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Accuracy of your Quartz Chronometer?

Posted: Fri Jun 22, 2018 7:15 am
by Watchamacallit
Are others happy with the accuracy of their Chronometers, such as the C7, VW4, C30? My C7 Rapide Chronometer Mk 2 is not worn every day and has thus far gained about 1 second per month over the past 8 months. I have only been tracking visually using https://time.is/ so I need to get it entered into the WatchCheck App for better on/off wrist comparisons.

I am happy with the accuracy as well as with the looks/design of the C7 dial. Its appeal has held up well.

Re: Accuracy of your Quartz Chronometer?

Posted: Sat Jun 23, 2018 3:22 pm
by Amor Vincit Omnia
I set my Ascari COSC at the end of March. Currently between +2/+3.

That sounds OK. About +1 per month.

Re: Accuracy of your Quartz Chronometer?

Posted: Sat Jun 23, 2018 5:06 pm
by Laird
All my COSCs seem to perform pretty much as the Cert documents - altho I dont really use Lab techniques !

Re: Accuracy of your Quartz Chronometer?

Posted: Wed Jun 27, 2018 7:54 am
by Watchamacallit
Also my C3 mk2 (not a COSC) appears to have lost about 1 second per month over the past year. So it is performing nearly as well as my C7 Rapide Mk 2.

I am not totally certain of my memory and interactions with resetting time so I hesitate to post that as factual. I was resetting the watch before entering into the WatchCheck App and noticed that the time is 16 seconds slow. And the date wheel is 11 days behind, meaning the date would correspond to having been last set in Jan/Feb 2017. That sort of jives with my memory as I think I have only ever reset the watch once after noticing it get too far off (IIRC it was accurate from day 1, maybe off a couple of seconds per month during the time I was wearing it almost every day.) If the battery lasts I can get another reading.

Re: Accuracy of your Quartz Chronometer?

Posted: Fri Sep 14, 2018 9:56 am
by Watchamacallit
Updating this thread since I am seeing a curious result with three of my favorite quartz watches. The results are nearly upside down from what one might expect. The hard data was measured with the WatchCheck app (which itself is subject to user error timing in pressing the measurement key) and is over a relatively short time period of 11 weeks. But I am taking into consideration how these watches have been performing over their lifetime and the watchCheck measurements are relatively correct/good.

The three watches from best performing to worst performing are:

1) C3 mkII chronograph. A limited edition Wimbledon with a 'regular' quartz movement. It has gained 0.9 seconds over the 11 weeks. So on pace for about +4 seconds/year. The watch sat in the watch box the whole time and sadly was not worn for even one day, even though the case size and style is great. When it was new it was worn a lot. It has always been accurate but I do not think it was this accurate when brand new and wearing it every day.

2) C7 Rapide Chronometer - Limited Edition (mkII). This is a COSC quartz advertised at +/- 10 second/year. It has gained 2.4 seconds over these same 11 weeks. So roughly 11 seconds/year at that pace which is within the margin of user measurement error. This jives with previous months were it appears this watch may gain about 10 seconds over the whole year. Which is fine considering this watch also has a quickset hour hand and has become one of favorite watches. It will be easy enough to hack the movement, or just know that it is reliably XX seconds fast. A fantastic watch. I really like the dial layout and overall look of this watch even if I prefer the smaller case size of the C3 mkII. I wear it frequently but not every day.

3) Grand Seiko SBGF - Which has a 'highly' accurate quartz movement, but it is an earlier generation and not the current 9F movement. I bought this watch used because I liked the dial, smaller/thinner case size, high water resistance (at least when new), and most importantly because it has a quickset hour hand when compared to the newer 9F movement. It has gained about 4.6 seconds in 11 weeks. So about 22 seconds/year which is outside its advertised specifications of +/-10 and is thus the worst performer, even though it was the most expensive watch when new. I have worn this watch the most over the past 11 week period due to lots of international travel and wanting to wear a smaller lightweight watch in the summer. I wish it were as accurate as advertised but it is still a very nice watch with a great dial.
When the C65 was released it reminded me of this watch. (In a different thread I wished that CW could take up the mantle of creating a similar HAQ based on their C65, to get the best of all worlds....Great styling, go anywhere at anytime water resistance, extra timing function off the bezel, always accurate, small, thin, quickset hour for traveling, great brand, etc.).

