By TLex The ocean is the playground of the new millennium, more and more of us are venturing into the deep blue, advances in diving technologies, ever sophisticated dive computers and hi-tech diving equipment are all accessible even to the novice diver. Why then are mechanical depth gauges still being incorporated into diving wrist watches?
It’s true that depth gauges can serve as a backup to your dive computer, as can an elapsed dive scale on your dive watch, but lets not kid ourselves here, this is not why watch companies like Favre-Leuba, Jaeger-LeCoultre or IWC have created watches like the Bathy V.2, Master Compressor Diving Geographic Pro or the Aquatimer Deep Two.
Besides being uber-cool, these watches head up their latest dive watch families. And as with diving tourbillions they perfectly showcase what the watchmakers are capable of. They are created using the most the exacting and advanced technologies, are rigorously tested, and in the case of IWC and JLC are put through their paces in the element that they were intended for.
Sadly, as is with probably 90% of dive watches, these marvels of modern engineering once leaving the boutique, rarely fulfill their destinies as depth meters, but that’s not to say they aren’t revered and marveled at. They capture the hearts imaginations of diver’s and horologists alike. They promise adventure, invite journey into the deep, but guarantee serious misadventure into depths our wallets and bank accounts.
Below are unarguably the top three mechanical depth meters available today; the Favre-Leuba Bathy V.2, the IWC Aquatimer Deep Two and the JLC MC Diving Geographic as well as its rose gold sibling the MC Diving Geographic SEALs . I have included the Panerai Submersible Depth Gauge (PAM00193) and the Pierre Kunz Spirit Diver G021 for the sake of interest. They don’t use mechanical depth gauges, but do fall into the category of hi-end dive watches.
Below I have taken much text, specs and images (some of them quite rare) from the related press releases as no one can explain better their own technologies and instruments than the manufacturers themselves. Happy diving!
JLC MC DIVING PRO GEOGRAPHIC In basic functional terms, the Master Compressor Diving Pro Geographic allows the reading of time in two time zones. The first is read off the watch’s central hands, while the second is found on the 24- hour format subdial at nine o’clock. This display is synchronized to the city disc located in an aperture at six o’clock; turning this disc to any of the 24 cities representing our 24 time zones will give you an instant reading of time there in the subdial.
But to focus on the simple second time zone abilities of this timepiece is to overlook its truly remarkable innovation. Strap on the watch and your eyes will naturally be drawn to the lefthand side of the titanic 46.3-mm watch case — home to the most technically advanced, all-mechanical diving device known to man, Jaeger-LeCoultre’s proprietary depth gauge.
This marvel of engineering is composed of 24 elements and represents a relentless 1,500 hours of research and development. It takes two hours to assemble and provides an accurate reading of depth to within one meter from zero to 80 meters below sea level. Look closely at the depth gauge and you’ll find a rectangular opening devoid of sapphire crystal that exposes the alchemic workings, known as the membrane. The membrane is the actual apparatus that translates water pressure into a reading of how deep you’re submerged on the watch dial.
In the process of creating the Master Compressor Diving Pro Geographic, Jaeger-LeCoultre studied all other mechanical depth gauges. It found that the Achilles’ heel of these previous systems was that they depended on water entering the internal mechanism to tell depth, which allowed debris to clog the device. In Jaeger-LeCoultre’s proprietary system, water never enters the internal mechanism.
Instead, the contraction and return of the depth gauge’s membrane as water pressure rises and diminishes is supported by a specially calibrated spring around the rail mechanism that allows consistent and accurate travel for the rail at all times. The correct functioning of the membrane is dependent on the correct calibration of this spring.
The origin of the intricate and brilliant engineering of this device is innately connected to the brand’s famous innovation, the Atmos clock; a clock which requires no winding and derives its energy purely from tiny variations in environmental temperature or pressure. Says Jerome Lambert, “Inside the Atmos is also a membrane that contracts and expands according to environmental temperature.
The only difference is that inside the Atmos is a gas that expands or contracts. The solution we have achieved is a spectacular demonstration of how we’ve used our rich history and the total integration of our manufacture to solve age-old problems with totally new solutions.”
