Tudor Black Bay Part 2

Tudor shook up the watch industry with the release of the Black Bay in 2012. This collection, with a design that exceeds its price range, was further enhanced by the adoption of an in-house movement. This evolution was brought about by Tudor's half-century of commitment to diver's watches.

BLACK BAY CERAMIC [Ref. M79210CNU]
A super-antimagnetic model equivalent to a Master Chronometer

　Tudor burst into the mainstream of diver's watches with the release of the second-generation Heritage Black Bay (Ref. 79230) in 2016. Featuring a popular retro-chic design, a long power reserve of approximately 70 hours, and an automatic movement with a silicon balance spring and free-sprung balance, these watches boast some of the highest specs in their price range.

　However, Tudor has continued to improve this masterpiece. The Black Bay Ceramic, released in 2021, not only uses ceramic for the majority of the exterior, but also meets the Master Chronometer standard, which requires magnetic resistance of 15,000 gauss. The Master Chronometer standard had long been the exclusive domain of Omega. Who would have imagined that Tudor would also adopt it?

　The case structure is also completely different from existing Black Bay models. At first glance, it appears to be made entirely of ceramic, but in fact it is a stainless steel inner case with a ceramic outer frame, to which a stainless steel bezel and case back are attached. The reason for not making the entire watch out of ceramic is probably to retain Tudor's unique rotating bezel mechanism and to give it a screw-down case back. If the bezel were made of hard ceramic, it would damage the rotating bezel mechanism, and a ceramic inner case would not be able to be threaded. This robust design is a great feature of Tudor's diver's watches, which have been around since 1954.

　Since the release of the Black Bay in 2012, Tudor has undergone significant changes, both internally and externally. This model is a symbol of Tudor's aggressive approach. So how did Tudor achieve the Master Chronometer standard, which was previously thought to be impossible to achieve?

METAS testing lab installed
The latest news from the Manufacture

For a long time, Omega had the sole domain of the METAS Master Chronometer standard. While theoretically possible, other companies thought it impossible to adopt this standard, but Tudor has managed to meet it. So how did this become possible? Let's explore the background and reasons behind it.

　The Master Chronometer standard set by METAS (Swiss Federal Institute of Metrology) is arguably the most stringent standard currently in place for mechanical watches. While it does not include extreme shock resistance tests like those required by the Fleurier Qualité, it does test almost all of the functional characteristics required of a mechanical watch, including precision, magnetic resistance, water resistance, and power reserve.

　Any manufacturer of mechanical watches in Switzerland can undergo Master Chronometer testing, but until 2021, Omega had a monopoly on this. There are three reasons for this. First, unlike COSC chronometers, the accuracy must be measured with the movement still in the case. While this may seem simple at first glance, if the accuracy is not satisfactory, the movement must be removed from the case. Unlike COSC chronometers, which test the movement alone, mass-producing Master Chronometer models requires setting aside space for testing within the assembly factory. Unless a manufacturer intends to widely adopt Master Chronometers in the future, it will be virtually impossible to find this kind of space within the factory.

　The other requirement is ultra-magnetic resistance of 15,000 gauss. To achieve this, a silicon balance spring must be used, which is completely non-magnetic. However, there are very few watch manufacturers, even in Switzerland, that can use this component. In addition, other important components must also be made of non-magnetic materials. While such components are not difficult to obtain, non-magnetic materials wear out easily. As far as I know, even in Switzerland, there are only a handful of manufacturers that are capable of working on tribology (the science of friction).

　The final challenge is the "accuracy test with two different power reserve levels." This tests the accuracy when the mainspring is at 100% and at 33%. While this may seem easier than the 15,000 gauss test, it is in fact the most difficult.

　Omega's co-axial escapement is based on the detent escapement previously used in marine chronometers. While complex and difficult to manufacture, it has the advantage of being able to maintain accuracy even when the mainspring is low. This is said to be the reason why the Master Chronometer standard, which Omega helped establish, includes an accuracy test with the mainspring remaining at 33%.

　In contrast, the Swiss lever escapement used in the majority of mechanical watches is highly productive and resistant to shocks, but once the mainspring runs low, accuracy quickly deteriorates. It is said that using a lightweight silicon escapement can alleviate this problem, but it still does not maintain the same stability as a co-axial escapement. This is why one designer at the Richemont Group bitterly stated, "The Master Chronometer standard is based solely on the co-axial escapement."

　However, Tudor overcame these challenges and successfully achieved Master Chronometer certification with the Black Bay Ceramic. It's probably no coincidence that the first model was made from ceramic. French journalist Gregory Pons wrote, "The ceramic case and silicon balance spring (used in the Black Bay Ceramic) are non-magnetic, and the all-tungsten rotor is also virtually non-magnetic. Therefore, it was probably easier to make it a Master Chronometer than other models" (excerpt from BUSINESS MONTRE).

　According to Tudor, "Work with METAS began at the end of 2019, leading to the establishment of a METAS inspection process within the Geneva factory" (excerpt from LE TEMPS). The introduction was made possible because Tudor's factories are unusually efficient for a watchmaker. The aforementioned SJX, who actually visited the Tudor factory in the Acacia district of Geneva, made the point of writing that the factory thoroughly implements a Toyota-style "just-in-time production system" that includes kaizen, as well as the so-called "5S" (sort, set in order, shine, standardize, and sustain).

　According to Gregory Pons' report, the METAS testing process has been set up in a corner of the new building, where finished watches undergo static accuracy tests in six positions and two temperatures, magnetic resistance to 15,000 gauss, water resistance to 200m, and power reserve tests at 100% and 33% to ensure they comply with Master Chronometer standards.

　What's interesting is that the 15,000 gauss magnetic resistance test is carried out entirely on an assembly line basis. Pons explains that the annual production of Master Chronometer models is still small, but this assembly line process is evidence that Tudor will mass-produce Master Chronometer models in the future. Water resistance is also checked to ensure it complies with ISO standard 22810 (revised in 2010). This is an unprecedented attempt to conduct water resistance tests that comply with official standards, rather than simply conducting water resistance tests.

　The introduction of the Master Chronometer further enhances the Black Bay's competitiveness. However, Tudor's strengths don't end there. On the next page, we'll look at another initiative: the exterior. The reason the Black Bay has become so popular today is not only because of the excellent performance exemplified by the Master Chronometer, but also because it embodies the so-called "chic sports" style.