The Chronomaster Sport is part of the Anniversary Editions with which Zenith is celebrating the brand’s 160th anniversary – and one of the most significant movements in history.
In celebration of its 160th anniversary, Zenith is presenting the Blue Ceramic Chronograph Trilogy – 160th Anniversary Edition, which brings together three of its most significant chronographs: the Chronomaster Sport, the Defy Skyline Chronograph and the Pilot Chronograph. All three models share cases crafted from a blue ceramic developed specifically for the occasion. Among them, the Zenith Chronomaster Sport stands out – not simply as the evolution of a single model line, but as a story inseparably linked to one of the most important chronograph movements in modern watchmaking: the El Primero. This article therefore explores both the aesthetic and technical development of the Zenith Chronomaster series, focusing in particular on the high-frequency calibre that has set standards since 1969 – and continues to define the identity of the Zenith Chronomaster collection to this day.
We are in the 1960s: the self-winding movement had existed in various forms since 1770, when Swiss watchmaker Abraham-Louis Perrelet developed the mechanism for pocket watches. And yet, no watch brand had ever succeeded in integrating an automatic winding system into a chronograph movement. This absence was due in part to the fact that an automatic system requires space for the rotor, its bearings and winding mechanism, while a chronograph, on the other hand, demands room for the coupling, column wheel or cam switching mechanism, along with additional wheels and levers. As such, it was extremely difficult to combine both constructions without making the movement too thick or compromising mechanical stability.
This challenge – long regarded as virtually insurmountable – was reason enough for Zenith’s management at the time to commission a feasibility study for a self-winding wristwatch chronograph in anticipation of the company’s 100th anniversary in 1965. After all, Zenith had built a reputation for highly precise and sophisticated calibres ever since its founding in 1865. No other watch brand has won as many chronometry prizes as Zenith – 2,333 to be precise. The most famous movement to make headlines in these chronometry competitions was the calibre 135-0, produced during the 1950s, which alone secured 235 prizes. This legacy was by the way honoured by the brand earlier this year with the limited G.F.J. edition, featuring a modernised version of the calibre 135 and a dial made of lapis lazuli.)
In 1962, Zenith began developing its self-winding chronograph. The specification sheet, drawn up under the direction of Raoul Pellaton, laid out the key criteria for the new chronograph: it was to be a high-frequency calibre operating at 36,000 vibrations per hour (5 Hz). In order to claim the title of the world’s thinnest chronograph, the height of the movement had to be limited to 6.5 millimetres. This meant it could not be a modular chronograph (i.e. a hand-wound chronograph with an added automatic module), but instead had to be a fully integrated construction. Finally, it also had to be capable of measuring tenths of a second. Taken together, these criteria described what would become the most advanced chronograph movement the industry had seen up to that point – and one that was twice as precise as conventional chronographs thanks to its ability to measure tenths of a second.
However, meeting these demanding requirements – in addition to the already considerable challenge of creating the first automatic chronograph ever, something no watch brand had achieved before – resulted in substantial additional development work. It soon became clear to the Zenith engineers that the movement would not be ready in time for the company’s 100th anniversary.
One major obstacle arose from the high frequency of 36,000 vibrations per hour: the lubricants available at the time were not designed to withstand such loads and risked being flung off by the intense oscillations, especially from components like the escape wheel or the escapement. In response, Zenith developed a new escapement solution in 1967 using a dry lubricant based on molybdenum carbide, chosen for its particularly low coefficient of friction. The team was further motivated by circulating rumours in the Swiss watch industry that a strong alliance between Breitling, Hamilton-Büren, Dubois-Dépraz and Heuer-Léonidas was also working on a pioneering automatic chronograph.
This meant that the project could only be unveiled on 10 January 1969, after seven years of research and development: with the El Primero (“the First”), Zenith introduced the world’s first fully integrated automatic chronograph movement. It is important to note that El Primero was originally the name of the watch collection, not the movement itself; internally, the calibre was designated as 3019 PHC.
Four weeks later, the Breitling alliance presented the Chronomatic Calibre 11 – also an automatic chronograph movement. However, the El Primero distinguished itself in several key respects. Despite its complexity, comprising 278 components, it was 1.2 millimetres thinner than the competing Calibre 11. Furthermore, while the Calibre 11 – made famous by the square-shaped TAG Heuer Monaco – featured only a micro-rotor and beat at 19,800 vibrations per hour, the El Primero operated at a high frequency of 36,000 vibrations per hour (5 Hz). The Calibre 11 also offered a power reserve of around 42 hours, compared to approximately 50 hours for the El Primero.
