The history of the Seamaster 600 starts in 1967 when Omega took advantage of the experience of a consultant specialising in diving watches, his name was Frederic Robert. Robert himself was the founder and creator of the Aquastar watch company. In the same year Omega patented the case of the Seamaster 600, and in 1968 entrusted its management to Robert.
These years represent an important historical period for this brand, that was also engaged on the space front with their Omega Speedmaster, the iconic chronograph that conquered space and, soon after, the moon.
Building on this experience, Omega decides to create a professional diving watch that could meet the needs of those who practised diving work. The only goal of the Seamaster 600 was to be a durable and reliable tool. This watch had to be able to withstand extreme depths below sea level and constant pressures that could occur during the time spent in the decompression bells.
The Seamaster 600 was named by French divers PloProf from the contraction of the words PLOngeur (diver) and PROFessionel (professional).
In 1970, the only private organisation on the planet that could adequately test the PloProf in the environment it was designed for was Comex, a company specialising in underwater work. An industry leader, Comex helped develop this iconic watch created exclusively to be used as a work tool. For this reason its lines were designed to be functional for a professional diver, on the contrary commerciality and aesthetics were put in the background.
Created, in 1961, in France in Marseille by Henri Delauze, Comex specialises in deep oil and gas pipeline construction operations. This company was a pioneer in deep saturation diving experimenting with gas mixtures (nitrogen, oxygen and helium) and underwater equipment, in addition, Comex also designed a hyperbaric experimental centre.
The creator of the Comex personally participated in the first helium dives to the depth of 335 m and 360 m.
Commissioned by oil companies to work on an underwater pipeline in the Gulf of Ajaccio, off the French coast, Comex tested the PloProf 600 during the Janus II mission in 1970. For eight days, three men stayed in a pressurised chamber 200 m below sea level, going out, alone, to work in shifts of 3 hours a day at a depth of 253 m.
In 1952, before founding Comex, Henri Delauze met and worked, for 3 years, with Jacque Ives Cousteau at OFRS (French Office for Submarine Research).
The figure of Cousteau is important in the world of diving. It was he who, in 1943, invented the Aqua-lung air respirator, which allowed the diver to stay underwater for a long time, thus giving life to scuba diving. In addition, in 1962, he was the first to experiment with his collaborators with the use of underwater bells, while, in 1963, he developed an underwater camera called Calypso Phot. Cousteau won three Oscars as a director of his documentary films. In his films you can admire the iconic PloProf 600.
One of the problems which can occur in professional dives in saturation, that is the explosion of the watch glass.
During days of stay in the underwater habitat (an environment where divers stay between dives) the internal pressure of the chamber is equal to that of the operating sea depth.
This pressure compresses the molecules of the breathable gases. Helium molecules, being smaller, can penetrate clocks unlike air and water.
The helium molecules, expanding, that is, returning to their original shape, compress the watch from the inside causing it to explode.
The air we breathe on the surface becomes toxic when breathed in deep immersion.
Helium is an inert volatile gas that is used in breathable gas mixtures to replace nitrogen, thus preventing narcosis. This gas facilitates breathing and allows you to perform professional work in immersion. Nitrogen is a gas that is found for 78% in the air and that, if compressed, can overcome the alveolar barrier and bind to oxygen creating nitrogen oxide, also known as exhilarating gas, which is toxic.
Once the diving activity is finished, in case of ascent, the decompression steps must be carried out; alternatively you can decompress (to eliminate the inert gases in the body) dry, through the hyperbaric chamber for decompression. During this process the pressure is gradually brought back to that of the Earth’s surface of 1 atmosphere.
The Omega PloProf Seamaster 600 was built with the best cutting-edge techniques for the time.
To limit the chances of helium penetrating inside the watch, Omega created a monobloc case. With this type of structure the components, such as calibre, dial and glass, were inserted from above.
The mineral glass with external edging, was blocked by a gasket and a metal screwed ring. This solution guaranteed the anchoring of the glass and exceptional waterproofing.
Another feature is the use of Uranus steel or 904 L, an alloy with high corrosion resistance. Omega was the first to use this metal in watchmaking, Comex’s immersion instruments also used the same type of steel.
The bezel is fundamental for a diver; the problem of accidentally moving it in dive was solved by Omega with a locking device, a red plastic button that only when pressed allows the bi-directional bezel to be rotated.
Another iconic feature of the Seamaster 600 is the double crown with safety device: the first removable square crown allows the adjustment of the setting in time, while, the second crown with classic round shape by screwing itself brings the square crown to itself, thus allowing the airtight closure of the watch.
