The Call of the Sea: The Omega Seamaster 600 vs the Rolex Sea-Dweller

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Jacques Costaeu arriving on his ship by helicopter. Like a boss.

Jacques Costaeu arriving on his ship by helicopter. Like a boss.

Humanity has always been fascinated by the sea and the contradictions that lie within it: simultaneously providing a bounty of resources, yet seconds away from destroying anything caught in its wrath. Throughout history our knowledge of the sea was limited to the endurance of our lungs. As the world rocketed towards the stars at breakneck speed, it was anyone's guess what lurked in the deep. For years there had been developments in breathing apparatuses  with the main goal of moving away from the tether that restricted the movement of divers. But it wasn't until Jacques Cousteau developed the Aqua-Lung in partnership with Emile Gagnan, which utilized compressed air in cylinders worn on divers backs, that divers were allowed an unparalleled amount of freedom beneath the waves.

The Rolex Submariner is by far the most recognizable diving watch ever made. Whilst it is true that the Omega Seamaster 300 launched only four years after the Submariner and was just as capable, it never obtained the same level of reverence amongst divers and watch fans. For the time, the extreme levels of waterproofness the Submariner exhibited (First 100m then later 200m) were completely unnecessary, as most divers were unable to go deeper than 60 meters due to complications from water pressure affecting oxygen reserves.  Since 1961, the Compagnie Maritime d'Expertises (COMEX) had been dedicated to exploring the oceans depths and advancing scientific understanding about the "hidden" 70% of the earths surface. Since its inception, COMEX had maintained close ties with both Rolex and Omega, issuing divers the Omega Seamaster Reference 165.024 as standard.

Rolex Submariner Ref. 5513

Rolex Submariner Ref. 5513

In the late sixties COMEX started pioneering a new method of diving called "Saturation Diving" which allowed divers to stay submerged for much greater lengths of time. For long dives there was always a danger of decompression sickness (more commonly known as the bends) which occurred when inert gas that had been absorbed by the body formed bubbles under the pressure of decompression. These bubbles could then block blood vessels or damage nearby cells. By having the divers breathe a mixture of helium, hydrogen and oxygen in their tanks and then having them breathe the same mixture in a pressurized underwater environment, the divers could last for days (or even weeks) underwater and only resurface once at the end of the dive, thus reducing the risk of the bends significantly. However, the human body is much more adept at disposing of helium than a watch case is. The divers found that helium molecules would pass through the seals of a watch and expand. Violently. Imagine a champagne cork but made of the crystal of a watch. Not what you want to be happening hundreds of meters underwater in a small capsule. By the end of the decade COMEX aimed to send divers down to depths of 300 meters, 100 meters deeper than the highest rated Submariner or Seamaster could handle. This objective was the motivation for the Rolex Sea-Dweller and Omega Seamaster 600.

A diver breathing hydrogen can’t live without his Rolex. In diving, time is a crucial piece of information. Be it operations, changing gas mixtures, timing decompression stops, entering and exiting the diving bell, it’s all a matter of seconds. Having a precise, robust, reliable watch was of vital importance
— Henry Germain Delauze, President of COMEX

Omega decided to completely start afresh from anything they had made before and it took four years of development to produce the Ref. 166.077, the Omega Seamaster 600, in 1970. Their original plans had been to fashion a watch using titanium (10 prototypes had already been made) but titanium was very expensive to buy and very difficult to machine. In lieu of titanium, Omega developed a solid stainless steel mono-block case; by forgoing the removable case back, the only two points of entry for water were the crown and the crystal. After chemical treatment to make it anti-reflective and anti-abrasive, a 4mm thick mineral crystal was tested at being able to withstand pressure of up to 60 atmospheres. If you look at the crown on the Seamaster 600 you could be forgiven for thinking that it is square, however this is just a shield that would stop the crown from unwinding accidentally under pressure. Due to the large crown guards and this extra cover, Omega decided to place the crown at the 9 o'clock position so divers could move their right hand free from obstruction. The name PloProf actually came from the French divers who used the Seamaster, Plongeur Professionel, Plo. Prof. Rather than the standard uni-directional bezel, the bezel on the Seamaster was bi-directional and was activated by pushing the orange button located on the side of the watch. 


