The Sinking Man’s Watch: Testing the Omega Seamaster Ploprof

In this feature from the WatchTime archives, we test the Omega Seamaster Ploprof, a re-edition of a classic divers’ watch from 1970 with double the original’s water-resistance and a manufacture caliber. Scroll down for the results, along with a gallery of original photos by Nik Schölzel.

It was 1970, in the midst of an era that delighted in unusual shapes and bright colors, when Omega first released the attention-getting Seamaster Professional 600m, nicknamed the Ploprof. The watch, designed in collaboration with the French industrial diving company Comex, was conceived for professional use: the name “Ploprof” stands for plongeurs professionels, or professional divers. While Omega emphasized its functions, the model perfectly suited the styles of the 1970s, with a gigantic and unusually shaped case, a red button to unlock the divers’ bezel, a bright orange strap and a minute hand of the same color.

The original Omega Ploprof’s water-resistance of 600 meters was extraordinarily high for its day.

The Ploprof achieved fame in the wake of the spectacular underwater missions in which it participated. The most important of these was the Janus Program, with which Comex tested saturation diving for the Elf petroleum company. Three divers manned a pressured chamber 200 meters below the surface of the Gulf of Ajaccio, off Corsica, for eight consecutive days, during which they worked on the seafloor at 250 meters’ depth for up to six hours each day, setting a new depth record. Rolex at this time was experimenting with the helium valve, which it used for the first time in the Sea-Dweller in 1971, but Omega pursued a different strategy with its Ploprof: the case was constructed and insulated so that helium atoms couldn’t penetrate it during the saturation dive, preventing the danger of explosion during the subsequent decompression.

The Ploprof’s pioneering role in the exploration of the underwater world and its water resistance of up to 600 meters, an extraordinarily high degree for its day, made it a cult watch, but its high price — twice that of a Rolex Submariner — made it unaffordable for many.

The new Ploprof, which debuted in 2009, looks very similar to its predecessor, but several differences become apparent at a second glance. The original had a one-piece case with a crystal applied under extremely high pressure and secured by a screwed ring, while the new model’s case has a separate caseback. An applied, pressure-fit cover is affixed to the case by a screwed-on ring. The old caseback was adorned only with a striped pattern, but the new one has both stripes and the Seamaster line’s seahorse icon in raised relief. (Click on photos for larger images.)

Omega Ploprof models 1970 and modern
The original Ploprof from 1970 (top), has a rubber-coated button and rectangular crown. The modern version (below) has a more user-friendly crown and an aluminum-coated button.

A nearly 0.5-cm-thick sapphire crystal ensures adequate resistance to pressure on the front of the case, enabling the Ploprof to withstand pressures equivalent to those found 1,200 meters underwater. Thanks to the case’s new construction, with its removable back, the Ploprof now also has an automatic helium valve so professional divers can wear it during saturation dives. The valve is positioned on the underside of the orange button’s outrigger and marked with the chemical abbreviation “He” (for helium) beneath a coating of clear lacquer. The case is very well crafted; the beveled and polished edges contrast beautifully with the other surfaces, which have a matte-brushed finish.

The modern Ploprof’s rotatable divers’ ring is covered by a calibrated scale made of scratch-resistant sapphire printed with a luminous minute-circle.

Minor changes have also been made on the dial. The date is no longer located at the 3 o’clock position but has been shifted to 4:30. A luminous index now occupies that space at 3 o’clock, adding to the dial’s very symmetrical appearance. The luminous indices on the new model are applied and polished, which makes the dial look much more valuable than it had looked with the old lacquered indices. The same is true for the stainless-steel button that unlocks the bezel. It is surrounded by an orange, anodized aluminum ring, which replaces the old model’s rubber ring. The combination not only looks better, but it’s also significantly harder.

Omega Seamaster Ploprof angle
The divers’ bezel is covered with scratch-resistant sapphire.

The new rotatable bezel is considerably sturdier, too. Its predecessor had been made of Bakelite, which easily developed hairline cracks; now the rotatable divers’ ring is covered by a calibrated scale made of scratch-resistant sapphire printed with a luminous minute-circle and a black background. Nonreflective coating on its outer surface ensures that it remains easy to read under all lighting conditions.

