This might be the only Jaeger-LeCoultre that’s difficult to wear with a suit. The Master Compressor Diving Pro Geographic is a thoroughbred tool watch: an instrument designed for a specific purpose, with a particular aim in mind dictating the technical options adopted, along with styling to match. Its intended use is embodied in the Diving Pro name, clearly marking it out as a piece for professionals.
Radical
The Master Compressor line is the most recent offshoot of a family tree that started with the Deep Sea and the Polaris, two other Jaeger-LeCoultre creations aimed at divers. The difference is that these two watches preserve a degree of urban chic, being designed for conventional depths, whereas the Master Compressor Diving line is more radical and above all more technical, with water resistance guaranteed to depths of between 300 and 1,000 metres — in the latter case, by virtue of a case that’s up to 5mm thick and a sapphire crystal 3.6mm thick, capable of withstanding the 890kg of pressure exerted at this depth.
A Family Resemblance
Three versions were produced: the Diving Pro Geographic, the Diving GMT, and the Diving Chronograph, respectively rated to 300m, 1,000m, and 1,000m. Each has a date window and a running indicator, the latter being mandatory to secure ISO 6425 divers’ watch certification.
The Diving Pro Geographic features a 24-hour display, with reference cities for various time zones. The Diving GMT has a second, 24-hour dial. And as its name suggests, the Diving Chronograph sports a chronograph. The Diving Pro Geographic also boasts another quite unusual attribute: a mechanical depth gauge. Its presence is hinted at by the technical unit bulging out from the frame between 8 and 10 o’clock and, on the dial, by the related scale.
Offspring of the Atmos
The workings of the unit are directly inspired by a system that’s been implemented by Jaeger-LeCoultre for almost a century now on its Atmos clocks: a membrane that responds to variations in pressure. In the Atmos, the clock is powered by variations in atmospheric pressure. In the Diving Pro Geographic, variations in water pressure activate a rack connected to a central, blue indicator hand.
The pressure exerted by the water column on the external unit causes the pointer to travel along a logarithmic scale. When the indicator is at 4 o’clock, the pressure is zero. The scale then increases in one-metre increments up to a depth of 50 metres. Thereafter, each segment corresponds to two metres, through to the end of the scale at 80 metres.
There’s nothing new about the technical principle at work in this depth gauge (Oris has done something very similar), but Jaeger-LeCoultre’s expertise with the Atmos has enabled the firm to add some clever touches to the unit’s construction, not least in that no seal is required — with the result that there’s never going to be one that will need changing. This makes the Diving Pro Geographic more reliable in the long term.
Did you say compressor?
The GMT, Chronograph and the Pro Geographic Master Compressor have all undergone one thousand hours of testing in Jaeger-LeCoultre’s in-house Master 1000 Hours programme, which certifies that the watch works perfectly in any circumstances.
One other special feature is that the crown on each of these models is secured by an original system developed especially for the range: a little winglet-shaped key that connects the crown to the frame. If this displays a blue triangle, the crown is released: the watch mustn’t be taken diving. A white triangle, on the other hand, indicates that the crown is properly locked: you’re ready to dive! Turning this key is actually what compresses the seal between the crown and the frame — and that’s why the collection is named Compressor.
This year GMT Magazine and WorldTempus have embarked on the ambitious project of summarising the divers watch since 2000 in The Millennium Watch Book - Divers watch, a big, beautifully laid out coffee table book. This article is an extract. The Millennium Watch Book - Divers watch is available in both French and English here:
