What is a Chronometer? Good info.

[Bisquitlips]

1. What is a chronometer?

A chronometer is an extremely accurate watch or clock. It takes its name from the Greek words (chronos + metron) meaning to measure time. A Swiss chronometer is a watch, usually mechanical, whose precision has been tested and verified by an official Swiss watch testing bureau. The watch comes with a ratings certificate issued by the institute. The chronometer designation is a badge of honor, proof that the watch is of superior quality.

2. What does a watch have to do to earn the title of chronometer?

The watch's movement must pass a battery of severe tests conducted for 15 days and nights. The movement's accuracy is checked in five different positions and at various temperatures which simulate conditions under which the watch will be worn.

3. Who conducts the tests?

The Swiss Official Chronometer Control (Controle Officiel Suisse des Chronometeres, or COSC, in French). COSC is an independent association governed by the Swiss Civil Code.

Watch companies desiring the chronometer designation on their best pieces send movements to COSC. (COSC tests uncased movements; the companies case the movements after the tests.) COSC issues a performance certificate for each timepiece which successfully passes the tests.

There are three COSC centers in Switzerland where watch companies send movements to be tested--in Geneva, Bienne and Le Locle.

Switzerland has been officially testing chronometers since 1878. COSC as it exists today was founded in 1973.

4. What tests are run on the watch?

COSC conducts elaborate precision tests on the movements using cameras and computers, which analyze the data. COSC performs seven different tests. Failure to meet the minimum standard in any one of the tests means that a movement is rejected. The tests are complicated. Here is an attempt at a simple summary:

Test 1: Mean Daily Rate: After 10 days of tests, the mean daily rate of the movement must be within the range of -4 to +6 seconds per day. COSC determines the mean daily rate by subtracting the time indicated by the movement 24 hours earlier from the time indicated on the day of observation.

Test 2: Mean Variation in Rates: COSC observes the movement's rate in five different positions (two horizontal, three vertical) each day over 10 days for a total of 50 rates. The mean variation in rates can be no more than 2 seconds.

Test 3: Greatest Variation in Rates: The greatest of the five variations in rates in the five positions can be no more than 5 seconds per day.

Test 4: Horizontal and Vertical Difference: COSC subtracts the average of the rates in the vertical position (on the first and second days) from the average of the rates in the horizontal position (on the ninth and tenth days). The difference must be no more than -6 to +8 seconds.

Test 5: Greatest Deviation in Rates: The difference between the greatest daily rate and the mean daily test rate can be no more than 10 seconds per day.

Test 6: Rate Variation Due to Temperature: COSC tests the movement's rate at 8 degrees Celsius (46 degrees Fahrenheit) and at 38 degrees C (100 degrees F). It subtracts the cold temperature rate from the hot temperature rate and divides by 30. The variation must be no more than 0.6 seconds per day.

Test 7: Resumption of the rate: This is obtained by subtracting the average mean daily rate of the first two days of testing from the mean daily rate of the last test day. The resumption of rate can be no more than 5 seconds. Simple, isn't it? If a movement meets the standards, COSC issues a certificate designating it as a "chronometer."

5. How many movements does COSC test each year and how many certificates are issued?

In 1995, COSC tested 844,043 movements. That was down slightly (-4.5%) from 1994 when a record 883,714 movements were submitted for testing. The vast majority of the movements sent in for testing pass. In 1995, COSC issued 814,868 certificates, 96.5% of those submitted. That means chronometers represent about 2% of Switzerland's total production of complete watches.

6. Why are most chronometers mechanical watches?

Just one-third of 1% of the movements submitted for testing in 1995 (3,026 total) were quartz movements. That's because electronic quartz technology is by definition an ultra-precise form of timekeeping and there is less need to demonstrate a quartz watch's accuracy. That's not the case with mechanical watches. Even so, COSC has developed stringent regulations which quartz watches must pass before they can be called chronometers. Worth noting: by far the leader in Swiss quartz chronometers in 1995 with two-thirds of the total certificates issued was Krieger Watch Corp. of Miami Beach, Fla.

7. Do many companies apply for chronometer certificates for their watches?

More than 60 firms submitted movements to COSC in 1995.