The result is very attractive, indeed. The time display and the divers’ bezel are both legible day and night. The dive scale, with numerals and a triangle, glows just as brightly as the hour hand, the minute hand and the indices on the dial. Even the seconds hand has a luminous rectangle so that its motion can be seen underwater to confirm that the watch is still running. Because of this combination of features, the Ploprof satisfies industrial diver’s watch standards DIN 8306 and ISO 6425, which many other so-called divers’ watches do not.

Another alteration simplifies the operation. The rectangular crown on the original Ploprof had been set flush with its protector; the wearer had to turn a screw in front of the protector to operate the crown. Also, the crown’s shape made it somewhat difficult to turn when resetting the hands. The modern system is much more user-friendly: when screwed outward, the front part of the closed protector moves along with the crown, which is easy to grasp and to turn.

Omega Seamaster Ploprof back
In contrast to the original’s one-part case without an opening in the back, the new Ploprof has an applied caseback held by a screwed ring.

A special feature distinguishes this construction: when the crown is in its second extracted position, it can be used in the usual way to adjust the hour hand and minute hand and to stop the balance, activating the stop-seconds function. In its first position, it can be turned to reposition the hour hand in single-hour increments while the seconds hand keeps running, which also resets the date display either forward or backward. Thus, the date can be quickly reset even though the watch doesn’t include a quick-reset function for the date display. (However, when the hour hand is reset backwards, the date display doesn’t switch to the previous date until the hour hand has reached the 8 o’clock position.) This independently adjustable hour hand is particularly practical when the wearer travels to a new time zone or needs to synchronize his watch with daylight savings or standard time.

Omega has revived the “sharkproof” Milanese bracelet, a woven-steel type that was popular in the 1970s and used on the original Ploprof.

Setting the diver’s bezel is a bit more complex. First, with your middle finger, you have to forcefully press the orange button and keep it pressed down while your thumb and forefinger turn the bezel in whichever direction you require. This sounds more complicated than it actually is, but it can be difficult if you’re wearing gloves or if your bare hands are wet. The complexity is nonetheless worthwhile because it guarantees that the bezel cannot be inadvertently repositioned.

Omega also revives the Milanese (what it calls “sharkproof”) bracelet, a woven-steel type that was popular in the 1970s. This one has individual links on the clasp, like a conventional steel bracelet, so it can be conveniently shortened and lengthened. The bracelet is very well crafted — very supple and entirely without sharp edges or corners.

The folding clasp on the Milanese bracelet is pleasantly user-friendly. Two large buttons make it easy to open the clasp; just apply pressure gently with your thumb to slide out the built-in extension mechanism to a maximum length of 26 millimeters. Afterward, and also after having reclosed the clasp, the bracelet can be shortened in single-millimeter increments until it fits snugly but comfortably around its wearer’s wrist. If an even longer bracelet is needed to wear outside the sleeve of a diving suit, the added 22-mm extension piece can be folded out of the clasp. The entire system is very well thought out, extremely sturdy, and very simple to operate. Furthermore, the massive clasp with its beveled and polished edges perfectly matches the Ploprof’s case.

The redesigned bracelet increases the wearing comfort of the new Ploprof, despite the watch’s heavy weight of 279 grams and brawny overall width of 55 millimeters. However, the raised relief of the seahorse emblem and stripes on the caseback presses somewhat uncomfortably against the wrist. The new model, like its 1970s predecessor, is also available with either an orange or a black strap. The modern strap is made of rubber and goes well with the watch’s styling, but it offers very little counterweight to the heavy case and makes the watch look top-heavy on the wrist.

All in all, Omega has succeeded in adapting a charming 1970s design for contemporary audiences without making the watch look old-fashioned or inappropriate. Many small details were taken into consideration for this update: the raised bars on the flanks of the crown and bezel are polished while the lower-lying interstitial spaces are matte. Other fine details, such as the applied indices, also contribute to the watch’s luxurious look. In a nutshell: good retro design that satisfies modern demands.