Equipped with a ball-bearing rotor that winds in both directions, a traditional column-wheel mechanism, horizontal clutch, and tenth-of-a-second precision, the El Primero marked the beginning of a remarkable success story. Today, it holds the record as the longest continuously produced chronograph movement in watchmaking history – 56 years and counting. In total, 21 watch brands have used this movement at one time or another, including Rolex, Movado, Parmigiani, and TAG Heuer.
The El Primero was expected to make a resounding impact thanks to its technical superiority – but few could have foreseen that the developments just around the corner would prevent Zenith from fully capitalising on its achievement. More than that: for a long time, it would remain the last mechanical movement to leave the halls of the Zenith manufacture. The year 1969 not only saw the debut of the first automatic chronograph movement, but also the introduction of the first quartz watch – a new technology that was both more affordable and more accurate than its mechanical counterparts, with all the well-known consequences that followed.
As the market situation worsened and interest in mechanical watches continued to decline, Zenith found itself increasingly under pressure. A rescue plan was needed. The merger with two other watch companies to form the “Mondia Zenith Movado” holding appeared to offer the most promising solution. In 1971, the holding came under the majority ownership of the Zenith Radio Corporation. A further turning point came in 1975: amid falling and therefore no longer profitable production volumes, the new owners ordered the irreversible discontinuation of the El Primero. Mechanical watch production was to be halted entirely; all plans and technical documentation were to be destroyed, along with tools, components and remaining movement blanks. The declared goal: a purely quartz-driven future.
It is thanks to the conviction of one man that the El Primero ultimately became one of the great success stories of modern watchmaking: Charles Vermot, Zenith’s senior engineer in movement production. Faced with the devastating decision to end mechanical watchmaking, and acting with remarkable foresight, he secretly archived all the technical drawings and, above all, hid the 150 presses required to manufacture the movement’s components in the attic of the manufacture. Together with his brother, who also worked at Zenith, he walled up production documents, plans, machines and tools in the upper floor of the factory in Le Locle. His goal was to preserve the legacy through the quartz era and one day make it possible to resume production of the landmark chronograph movement.
The turning point came in the 1980s: first Ebel, then Rolex began to turn their attention back to mechanical chronographs. The El Primero resurfaced and was even chosen by Rolex as the base movement for what would become its hugely successful Daytona series – appealing to the brand on two fronts: the El Primero was automatic and also slim enough to fit within Rolex’s case proportions. Now, it was Charles Vermot’s moment: by secretly storing the 150 presses and documentation, he saved Zenith from enormous costs and made the resumption of production possible in the first place. In 1984, Zenith signed a supply agreement with Rolex that secured the company for the next 15 years. Vermot himself was celebrated within the manufacture for his foresight and became a hero of the brand.
As demand for mechanical luxury watches began to rise again, Zenith also revived the El Primero in its own watches. The brand – which had been sold by the Zenith Radio Company (now part of LG Electronics) to the Le Locle-based engineering firm Dixi in 1978 – once again began producing chronographs powered by the El Primero.
The first version of the El Primero movement was fitted into various references between 1969 and around 1972. But if one reference can be considered the definitive embodiment of the original El Primero line, it is the A386. Produced from 1969 to 1972 in just around 4,500 pieces, the model introduced several defining features to the Zenith portfolio: the emblematic star logo, the red chronograph seconds hand, and a new type of dial distinguished by its characteristic “tri-colour” design – a stark contrast to the mostly monochrome chronograph dials of the 1960s.
Yet this colour differentiation of the sub-dials was not merely aesthetic – it also had a practical function by enhancing legibility. A pale silvery grey for the running seconds at 9 o’clock, a vivid blue for the 30-minute counter at 3 o’clock, and a dark anthracite for the 12-hour counter at 6 o’clock made each totaliser clearly distinguishable from the others. What truly set the A386 apart, however, was the fact that Zenith would elevate the “tri-colour” sub-dial layout to a defining design code for the entire Chronomaster line – a visual legacy that would continue through countless evolutions and still lives on today, particularly in the Zenith Chronomaster Original line.
The Zenith Chronomaster collection as we know it was formally introduced in 1994, but its roots go back to 1969 with the A386 , the ancestor of today’s Chronomaster, which debuted the El Primero calibre together with the tri-colour counters that became a Zenith signature. Over the following decades, Zenith continued to explore sport-oriented chronographs: from the De Luca to the Rainbow and other emblematic models, each brought its own ingredients that would ultimately shape the Chronomaster’s identity leading to the official launch of the collection in 1994.