The Seamaster 600 was and remains a complex and expensive watch. At the time, when it was launched on the market it cost twice the list price of a Rolex Sub Mariner.
At the time of its market launch, in 1971, PloProf had been tested guaranteeing an immersion depth of 1000 m, abundantly exceeding the 600 m of its name. A test carried out in the laboratory, at Ocean System Inc., confirms that the Seamaster 600 reached a hypothetical immersion depth of 1370 m before the strong pressure, compressing the glass against the hand of seconds, blocked the mechanism by stopping the clock.
The historical memory of this watch has been lost also thanks to the fact that being a diving watch it was subjected to maintenance and replacement of components, such as the dial, in case of water infiltration.
There are three commercialised versions of PloProf with reference 166,077.
The three series have some differences, such as the hour hand which, especially in the prototypes and in the first series, presents a greater application of tritium and the bezel with different fonts of the numbers, in particular the number 30 which, initially, was round, and later becomes squared around 1975.
The most important change is the arrangement of the words at 6 o’clock in the dial.
Thanks to research and studies A. Isnardi in the book Omega Seamaster Vintage managed to place the three series in chronological order:
1 series – SEAMASTER 600 PROFESSIONAL
2 series – PROFESSIONAL SEAMASTER 600
3 series – SEAMASTER 600m/2000ft PROFESSIONAL
The first series (600 in the middle) is seen in several pre-production prototypes (year 1969) and in official and marketed models up to 72.
In this version, the surface of the dial is at best rough and at worst with surfacing bubbles. This problem occurred due to the ineffectiveness of the printing paint, which was very sensitive to moisture.
It is assumed that these dials were replaced by the second series (600 below) which is considered the official version and was marketed from April 1971 until 1975.
In the third series in addition to the writing in metres is added the depth of standing (600m/2000ft). This version of the dial, adopted from 1975 to 1979 year of end of production, is the definitive one. This configuration is the same as the one used for the supply dial with luminova.
Although indexes and hands are treated with tritium, in all three PloProf series, the classic indication of T (Tritium) never appears between the Swiss Made inscription.
There are countless military assignments for this watch, recently, it has been discovered a PloProf 600 with archive excerpt assigned to a mission in Alaska.
Another curiosity concerns the famous Italian Fiat entrepreneur Gianni Agnelli who was often photographed with this iconic model; he used to wear watches over the cuff of his shirt.
The Seamaster 600 after almost 8 years (from 1971 to 1979) goes out of production. The advent of quartz destabilises the world of watchmaking and annihilates the latest true underwater watch.
Fortunately, however, at the beginning of the second millennium, mechanical watchmaking is resurrected, and in 2010 Omega re-proposed the PloProf 1200 m in a modern key with the latest generation of features: Co-Axial calibre, helium valve and sapphire glass bezel. In addition to steel, the PloProf 1200 m is proposed in titanium.
In 2023, for the 75th anniversary of the Seamaster line, Omega is offering a new edition called Summer Blue. Among these models stands out the new reinterpretation of the Seamaster PloProf 1200.
This third generation fully embodies the vintage style of its 70s predecessor. Obviously, the techniques and materials used are of the latest generation as can be seen from the use of the manufacture calibre Co-Axial 8912 and the ceramic coated release button.
In addition, as regards the technical characteristics, Omega returns to the use of the monobloc case made from a single piece of steel turned and embellished with a valve for the exit of helium.
In the latter version Omega proposes other features of the past, such as the sea blue colour dial and the Isofrane-style rubber strap that remains the configuration most loved by fans.
Its price list of €15,900 is challenging, but the market for this type of watch is reserved for the most demanding collectors.
You can always consider buying a vintage PloProf which, for now, in excellent condition, is priced lower than the new models.
My journey as an enthusiast led me to appreciate and learn about the vintage world of this professional underwater watch. Initially, I catalogued and examined the subjects relating to the Ploprof 600 (advertising, vintage instruction booklets, bracelets, boxes etc..), finally I managed to collect one.
This experience allowed me to contribute with a small participation in Alberto Isnardi’s book, Omega Seamaster Vintage, the only book dedicated to this category. You can define it a book in the book, since inside there is a chapter dedicated exclusively to the Seamaster PloProf 600, as well as the more famous Seamaster 300.
For those who want to try their hand at finding this watch, the book is a great guide that will help you through the pitfalls of buying a PloProf.
If you are looking for an extraordinary timepiece that has marked the history of underwater watchmaking then you are in the right direction!
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