Perpetual calendar watches with record-breaking power reserves

Perpetual calendar watches that work for days, weeks or even months on a single wind are in the ascendant, as horologists propel the power reserve. Nick Foulkes reports

65 days: Vacheron Constantin platinum Traditionnelle Twin Beat Perpetual Calendar on alligator strap, £195,000
65 days: Vacheron Constantin platinum Traditionnelle Twin Beat Perpetual Calendar on alligator strap, £195,000

Picture the scenario: you’re leaving on holiday. Actually, more of a sabbatical. For two months you’ll travel the world ticking items off the bucket list: clambering up to Machu Picchu, seeing the sun rise over Angkor Wat, diving with whales in Polynesia, channelling your inner David Attenborough with gorillas in Rwanda, and generally going to places and doing things that are incompatible with wearing a classic perpetual calendar watch.

Detail of the Vacheron Constantin Traditionnelle Twin Beat Perpetual Calendar
Detail of the Vacheron Constantin Traditionnelle Twin Beat Perpetual Calendar
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After 60 days you return home with a head full of memories, a phone full of photographs and a long list of domestic chores, among which is the arduous task of resetting your watch. It is almost enough of a palaver to put you off wearing one. The day, date, month, year and – depending on the model – moonphase indicator all need to be synchronised, by using a pin to activate tiny pushers concealed around the case wall (but without scratching the case), pressing hard enough to make the changes, and in the right order to avoid, say, the tweaks to the moonphase altering the date. Of course, it’s possible to just advance the watch using the crown, but trust me, the fingers soon get very tired.

70 hours: Jaeger-LeCoultre white-gold and enamel Master Ultra-Thin Perpetual on alligator strap, €55,200
70 hours: Jaeger-LeCoultre white-gold and enamel Master Ultra-Thin Perpetual on alligator strap, €55,200
5 days: Baume & Mercier stainless-steel Clifton Baumatic, £2,450
5 days: Baume & Mercier stainless-steel Clifton Baumatic, £2,450

It is the definition of a high-class problem, and Vacheron Constantin is one high-class watchmaker that is solving it. The result of four years’ work, the Traditionnelle Twin Beat Perpetual Calendar (£195,000) can run for up to 65 days before needing rewinding. Its power reserve – the autonomy that movement has when fully wound – is a technical tour de force. If one thinks of it like miles per gallon, this is akin to driving from Moscow to Marbella on a single tank. Traditionally, power reserve has been extended by using a much bigger mainspring, or a number of mainsprings, which store more energy when fully wound, and by optimising the gear-train efficiency, so minimum energy is expended beyond that required to move the hands. Vacheron wanted to try something else, as style and heritage director Christian Selmoni explains. “The idea was to extend power reserve in a different way to adding barrels and barrels, so the Twin Beat has two gear trains. This is totally rethinking the question of power reserve in a mechanical watch.”

50 days: Hublot sapphire-crystal MP-05 LaFerrari Aperta on rubber strap, £458,000
50 days: Hublot sapphire-crystal MP-05 LaFerrari Aperta on rubber strap, £458,000
Detail of the Hublot MP-05 LaFerrari Aperta
Detail of the Hublot MP-05 LaFerrari Aperta

To return to the automotive analogy: as hybrid cars switch between petrol and electricity, so the Twin Beat wearer can select a high-frequency 5Hz oscillator or a much slower, less power-consuming one of 1.2Hz. The power comes from a mainspring housed in a double barrel at 12 o’clock. A differential system means that with the push of a button, the wearer can slip between normal and extended power reserve. This, combined with an instant jump system that accumulates energy throughout the day and uses four times less torque than normal to change the date, enables the extension to 65 days (though, Selmoni admits, the lower frequency performs best when the watch is lying flat).

9 days: Chopard white-gold LUC Quattro on alligator strap, £20,800
9 days: Chopard white-gold LUC Quattro on alligator strap, £20,800
22 days: Bovet rose-gold Amadeo Braveheart on alligator strap, £369,600
22 days: Bovet rose-gold Amadeo Braveheart on alligator strap, £369,600 | Image: Marc Gysin Photo

This achievement has focused attention on power reserve, an issue that currently occupies watchmakers as advances in technology permit significant gains. Today, many high-end brands offer timepieces with 10 days’ power reserve – among them Richard Mille with its RM 58-01 (£614,500) and Panerai’s Luminor GMT (£14,500) – and even more. Blancpain has managed to squeeze 12 days out of its tourbillon (£114,000), and Bovet has gone as far as 22 days with its Amadeo Braveheart (£369,600).