Romain Marietta, Chief Product Officer at Zenith
In the mid-1990s, a quarter of a century after the debut of the El Primero, Zenith ushered in a new era: at Baselworld 1994, the Zenith Chronomaster collection was introduced. From then on, the line was not only tasked with showcasing the brand’s expertise in complications and precision, but it also became Zenith’s core collection – and thus the principal stage for the El Primero chronograph calibre.
In its early years, the Zenith Chronomaster line leaned heavily on classical models, combining the full calendar with moonphase and chronograph functions. A key model from this early phase that embodied this aesthetic was the Zenith Chronomaster Ref. 01.0240.410. Based on the classic high-frequency chronograph, it added a complete calendar with moonphase, displaying the day of the week, date, and moonphase – alongside the chronograph seconds, 30-minute and 12-hour counters.
With its round, double-stepped case and fully silver-coloured dial, the Zenith Chronomaster at that time – in contrast to today – was clearly aimed at a more traditional clientele. Inside, the calibre 410 operated with 354 components and a precise column-wheel mechanism; it was also chronometer-certified (COSC).
In 2010, Zenith once again returned to the core strength of the El Primero – its high frequency – and made visible on the dial what had already been a defining feature at the movement’s launch: the ability to measure time intervals down to a tenth of a second. With the El Primero Striking 10th, limited to 1,969 pieces, Zenith for the first time displayed this precision visibly on the dial. To achieve this, the central chronograph seconds hand completed one full rotation not in 60 seconds, but in just 10 seconds. As a result, it moved six times faster than the hand of a conventional chronograph. In addition to this technical innovation, the watch also introduced aesthetic elements that would go on to shape many future Zenith chronographs.
Visually, the Striking 10th echoed the original A386 with its overlapping tri-colour sub-dial layout and red chronograph seconds hand on a silver dial. However, it broke with that concept in one key aspect: at 3 o’clock, instead of a 30-minute counter, it featured a chronograph seconds counter, and at 6 o’clock, instead of a 12-hour counter, it showed a 60-minute chronograph counter. With the Striking 10th, Zenith’s aim was not to measure longer time intervals – the focus here was clearly on the display of fractions of a second.
In order to read the elapsed tenth of a second precisely when the chronograph is stopped, the dial features a finely graduated scale with 100 individual markings around the outer edge. This became a central design element, later integrated into the bezel in subsequent generations of Zenith chronographs – and remains a defining aesthetic feature of the modern versions.
Inside the watch, the standard El Primero components were supplemented with eleven additional parts, bringing the total to 326 components – all in order to fully harness the potential of the 36,000 vph movement. The result was the automatic calibre 4052 B, measuring 6.6 millimetres in height. Its construction is visible through the sapphire crystal caseback, revealing, among other elements, the blue, double-layered silicon coupling wheel that drives both the constantly running seconds at 9 o’clock and the central chronograph hand. Silicon was chosen specifically because it is 3.5 times lighter than traditional materials, thereby reducing wear and friction – particularly important since this wheel remains in constant motion, even when the chronograph is stopped. The silicon wheel has exactly 100 teeth, which – given that it completes one full rotation every 10 seconds – corresponds to 100 impulses, or 10 per second. This detail directly inspired the model name “Striking Tenth.” Furthermore, the calibre was equipped with a newly developed stopping mechanism designed to deliver the desired level of precision. More specifically, a braking lever slots between two of the 100 teeth on the chronograph centre wheel, bringing the central chronograph hand to an immediate and exact stop.
2019 was another milestone year for Zenith: it marked the 50th anniversary of the El Primero movement. As part of the celebrations, the brand introduced a series of reissues – including the A384 and A386 references – as well as the Zenith Chronomaster 2. This model, limited to 250 pieces each with either a blue or black ceramic bezel, stood out not only for its contemporary aesthetic, but above all because Zenith used it as a platform to debut the further-developed El Primero calibre 3600.
