Credits: Article and images by Ian Skellern @ Quill & Pad. See the original article here - https://quillandpad.com/2023/11/25/a-comprehensive-look-at-mechanical-depth-gauge-watches-reprise/
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Aside from Favre-Leuba, there have been three other companies working with membrane depth gauges. One was IWC, who followed up its Aquatimer Deep One with two membrane depth gauge models: Deep Two (2009-2014) and Deep Three (2014-2018).
The IWC Deep Two uses a membrane depth gauge, which probably worked well enough since the brand also came out with a Deep Three with one as well. Unfortunately, IWC stopped production of diving watches with depth gauges in 2018.
Two years before the Deep Two came out with its interesting version of the membrane depth gauge, Jaeger-LeCoultre introduced its take on an aneroid box on a watch that transposed water pressure without letting any water enter the watch.
The JLC Master Compressor Diving Pro Geographic perhaps holds the world record for the diving watch with the longest name, however it featured a new kind of membrane pressure gauge. Instead of a flat chamber with a big membrane (that would require a big case), the Jaeger-LeCoultre Master Compressor Diving Pro Geographic used a vertical chamber with a small pressure lid and a spring inside – so it’s not quite an aneroid can.
This watch also incorporated a second time zone (the subdial at 9 o’clock) and a power reserve indication (5 o’clock) in addition to the date. So many complications in one watch certainly account for the long name.
The Diving Pro Geographic also came in a limited gold edition for the Navy Seals: fighting men meet luxury watch. This timepiece certainly loves contradictions!
There were also some problems with membrane depth gauges even if they didn’t clog. The problem with the models from IWC and Jaeger-LeCoultre was the quite small pressure plate, the device that is pressed inside the watch by the water, moving a spring that activates a system of gears to display the depth.
The problem: the smaller this plate was, the more difficult it was to get an exact “data transfer.” Thus, the reliability of the indicated depth is put in question – a question that could become life threatening when diving to a depth of 80 meters. As fantastic this mechanism might be in theory, it was questionable as reliable equipment for the serious diver.
As a collector with limited money, I would have gone for the IWC Deep Two with its great history and great mechanics. Nobody is doing decompression dives with this watch anyway.
That leaves two brands: Favre-Leuba with its “new” 2018 Memodepth and Blancpain, who introduced the X Fathoms exactly ten years ago – which still has one problem in regard to membrane depth gauges: the membrane itself.
An aneroid can depth gauge in the old sense features a metal membrane that compresses when descending and depresses when ascending. Over time, this membrane will weaken and wear out, at which point you either recalibrate the depth gauge before each dive (to keep it very precise) or suffer with misreading after a while.
And, to get a bigger surface for better pressure transmission you need to have a bigger watch case. Just compare the relatively small IWC and Jaeger-LeCoultre watches with conventional depth gauges. These instruments are really big. Thus, both the Favre-Leuba and the Blancpain X Fathoms are big!
The membrane still leaves one problem open. As I mentioned earlier, the depth reading in the first 12 meters should be as precise as possible to allow for decompression stops that normally take place at 12, 9, 6, and 3 meters.
For depth gauges it’s either great decompression readings or more precise depth indication down deeper, so deep-sea divers often use two instruments. This is no problem if you buy two depth gauges that cost about €50 apiece, but I have never seen a diver with both a Favre-Leube and an Oris!
The Blancpain X Fathoms is the mother of all diving watches with a depth gauge inside highlighting what a leading Swiss watch manufacturer is capable of – especially when divers are part of the company’s leadership.
Aside from solving the problem of the metal membrane in an aneroid can, the X Fathoms also solved the problem of getting two different readings for its depth measurements: one for diving deep (91.45 meters = 50 fathoms) and the other for a detailed scale of decompression depth readings – plus an extra decompression timer on top – to make full use of the big dial in the 51 mm watch case.
In a word big is beautiful – if it weren’t for its big price tag of €30,000!
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Credits: Article and images by Ian Skellern @ Quill & Pad. See the original article here - https://quillandpad.com/2023/11/25/a-comprehensive-look-at-mechanical-depth-gauge-watches-reprise/