Omega Omega Seamaster Automatic 120m Chronograph "BIG BLUE” ST 176.004  with Extract of the Archive

Omega Seamaster Automatic 120m Chronograph "BIG BLUE” ST 176.004 with Extract of the Archive

Brand: Omega
Model: Seamaster Automatic 120m Chronograph
Reference: 176.004
Gender: Male
Year: 1974
Material: stainless steel
Dial Color: Blue
Dimensions: 44 mm
Watch Movement: automatic
Bracelet/Strap: stainless steel bracelet
Box/Paper: Extract of the Archive
Condition: Excellent

Omega Seamaster Automatic 120m Chronograph "BIG BLUE” ST 176.004

WRIST ICONS is proud to present one of the real diving icons. Won't you love the quirky design of this iconic Omega Seamaster Big Blue? This watch is nick named the Big Blue to its design and size. This is a really impressive tool watch that oozes 70ies coolness and was not only funky but also very functional.

History of the Omega Seamaster diving watches

  • -During the winter of 1942–1943 the Aqua-Lung was invented in Paris  by two Frenchmen: the engineer Émile Gagnan and the Naval Lieutenant ("lieutenant de vaisseau") Jacques Cousteau. It allowed Cousteau and Gagnan to film and explore more easily underwater. The Aqua-Lung was the first open-circuit, self-contained underwater breathing apparatus (or "SCUBA") to reach worldwide popularity and commercial success.
  • - In the late 1940s and early 1950s, La Spirotechnique started exporting the Aqua-Lung and leasing its patent to foreign companies (like the British Siebe Gorman). These operations found great success. When the Aqua-Lung became available for commercial use, divers around the world found a scuba device smaller and easier to carry than its precursor, which was only helpful for shallow diving. In addition, and most importantly, the Aqua-Lung could be mounted on stronger and reliable air tanks holding up to 200 atmospheres, allowing extension of diving duration to more than an hour at significant depths (including the needed time for decompression stops). At that time many watch brands made tool watches. But due to the invention of the Aqualung it became necessary to have a timing machine to time dives.  
  • - In 1953 Blancpain was the first to introduce a proper diving watch followed a year later by Rolex. Many brands started to bring diving watches to the market that were capable to read the time underwater, were hermetically sealed and capable of withstanding shocks.
  • - In 1957 the world was greeted by the arrival of Omega’s famous broad arrow trilogy: Speedmaster, Railmaster and importantly the Seamaster 300. The Seamaster 300 was Omega’s first true divers watch. The watch was guaranteed to 200m although tests equivalent to 300m have been carried out without water ingress, hence the rear of the watch carried the title ‘certified high pressure waterproof Seamaster’. This watch was designated the CK2913 which was replaced in 1960 by CK14.755 (calibre 552) The CK14.755 reference did not have the “broad arrow” hands and also used a different movement (Caliber 552).
  • - In 1962 came the second generation of the Seamaster 300 which then became ST165.014 and thereafter reference ST165.024 in 1963-64. The watch using a crown and dial variation complied with the Ministry of Defence DEF STAN 66 guidelines and was issued to all sectors of the British Army. Jacques Cousteau and his team used the Omega Seamaster 165.024 during the under water experiment Precontinent II that was conducted in the Red Sea in July 1963.
  • - In the late 1960s underwater exploration, off-shore oil constructions and maintenance, as well as applications such as scuba diving, water sports, and sub-aqua military and naval special forces, saw an increase in demand for more robust watches designed for diving operations at greater depths.
  • In 1968, with the development of saturation diving, Omega started to cooperate with the COMEX to develop even more extreme watches. There was a need to develop even better diving watches that were capable of withstanding deeper and deeper submersion. Helium valves, use of exotic metals, and many other technical novelties happened at this period, exponentially increasing water resistance in watches. The COMEX used Omega watches for testing on both its Physalie (1968-1972) and Janus (1968-1977) programmes. By 1968, Omega had developed two kinds of prototypes following the same requirement specifications. Two Ploprof projects coded internally ‘Ploprof 0’ and ‘Ploprof 1’ that would ultimately become commercial models. They introduced the Ploprof and the Seamaster 1000 watches that battled with Rolex to become the preferred diving watches by COMEX.One Issue that still concerned COMEX was helium infiltration, which carried the danger of causing a watch crystal to pop out during decompression. There is no proof that this problem occurred with any Ploprof, and later tests by the American diving research centre Ocean Systems Inc. in Tarrytown, NY, certified that the Ploprof was ‘more watertight’ than a submarine. However, COMEX wanted to be sure to combat the helium infiltration issue, rather than trust improved watch-case sealing. They chose to continue their research work with Rolex and Doxa to test their new Helium Expulsion Valve (HEV) designs. HEVs were incorporated in the Rolex SeaDweller which Comex used reliably for many, many years.
  • - In 1973 Omega introduced the reference 176.004 ST – SEAMASTER “BIG BLUE” DIVER’S CHRONOGRAPH. This watch moved away from the concept of a three hand watch which in conjunction with the bezel could be used to measure elapsed time up to an hour. The introduced a diver watch with a chronograph movement modified with a central minute hand. The minutes counted would be the minutes displayed from zero, so the diver could more easily understand how much time had elapsed. The engineers at Omega had the idea to overcome the combination of the three hand/bezel offerings and produce a chronograph with a big central minute hand.