But what defined this movement, which Zenith itself described as the “next generation” of the El Primero? The calibre 3600 inside the Zenith Chronomaster 2 combined elements from the El Primero calibre 400 (reintroduced in 1987) and the 4052 B from the Striking 10th. It featured a chronograph mechanism capable of measuring tenths of a second, with the distinctive red central seconds hand making one full rotation every 10 seconds. New to the calibre was the inclusion of a stop-seconds (hacking) function, allowing for precise time-setting – a feature previously absent from the El Primero. The power reserve was also increased from 50 to 60 hours. In addition, the movement received a redesigned geartrain and wheel architecture, an enlarged and repositioned column wheel, and – most significantly – an optimised lateral clutch, which we will examine in more detail shortly. As part of the new stop-seconds functionality, the crown positions were also reconfigured to follow the widely used sequence of manual winding, quick-set date, and time-setting.
Aesthetically, the Zenith Chronomaster 2 also followed the historical A386: it adopted a variation of the El Primero’s signature overlapping sub-dial layout – blue at 3 o’clock (chronograph seconds), anthracite at 6 o’clock (chronograph minutes), and light grey at 9 o’clock (small seconds). In addition, the Zenith Chronomaster 2 introduced two new design elements: first, a bezel made of black or blue ceramic, graduated from 0 to 10, enabling precise time measurements; second, a skeletonised dial that exposed not only the entire date disc but also parts of the movement itself.
The objective behind the development of the calibre 3600 was clear: greater modularity, improved industrial production, and simplified assembly and regulation. At the same time, it opened up the possibility of being used in models that were as contemporary in appearance as the movement itself – a direction fully realised in 2021 with the launch of the third generation of Zenith chronographs: the Zenith Chronomaster Sport, powered by the El Primero calibre 3600.
Following the El Primero Striking 10th (2010) and the Chronomaster 2 (2019), the Zenith Chronomaster Sport became the third timepiece to bring precise short-time measurement to the wrist. It not only added a modern aesthetic to the Zenith Chronomaster collection, but – thanks to the calibre 3600 – also introduced concrete improvements over the previously used EP400 in the brand’s standard production models.
While the El Primero 3600 shares its core architecture with the El Primero 400, it differs in several crucial respects – most notably in the addition of a stop-seconds function and an improved power reserve. But above all, the most significant change lies in how the connection to the chronograph centre wheel – and thus to the central chronograph seconds hand – is established. Instead of relying on a secondary seconds wheel mounted on the axle of the regular seconds wheel, the 3600 uses a patented clutch system that resembles a foudroyante mechanism. This provides a direct link between the escapement wheel and the chronograph centre wheel.
The gear ratios are designed so that the central seconds hand makes exactly 100 steps during a full 10-second rotation. In order to ensure efficient energy transmission for such a geartrain, every component – from the wheels and pinions to the tooth geometry – had to be recalculated from scratch. This level of optimisation was only made possible through the use of custom-developed computer algorithms – an approach that would have been inconceivable over fifty years ago, when the original El Primero 400 was created.
The Zenith Chronomaster Sport, introduced in 2021, presents an aesthetic that preserves key characteristics of the original A386 while reinterpreting them through a contemporary design language. The model continues to feature a case with faceted, angular lugs and piston-style pushers – both elements that defined the look of the A386 back in 1969. The tri-colour design of the overlapping sub-dials also remains a core element of this third-generation chronograph. Arranged in a V-shaped tri-compax layout at 3, 6 and 9 o’clock, the configuration includes a 60-second counter (3 o’clock) and a 60-minute counter (6 o’clock) for the chronograph function, as well as a constantly running small seconds sub-dial (9 o’clock). These totalisers are slightly recessed with fine concentric grooves and are distinguished above all by their colours – classic blue, anthracite and light grey, just as seen on the historic El Primero A386 from 1969. Between 4 and 5 o’clock, a discreet date window with rounded corners is positioned – a typical El Primero design cue that has been retained in the Chronomaster Sport.
Entirely new for the Chronomaster line was the use of a black ceramic bezel with the familiar tenth-of-a-second scale. With this, Zenith gave the Chronomaster Sport a more technical and contemporary appearance – while also introducing practical advantages: the ceramic is virtually scratch-resistant and highly resistant to UV exposure. One of Zenith’s design hallmarks is the way the brand continues to use the bezel as an expressive element – introducing new colours, alternative materials, or even gem-set variations. A glance at the current Chronomaster Sport collection reveals just how versatile and adaptable this modern design has become.
The Chronomaster Sport has become a cornerstone of our collection. It brings together over fifty years of chronograph development at Zenith in a format that is contemporary, versatile and clearly identifiable as part of our lineage. With its 41 mm case, ceramic bezel graduated to 1/10th of a second, and the tri-colour counters that have become a signature, it represents the modern expression of our chronograph expertise.
