Automatic Watch Accuracy - One Member's Perspective

[belk7]

First of all, there have been many, Many, MANY previous threads on watch accuracy, so if you are sick of the topic - stop reading now. I just thought I would to offer my own thoughts, along with a couple of interesting results of my own non-scientific measurements for anyone who might be interested.

I have stated in other threads and in coversations with other members that I am not a person who is obsessed with watch accuracy. Automatic watches are complicated machines, and each has it's own "personality". Every watch is just not going to run spot-on out of the box. However, I do like to check all of my autos a couple of times a year for a period of two weeks just to make sure that their behavior isn't changing a great deal over time. If a watch is consistent in its performance, and you want the accuracy improved, a simple regulation by a competent watchmaker will do the trick almost every time. But to me, an inconsistent watch may need some greater attention. A Rolex in particular is capable of incredibly consistent performance, and if the timekeeping is all over the place, then I'm going to get it looked at by someone who knows what they are doing.

I have just completed a two week (or close) check on several frequently worn watches in my current stable. The results are interesting to me, but should be taken with a degree of infomality as they are there are many other factors that could affect the results. The majority of these are actually worn in rotation, get the occasional hand wind to keep them running over my timing period, and are stored in a case dial-up when not being worn.

The most accurate watch in my collection is my one-year old EXPII. There are debates about whether the 3186 movement with the blue hairspring is truly better or just marketing, but mine does have that movement and is only watch I own which truly is dead-on accurate. It may be off a second one way or the other on a daily measurement, but over two weeks it is off by exactly zero seconds. This amazes me. My other Rolex's are all very consistent and respectable as well. M serial 16613 is around +4/day, 16750 from 1982 is at +3/day, and my 48 year old (that's right 48 years old) 5513 is at -8 to -10 sec/day. Rolex movements kick serious butt.

My recently acquired JLC Master Calendar has extraordinarily consistent results as well (off less than 1 sec/day in about 10 days). The next ones are a bit of a surprise - I've had two Seiko auto's (both sub $200 watches) that both have consistently run within 2 seconds/day. One of these has the 7s26 movement, and the other has the 7s36 movement. These are the only watches that have gone on a winder as they cannot be hand-wound. I know some monster owners who have had very fast timing results with the 7s26, so maybe I've just been lucky with these. My PAM 104, IWC Portuguese and two Sinns run respectably well. My U1 is in for warranty service right now due to an issue with the stem, and will get regulated as part of the service.

Two examples of ones that are not very accurate but in different ways: My Omega Connie (1959 vintage) is running all over the place. The results clearly indicate to me that it needs a service. My Marathon SAR runs very fast, but is consistent. I do not feel that it is need of service, and do not plan to send it off just for regulation. I'll just set this one when I wear it and not worry about it for a while.

Again, I'm posting my perspective on the topic and these results for general interest only, particularly for recent members who may not be worn out from the numerous previous accuracy posts. Those of you who are worn out by this topic can blast away

[Frogman4me]

Very interesting read, it appears we have similar taste in watches as well as performance. My most accurate auto was my 3186 GMTIIC which deviated +2/day. my 14060 3000 movement was consistent but -2/3 after I got it regulated. My two 7s26 movments run great considering the cost as well as my smn033 which runs the 7s36 movement. Seiko makes amazing autos for the cost I must say. My speedy pro runs 5 secs fast but my vintage omega MKII is all over the place as I know it needs service.

I am currently searching for a Marathon SAR May 2006 contract model as they are hard to come by these days. Any chance you want to sell yours...lol

[padi56]

Originally Posted by belk7

First of all, there have been many, Many, MANY previous threads on watch accuracy, so if you are sick of the topic - stop reading now. I just thought I would to offer my own thoughts, along with a couple of interesting results of my own non-scientific measurements for anyone who might be interested.

I have stated in other threads and in coversations with other members that I am not a person who is obsessed with watch accuracy. Automatic watches are complicated machines, and each has it's own "personality". Every watch is just not going to run spot-on out of the box. However, I do like to check all of my autos a couple of times a year for a period of two weeks just to make sure that their behavior isn't changing a great deal over time. If a watch is consistent in its performance, and you want the accuracy improved, a simple regulation by a competent watchmaker will do the trick almost every time. But to me, an inconsistent watch may need some greater attention. A Rolex in particular is capable of incredibly consistent performance, and if the timekeeping is all over the place, then I'm going to get it looked at by someone who knows what they are doing.

