Putting accuracy into perspective
Excerpt from an old article I stumbled across.
Internally I shake my head a bit when I hear someone complain when their watch is off by 4-6 seconds per day… It’s rarely conveyed to a client the incredible accuracy of mechanical watches.
I know some of you are thinking “well I paid hundreds or thousands of dollars, I expect it to be dead on accurate”. While I understand that train of thought, if you are one of those complainers, digest this information and see if I can convince you to be a little bit less critical…
The rate of a mechanical wrist watch measured in Hz (hertz). 1Hz is equal to 2 vibrations. A vibration is one turn of the balance wheel (which is what makes the tick sound)…
This being easy enough to understand, many of today’s mechanical wristwatches function at 4Hz or 28,800 VPH (vibrations per hour) which equates to 8 ticks per second. Let’s put that into perspective…
28,800 vibrations per hour x 24 hours = 691,200 vibrations per day
The current standard tolerance for a COSC certified chronometer wristwatch is +6/-4 seconds per day.
A 6-second interval contains 48 vibrations.
This means that if a watch is off by 6 seconds, it would be off by only 48 vibrations out of a 691,200! That means out of every 14,400 vibrations, the watch is off by one tick!
A COSC Certified Chronometer is 99.9930556% accurate at the worst!
And imagine, these incredible machines were designed and created over a century ago without the aide of computers and modern technology!!!
So when your watch is off by 10 or 15 seconds in a days time, maybe it won’t bother you so much now.
Credit to the original author: Mr. John Keil 7/17/2017
If you bought a used wrist watch that only had an hour and minute hand, is it still a secondhand watch? 😜
15 seconds per day off doesn’t bother me after one day, it bothers me after 3.
Very well done
Less than 10 is acceptable. On the wrist.
That’s an interesting way to look at it. In real world terms, I think of it like this. If your watch is -10 seconds per day, what happens? You set it, and you’re just over a minute late for a meeting the following week? So what? Who would even notice that?
In practical terms, an accurate watch needs to be reset every few weeks to avoid being off a notice amount. I mean sure, you can notice it’s off compares to your phone or whatever, but not enough to make any practical difference.
And if it makes you feel better, pretend you paid for design or heritage or something else besides accuracy.
That’s an interesting way to look at it. In real world terms, I think of it like this. If your watch is -10 seconds per day, what happens? You set it, and you’re just over a minute late for a meeting the following week? So what? Who would even notice that?
In practical terms, an accurate watch needs to be reset every few weeks to avoid being off a notice amount. I mean sure, you can notice it’s off compares to your phone or whatever, but not enough to make any practical difference.
And if it makes you feel better, pretend you paid for design or heritage or something else besides accuracy.
Preach!! Brother Preach!!
Have Mercy !! 🥳😜
If it its more than +-10 spd throw it in the trash and burn it with gasoline 🤣
I recently did a thread on the accuracy of my own collection and found that one of my Tag Carreras is running so fast that it could almost help my wife be ready on time 😂
It's that quest for accuracy over many generations and millennia that's led to this point. It's truly amazing we can buy a watch that's only a handful of seconds off.
What a time to be alive 😁👏🏻
Word!
In my eyes, 30 seconds late is meaningful - in that time you can miss an exam, a flight gate closing, interview, etc..
Based on that, at 10 seconds a day, you need to reset your watch at least 2 times a week. That means:
Waiting for the seconds on your watch to tick round to 12 for an accurate reset = 30 seconds on average waiting for perfect alignment.
Setting the hands = 10 seconds.
Then waiting for the new time to catch up before perfectly plunging the crown = 30 seconds.
70 seconds per reset, twice a week = 140 seconds x 52 weeks x 80 years = 6.7 days of your life wasted setting your miyota movement.
However, at 2 seconds a day = reset once a month = 70 x 12 x 80 = 0.78 days.
Imagine lying on your death bed, loved ones all around you, grandson eagerly eyeing your Rolex.. What would you give for that extra 6 days of life!?
