Ferdinand Berthoud - Chronomètre FB RSM with Deadbeat Seconds

The new Ferdinand Berthoud Chronomètre FB RSM combines a tourbillon regulator with fusee-and-chain to deadbeat seconds and stop-seconds. Price €258,00

With the new Chronomètre FB RSM recently presented by Ferdinand Berthoud, their exclusive tourbillon regulator with fusee-and-chain transmission is further enhanced, for the first time, by two sophisticated complications: independent deadbeat seconds visible on the dial side and a stop-seconds mechanism.

Its FB-T.FC-RSM calibre features a pillar-type architecture, in which both the barrel and the inverted fusee are suspended and patented. This fusee-and-chain mechanism is inspired by that of Ferdinand Berthoud's marine chronometers. 

It ensures the distribution of energy by delivering ‘constant force’ to the patented tourbillon with direct-drive seconds.

This construction reduces the thickness of the movement – which at just 9.89 mm remains very thin for its category despite the integration of an independent deadbeat seconds mechanism.

The Chronomètre FB RSM offers a unique take of the regulator-type display. The hours are read off via a rotating disc at 2 o'clock; the minutes are indicated by a facetted and skeletonised hand on the subdial at 12 o'clock; the seconds hand occupies a central position on the watch face. 

The “SM” letters added to the calibre name refer to the deadbeat seconds mechanism ("seconde morte" in French), while a balance-stop device enables the tourbillon to be stopped when setting the time to the exact second. 

The creation of a deadbeat seconds mechanism is a major challenge for any watch that claims to earn chronometer certification. This is because stopping and restarting the central hand in one-second jumps involves three steps: stopping the gear train concerned; storing the torque it continues to produce during this pause; and then releasing it all at once after one second. Since the regularity of the torque is the essence of a constant-force calibre, interrupting its flow 60 times a minute without compromising its linearity is a true technical feat. This explains why the majority of deadbeat seconds movements fail to achieve COSC certification which, instead, was awarded to the Chronomètre FB RSM.

Beating at the frequency of 21,600 vibrations per hour, this movement offers 53 hours of power reserve, visible from the back.

The 18-carat gold dial is hand-engraved and bears the "No. 8" inscription like the original No. 8 Marine Clock created by Ferdinand Berthoud in 1768, the inspiration for the FB RSM model. 

The deadbeat seconds mechanism is visible through a special symbolically figure-eight-shaped aperture at 9 o'clock. 

Only 20 movements will be produced, and several aesthetic elements can be chosen by the collector, including the shape of the case that can be round or octagonal. The round rose gold and white gold cases shown in the pictures of this article measure 44 mm x 14.30 mm.

The Ferdinand Berthoud Chronomètre FB RSM has an indicative price of Euro 258,000. ferdinandberthoud.ch