58 days: Rebellion titanium T2M on ostrich strap, price on request
58 days: Rebellion titanium T2M on ostrich strap, price on request
Detail of Rebellion T2M
Detail of Rebellion T2M

In the past decade, extreme power reserve watches have been pushing the upper limits ever higher. As its name suggests, A Lange & Söhne’s Lange 31 (€145,100) offers 31 days’ reserve, but needs a 46mm case to house the massive single barrel. In 2010, Rebellion linked six barrels for a whopping 41 days. Hublot managed in 2013 to fit 11 barrels and a tourbillon into a watch with 50 days’ reserve (£458,000), but last year Rebellion hit back with the T2M (price on request), an eight-barrel behemoth with 1,400 hours – almost two months. Rebellion sponsors endurance racing, suggesting another automotive analogy. Just as racing cars are built in single-minded pursuit of performance, so these watches have tended to be constructed with extreme autonomy as the goal, even if it dominates the watch, its size and its design.

10 days: Richard Mille rose-gold RM 58-01 Tourbillon World Timer – Jean Todt on rubber strap, £614,500
10 days: Richard Mille rose-gold RM 58-01 Tourbillon World Timer – Jean Todt on rubber strap, £614,500
10 days: Panerai ceramic Luminor GMT 10 Days on leather strap, £14,500
10 days: Panerai ceramic Luminor GMT 10 Days on leather strap, £14,500

But increasingly, extended power reserve is making its way into more general production pieces. At the same time as Vacheron launched Twin Beat, Jaeger-LeCoultre had less spectacular but arguably more real-world-relevant news: a perpetual calendar (€55,200) with an attractive blue enamel dial, in which the power reserve had almost doubled from 38 to 70 hours (not enough for a sabbatical, but more than sufficient for a weekend). Significantly, this substantial gain has been achieved by optimising the in-house Calibre 899, which first appeared back in 1982. By removing the barrel cover, Jaeger was able to increase the spring’s width by 40 per cent to provide a power boost, while reworking the escapement has reduced the energy lost through friction – all within a self-winding calibre just 3.3mm high.

12 days: Blancpain gold and enamel Villeret Tourbillon Volant Heure Sautante Minute Rétrograde on alligator strap, £114,000
12 days: Blancpain gold and enamel Villeret Tourbillon Volant Heure Sautante Minute Rétrograde on alligator strap, £114,000
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It is a similar story at Grand Seiko, which has taken its renowned Spring Drive movement (around for 20 years, but traceable to a 1970s patent) and extended the power reserve from three to eight days for the calibre 9R01 (from £45,000), which made its debut in 2016. “It delivers a reserve of 192 hours, thanks to three barrels arranged in sequence and the precision of the engineering,” explains Kiyoko Niwasaki, director and executive vice president with special responsibility for Grand Seiko. “Precise manufacturing and polishing deliver reduced friction, as does the removal of the intermediate wheel, which increases the efficiency of the energy transfer. The use of rubies in the barrels also contributes, reducing the friction between the barrel cover and the arbor as the mainspring unwinds.”

New materials play their part in other movements too. Seiko worked six years to develop a new alloy for the 9S85’s mainspring: elasticity was increased by 6 per cent and its performance remains stable even when the power reserve is low. Over at Chopard, Karl-Friedrich Scheufele also talks of new spring materials and using silicon parts to reduce friction. He is most famous for his LUC Quattro; an updated version, released last year (£20,800), boasts nine days of power reserve (though he prefers to claim eight and a half with accurate timekeeping). Launched in 2000, the Quattro movement was a marvel, with 1.8m of springs in a quadruple-barrel configuration.

But in newly designed movements, extended power reserve is no longer the preserve of elite brands. Last year, Baume & Mercier launched Baumatic (£2,450), a modestly priced real-world watch that was almost blasé about its five days’ power reserve, with chronometer levels of accuracy – a feat achieved mostly through use of silicon parts, particularly in the new Powerscape escapement.

Meanwhile, intrepid haute horlogerie brands are researching movements that will need winding just a handful of times a year. Parmigiani Fleurier is working with Pierre Genequand, a specialist in the recondite discipline of spatial engineering technology using the frictionless properties of flexible joints. He has applied this erudition to a watch movement that claims 70 days’ autonomy. According to CEO Davide Traxler, the project is currently “under stability research”. At this breakthrough’s heart is a regulator of silicon machined to micron level. It looks nothing like the traditional anchor escapement. In fact, had I seen only a drawing of it, I would have identified it as an obscure spacecraft from one of the less-known Star Wars films.

But at least I’m able to see it. Robert Greubel and Stephen Forsey are pressing ahead with exploiting nanotechnologies so advanced they can reduce the size of a movement by up to 90 per cent. If Parmigiani recalls Star Wars, Greubel Forsey’s innovation is a case of Honey I Shrunk the Movement. A terribly excited Forsey told me that his initial Nano Foudroyante optical system (available only as a unique piece, made to order) uses virtually no power – but I only grasped its importance when he said he will be able to multiply the power reserve by a factor of 60. In other words, he can take the energy required to run a movement for three days and power it for 180. He started to explain, but I stopped him with a quotation from Arthur C Clarke: “Any sufficiently advanced technology is indistinguishable from magic.” The same is true when it comes to sufficiently advanced power reserve.

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