8. How is the demand for chronometers?

Despite the drop in requests in 1995, there has been a surge of watch company applications for chronometers in this decade. COSC data shows that the number of movements submitted bottomed out in 1976 at 225,712. Requests did not pass the 300,000 unit mark again until 1984. It rose steadily throughout the late 1980s but has soared in the 1990s, reflecting the strength of Rolex, in particular, and the general revival of Swiss mechanical watches on world markets. In 1990, the number of movements submitted to COSC passed the 600,000 unit mark for the first time. By 1994, the number had reached 883,714, an increase of 43.5% over 1990.

9. Which firm is the leader in production of Swiss chronometers?

Rolex is the undisputed chronometer king. An amazing 83% of all chronometer certificates issued by COSC in 1995 went to Rolex--more than 675,000 of them. You get some sense of Rolex's dominance when you realize that only five firms (one of them a group, really) produce more than 6,000 chronometers a year. The second largest producer of chronometers is TAG Heuer (51,638 certificates in 1995), followed by Omega (31,135 certificates), the Cartier Group (6,393) and Bulgari (6,056).

10. What is the difference between a chronometer and a chronograph?

The terms sound similar but they have nothing to do with each other. A chronometer, as we have seen, is a superior timekeeper. A chronograph is a watch with a stopwatch function.

[directioneng]

Smart ass. :chuckle::chuckle:

YOU post THIS after all the dumb questions you ask. :rofl::rofl:

[Flaxmoore]

Okay, and the "Superlative"? Marketing fluff or a legitimate term?

[Nods]

Very informative, thanks

[padi56]

Now this is the copy of the European chronometer Din certificate for my Dreadnought watch as you can see +0.4 seconds a day,not bad for a so called humble ETA 2824-T2 movement,less than half a second a day.The European Din is to a much higher standard, so is Japanese equivalent -2+4 a day,and the Swiss COSC -4+6 and the Dreadnought cost at the time 2003 just £400 but now exchange hands for quite a bit more sometimes Rolex money.

http://img224.imageshack.us/img224/3584/prs221aq0vv8.jpg (http://imageshack.us)

Okay, and the "Superlative"? Marketing fluff or a legitimate term?
Superlative is just a pure marketing word, fact most mechanical movements today if carefully regulated could meet the Swiss COSC standard.

[SweepingSH]

in my browser. Have heard a lot about COSC but never seen it explained so thoroughly before.

Thanks

[hflee55]

excellent stuff!

[pz93c]

Anyone know what organization tested before the COSC came into being?

Those standards?

Thanks.

[padi56]

Anyone know what organization tested before the COSC came into being?

Those standards?

Thanks.

IMHO today the COSC test is just a pure marketing ploy this is a direct quote from Watchbore estimates that at least 15,000 Rolex movements failed in 2001-2. According to Rolex, the rejects are re-regulated or fixed, and sent back to COSC until they pass.Rolex Quote. "We don’t use COSC to tell us how good our movements are," said a source deep inside the Wilsdorf Rolex foundation. "We test them ourselves. All we want is the chronometer certification, it’s only for marketing."... I rest my case the COSC test now just a pure marketing ploy. .

The Rolex ladies Datejust with cal 2235 is the most consistently precise and accurate movement tested by COSC.But don't forget that Rolex is the largest movement supplier for the COSC test.With the ETA 2892 Rolex Cal 3135 and the Valjoux 7750 given excellent results.The most precise machine tools are only viable in high-volume production watches.While its possible to get chronometer standards to hand crafted watches ,its very time consuming and needs a lot of adjustment and failures are quite high making more expense.But your massed produced machine made movements are far more consistent in getting though the COSC test simply because they should be all the same.

But looking at the other sign of the coin today any modern day wristwatch chronometers are, by the almost 300 year old 18Th century navigational standards imposed on John Harrison H4 watch,quite laughably inaccurate even by todays standards.How about just 5 seconds slow after 63 days at sea,not bad for a almost 300 year old watch.When you think he had very primitive tools by todays standards all hand made no computer aided help now thats a real watchmaker.