Every aspect of the depth gauge system has been optimized for robust performance over time. Movement of the rail is translated via the transmission pinion to a rack system, which interacts with a centrally-mounted snail cam through geared teeth.
The rack and snail cam is used in numerous horological complications — perhaps most famously in minute repeaters — and Jaeger-LeCoultre’s mastery of the world’s most complicated micro-mechanical marvels gives it tremendous expertise in the optimization of these elements.
The rack here has been calibrated to cause the centrally mounted snail cam to shift in position, which in turn triggers the movement of the high-visibility blue depth gauge hand around the perimeter of the dial.
This entire system is on full display, adding to the visual pyrotechnics on the dial, yet arranged such that it does not distract from its time-reading or depth-reading functions. Says the watch’s designer Magali Metrailler, “We know that in a contemporary watch, owners want interactivity where they can see how their watch functions. Because this watch will be used in high-performance and demanding situations, we had to balance this optimal visibility for all indications.”
With the brilliantly innovative design of Jaeger-LeCoulture’s depth gauge, the wearer also does not need to descend underwater to test its function. He can do so by simply pressing on the head of the system and observing the movement of the corresponding hand on the dial.
This adds a huge margin of safety during pre-dive safety checks. And because it is a fully mechanical system — the only such system being commercially produced in a timepiece — it will continue to function without the need for a battery to power it, making it, possibly, the last diving watch you’ll ever need to buy.
JLC MC DIVING PRO GEOGRAPHIC SEALs A technical feat, this timepiece is fitted with a patented mechanical depth gauge, housed on the side of the case. Its geographic movement allows the wearer to select a city simply by rotating the crown to display its time on a large disc at 9 o’clock. A limited series if 300 watches in 18-carat pink gold produced in partnership with the U.S. Navy SEALs®, the elite diving unit of the U.S. Navy.
FAVRE-LEUBA BATHY V.2 More than 40 years after its revolutionary impact on the world of diver’s watches, the legendary Bathy is making a major comeback in an automatic version! Its innovative depth gauge works on a beryllium copper membrane which contracts under the pressure of the water entering the double back. The deviation is less than 0.18%! Such precision – pushed to its limits in the most extreme conditions – is one of the hallmarks of Favre-Leuba, a company that has been making watches for almost 300 years.
Movement Automatic, exclusive FL 305 caliber, 23 jewels, 28,800 vib/h, 224 components, 44-hour power reserve
Functions Hours, minutes, seconds, date, depth gauge to 45 meters or 150 feet, decompression-stage indicator, diving-time gauge
Case Grade 5 titanium, 46 mm
Anti-reflective convex sapphire crystal
Screw-down, engraved double back with membrane depth gauge (meters or feet)
Dial Galvanic black, engine-turned by Favre-Leuba
Rotating flange and large Arabic numerals
Depth indicator in red, yellow or orange
All elements coated with Superluminova
Bracelet/Strap Grey rubber with buckle
PANERAI LUMINOR SUBMERSIBLE DEPTH METER PAM00193
Movement Automatic mechanical, exclusive Panerai OP XV calibre, 13¼ lignes, 21 jewels, Glucydur® balance, 28.800 alternations/hour. Incabloc® anti-shock device. Power reserve 42 hours. Côtes de Genève decoration on the bridges. Panerai personalized oscillating weight. Chronometer Certificate (C.O.S.C.). Depth-gauge electronic module with Metas individual certificate.
Functions Hours, minutes, small seconds. Depth gauge functions: indication of the maximum depth reached during the most recent dive, indication of the amount of battery power left, depth indication during a dive.
Case Diameter 47 mm, titanium. Brushed steel push button at 10 o’clock for the depth gauge functions. Device protecting the crown (protected as a Trademark) in brushed steel.
Bezel Brushed steel anti-clockwise unidirectional rotating bezel with graduated scale for measuring the duration of immersion and ratchet click at minute intervals, applied polished steel index.
Material Screw, titanium.