Romain Marietta, Chief Product Officer at Zenith
This version dresses the Chronomaster Sport in a 41 mm case crafted from 18-carat rose gold, with colour-matched pushers and crown. The black ceramic bezel features gold-coloured engravings of the 1/10th of a second scale and contrasts both with the scale itself and the light dial. The latter has a matte white finish and carries the signature three sub-dials in blue, grey, and anthracite found on the original model. The faceted hands and hour markers, coated with Super-LumiNova, appear in a gold tone and stand out clearly against the black bezel. An integrated rubber strap and water resistance of 100 metres complete the watch. Through the sapphire caseback, the El Primero 3600 is visible, with its star-shaped rotor creating particularly strong contrast in this version. Retail price: €25,300.
As one of the two original launch versions of the Chronomaster Sport introduced in 2021, this model combines a 41 mm stainless-steel case with a matte white main dial and the signature tri-colour sub-dials, framed by a black ceramic bezel engraved with a white 1/10th of a second scale. Polished and faceted hour markers, along with rhodium-plated main hands, are coated with luminous material and stand out clearly against the light-coloured dial. Notable details include the star-shaped counterweight on the central chronograph seconds hand, as well as its red-tipped end – a design feature echoed in the small hands of the chronograph seconds and chronograph minutes sub-dials. This version is worn on a stainless-steel bracelet. Price: €12,000.
With the Chronomaster Sport in titanium, Zenith presents a watch that clearly stands apart from the other models in the collection. A titanium bezel, replacing the ceramic typically used in the line-up, combines with a sunray-brushed grey dial to create a consistently monochromatic look. To maintain this effect, Zenith even breaks with the traditional sub-dial colour scheme: instead of blue, grey and anthracite, the totalisers appear in anthracite, light grey and silver. This titanium version also offers a noticeably lighter feel on the wrist – weighing just around 105 grams compared to 148 grams for the stainless-steel models. Rhodium-plated hands and markers with black inlays and luminous coating ensure good legibility, while red accents – such as the tip of the central chronograph hand or the reference to the “36,000 vph” frequency – provide subtle contrasts. Price: €12,500.
In this colourful version, both the bezel and dial are rendered in a rich green tone, while the case and bracelet are crafted from stainless steel. On the green lacquered dial, the three sub-dials appear in blue, light grey and dark grey, preserving the classic tri-colour layout. The hour markers and hands are rhodium-plated and filled with luminous material, while the date window at 4:30 is discreetly integrated in matching tones. The technical specifications and dimensions remain unchanged: the El Primero 3600 automatic calibre operates at 5 Hz and offers a power reserve of 60 hours – just like the other Chronomaster Sport models. Price: €12,000.
In January of this year, Zenith introduced the Chronomaster Sport Rainbow – a gem-set version of its high-frequency chronograph. The 41 mm case is made of 18-carat white gold. The bezel is set with a total of 50 baguette-cut gemstones – including 40 sapphires (~3.9 carats) and 10 diamonds (~1 carat) – arranged to form a rainbow gradient. The diamonds, which interrupt the colour flow, also mark the 10-second intervals. The black dial features hour markers set with coloured sapphires, continuing the bezel’s rainbow theme. Despite the vibrant use of colour, the tri-colour sub-dials remain in the signature shades of grey and blue. Price: €114,900.
To mark its anniversary, Zenith presented a trilogy of three of its most iconic chronographs – a Chronomaster Sport, a Defy Skyline, and a Pilot Chronograph – united by a single material: blue ceramic. The colour was developed specifically for the occasion and reflects the brand’s signature shade. All three models are limited to 160 pieces and can be purchased either individually or as part of a set.
The 41 mm case of the Chronomaster Sport, including pump-style pushers and faceted lugs, is crafted entirely from blue ceramic. The same tone continues on the sunray-brushed dial, which features the tri-colour, overlapping sub-dials in their characteristic arrangement. Inside, the anniversary model follows the familiar formula: it is powered by the El Primero 3600 calibre, which beats at 36,000 vibrations per hour and enables the chronograph seconds hand to complete one full rotation of the dial every 10 seconds.
Through the sapphire caseback, not only the architecture of the movement can be admired, but also the skeletonised rotor, engraved with the inscription “160th Anniversary.” The Chronomaster Sport 160th Anniversary Edition is delivered with two straps: a blue ceramic bracelet with a ceramic folding clasp and a blue rubber strap with a stainless-steel folding clasp. The new Chronomaster Sport 160th Anniversary Edition is available now for €23,700.