Design of the Big Blue

 Nowadays this is a big watch, even more if you take it into perspective of the early 70ies. It was a real tool watch with a new kind of timing compared to the early 3 hand diving watches. This watch had a different design for additional legibility. The contrast of colors between the blue dial and the bezel against the luminous indexes, numerals on the bezel, and hands guaranteed high visibility even in dark waters. The pop of orange used on the tip of the chronograph minute counter added visibility as well, giving an extra nod to the 70s quirky charm. The minute and hour hands are fat and the hour indicators are big chunky blocks full of tritium paste. After many years of use and due to the specific characteristics of the tritium as a material, the blocks soften started to deform and literally spill onto the dial. (what actually also happened with the original dial of this particular watch)

Like the Mark III and the Flightmaster, it is one of the quintessential executions of the Omega “pilot-style” helmet-shaped case. Omega referred to the shape as “anatomic” in that it was designed for comfort to conform to the shape of the human wrist. The helmet-shaped case is distinctive. The company first introduced helmet cases in 1969 in their Flightmaster model (see here and here for two in-depths about the Flightmaster)  and continued the trend with the Speedmaster MkIII. The Big Blue had its case milled from a solid block of stainless steel contoured in such a way to be extremely comfortable while at the same time offering protection for the watch from shocks and bumps during the dive.

According to the extract of the Archive this example has been produced on December 6th of 1974 and has been delivered to Spain. You can rock this watch with its beautiful bracelet or go casual and wear it with a WRIST ICONS premium NATO seatbelt strap.


Now let’s dive into the technical details of this caliber.

This Omega Seamaster Automatic 120m Chronograph has the famous Omega caliber 1040. This caliber was the first self-winding chronograph movement used by Omega.

In the early 1970’s, Lemania introduced its own version of the automatic chronograph caliber, the cal.1340, running at 28,800bph with 22 jewels having a 44-hour power reserve. Omega also introduced the same caliber as the cal.1040, having a 24-hours indicator placed at 9 in the second sub dial. It was a rhodium-finish caliber, having a cam/lever combination and other architectural choices inherited from its ancestors (Omega 27 CHRO 12). It had a delrin blocking lever and a date with a quickset function as well, while the rotor was mounted on ball bearings so it could wind the movement in both directions.


This particular Omega Seamaster 120m Big Blue has just undergone a full service. This work was carried out by an Omega Service Center certified watchmaker using original parts. All of the spare parts such as the original dial and case back are still with the watch.

As with all of our pre-owned watches this watch comes with a full 12 month WRIST ICONS warranty that will be invoked from the day of purchase. Further: everything is cleaned before sending the items.

  • Brand: Omega
  • Model: Omega Seamaster Automatic 120m Chronograph
  • Reference: 176.004
  • Calibre: calibre 1040 automatic movement with date function, 24 jewels, frequency 19800 A/h, power reserve: 46 hours
  • Movement No: 36.258.6xx signed Omega
  • Case: It has a polished stainless steel water resistant case made by Ervin Piquerez SA in Bassecourt, Switzerland (also referred to as EPSA, and known for creating Super Compressor diving cases for Jaeger-LeCoultre and other prominent Swiss watch manufacturers). Case comes with a screw down crown and screw case back
  • Dimensions: Case length 52mm diameter, case height 17mm diameter, case width 44mm diameter
  • Bezel: comes with the uni-directional rotating bakelite bezel with heavy set text with triangle
  • Crystal: Plexiglass
  • Dial: new luminova dial and hands, and also the original tritium parts as spares. It is a blue dial with luminous hands and markers, date at the 3:00 position, 12 hour register at the 6:00 position, and the 24 hour indicator at the 9:00 position.
  • Crystal: Original Acrylic w/Omega Logo in
  • Bracelet/Strap: fitted on a Omega 1162/172 stainless steel bracelet Lug Width: 20mm
  • Box/Papers: comes with Extract of the Archive
  • Condition: Pre-owned. Excellent condition with some light signs of wear to case and crystal.



12 month warranty
14 day returns