Dial Black with luminous Arabic numerals and hour markers. Depth gauge scale on the outer part of the dial, with three different scales of accuracy:
from 0 to 20m from 20m to 60m from 60m to 120m
Crystal Sapphire, made from corundum, 3 mm thick. Anti-reflective coating.
Water-resistance 120 meters.
Strap Panerai personalized rubber strap and brushed steel large-size buckle. Supplied with a steel screwdriver and a second interchangeable strap for diving.
IWC AQUATIMER DEEP TWO Technically speaking, the Aquatimer Deep Two is the ambassador of the new collection. Its predecessor, the GST Deep One, which featured a unique mechanical depth gauge with a split hand, had already demonstrated IWC’s right to a place in the echelons of watch making technology.
The Aquatimer Deep Two, with its further improved depth gauge mechanism, underlines this. As in the case of its predecessor, a wheel train is activated by water pressure and converts it into a movement on the depth gauge indicator.
The latter displays current depth and maximum dive depth down to 50 meters. The Aquatimer Deep Two is water-resistant to 12 bar. The newly developed rotating outer bezel with its high-quality coating (which continues to glow for a long time underwater) makes it very easy to read. The Aquatimer Deep Two continues to probe the depths of the oceans with the precision, unmatched performance and masculine understatement that is typical of IWC.
PIERRE KUNZ SPIRIT DIVER G021 SPORT The first diving model for Pierre Kunz, a design governed by the very precise criteria of Swiss watchmaking. A simple, trendy model full of contrast, reminiscent of the submarine influence and the mechanical appearance of machine rooms. With traditional hours and minutes functions and seconds on a rotating disc, the Spirit Diver defies the depths thanks to the depth gauge inserted then fixed on the side of the case. This has become essential, not just an aesthetic, modular accessory.
This robust depth gauge holder hollowed out in Blaktop steel houses a sapphire glass tube which like a spirit level indicates the depth the diver has reached up to eighty meters. Pierre Kunz research - constantly at the quest of perfection and extraordinary challenges - has worked closely with major specialists to produce this 3.3 cm depth gauge. Successful miniaturisation, whereby the Spirit Diver can reproduce the depth and provide a permanent display when diving or returning to the surface.
The Spirit Diver keeps the brand's mascots with a highly readable texalium dial, trimmed with an index in super-luminous material. Black texalium, silvered texalium models or, as a diversion from the usual, diver flag models.
The diving watch dial is sober and specific, with trapezium index, technical figures and a central screw-in applique enfolding the seconds disc. The entire watch mirrors the abyss divers feel they are entering, with juxtaposed concentric, functional circles.
The 44 mm diameter sport case in steel and Blaktop steel, trimmed with a toothed bezel turning in one direction. The bezel is finely sanded producing a very matt finish and exposing rubber index which enhance the whole. The Blaktop steel crown is protected for strength and solidity, both features of the sport line.
The Spirit Diver is water-resistant to 100 meters. The watch caseback is covered with sapphire crystal. The strap is rubber printed with a texalium texture and fitted with a folding steel buckle.
In Sapphire mineral glass
Components in stainless steel with Rhodium plate finish
Graduations: Laser etched with ceramic ink infill
Pressure tests were conducted with the unit placed in various positions to stimulate actual underwater use. In addition units were subjected to movement underwater to determine the extent of water ingress if any.
Units were tested on their own as well as with the range of contrasting backgrounds to determine the best format for the depth gauge display. In addition, different internal diameters were tested to determine the most suitable format for the finished tube.
The unit was repeatedly taken from zero to maximum pressure to asses repeatability and stability of corresponding pressure readings.
Technique Reference: G021 SPORT
Movement Automatic, caliber PK 2001-1519-B, base ETA 2892, ø25.6mm, high 6.27mm, 25 rubies, 28800 A/h.
Functions hours, minutes and seconds. 42 hours power reserve.
Dial black or slivered texalium, or lacquer with the diver flag.
Case Fluted Empire-style case in steel or Blaktop steel, 44 mm diameter, high 13.75mm, sapphire glass.
Strap rubber with texalium texture.
Water-resistant to 100 meters