Do you prefer watch accuracy or stability?

DoctorEvil

Interesting thread and thanks for starting it OP.
I've seen this topic come up a couple of times in the past and remember reading a post from an ex naval officer saying he prefers a watch to be stable. The reason is so that he can determine what the exact "reference time" is on any day based on when he last synchronised his watch. I must say that I tend to agree with him although a watch that's also accurate would be a bonus.

Owlsu

Watches can definitely be both at the same time - my 1861 Speedmaster came from the AD brand new as a consistent +16spd no matter what position it was in, I took off the back and nudged the needle a bit until I worked out which direction made it go faster and which slower and eventually I got it running at a consistent +0.2spd regardless of position or wear. It stayed this way for about a year until I dropped it one day and it started running +4spd.

The fact that a £3,000 hand-wound mechanical watch with a 40 or 50 year old movement could run this accurately was all I needed to convince me that all the brand new inventions and marketing points of luxury watch movements are a bit of a gimmick really and you don't need to spend £20,000 to get something that can rival quartz. Even some of my G-Shocks run at +1spd, but then again others run at +1 second per month.

All the stuff about column wheel chronographs or parachrom springs and co-axial this and that doesn't mean much in the real world when a 1861 Speedmaster can consistently run at +0.2spd.

Donn Chambers

From a purely scientific/engineering perspective in terms of navigation, stability is more important than “accuracy” in the case as it is defined here. A timepiece that has a highly stable rate of change (even if it is quite large) can be corrected after the fact to be “accurate” given the knowledge of the offset. This was important for computing longitude with marine chronometers. So, for example, you have established that your chronometer has a consistent and stable rate of -10 s/day at any position, you can just read the time and add a correction to get the “true” time by multiplying the rate by the number of days since it was last synched to a valid time reference.

But if it is wildly fluctuating by positive/negative excursions but on average is zero, you can’t make a simple adjustment and your calculation of the longitude at any particular time can be significantly off at any particular time.

this is why precise clocks on spacecraft (still needed for scientific measurements) are called ultra stable oscillators, not ultra accurate oscillators. The stability is key.

In terms of the original question, regarding our wristwatches, I still think stability is more important, because a stable watch can be regulated to have a consistent rate stability closer to 0 if it was already stable at a faster/slower rate. You can’t do that if it was not stable to begin with.

Donn Chambers

From a purely scientific/engineering perspective in terms of navigation, stability is more important than “accuracy” in the case as it is defined here. A timepiece that has a highly stable rate of change (even if it is quite large) can be corrected after the fact to be “accurate” given the knowledge of the offset. This was important for computing longitude with marine chronometers. So, for example, you have established that your chronometer has a consistent and stable rate of -10 s/day at any position, you can just read the time and add a correction to get the “true” time by multiplying the rate by the number of days since it was last synched to a valid time reference.

Donn Chambers

From a purely scientific/engineering perspective in terms of navigation, stability is more important than “accuracy” in the case as it is defined here. A timepiece that has a highly stable rate of change (even if it is quite large) can be corrected after the fact to be “accurate” given the knowledge of the offset. This was important for computing longitude with marine chronometers. So, for example, you have established that your chronometer has a consistent and stable rate of -10 s/day at any position, you can just read the time and add a correction to get the “true” time by multiplying the rate by the number of days since it was last synched to a valid time reference.

But if it is wildly fluctuating by positive/negative excursions but on average is zero, you can’t make a simple adjustment and your calculation of the longitude at any particular time can be significantly off at any particular time.

this is why precise clocks on spacecraft (still needed for scientific measurements) are called ultra stable oscillators, not ultra accurate oscillators. The stability is key.

In terms of the original question, regarding our wristwatches, I still think stability is more important, because a stable watch can be regulated to have a consistent rate stability closer to 0 if it was already stable at a faster/slower rate. You can’t do that if it was not stable to begin with.

Leviathan

Hello OF community,

I was in a discussion with a fellow watch-collecting friend the other day on mech/auto watch accuracy.

He was telling me how his serviced Rolex 16610 Sub was very stable across all positions, but with mediocre accuracy at a firm -2 s/d.

Conversely, my SMP 8800 Diver is more “accurate” but less stable, getting anywhere from 0-4 s/d largely dependant on night resting positions and, naturally, wear behaviour.

So the question is, do you prefer a movement that is stable but somewhat inaccurate, or a watch that is accurate but more subject to deviations across positions? Thanks!

C CalTurk

This is exactly the way to think about watch performance. It's kind of funny because I think a lot of people in our hobby get wrapped up in how accurate a watch is compared to the atomic clock, I know I've definitely been guilty of this in the past.