And before the Swiss COSC was formed as it is now there were Observatory testing and competitions to a much higher standard

And during the entire 23 years of testing, 5093 wristwatches were submitted for certification, and only 3253 were passed, about 64%. Just a few manufacturers participated, and only Omega and Patek did so every year. The others were: Rolex, Zenith, Longines, Movado, Vacheron & Constantin, Ulysse Nardin, Cyma and Favre-Leuba, along with numerous independent professional watchmakers.That was until Seiko come on the scene and started to wipe the floor with the Swiss watch industry.Only 2 brands in the + 23 years of the competitions submitted movements of serial production for retail sale(Seiko and GP).All others were specially made movements just for the competition.And it was ended by the swiss in the early 1970s after two straight wins by the Japanese straight off the production line Seiko Grand watches.

Seiko first entered the competition,with other watches from all over the world,including most of the Swiss high end brands.For a much higher standard than the COSC,the Astronomical Observatory Authorisation Chronometer Standard (+/- 2/3 seconds/day) Out of many watches summited only two passed this test Seiko Grand just a production model, and Giraud Peregaux this time a specially build for the test model.And in the late 60s there were only two companies, who could sell watches, passed astronomical observatory authorisation Chronometer in those days. ---Seiko and Giraud Peregaux.As the Japanese had dominated in the late 60s and the two preceding events, in 1972 some Swiss watch manufacturers demanded the end of the observatory competitions,and it was ended in 1973,thats when the lesser COSC was founded.

Its a plain fact that any Swiss manufacturers who submit watches for the chronometer rating today. The standards used are so very dated and so watered down by the earlier standards that 90% of all watches submitted pass the tests.Fact any modern day movement any brand with a bit of careful regulation could easily pass the COSC test

[lbcgav]

But looking at the other sign of the coin today any modern day wristwatch chronometers are, by the almost 300 year old 18Th century navigational standards imposed on John Harrison H4 watch,quite laughably inaccurate even by todays standards.How about just 5 seconds slow after 63 days at sea,not bad for a almost 300 year old watch.When you think he had very primitive tools by todays standards all hand made no computer aided help now thats a real watchmaker.


Longitude should be required reading for this forum. Great book.

[moby33]

Longitude should be required reading for this forum. Great book.

LOL. My father gave me that book during my second year at the Naval Academy...great read indeed. Still have it around the house somewhere. :cheers:

[padi56]

LOL. My father gave me that book during my second year at the Naval Academy...great read indeed. Still have it around the house somewhere. :cheers:

Longitude should be required reading for this forum. Great book.

Agree a very interesting book indeed and makes you think if guys like Harrison was around today in this modern age.What would wrist watches be like,in real terms of accuracy with mechanical watches we have not progressed that far since his day.

[luger]

COSC is an independent association governed by the Swiss Civil Code.

I am not so sure "governed" is the correct word. I am tempted to equate the idea of "governed" with the word "official" in the name COSC. And thus, I would presume that COSC must have some governmental sanction or authorization and therefore an enabling statute. However, I do not know what that sanction, statute or regulation is, or where to find it. The verbiage about the "Swiss Code" which one will find, among other places, on the back of a current form of the COSC Chronometer Certificate, actually directs you to the section of the Swiss Code that authorizes "non-profit organizations" but nothing more. In other words, does anyone have a source or citation to the law governing COSC or making it "official". Granted it involves three cantons (and lets not forget, FHS, a trade organization) so nevertheless, I would be satisfied with any Cantonal Law as well as any Federal Law, but I really think there must be some law or regulation governing COSC. ISO standards (such as 3159) are not enough. ISO standards have no legal force unless they are themselves adopted by National Law (in the case of Switzerland, that would be Federal Law.) Thanks.

[slc1310]

oh, so much to learn in such little time. That was excellent thanks

[jlovda]

The verbiage about the "Swiss Code" which one will find, among other places, on the back of a current form of the COSC Chronometer Certificate, actually directs you to the section of the Swiss Code that authorizes "non-profit organizations" but nothing more.

Underwriters Laboratories is a non-profit organization that is not controlled by the government but sets the US standards for fireproof safes, electrical equipment, etc. COSC could be the same type of organization.