The Favre-Leuba Raider Bivouac 9000 is the first mechanical watch that will tell you the altitude on top of Mt Everest — and higher up

TECHSPECS

Case Size: 48mm

Case Shape: Round

Case Material: Titanium

Movement: Manual winding

Strap Material: Leather

Strap Colour: Grey with pin buckle

Dial Colour: Grey

Gender: Men

Water Resistance: 30m

Glass material: Sapphire crystal

Warranty Period: Two years

Price in India: Rs 5.31 lakh

ALTIMETER

No, that red central hand isn’t the seconds hand. Seconds are on the subdial at nine o’clock. The big red hand points out the altitude on the bidirectional rotating bezel that’s graduated in 50m steps, up to 3,000m. So, one full clockwise turn indicates a gain of 3,000m. During a climb, the small red hand of the subdial at three o’clock turns too, until, after three full rotations of the central hand, it arrives at its final destination of 9,000m above sea level. (You’ll need to fly up the last bit though).

TOUGH EXTERIOR

The Bivouac 9000 is meant to be a tough watch that one can actually use on expeditions to high mountains. It is a big and chunky watch made of titanium. It has a toothed bezel that one can turn even with a gloved hand. The screw-down crown (to prevent fluids from leaking into the case) is big to make winding the watch easy

AIR PRESSURE DISPLAY

The Bivouac 9000 shows the current air pressure or any change in it at a particular altitude. It will indicate if the weather is turning stormy or fair depending on whether pressure is falling or rising

The Favre-Leuba Raider Bivouac 9000 looks purposeful. With a diameter of 48mm and a thickness of 18.7mm, it is a big watch that stands out with its grey titanium case and leather strap. And its red pointers and graduated bezel give it an industrial look. In a way, that is not too far away from fact.

The Bivouac 9000 takes its name from a watch that Favre-Leuba made in 1962. That one could measure altitude up to 3,000m above sea level and was path-breaking in its time. The current model, the 9000, takes that idea and bumps it up three-fold. It holds the distinction of being the first mechanical watch that can measure altitudes of up to 9,000m above sea level. So, you could be standing on top of Mt Everest.

If one were looking for a mechanical device to do that job, one would typically use an aneroid barometer. Well, so does the watch. Its mechanicals are in two main parts. There’s the time-measurement machinery. It’s the robust hand-wound FL311 movement.

On top of that is the tiny aneroid barometer with its corrugated airtight capsule made from special alloy (remember high school physics?). It expands when the air pressure drops as the wearer climbs and contracts when the air pressure rises during the descent. They trigger linear movement, which is then converted into a rotational movement to indicate the altitude.

Air needed to measure altitude enters the chamber containing the barometer capsule through a 3mm opening in the case, which is protected by a perforated membrane. It is a fairly simple mechanism in principle and, possibly, that is how the chances of failure have been minimised.

The subdial at three o’clock is the air pressure indicator calibrated in hectopascals. If at a particular spot, say the Everest base camp, the watch shows a fall in pressure in the morning compared with the previous evening, the chances are that stormy weather is approaching and the bigger the drop the greater the chances of that. The converse is also true, that is, if the pressure increases, the weather would be fair. So mountaineers, for instance, can decide whether on not to go ahead with a climb on a particular day or wait for weather to improve using the Bivouac 9000.

The third part of the mechanism is the power-reserve indicator. It has been created with very few parts. When fully wound, the watch can run for 65 hours.

The interesting thing that this watch has been able to achieve is to measure air pressure, for which it has to be open to the atmosphere, along with water resistance up to 30m, for which it has to be closed to the surroundings. It does this using a fine but tough membrane made from a micro-perforated water-repelling material across the air inlet. It lets air but not water or dust particles through. The holes need to be as small as possible while still being large enough to allow air to circulate. So they had to be calculated and tested with extreme precision.

At Rs 5.31 lakh a piece, the Raider Bivouac 9000 doesn’t come cheap. But then, it will be ready to give you company no matter how high you go — on land.

— Abhijit Mitra