Throughout the years there have been pieces of technology that have gone far above and beyond the call of duty. The PloProf is one of those pieces. It. is. insane. When Omega first launched the Seamaster 300 in 1957, it was actually only water resistant to 200m and was only called the 300 because it sounded better. So it was a reverse twist of fate that the PloProf was actually tested under far stricter conditions than its claimed 600m. Tested to a simulated depth of 1370m, the only reason the watch wasn't tested further was that the glass expanded and had jammed the second hand stopping the watch. Once the pressure subsided the movement started working perfectly again. Whilst Rolex had opted to go for a more high-tech approach, Omega instead went for sheer brute force (very well engineered and brilliantly designed brute force, mind). Not that I think it was a bad approach, as in fact I prefer the sheer nonsense of the PloProf over the more refined and technically advanced Sea-Dweller.  At the time the PloProf was Omega's most expensive piece, but I doubt that they ever recouped the cost of development even with a nine year production time. For the general public its unwieldy size of 54mm by 45mm was just too huge. Even today it's considered a beast, so think what it must have been like back in 1970! 

I think it would be a fair assessment of Rolex to say that they are the more conservative of the two companies. Whilst Omega was designing a completely new piece that would just tough it out against helium, Rolex decided on a more elegant approach and took to modifying an existing Submariner reference, the 5513. It is interesting to note that on the Rolex website they write that making a watch impervious to helium is "a practically impossible task". Obviously no-one told them about the PloProf! What Rolex developed would soon become the standard for all professional diving watches thereafter, the Helium Escape Valve or HEV. By having a uni-directional valve on the side of the watch, it would allow the small helium molecules to exit the watch without causing any damage. In November of 1967 Rolex applied for a patent for the HEV valve but released the new Ref. 1655 anyway, two years before the patent was granted.

This piece is considered one of the rarest Rolex Diving watches as there were only a very very small amount made with estimates ranging from fifty to several hundred pieces, all with "PATENT PENDING" engraved on the case back. The two red lines of text on the dial that read "SEA-DWELLER" "SUBMARINER 2000" soon meant that the piece was dubbed the Double Red Sea-Dweller. Never let it be said that watch enthusiasts are unimaginative with their nicknames. Once the patent was approved, the Ref. 1655 would be in-production for a little over a decade until the Ref. 16660 would replace it in 1978. The red lines were removed in favor of an all white look that was soon dubbed "The Great White". The 16660 also boasted an increased depth rating of 1220m, a new movement and sapphire crystal.

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After COMEX had tested both the Seamaster 600 and the Rolex Ref. 5513 with HEV modification they decided that they prefered the more elegant HEV solution to the PloProf. Whilst I personally think the PloProf is a far more interesting watch, I can see why the technically superior (and far smaller) Rolex would be a professional's choice. For the next thirty years Rolex maintained a very close relationship with COMEX and would produce a number of Submariners and Sea-Dwellers for them. These watches would become very prized by collectors as they were only issued to COMEX divers and featured COMEX branding on the dial and case back. One of the most collectible references is the 1680 which was an experimental Submariner which didn't have the HEV and failed the pressure tests. Deemed useless for saturation diving it was given to COMEX office workers and officials as gifts in 1978. Many of these watches didn't survive in their original condition as owners didn't care for the branding so either sold them off or had the dial replaced with one from a standard submariner. Needless to say these pieces hold a high price now, with one making its way into John Mayer's collection, which he showcased on one of the first episodes of Talking Watches.

What I find so fascinating about the development of these two watches is the completely different approaches that Rolex and Omega took. Only a few years before Rolex had made the experimental Deep Sea which managed 10,916 meters (35,814 feet) underwater without failure, so Rolex had experience of building something to the extreme. Instead they chose to to innovate a completely new method which changed the face of diving forever. In another world perhaps the PloProf would have been chosen and it now would be the face of modern diving? I don't think it would look quite as good underneath a white tuxedo cuff mind. 

I'd like to thank Eric Ku of 10pastten for the beautiful photographs of several vintage Submariners and Sea-Dwellers. I highly recommend anyone wanting more detailed information about the Sea-Dweller to visit