Re: Accuracy of your Quartz Chronometer?

Posted: Sat Dec 01, 2018 10:07 am
by Watchamacallit
A quick update (this will be the last one until years from now, and only then if the trend changes, as to not bore people).

After 5 months and wearing all 3 watches to various degrees, WatchCheck has recorded:

1) C3 mkII chronograph --> -0.3 seconds deviation. So on pace for recording less than 1 second of deviation over the whole year. This has not been exactly a straight line performance but has always tracked closely to time.is. It is remarkable performance and within the margin of error of using the smartApp (human variation of pressing button to record the current time). While this is a high quality watch I could not imagine it performing so well. Lucky for me.

2) C7 Rapide Chronometer Limited Edition (mkII) --> +5.1 seconds deviation. So about 1 second per month. So still a good chance that it will track within the 10 second/year COSC specification across a full year of temperature swings. Since I do not wear it every day, maybe that has been a negative factor.

3) Grand Seiko SBGF --> +32.1 seconds deviation. So averaging almost 1.5 seconds per week. This watch saw the most wrist time and spent time in the tropics (in 90F+ temps) and had the most variation between intermediate measurements. Though I did not take many intermediate measurements so I did not get a good gauge on when it runs slower or faster. But overall it has been very disappointing. I need to open the case back to see if the movement is real or fake. This is a used watch that when new was supposed to operate within +/-10 seconds per year, though the movement is known to "age" and drift beyond those specs after some years/decades like my example is. Still many basic quartz movements are accurate to within 1 minute/year. My old Timex Weekender probably tracks better but I have not explicitly measured it (I have not reset the time in 3-4-5 years and it is off by around 1 minute or so). I should go back to wearing my automatic diver when on vacation rather than this watch.

Re: Accuracy of your Quartz Chronometer?

Posted: Sat Dec 01, 2018 9:17 pm
by hughesyn
Watchamacallit wrote: Sat Dec 01, 2018 10:07 am
2) C7 Rapide Chronometer Limited Edition (mkII) --> +5.1 seconds deviation. So about 1 second per month. So still a good chance that it will track within the 10 second/year COSC specification across a full year of temperature swings. Since I do not wear it every day, maybe that has been a negative factor.
COSC average rate is ±25.6 seconds per year at 23°C, and
temperature sensitivity equivalent to ±73.1 seconds per year at 8°C or 38°C.
So still well within spec.

±10 spy should be achievable with a regular wearing.
It's strange that CW use the word 'certified' alongside the 10 second per year claim. Certified by whom? ETA probably say it will achieve 10 spy (with some caveats), but it will still get a COSC certificate at 25 spy.

Good to hear it performs as it should.

Re: Accuracy of your Quartz Chronometer?

Posted: Sun Dec 02, 2018 11:04 am
by Watchamacallit
Thanks @hughesyn for your comments. I must be the one who is conflating COSC with +/- 10spy. My C7 came with a COSC certificate noting the time deltas in various positions (as if it were a mechanical movement) and it was advertised on the website as having an accuracy of +/- 10spy, so those two attributes are probably distinct from each other. Various HAQ watches from Grand Seiko, Citizen, Longines, etc, got me to thinking that +/- 10 spy is readily achievable even though it does take extra effort and engineering.

While I have liked my C7 from day one, I appreciate it even more many months later.

Re: Accuracy of your Quartz Chronometer?

Posted: Mon Mar 09, 2020 7:54 am
by Watchamacallit
One more long term update. About a week ago I did a time check with the "WatchCheck" app. Both CW watches are still running on their original batteries while the Grand Seiko is now running in low battery mode, so it will get reset soon. I wish I would have started tracking all my watches from the day they were purchased but I think I have enough data points to see some trends.

