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2017.12.05

Favre-Leuba

This is the original bivouac carried by French polar explorer Paul-Emile Victor and his team when they set out for Adelie Land in Antarctica. They highly praised its accurate altitude display, which showed altitude in 25m increments.

Photographs by Masanori Yoshie, Ryotaro Horiuchi
Interview and text by Hiroyuki Suzuki

Mechanical altimeters reach their peak

　The Bivouac 9000, released on the occasion of the 280th anniversary of the company's founding, is a model that largely follows the aneroid barometric altimeter developed in the 1960s,
This is a remarkable piece of work that has expanded the measurement range to an altitude of 9000m. It has been developed as a pure successor, without adopting the "reproduction method" that is popular these days. How has it been possible to achieve both waterproof performance that ensures practicality and overwhelming altitude measurement performance?

FAVRE-LEUBA “Bivouac 9000”

The Bivouac 9000 is equipped with the Cal. FL311. A simple "conversion device" using comb teeth converts the volume change of the aneroid cell, up to 0.4 mm, into an altitude equivalent of 9000 m.

The aneroid cell installed inside Cal. FL311 incorporates a new shape to increase the expansion rate, while also being adjusted to ensure uniform expansion rates for each part. The mechanical reading section is made up of only four parts.

　Every brand with a long history has a legend to revisit. In the case of Favre-Leuba, which was founded 280 years ago, the first example would be the Bivouac, released in 1962. This model, featuring the world's first mechanical altimeter (an aneroid barometric altimeter), is one of Favre-Leuba's most notable innovations. During the company's golden age in the 1950s and 1960s, the brand actively developed in-house movements, beginning with the FL101. Favre-Leuba was likely the first to successfully mass-produce the double-barrel + center-second automatic movement, which is now commonplace. However, after a period of virtual dormancy following the quartz crisis, the company was resurrected by the Tata Group in 2011. Since then, the brand has once again demonstrated a proactive approach to R&D. A key figure in this development is Patrick Curie, former technical director at Eterna, who joined the company in 2015.

　Curie says that in developing the new Bivouac, he aimed to "not reproduce but improve on the same technology." The method of mechanically reading the expansion rate of the anaerobic capsule (aneroid cell) and converting it to altitude (or air pressure) is the same as the original Bivouac, but the new Bivouac 9000 has improved its display performance to an altitude equivalent of 9,000 meters. Since the highest peak, Mount Everest, is 8,848 meters above sea level, there is no altitude that the Bivouac 9000 cannot measure as long as you have your feet on the ground.

Bivouac [1962]

　Incidentally, the previous measurement record was up to an altitude of 5,000m with the Breva (developed by Chronode). So how was it possible to suddenly expand the measurement range to that extent? The answer is the new aneroid cell shape. The new cell, jointly developed with a certain developer (effectively a monopoly), has a maximum expansion width of 0.4mm. This small volume change is allocated to an altitude of 9,000m with three rotations of the center hand. Furthermore, as a result of promoting structural efficiency, the "conversion device" is made up of just four parts.

　This model established the technique of converting the expansion rate of the aneroid cell inside the case into altitude. The rotating bezel is equipped to preset the reference altitude according to atmospheric conditions. If your altitude remains constant, the movement of the hands indicates changes in air pressure. Manual winding (Cal. FL10032/Pezeaux base). 21,600 vph. Power reserve approximately 40 hours. Stainless steel (diameter 40mm). Reference product.

Bivouac 9000 [2017]

　The reason such a simple structure was possible is also due to the characteristics of the base movement. The base is a hand-wound movement made by EMC, Eterna's parts company. Like the original Bivouac, this movement has a large space in the center, which made it possible to install a thick module. Curie's experience, with his intimate knowledge of Eterna's characteristics, was put to good use in everything from selecting the base movement to arranging the module.

　Another major feature of the Bivouac 9000 is its water resistance. For the aneroid cell to function properly, outside air needs to be introduced into the case, making water resistance the most difficult thing to achieve. However, the Bivouac 9000 is equipped with a moisture-separating membrane at the 9 o'clock position, making it water resistant to a depth of 30m. Combined with a lightweight case despite its large size, this ensures practicality that makes everyday use stress-free, which is another of its great advantages.

　This is the successor to the Bivouac, released in 2017. It features a new aneroid cell that has been adjusted to increase the expansion rate while ensuring that the volumetric changes of each component are even. A hydrophobic micro-perforated membrane at 9 o'clock prevents moisture from entering the case when air is introduced. Hand-wound (Cal. FL311/EMC 3903M base). 21 jewels. 28,800 vph. Power reserve of approximately 65 hours. Ti (diameter 48mm, thickness 18.7mm). Water resistant to 30m. Price: 850,000 yen.

Patrick Cury has been the head of development at Favre-Leuba since 2015. After working in the restoration department at Omega and at Rolex and Breguet, he became CTO of Eterna/Porsche Design and served as CEO of the company since 11.