How And Why Vacheron Constantin Approaches Watchmaking Innovation

A few months ago, Vacheron Constantin released an updated version of the Traditionnelle Twin Beat Perpetual Calendar—a minor update, one that would have flown under many a radar. But it is a good chance to talk about the Twin Beat, because it is always worth talking about. First released in 2019, it sports a unique perpetual calendar movement with two escapements: one for normal use, and one that extended the watch’s power reserve to over two months. There was nothing like it when it launched. There still isn’t.

The beauty of the Twin Beat is that it elegantly addresses an inconvenience that has plagued the perpetual calendar since its inception. It is a necessarily complex mechanism, one that has to keep track of the date, month, and year, as well as leap years with that pesky February 29th. When left to run normally, all that information encoded within its cams and gears will happily present itself sequentially as the days go by. But when it stops—a daily winding missed, or it is left forgotten in a drawer—then the sequence is halted. The only way to catch things up is to manually set it forward—a minor issue when it’s a day or two, but a much bigger hassle when it’s a week or a month.

One solution to this: keep the watch ticking longer by extending the power reserve. You could try to beef up the mainspring. Or you could reduce its energy consumption. Vacheron Constantin opted for the latter by using an escapement that ticks at 1.2Hz—two-and-a-half to four times slower than a regular watch, which takes up a fraction of the power. The problem with such a slow-beating escapement is that it is much less reliable in terms of timekeeping.

Enter the Twin Beat. It quite literally takes the best of both worlds. It has a high-beat 5Hz escapement for regular accurate timing, as well as a 1.2Hz escapement for low-power consumption. Add a toggle between the two—problem solved.

Easier said than done, of course. But the implementation of this system accounts for the rest of the Twin Beat’s mechanical beauty. It has a switching system that seamlessly stops one balance wheel to start the other. It has two independent gear trains. It has three differential systems to manage their inputs and outputs—one to send power from the coaxial double-barrel mainspring to the two escapements, one that connects the hands to those escapements, and one to manage the single power reserve display. All this, as well as the usual perpetual calendar functions, and the manually wound Calibre 3610 QP is only 6mm thick. The watch, with its platinum case, is highly wearable at only 12.3mm thickness with a 42mm diameter.

It might be a Traditionnelle, but the dial aesthetic has a distinctly modern approach. It is semi-openworked, with the top half sporting a grey, hand-guilloché dial plate, with the lower half in transparent sapphire revealing the movement beneath. Date and month are presented on their own clear discs, with the leap year window between them.

At 9 o’clock is the mode indicator, identifying which escapement is currently active. The pusher at 8 o’clock switches between them. The idea is that during active use, the watch is set to 5Hz, where it can deliver on its full accuracy. When a long period of storage is expected, the watch can be set to 1.2Hz, where the relative inaccuracy is less of an issue—when the user picks it up again a month or two later, it may need to be adjusted by a few minutes or an hour, but the date and month will be correct.

At 12 o’clock is the power reserve indicator, a single hand with two scales. The 5Hz escapement can be sustained for four days. The 1.2Hz escapement can keep going for up to 70 days. This is a five-day improvement over the 2019 model, thanks to optimisations made in the instant-jumping perpetual calendar indicators. Its black calfskin strap is also contrast-stitched and has a fabric weave pattern—very much a current-day, casual approach to luxury that had not quite taken hold seven years ago.

“The Traditionnelle Twin Beat Perpetual Calendar unveiled in 2019 was a concept watch, produced in only a few examples, which reflected Vacheron Constantin’s research into the power reserve of watch calibres,” Vacheron Constantin’s legacy and style director, Christian Selmoni, explains in a statement. “In recent years, as it has become a matter of prime importance to address users’ concerns about issues relating to the power reserve of mechanical watches, it was a natural step for us to undertake further development of Calibre 3610 QP.”

The Twin Beat is a high point in recent horological innovation, proposing a creative, elegant, and user-centric solution to a longstanding problem. It arrives at an interesting time, only a couple of months after Vacheron Constantin introduced its major technical highlight of the year—one that acts as a counterpoint to the Twin Beat, yet sharing a similar approach to innovation.

It was in April, during Watches and Wonders, that the maison unveiled the Overseas Self-Winding Ultra-Thin, sporting the new Calibre 2550. It comes in a sunburst salmon lacquered dial and a platinum case and integrated bracelet. With a 39.5mm diameter, it sits between the usual Overseas and Historiques 222, and it has a thickness of 7.35mm.

The Twin Beat wears its innovations much more obviously; the Ultra-Thin is much more understated by comparison. It is ‘just’ an automatic two-hand watch, after all. 7.35mm is an achievement, but not quite a record-breaker. And yet, the new calibre needed seven years to develop. The Twin Beat took only four.

“For Vacheron Constantin, time is key. We never do something in a rush, we do it in the right way,” Morgan Maillard, the maison’s style and heritage expert, says. “The idea was not just to launch a new ultra-thin calibre, but a true answer for our clients. Firstly, with a longer power reserve. And secondly…ultra-thin is always considered something more delicate, and we really wanted something very robust.” He adds that much of the development time was devoted to testing for reliability and shock resistance, something that can be quite a challenge for a movement that is ultimately only 2.4mm thick.

While Vacheron Constantin has a long history with ultra-thin movements, Calibre 2550 represents quite a few debuts for the maison. This includes its first-ever micro-rotor, presented in platinum. To achieve its 80-hour power reserve, it utilises an unusual double-barrel configuration, operating in series—inverted and stacked, and ‘suspended’ as it is supported on a single post. This allows the barrel covers to be removed, reducing bulk. The ratchet wheel was also removed, with winding torque delivered directly to the upper barrel. The gear train is arranged in a single plane, with two of its five wheels mounted on ball bearings, saving space and improving efficiency.

It was never meant to be record-breaking thinness. “It was to find the right balance, to find the key to make this calibre reliable and working as we want it—not too wide, too thick, too thin, with the long power reserve,” Maillard explains. Usability was, thus, key. This watch is not innovation for its own sake—it is meant to be the right solution for the wrist that needed it, and an everyday companion as well. This is why the Overseas was selected as the debut platform for this movement. “We wanted to show that an ultra-thin watch can be a daily partner,” Maillard says, noting the collection’s renowned versatility. Even the choice of platinum alloy takes this into account—the platinum 950 used has a five per cent copper and gallium makeup and is thermally hardened, offering up to 2.7 times greater shock and scratch resistance than typical platinum alloys.

Ultimately, the Overseas Ultra-Thin was meant to fill a niche that a certain type of Vacheron Constantin client was looking for. “It’s as thin as you need, but still has some presence on your wrist, not being so thin that you lose the style and DNA of the maison,” Maillard explains. “We could have done something different, much thinner, but then we wouldn’t get the 80 hours, the robustness, or the design of Vacheron Constantin. I think the most important thing is to have something wearable. We never compromise between design and technique.”