The C7 Rapide Chronometer is the most consistent and overall "winner". Though it is not the best in absolute terms, it has shown less variance season-to-season and runs slightly fast. Over 620 days (slightly more than 20 months) it has gained just over 24 seconds. On average gaining 0.039 seconds/day.

The C3 Malvern chronograph mkii remains the closest in absolute terms, but it comes in "second place" in my view because it is running a touch slow and it shows more variance season-to-season (appears to slow during the winter). It has lost just over 19 seconds over the same 620 days. On average losing 0.031 seconds/day.

The Grand Seiko SBGF has been disappointing and comes in way last. It was reset somewhere along the way and has a shorter tracking period of 486 days (about 16 months) and has gained just over 110 seconds during that period. On average gaining 0.23 seconds/day. Which is fine for a quartz watch but not one that was intended to run at +/-10 seconds per year.

A group picture:
CW_C7-GS-CW_C3-2020-March.jpg

Re: Accuracy of your Quartz Chronometer?

Posted: Mon Mar 09, 2020 10:40 am
by Galton321
If you are buying a chronometer, since you are paying extra for the privilege you should expect it to work as advertised. That said if you need to measure time within such tight tolerance maybe you need to pay a visit to the NPL and borrow their atomic clock.😊

Re: Accuracy of your Quartz Chronometer?

Posted: Mon Mar 09, 2020 7:57 pm
by Lavaine
Watchamacallit wrote: Mon Mar 09, 2020 7:54 am The Grand Seiko SBGF has been disappointing and comes in way last. It was reset somewhere along the way and has a shorter tracking period of 486 days (about 16 months) and has gained just over 110 seconds during that period. On average gaining 0.23 seconds/day. Which is fine for a quartz watch but not one that was intended to run at +/-10 seconds per year.
As you said, the GS is an older model. I'm guessing it's older than the others, and has probably drifted a bit in the intervening years. You did mention it's in low battery mode now. Might be a good opportunity to have the timing tweaked a bit.

Re: Accuracy of your Quartz Chronometer?

Posted: Tue Mar 10, 2020 4:10 am
by Watchamacallit
I think my GS was produced in 2003. It has the 8J movement instead of the 9F so I am not sure it can be adjusted, but perhaps I should ask Seiko about that, since I like wearing the watch due to the slender size. I have read that quartz movements can age and change....though I am not exactly sure how a quartz crystal would continue to age and change shape once it had been grown and cut down to size. I have a 1970's Seiko quartz that is still within spec and about as accurate.

I enjoy wearing all 3 of these watches. It is interesting to wear the Seiko and C7 on back-to-back days and thinking that the one I just put on is too big or too small until my eye gets readjusted.

Re: Accuracy of your Quartz Chronometer?

Posted: Fri Mar 13, 2020 1:43 am
by rieslingguru
Quick question. Is there any lume on the C7? Lovely collection you have there by the way!


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Re: Accuracy of your Quartz Chronometer?

Posted: Fri Mar 13, 2020 9:07 am
by Watchamacallit
Yes, there is a tiny bit of lume on both hands of C7. The narrow cut down the center of the hand is filled with lume. It is quite weak but it sort of works in that after leaving a brightly lit room and the eyes are given a few minutes to adjust to dim light it becomes visible. Though I think its main purpose is to provide better contrast in different artificial light environments and to help guide the eye to the exact place it is pointing.

When I was collecting the watches together for the photo I had shined a flashlight inside the draw looking for the Seiko. So after my first photo attempt I realized only the GS watch was lit up, so I then briefly lit all 3 watches before taking the picture posted above.

Attached another photo showing the lume. It was taken with a smartphone in night sight mode. So the lume is brighter in the photo than it actually is in reality.
CW_C7-GS-CW_C3-2020-March-lume.jpg

Re: Accuracy of your Quartz Chronometer?

Posted: Fri Mar 13, 2020 1:58 pm
by rieslingguru
Thanks mate. I kind of wish CW would continue to bring these quartz chronometers to their collections.


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