FAVRE-LEUBA Bivouac 900
A wristwatch capable of measuring altitudes of up to an incredible 9,000 m above sea level! Favre-Leuba has made that possible with its Bivouac 9000 on the Manufacture’s 280th anniversary.
Switzerland’ second-oldest watch brand provides ample proof that ingenuity and unrivaled innovation continue to inspire everything it does. The Bivouac 9000 is a watch that really pushes the boundaries – a watch that achieves something previously thought impossible.
The inspiration for this groundbreaking creation comes from the company’s own history: in 1962, Favre-Leuba launched the world’s first mechanical wristwatch capable of measuring air pressure and altitudes of up to 3,000 m above sea level. The outstanding reliability and precision of this watch, as well as the fact that it was extremely easy to use and read, quickly, made it a permanent feature on the wrists of mountain climbers, pilots, explorers, and every pioneer who achieved great things thanks to their courage and persistence.
The Bivouac 9000 still measures altitude with the aid of an aneroid barometer, but now does so up to an incredible height of 9,000 m above sea level. The red central hand indicates the altitude on the bidirectional rotating bezel, which carries a scale divided into 50-m steps, up to 3,000 m. One full clockwise rotation of the red central hand thus indicates a climb in altitude of 3,000 meters. During a climb, the small red hand of the subdial located at 3’o clock continues to turn too, until, after three full rotations of the central hand, it arrives at its final destination of 9,000m above sea level. The bezel is held securely in place by a two-way ratchet mechanism that prevents it from being unintentionally moved to a different position.
The heart of the barometer is an airtight capsule made from a special alloy. The capsule expands when the air pressure drops as the wearer climbs and contracts when the air pressure rises during the descent. The expansion and contraction of the capsule trigger a linear movement, which is then converted into a rotational movement to indicate the altitude. The altitude is made visible by the red hands on the stone-gray dial. The atmospheric air that is required to measure the altitude enters the chamber containing the barometer capsule through a three millimeter opening in the case, which is protected by a perforated membrane.
It is not until you consider that the difference between the air pressure at sea level and at the summit of the world’s highest peak does not even amount to one atmosphere (approx. 0.7 bar), that you can begin to guess how intricate the mechanism inside the Bivouac 9000 must be to precisely measure altitudes up to 9,000 m.
Unlike the 1962 Bivouac, the new version is also watertight. This is because the air inlet in the case, which is required for the barometer, is protected by a fine but tough membrane made from a micro-¬perforated hydrophobic material. This membrane allows air – but not water or dust particles – to pass through.
Together with the altimeter and air-pressure display, the dial also features a power-reserve indicator at 12’o clock. This gives the wearer plenty of warning when the watch needs to be wound after the movement has been running for around 60 hours. In line with Favre-Leuba’s long tradition of challenging the status quo, of routinely defying convention, of seeking to follow new paths in pursuit of innovative solutions, the mechanism that drives this power-reserve indicator is also anything but standard. It is designed in such a way that it does not affect the height of the movement and carries out its complex task with as few components as possible, which makes it much more reliable. Generally, the lower a number of components required for a mechanism, the less likely it is to malfunction. For the power-reserve indicator of the Bivouac 9000, the English differential screw system has been modernized, optimized, and adapted to perfectly meet the needs of this watch.