I have just completed a two week (or close) check on several frequently worn watches in my current stable. The results are interesting to me, but should be taken with a degree of infomality as they are there are many other factors that could affect the results. The majority of these are actually worn in rotation, get the occasional hand wind to keep them running over my timing period, and are stored in a case dial-up when not being worn.

The most accurate watch in my collection is my one-year old EXPII. There are debates about whether the 3186 movement with the blue hairspring is truly better or just marketing, but mine does have that movement and is only watch I own which truly is dead-on accurate. It may be off a second one way or the other on a daily measurement, but over two weeks it is off by exactly zero seconds. This amazes me. My other Rolex's are all very consistent and respectable as well. M serial 16613 is around +4/day, 16750 from 1982 is at +3/day, and my 48 year old (that's right 48 years old) 5513 is at -8 to -10 sec/day. Rolex movements kick serious butt.

My recently acquired JLC Master Calendar has extraordinarily consistent results as well (off less than 1 sec/day in about 10 days). The next ones are a bit of a surprise - I've had two Seiko auto's (both sub $200 watches) that both have consistently run within 2 seconds/day. One of these has the 7s26 movement, and the other has the 7s36 movement. These are the only watches that have gone on a winder as they cannot be hand-wound. I know some monster owners who have had very fast timing results with the 7s26, so maybe I've just been lucky with these. My PAM 104, IWC Portuguese and two Sinns run respectably well. My U1 is in for warranty service right now due to an issue with the stem, and will get regulated as part of the service.

Two examples of ones that are not very accurate but in different ways: My Omega Connie (1959 vintage) is running all over the place. The results clearly indicate to me that it needs a service. My Marathon SAR runs very fast, but is consistent. I do not feel that it is need of service, and do not plan to send it off just for regulation. I'll just set this one when I wear it and not worry about it for a while.

Again, I'm posting my perspective on the topic and these results for general interest only, particularly for recent members who may not be worn out from the numerous previous accuracy posts. Those of you who are worn out by this topic can blast away

Simple short answer accuracy mainly comes from how any watch is regulated.

[belk7]

[QUOTE/]I am currently searching for a Marathon SAR May 2006 contract model as they are hard to come by these days. Any chance you want to sell yours...lol[/QUOTE]

David, it does sound like our tastes are quite similar. I have to agree that the Seiko movements are pretty strong at a very low price. Word is that the things will just about run forever as well.

I had heard that the 2006 run on the SAR was getting low. Mine is a 2006, and while I would love to help you out, I just can't imagine getting rid of it. Keep an eye out, though. One will surely show up on one of the boards. Of course, they could do another run at some point.

Originally Posted by padi56

Simple short answer accuracy mainly comes from how any watch is regulated.

You are, as usual correct, Padi. I just wanted to express my opinion on the value of checking them every so often. I previously owned one watch which varied significantly near the end of its warranty period. The manufacturer agreed that it was out of spec and I got a full service under warranty, which likely saved me over $500 in another couple of years had I not been tracking the timing.

[Speed]

Thanks for posting. I found it interesting to read your observations. I want to do a similar study on my watches - just for the heck of it.

I have a Monster as well. Love it. Just wish it had the ability to wind !

[bigjon]

Just checked my subc again and is still spot on to the second over the past 6 weeks. If I didn't hear it ticking when I put it up to my ear I would think it was a quartz movement! Again, not expecting this kind of accuracy from a mechanical watch but definitely surprised.

[GradyPhilpott]

What do you use for a reference?

[belk7]

USNO Master Clock. I could also use my "tough atomic" g-shock in a pinch

http://tycho.usno.navy.mil/simpletime.html

[Thurnau]

My DJII looks like near perfect for 3 months, I compare when I have to change the date or when I am early for something.
My DJ's ussually are about 5 minutes fast after only one month.

[dmarciano82]

Interesting find from this experiment!

[GradyPhilpott]

Originally Posted by belk7

USNO Master Clock. I could also use my "tough atomic" g-shock in a pinch

http://tycho.usno.navy.mil/simpletime.html

As I'm sure you know from your having chosen the USNO clock as your reference that having a good reference is of the utmost importance in timing your timepiece.

Seconds really do count, because your dealing in seconds. When a person tells me that his watch keeps perfect time, I'm always leery, because nothing keeps perfect time.

There are a few astronomical timescales, but the one that is most important to us in our daily lives is called T1. T1 is the time kept by the earth in its daily rotation.

The earth is not really that stable, but if we are to have some semblance of order here on the earth in terms of night and day, we have to stay in time with the planet we live on.

