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Zenith Chronomaster Sport 41mm Black
Ref. 03.3100.3600/21.R951
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Stepping up in the same dial colour
The El Primero movement has been in continuous production since 1969, making it one of the few calibres whose provenance is not a marketing claim but a matter of record. The 3600 variant pushes that frequency to the point where the central chronograph hand completes a full rotation every ten seconds, which means the sweep you watch is not an approximation of elapsed time — it is 1/10th-of-a-second precision made visible. The black lacquered dial carries the tri-colour sub-dials that have always distinguished an El Primero from imitators: blue, anthracite and light grey arranged so each counter reads cleanly against the others. The ceramic bezel is graduated to match, its 1/10th-second markings there to confirm what the movement is actually doing rather than to decorate it. The rubber strap sits flush with the case rather than sitting proud of it, which keeps the profile composed on the wrist and makes a folding clasp feel appropriate rather than excessive. The exhibition caseback is worth knowing about: 311 parts at 5 Hz is an organised spectacle, and Zenith has left it visible on purpose.
- Reference
- 03.3100.3600/21.R951
- Brand
- Zenith
- Collection
- Chronomaster
- Case size
- 41mm
- Case thickness
- 13.6mm
- Case material
- Stainless steel
- Case shape
- Round
- Dial
- Black
- Crystal
- Sapphire
- Movement
- Automatic
- Calibre
- El Primero 3600
- Functions
- Chronograph, Date
- Water resistance
- 100m
- Bracelet / strap
- Rubber strap
- Strap colour
- Black
- Clasp
- Folding clasp
- Lume
- Super-LumiNova
- Retailer
- Mappin & Webb
Additional specifications
- Power reserve
- 60 hours
Learn more about Zenith
Georges Favre-Jacot founded Zenith in Le Locle in 1865, aged twenty-two, with an idea that was radical for the Swiss industry: bring every trade needed to make a watch — movement, case, dial, hands — under one roof and one management. The integrated manufacture was largely his invention, and the Le Locle site he built is still in use.
The approach produced results at observatory trials, where Zenith accumulated more precision awards than any other manufacture. The name itself came from a calibre Favre-Jacot considered the summit of his work.
Its defining achievement is the El Primero of 1969, developed over seven years and announced in the same year as the Heuer-Breitling consortium's Calibre 11 and Seiko's 6139. It was an integrated automatic chronograph beating at 36,000 vibrations per hour, allowing measurement to a tenth of a second — a frequency almost nothing else matched for decades.
It nearly did not survive. When American owners ordered the mechanical tooling scrapped during the quartz crisis, a watchmaker named Charles Vermot hid the plans, presses, and cams in a walled-off attic. When demand for mechanical chronographs returned, Zenith could restart production because of him. Rolex used the El Primero in the Daytona from 1988 to 2000.
LVMH acquired Zenith in 1999.
- 1865
- Georges Favre-Jacot founds the integrated manufacture at Le Locle.
- 1969
- The El Primero automatic chronograph debuts at 36,000 vph.
- 1975
- Charles Vermot hides the El Primero tooling from destruction.
- 1988
- Rolex adopts the El Primero for the Daytona.
- 1999
- Acquired by LVMH.
Also in 6 collections
This watch appears in the Zenith Chronomaster range (19), Back in Stock (4,007), Stainless Steel Watches (2,833), Automatic Watches (1,417), Chronograph Watches (1,131) and Sports Watches (667).
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What the specifications mean
A mechanical watch for everyday wear.
Strengths
- 100m water resistance covers swimming and watersports
- Sapphire crystal, which resists scratching
- Luminous hands and markers for low light
- Sits in the lower half of Zenith's range as we list it
Zenith Chronomaster Sport alternatives
Watches from other brands at a similar price, style and size, so you can see what else your budget can buy.
| Specification | 03.3100.3600/21.R951 | 103926 | G0A43001 |
|---|---|---|---|
| Price | £9,900 | £9,400 | £11,400 |
| Case size | 41mm | 41mm | 42mm |
| Water resistance | 100m | 100m | 100m |
| Movement | Automatic | Automatic | Automatic |
| Strap | Rubber strap | Stainless steel bracelet | Leather strap |
| Power reserve | 60 hours | — | 50 hours |
| This watch | Closely matched |
|
Your new watch
Frequently asked questions, and things you should know about this watch
Can I swim with it?
Yes. At 100m it is rated for swimming and snorkelling, though not for diving.
Water resistance explainedWill the glass scratch?
Unlikely. Sapphire is second only to diamond in hardness and shrugs off everyday marking.
Sapphire, mineral and acrylic comparedDoes it need a battery?
No. It is automatic — the motion of your wrist winds it, and there is no cell to replace.
Quartz, automatic and solar comparedHow long does it run for when it's not worn?
About 60 hours fully wound — enough to survive a night off the wrist, but not a full weekend.
Cheapest place to buy
Both Mappin & Webb and Goldsmiths list it at £9,900, so choose on delivery and warranty rather than price.
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