11/18/2014
 2 minutes

Chronometer: How Important is Accuracy for a Mechanical Watch

By Christopher Beccan
Omega Speedmaster 57 Co-Axial Chronograph
Omega Speedmaster 57 Co-Axial Chronograph, Image: Bexsonn

They say time waits for no man but there is an exception to this saying. You see, mechanical watches have long been a sought after male accessory, even to a point where it is no longer an accessory but moreover an item of infatuation that is collected by many. However, for those who don’t quite understand or can at least sympathise with this habit, see it as more of a strange obsession. Why? Well for them, and quite understandably too, mechanical watches just aren’t as accessible as quartz watches – which isn’t explicitly true – but there is rather another interesting factor to why some also consider mechanical watches to be, well, just not that great minus the fact they tend to have quite lofty price tags attached to them: they are just not as accurate as one would expect.

Since the dawn of watches every watchmaker has long strived to reach perfection, with the utmost target being accuracy. But while watchmakers will make sure the timepieces they produce are as accurate as can be, by using a Witschi (an instrument to test the precision of mechanical movements), there are still daily deviations. Then you’ve got mechanical watches that sport what is called an “officially certified chronometer” movement, which is controlled by Contrôle Officiel Suisse des Chronomètres or COSC for short. What exactly does this mean? COSC (a non-profit organisation) was setup to test the accuracy of movements and have a certain set of rules that need to be adhered to when certifying any mechanical watch movement manufactured or assembled in Switzerland.

IWC Portuguese Chronograph 3714
IWC Portuguese Chronograph 3714 – Prices for chronometers on Chrono24

Though, make no mistake that even some movements made by the Germans, the Japanese, and even the Swiss that haven’t been certified actually surpass the COSC requirements.

Each uncased movement submitted by any brand is individually tested over a period of fifteen days, in five different positions, at three different temperatures. Over the duration of this test there must not be a larger deviation than between -4 or +6 seconds a day, though some may consider this to not even be accurate enough. What one must remember is that there are 86.400 seconds in a day!

The deviation is so small that you could say it’s like sailing from London to New York and only missing the full stretch by a couple of inches. Watchmakers over the years have tried to negate such deviations with pioneering inventions such as tourbillon movements and even more recently co-axial movements, but the fact remains that there are still deviations.

So is buying a quartz timepiece the answer? Not really because even these watches can be officially certified chronometers and they even have tighter regulations over a mechanical watch. So the real question is just how important is it that your watch be an “officially certified chronometer”? Not much but I think the majesty of a mechanical timepiece, with all its screws, barrels, and cogs is just a much cooler way of displaying the time than an iPhone; not to mention it doesn’t require any battery changes or charging.

Chronoswiss Opus Chronograph
Chronoswiss Opus ChronographImage: Auctionata

About the Author

Christopher Beccan

Christopher Beccan is the founder of the online magazine "Bexsonn," where he regularly writes about his two passions: extraordinary timepieces and whiskey. His work …

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