...Which is how I'm justifying my next purchase of a GS 9F Quartz!
I can reset my watch in less time than I can read and understand the calculations +6/-4 seconds give or take😉
I rarely wear the same watch 2 days in a row so I couldn't care less about accuracy.
I do get bothered my the accuracy of my mechanical watches, which is why I don't use them for everyday duties. A few seconds a day ok but after 2 or 3 or more then its a problem for me. I have quartz and wave-ceptor that I use for everyday. Its a shame, but mechanicals not that accurate.
Well said. We are ridiculous people in a ridiculous hobby.
I am conflicted too..
On one end I totally value what you are saying, having this marvelous tiny machine on my wrist miss 48 beats out of 691k is incredible.
On the other end I don't have an extensive collection to change often so I do get annoyed at seeing my time get off every day more until it gets too much for my liking.
I expect this to become less of an issue as I grow my collection and get used of setting the time every morning for the watch I pick :)
For me, accuracy is something that I desire, but don't demand. What I mean is, I want my watch to display the most precise, correct time that it is capable of displaying, but if it falls behind or gets ahead, it's not a problem. If I really need it to be spot on for the day I am wearing it, I will set it that morning, before heading out into the world, so that I know that it can't possibly be more than a second or two off during the majority of that day. Otherwise, I leave it be.
Also, let's not forget that mechanical and automatic watches can be regulated, to perform above and beyond standard specifications. It's like Scotty said in Relics, "A good engineer is always a wee bit conservative, at least on paper."😎 So the basic specs for a well-built watch are always not quite as good as the mechanism was designed to perform, and subsequent tweaking of that mechanism can make it even more precise.
https://youtu.be/ed88fkb2W0c
If you want to be insufferable and demand bang-on accuracy, stick with your phone or a Casio WaveCeptor.
For everything else, there is a watch for you.
Great post!!
Thanks for doing the math.
I'm sure many won't be won't be swayed by this perspective but IMO it sucks to be them. I'm happy with all of my watches , many of which are in the 10-15 sec/day range. I can't imagine being stressed by a mechanical device with a 99+% accuracy rate.
Luddites of the world unite. Timegraphers are the devils spawn!!!
lol, thats called a broken watch
That's why I have so many watches and switch them every day. They never get more than 10-15 seconds off because by the time they come back in rotation, I set them and they are accurate again. Glass half full.
(or I could just pull out one of my quartz watches)
I don't think 10s per day is too bad but why is it so astonishing that something beat exactly N times in a given 24h period under predefined repeatable circumstances? Each tick could be off by as much as 1% if the error is assumed random independent and for the deviations that are systematic there is a regulator.
A deviation of 0.01% over a period of one minute would technically be more impressive, over 24h not so much in my opinion.
If accuracy is the goal, I’d argue that one should not purchase a mechanical watch.
Newer technologies have emerged that are far more accurate. Quartz- there are high precision quartz watches that boast no more than 5 seconds drift in A YEAR (less than half a second each month). Or how about watches that connect to and synchronize with atomic clocks via radio daily (of which I own two).
It seems silly to me to complain about the accuracy of mechanical watches in this context.
I keep thinking of the frederique constant monolithic, which is a 40hz watch that still keeps within cosc levels, but not certified. That's 48 off of 6.9 million? Am I doing the math right?
I really don't see accuracy as an issue. I'm in the fortunate position to have multiple mechanical watches and setting them is part of the fun.
I'm in the middle of my Four Watches Four Weeks experiment and after a week of wear, my Zulu Time was 8 seconds out. My Spinnaker which is not COSC was only 17 seconds out and I wore that 24/7 for the last 5 days on a long weekend in Switzerland.
I've just moved on to my Longines Master Collection, also not COSC, so we'll see how that does (though it is purely for interest purposes).
Yikes. And I thought my 2-53 Pobeda was sad: