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Rugged Watch Criteria

Watches are jewelry and as a result there is a wide variation both in price and quality. I'd love to perform a study and scatter map price and quality. The most you could hope for is a straight line: higher price results in higher quality. But in reality I think what you'd end up with is a cloud with very little statistical correlation. Even if you were able to normalize for precious metals or technologies that lend themselves to aesthetics rather than robustness I don't think if would make much of a difference.

That hasn't stopped me from attempting the task for myself. There are several watch brands that spec (and in some cases overspec) their watches. Some invest heavily in new technologies, some use custom movements, some don't. Some are just a little more honest in what you are buying. On the opposite end are many watches that make no claims about anything and are modestly priced. Still others make grandiose claims about performance and charge for it. Sometimes those watch brands back it up and some don't.

So what I have done is cooked up a list of criteria, a specification if you will, for watch performance. And to make it easy to compare watches I have created a scoring system as well.

Watch design is essentially a two step process:

  1. Choose a watch movement with some minimum nominal performance.
  2. Design structure around the movement that minimizes any environmental variation from nominal to ensure performance does not vary.

IMHO analog watch movements are pretty good. They aren't as accurate as quartz and for that reason I prefer quartz most of the time. But I also think that the analog movement industry has stood still for too long. They are offering the same 3-5 9's quality of movements for literally decades now without much improvement. I don't wish to be too harsh. ETA has introduced the first affordable perpetual movement. And many movement designers are introducing these "double barrel" movements which increase the reserve to around 80 hours. But still Omega is the only vendor who is really addressing watch accuracy. No ultra stable watches have been produced in the analog segment. At least better than COSC. I know it is a herculean task but no public efforts made that I can find.

Accuracy is straightforward once you understand the concepts:

  • Accuracy over time: This is the long term accuracy of a watch. It is an average of all the fluctuations, perturbations, etc.
  • Max variation: Accuracy will have peaks/values though. One day it might be +2, the next -10. That still makes the average -6. There should not be too many extremes. I have not listed this as a requirement for my watch guide.
  • Isochronism: This is the term that defines how accuracy is affected as a function of the reserve. Watches typically have best accuracy at full winding (100% energy reserve) and get worse as they deplete. In other words over night or left at home for a day you can expect more drift than if it were on your hand being automatically wound and kept at 100%.

Here is the criteria for nominal watch accuracy:

Requirement Description Moderate Excellent
Nominal Maximum average accuracy to be expected from a randomly manufactured movement in a specific environment (e.g. humidity, temp,
no magnetism, etc)
+/-59s per month +/-5s per month
Isochronism Maximum error to be expected as a watch winds down and uses up its reserve (but of course hasn't stopped) 3-10s per day <3s per day

Here are the criteria for robustness:

Requirement Description Moderate Excellent
Env: Magnetism Resistance to magnetic fields. Very few things exceed ~1,500A/m 1,500-4,800A/m >4,800A/m
Env: Humidity/Water Resistance to humidity, water and low pressure 5-10bar 10bar
Env: Temperature Exposure to temperature including direct sunlight 0-40degC -10-60degC
Env: Shock/Vibe Shock comes from drops and knocks (e.g. tables) and vibe comes from equipment, driving, trains, etc. DIN9110/ISO1413 DIN8330
Env: Orientation Performance over watch orientation (e.g. face up, face down, on it's side, etc) 4 or 5 ALL (i.e. 6)
Strength: Case How resistant is the case to scuffs, scratches and dents? 100-500 Vickers >500 Vickers
Strength: Coverglass How resistant is the coverglass to scuffs, scratches and dents? Mineral/Acrylic Sapphire/Gorilla

And here are some functional criteria to round out the selection:

Requirement Description Moderate Excellent
Function: Night Readability How well does the lume work? How long does it last? 2-6hrs >6hrs
Function: Energy Reserve How many hours / months does the energy reserve last? Auto: 3-6days
Quartz: 24-42mths
Auto: >6days
Quartz: >42mths
Function: Style Subjective style requirements? Subjective Subjective
Function: Complications Any complications I desire in a new watch Subjective Subjective

The scoring system is weighted with the following terms:

  • Excellent Performance: +2 point
  • Moderate Performance: +1 point
  • Weak Performance: +0.5 point
  • Unspecified: -0.1 point

Any specification that does not meet at least Moderate is Weak. Any performance that is not specified receives a slight penalty. This is to encourage manufacturers to print more specifications and to stand by their (often very expensive) products. The top score is 26 points.

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