Omega Ploprof bracelet-buckle
The sturdy folding clasp, with its two extension pieces, matches the case’s design well.

The Ploprof’s interior is decidedly modern, as well. Inside its big case is automatic Caliber 8500, Omega’s first manufacture-developed base caliber from 2007, which has now been equipped with the improved co-axial escapement. The movement was constructed around the co-axial escapement and leaves sufficient space for its escape wheel to work with greater efficiency on three levels rather than only two. The balance is held in place not by a cock affixed on one side, but by a bridge that’s firmly screwed on two sides. This not only provides better protection against impacts, but also makes it possible to adjust the vertical play with greater precision, which in turn improves the accuracy of the rate. The balance spring breathes freely thanks to fine adjustment via weight screws on the rim of the balance, which swings at the unconventional frequency of 25,200 semi-oscillations per hour (3.5 hertz). The new Nivachoc shock absorption improves the centering of the balance pinion, which is also especially thin at the pivots to reduce positional error in the bearings. The movement holds a lengthy power reserve of 60 hours. The bidirectional winding rotor runs in a sliding bearing and winds two serially switched barrels. Thirty-nine jewels (out of a total 202 total components in Caliber 8500) minimize friction.

The Ploprof’s movement is built not only for sturdiness, but also for outstandingly precise timekeeping.

The decorations suit the movement’s modern architecture: the balance is coated with a layer of black chrome, the two barrels are coated with black DLC, and several screws are also blackened. Geneva waves, expanding outward in a spiral pattern, are the sole decorative engraving.

The movement is not merely built for sturdiness, but also for outstandingly precise timekeeping. COSC, the official Swiss chronometer-testing authority, has confirmed this accuracy by conferring its chronometer certificate. Thus, our expectations were high when we tested the Ploprof on our timing machine. The measured performance was even better than we expected: the greatest deviation among the several positions was satisfyingly small (just three seconds), as was the calculated average daily deviation (a gain of 1.5 seconds). Furthermore, the amplitude didn’t decline in the hanging positions, which we attributed to the balance’s intelligently conceived bearing.

With its large dimensions and martial exterior, the Ploprof is certainly not the right wristwatch for every occasion, and even with the nearly perfect rate results, the cost-benefit ratio could still be better. Its price of $9,700 is high, but is at least partially justified by the impressive water resistance, successful 1970s styling, outstanding craftsmanship, clever extension system for the bracelet, and, above all, the top-quality manufacture movement that’s both well designed and very precise.

Omega Ploprof caliber
Manufacture Caliber 8500 was designed for maximum robustness and precision.

+ Well-designed manufacture movement
+ Highly accurate rate
+ Clasp with built-in extension pieces to lengthen the bracelet

– Heavy weight
– Engravings on caseback press on the wrist

Manufacturer: Omega S.A., Rue Stämpfli 96, CH-2504 Biel, Switzerland
Reference number:
Functions: Hours, minutes, seconds, date; rotatable bezel secured by a button; helium valve
Movement: Omega 8500, automatic, chronometer; 25,200 vph; 39 jewels; two barrels; Nivachoc shock absorption; Glucydur balance; fine adjustment via weight screws on the balance; co-axial escapement; 60-hour power reserve; diameter = 29 mm, height = 5.5 mm
Case: Stainless steel; the 4.9-mm-thick sapphire crystal has nonreflective treatment on both its surfaces; fully threaded screw-in back; screwed crown, water- resistant to 1,200 meters
Bracelet and clasp: Stainless-steel Milanese bracelet, stainless-steel folding clasp with fold-out 26-mm extension piece and additional finely gradated 22-mm extension piece
Rate results (Deviations in seconds per 24 hours):
Dial up +1
Dial down +2
Crown up +1
Crown down 0
Crown left +3
Crown right +2
Greatest deviation of rate: 3
Average deviation: +1.5
Average amplitude:
Flat positions 275°
Hanging positions 276°
Dimensions: Diameter = 55 x 48 mm, height = 5 mm, weight = 279 grams
Variations: With black or orange rubber strap ($8,800)
Price: $9,700

