how much time there is left before the oxygen tank will be empty.

A lot of dive watch bezels have minute markings for the first 15 minutes after the zero marker, whereafter it turns to five-minute increments. The Omega Seamaster shown in the picture does have one-minute markings. However, they go from clearly visible lines to small dots after the 15-minute marker. An excellent example for the five-minute increment markings is to look at a Rolex Submariner.

How Divers Use The Bezel

Example of Setting The Zero Marker At Descent
Example of Setting The Zero Marker At Descent

People use their dive watches however they want. Yet divers have two different methods that they use to measure the time of their dive. In essence, the methods are setting the zero marker at descent/diving time, and the other is placing the zero marker at ascent time.

Setting the zero marker at descent time is most commonly used. The diver will have an exact time of when they descended hence an easy estimate of when they should start ascending. Using the marker at the starting of the dive will allow the diver to know when to ascent. This method is typically used for divers moving in depths closer to the surface.

Without getting too deep in the math, this method is also used as a diver will move in different depths throughout the dive. The rate at which the oxygen is used will vary depending on water depth, respiratory minute volume, and cylinder volume of the oxygen tank. You can read more about oxygen usage here.

Example Of Setting Zero Marker At Ascent Time
Example Of Setting Zero Marker At Ascent Time

Another but unconventional method is zeroing at the time of ascent. Decompression divers mostly use this method. The diver makes there regular dive, and when the minute hand reaches the zero marker, they know it is time to ascent, and hold decompression stops. Each time the diver reaches a new depth for decompression, the zero marker is set. This allows the diver to time the length of the decompression time as they are critical to their health.

Dive Watch Uses For Non-divers

If you are a desk diver like most dive watch owners, you can still enjoy the bezel for various tasks, the only limitation to using the bezel is if it is something that takes more than 1 hour, or the bezel has fewer markings than is needed. For example, if you need to roast a turkey for 47 minutes, precisely, but the bezel only has one-minute marking the first 15 minutes, it can be difficult to time anything with a time period of greater than 15 minutes.

Nonetheless, I have used my Omega Seamaster 300M Professional for a lot of things that did not involve diving:

  • Egg timer.
  • The length of something your partner only said took 5 minutes.
  • How long I actually use in the bath (Go water resistance).
  • Oven timer (Pizza, Ham, tenderloin, etc.).
  • Break time.

Once I used it to have the New York stock exchange open time in my local hours. I would need to use the hours hand, but it worked for that as well. It is, therefore, to say that only your imagination sets the limit of what you can use the bezel for besides being a good looking part of the watch.

What Is The Different Bezel Types?

While there are different types of rotation on the bezels, there are also different types of bezels—namely the external bezel, the internal bezel, and bezel coloring. The different bezels each have their pros and cons. While some prefer different bezels based on aesthetics, there is some practical use for each type of bezel.

External Bezel

The external bezel is the type of bezel you will generally encounter. The external bezel is attached to the watch case and is rotated with small springs and specialist washers. This is the type of bezel that you find on a Rolex Submariner, Tudor Black Bay, Omega Seamaster etc. The external bezel is what is easiest to operate, both under and over water.

The external bezel can suffer from debris, dirt, sand, or other stuff getting between the bezel and the watch case. This can make the bezel challenging to operate, and might even damage the watch. The best part of the external bezel is that the diver can use the bezel while being underwater.

Internal Bezel

Internal bezels is a bezel placed under the glass of the watch. The bezel will run on the outer edge of the dial. An internal bezel is very useful for multiple reasons:

  • When first set, it can’t accidentally be rotated.
  • No debris, dirt, sand, or other stuff can jam the bezel.
  • The minute hand is much closer to the bezel, making it more accurate when reading.

The disadvantage of an internal bezel is that once submerged, it cant be adjusted. Furthermore, the more holes made in the watch case, the more problems can occur to the watch itself.

Bezel Coloring

The coloring of the first 15-20 minutes on the bezel is done mostly for decoration. However, it has some functionality to it as well. You see, it is colored based on the tradition of the decompression stops the divers have to take to avoid decompression sickness. The decompression stops can take up to 20 minutes. Having the first 20 minutes of the bezel highlighted is easier when having a glance at the watch.

Jonas Henriksen

AllInWatches is founded by Jonas, who has a great interest in mechanical watches. All aspects of manual and automatic (mechanical) watches is a big interest and have been a passion since 2015, where the first automatic watch was purchased. Seeing the transparent case back and discovering the heritage of watchmaking piqued an interest in horology.

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