Beyond the Tudor Black Bay P01 — a Look at Different Locking Bezels

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For a whole assortment of reasons, some good and others bad, Tudor’s Black Bay P01 turned heads at this year’s Baselworld. Without a doubt, however, the most polarizing detail was the large locking bezel mechanism, a design pulled from a military prototype produced by Tudor back in the day. That mechanism, and its modern incarnation to some degree, was one driven by function, and for someone like myself and the latent engineer hidden somewhere deep inside me, I found it delightfully appealing. Now, I rarely need a timing bezel, let alone the safety that comes from a unidirectional one, so a bezel lock adds a further level of purpose to the design that I have no need for. With that said, I can’t help but like it.

Today, I’m going to take a look at some other bezel-locking mechanisms that have adorned dive watches over the decades, including quite a few that are readily available today.

To understand the solution that these locking mechanisms offer, one must first understand the problem. As a very fast and loose summary, the rotating bezel is a simple and effective tool — a quick way to set a marker against the minute hand, which then acts as an indication for reading the elapsed time. Different bezel markings can offer more utility in this area, including decompression bezels, but that’s enough grounding to set the scene. Now, if a bezel can be turned by hand, then it follows that it can be accidentally knocked and rotated. Blancpain filed the original patent for a unidirectional bezel, which means that should it get moved unintentionally, it will show a greater time between the bezel position and the minute hand. If your dive watch is going to give false information, then it’s far better to overestimate the elapsed time rather than underestimate it.

The Yema Superman, which dates back to 1963, is often credited as the first dive watch with a locking bezel.


The next logical step is to ask whether accidentally turning the bezel is something that does indeed happen, and if the answer is yes, then the solution must be some sort of mechanism that locks it in place so it can’t move in either direction. To date, there have been a variety of ways to solve this problem, and each one has a different impact on the design of the watch.

Image via Amsterdam Vintage Watches.

One of the most famous and distinctive examples of a locking bezel is seen on the Omega Seamaster 600 Ploprof. The huge and angular case on this hulk of a watch is amplified by the presence of the orange (originally red) button that operates the bezel lock — or bezel release, to be more precise. Here, the bezel can’t be turned unless the button is pressed. This functionality was developed in the late 1970s with input from Jacques Cousteau, so it has a fair amount of diving pedigree behind it. The Ploprof’s crown is similarly well protected. The result is a true tool watch where form follows function, and those safety elements are an integral part of this distinctive design.

But the Omega Ploprof wasn’t the first dive watch to feature a locking bezel. The Yema Superman, which dates back to 1963, is often credited as the first dive watch with a locking bezel. The 300m-rated Superman was a professional dive watch with a “safety brake stop.” The rotating bezel was effectively clamped into place by a bracket as the crown screwed in. The edges of the bracket nestle between the knurls of the bezel to stop it moving in either direction. This very simple component and implementation had an unfortunate flaw, however — if you ever needed to adjust or reset the bezel position, you would need to unscrew the crown — far from ideal if the watch is submerged.

The YEMA Superman Heritage, available today, faithfully recreates that iconic watch.

An obvious solution to this problem was actually implemented decades earlier, although not as part of a dive watch. The Weems rotary verge ring, patented in 1929 ,was a significant part of the evolution of the avigation watch. At that time, most mechanical watches did not hack — that is, the second hand did not stop when the crown was pulled out to set the time. As a work around, the bezel was used as a reference point against which to measure the seconds. When recalibrating the watch, the bezel would be rotated, keeping in synchronization with the second hand until the time signal, or “hack,” is heard.

Image courtesy of eBay seller Latriaz.

The first version of this watch did not include a way of anchoring the bezel in place. This was soon added, starting out as a lock from the lugs at 6:00, but eventually developing into a screw or crown near to the 2:00 or 4:00 position. Avigation watches featuring the Weems bezel lock were produced by Longines, Movado, Zenith and Omega (Tom Hardy famously wore one in Dunkirk), amongst others.

Sinn’s safety bezel . . .  is almost as accident proof as the bezel locks mentioned above, but you may never notice it unless you handle one of these watches.


Although watches with hacking seconds came soon after, making the Weems rotary verge ring redundant, many pilots watches still incorporate a lock, which works in the same way, though the bezel has a different use here. The Glycine Airman, first seen in 1953, showed the time on a 24-hour dial with a rotating 24-hour bezel, which offers the added functionality of a second time zone. The second crown, used to lock the bezel in place, is still present in the Airman today.

Photo via Analog Shift.

All of the locking bezel mechanisms mentioned so far are visible and, in many cases, very prominent. However, Sinn’s safety bezel, which is present on the T1, T2 and U1000 dive models, is almost as accident proof as the bezel locks mentioned above, but you may never notice it unless you handle one of these watches. The bezels are spring loaded, which means that they need to be depressed before they can be rotated, and, of course, they can only be rotated in a counter-clockwise direction.

Despite the Tudor Black Bay P01 prompting a negative reaction, I was intriguied to learn about the purpose behind the controversial design—the top lug/end link is a clamp that flips open to release the bezel, while the bottom lug is purely for a “balanced aesthetic.” I can’t claim to absolutely need some extra security in my watch to stop the bezel wandering — I’ve probably turned it through several rotations while staring out the window as I’ve written this article — but if I did, there are still a few implementations to choose from, some discreet, and some less so.

Let us know if you have a favorite bezel locking mechanism in the comments below.

Brad stumbled into the watch world in 2011 and has been falling down the rabbit hole ever since. Based in London, Brad's interests lie in anything that ticks, sweeps or hums and is slightly off the beaten track.
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