The atomic clocks in Ft. Collins, CO are so stable in their timekeeping that they are will only gain or lose a second every billion years or so.

However, we can't depend on them for accurate timekeeping unless we adjust them when necessary. Therefore, we have something called leap seconds and whatever it's called when seconds are subtracted, because of the earths travel and rotation.

Everything gets in the way of perfect time. The atomic clock in CO has to communicate with those who wish to use it, so we have to deal with the speed of light and the peculiarities of the atmosphere.

The internet introduces other problems, which I'm not very well versed in, but we see the issues all the time and they can be illustrated to some degree by the picture below.



This screen capture was taken of two windows working simultaneously. The one on the left is time.gov run by the National Institute of Standards and Technology (NIST) and the one of the right is the United States Naval Observatory (USNO).

NIST is kind enough to tell us how accurate the time we are looking at is and I can only presume that that is done by the site pinging my computer to see how much time it takes for the signal to come and go and then figureing the error from that information.

Therefore, it is important to use the same time reference all the time for the experiment that you describe.

The USNO doesn't provide us with any propagation error information, so we just have to accept that it's right. With no way to confirm one way or another, it is basically useless no matter if it is dead on all the time.

Your Casio Waveceptor is a good practical reference for many things and may be better than most, as long as you know when it last updated, which my G-Shock tells me. Every Casio I've ever owned gains to the microsecond one-half second every day.

It is impossible for me to say how many times I timed Casio watches over a twenty year period with my Realistic WWV receiver, but the number would be huge.

I'm being pedantic, I know, and I hope that you'll forgive me for that, but if you're going to try to record the accuracy of your Rolex, then you need to be aware of these factors.

Personally, I would suggest time.gov as your reference. I have found it to be stable and I'm informed of what the rate of error is without having to guess.

WWV broadcasts on frequencies of 2.5, 5, 10, 15, and 20 Mhz.

Just as soon as I can find it, I'm going to start using my Realistic receiver again just to test the NIST and USNO to see how synced they are to WWV.



http://en.wikipedia.org/wiki/Time_standard

http://en.wikipedia.org/wiki/Atomic_clocks

http://en.wikipedia.org/wiki/WWV_%28radio_station%29

http://en.wikipedia.org/wiki/NIST

http://en.wikipedia.org/wiki/USNO

[RedwinGV]

Originally Posted by GradyPhilpott

What do you use for a reference?

I own a Citizen that syncs w/ Colorado.

I don't know how one can check a computer sight since I've got to think that there will be delays depending upon traffic, computer, etc. I suspect if one uses the same connection and computer there should be some consistency, but even then, wouldn't there differences due to net traffic? Maybe it's too small to matter though.

[GradyPhilpott]

The time.gov site's accuracy is dependent on traffic and probably a lot more. I've seen the accuracy as high as .1 second to as low as .5 second and non-responsive due to high traffic.

However, I think it's the best site for referencing your watches and clocks, because it's almost always available and you know the rate of error every time it loads.

Even radio-controlled clocks can be way off in a couple of hours, because some lame-brain executive decided that since the clock updates every four hours, they can make a lousy time-keeper and that's all well and good as long as the clock updates every four hours, which it almost never does.

I have a Sharp radio-controlled alarm clock. It will gain as much as 20 seconds in four hours between updates.

Now even if it doesn't update for a couple of days, it'll still get you to work on time, but it's pretty useless for anything else. All my other radio-controlled clocks are accurate to less than a second a day without updating.

You just have to know your gear.

Like I said about Casio. If you can know when the last time a Casio digital watch updated, you can bank on it having gained one-half second a day. That kind of stability is pretty damn good, because it is predictable.

Predictability is very important.

[jrssv]

I've always thought three or four seconds off per day is a good trade off for not having to worry about a battery going dead when I'm in the middle of no where.

[GradyPhilpott]

Originally Posted by jrssv

I've always thought three or four seconds off per day is a good trade off for not having to worry about a battery going dead when I'm in the middle of no where.

It is, in my view, but it's a matter of personal priorities.

I used to be almost pathologically obsessed with time and its measurement.

It began when I was very young.

Thankfully now, I can just go about cheerfully admiring the beauty of my Rolex, knowing that it's somewhere in the neighborhood of the correct time.

It's like any watch, in that if you know it's rate of error and the date and time it was set, figuring the exact time to within a couple of seconds is not difficult at all.

Fortunately, I don't much give a hoot anymore about accuracy, except that I do want my Rolex watches to perform with COSC specs.