Bracelet and clasp (max. 10 points): Both are exceptionally well crafted and very sturdy. The quick-extension system is cleverly designed and practical. 10
Operation (5): Nearly everything can be quickly set and easily adjusted by the large and easy-to-grip crown; only the date needs to be reset by the independently movable hour hand. The diver’s bezel is somewhat cumbersome to operate. 4
Case (10): The outstandingly well-crafted and extremely pressure-resistant case has a scratch-resistant sapphire bezel and an automatic helium valve. 10
Design (15): The 1970s styling of the original model has been skillfully adapted to suit contemporary tastes without losing any of its retro charm. This uncommonly large watch might not be the most flattering choice for a person with a smaller physique. 14
Legibility (5): Luminous material, combined with large hands and indices, ensures that the time is perfectly legible day and night. 5
Wearing comfort (10): Despite its large size and enormous weight, the Ploprof is surprisingly wearable, but the engraving on the caseback presses a bit uncomfortably into the back of the wrist. 6
Movement (20): The Omega manufacture caliber is equipped with an improved co-axial escapement, a balance bridge, two barrels, an index-free fine adjustment system and an improved bearing for the balance, which is designed for a high level of precision. 18
Rate results (10): As good as it gets: three seconds’ deviation among the positions and +1.5 seconds’ average gain, with no decline in amplitude between hanging and flat positions. 10
Overall value (15): The high price is justified by the excellent quality of the craftsmanship and by the high precision of the movement. 13
TOTAL: 90 points

This article was originally presented in WatchTime magazine.





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  1. sylvio Bertoli

    The thing I like the most about this watch is the Milanese bracelet, a beauty that I look forward to see a revival of it in other brands.

  2. Troy Glasner

    The article says that the price is high. Is it though? Less than $10k for such a high quality watch? Compare this to an Omega 300 Titanium, Panerai Submersible or a Submariner or a Sea Dweller, I think this is fairly priced.

  3. Sylvio F. Bertoli

    The watch I do not like so much because it is too big, too bulky and too expensive but the Milanese bracelet is real winner..

  4. Raymond Kavanagh

    Really liked that comprehensive review. Best part was that it cost double the price of a Rolex Submariner!! Considering buyin a Ploprof in Dublin today to add to my Omega Collection. I find them far superior to Rolex in every way….

  5. Scott

    Beautiful watch. A true work of art. Hopefully Santa Claus is already taking requests, for I’ve been VERY GOOD this year. Ha! Ha!

  6. There is a 4 variant Ploprof which came out last 2015-2016 at Baselworld. 4 of which are all Titanium thus making it 40% lighter and also has the crystal case back which displays the Co-axial 8912 caliber. The newer model eliminated the date with a much cleaner look to the dial.



  8. Nice, thorough review. However, noting the date of the article I wonder why you have not reviewed the latest model as well.
    Also, I suggest that the comments regarding the He escape are not correct. At the beginning of dive watch development no manufacturer considered the effects of Helium entering a watch. When it was discovered that helium inside the watch could ‘pop’ the crystal a solution was sought and the ‘quick and dirty’ solution was to add the He valve to existing watch cases. That solution is not the most eloquent. Omega designed the Ploprof to withstand the He pressure inside the watch – not to keep He out! The He molecules are too small to keep them out of a watch case. Since the He valve is a possible point of water ingress (if it is faulty) it is not the optimal design to solve the He problem. He valves are a gimmick and they are unnecessary nowadays – robots (or ROVs) are making the dives. Making a watch like the original Ploprof, which can withstand the He pressure inside the watch is expensive and more complex than adding a valve to an existing case design. However, in the case of the latest Ploprof, which has an exhibition case back, the He valve is inevitable (in the unlikely event that a diver gets one saturated with He.

  9. Igor Michalojko

    Hi , I tried to purchase the March / April edition through your site and it wont let me download or
    add to cart, I’ve tried several times, and couldn’t even send you an e-mail, thanks Igor.

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