Where Have All The Chronometers Gone?

[Bigjim]

Originally Posted by Adelie

The problem with mechanical time pieces is that they need regular servicing, (2-5yr) in order to maintain a decent working condition. The infrastructure to do this servicing has mostly gone away, so what remains is rather expensive.

Consequently, I would bet that many were disposed of by folks that didn't know what they had, or they became worn and the owners didn't have the funds to service.

As a Celestial Nav guy this question is of interest to me: how can I obtain a cost effective mechanical timepiece that has a steady error rate. If you are interested for this reason I can put you onto a few things.

If you are just interested in them as Antiques, sorry, can't help much beyond what I've already written above.

If you are truly into celestial nav you want accurate time. Mechanical timepieces are never truly accurate. They will lose and gain time depending on many factors. I was a navigator in the US Navy and was appalled at how bad our chronometers were. We kept a log every day to track the rate of change.

At the time I bought a $30 Timex Marathon watch. Every day when I checked the chronometers I also checked by Timex. It was much more accurate than the mechanical timepieces. In a year I think it lost a second. I always used it to take my sun and star shots. I recently bought another Timex Ironman. I just bought a Cal 27 and will be practicing my celestial nav again. A long time ago I bought a sextant. I can't wait.

[RPZ]

Mechanical chronometers and watches can be very accurate. I've had at least one $300 mechanical Swiss watch not COSC certified that was accurate to about two seconds a day.

Apart from being a really good read, I recommend a book written by Dana Sobel entitled Longitude. Chronometers were being made in the 1700s that were accurate to within a couple of seconds a day(!).

Today really accurate COSC certified watches are not cheap, but they are there for anyone that wants one. A good cheap back up is a good digital watch, like the aforementioned Timex Ironman. Maybe two; they can fail. Batteries can leak etc

[Adelie]

Originally Posted by Bigjim

If you are truly into celestial nav you want accurate time. Mechanical timepieces are never truly accurate. They will lose and gain time depending on many factors. I was a navigator in the US Navy and was appalled at how bad our chronometers were. We kept a log every day to track the rate of change.

At the time I bought a $30 Timex Marathon watch. Every day when I checked the chronometers I also checked by Timex. It was much more accurate than the mechanical timepieces. In a year I think it lost a second. I always used it to take my sun and star shots. I recently bought another Timex Ironman. I just bought a Cal 27 and will be practicing my celestial nav again. A long time ago I bought a sextant. I can't wait.

With mechanical time pieces you need to do several things,
Protect them from shock
Store them in the same position always,
Protect against temperature swings,
Wind daily as near as possible at the same time.
All these are done to maintain as stable an error rate as possible.

With a known and stable error rate one can calculate the correct time from a time piece that is in error. In the long run you are going to get drift but it take a couple of months to get very far off.

If you can make landfall every couple of month and know where your are on the map, you can work a sight backwards to reestablish correct time without outside reference. Then you can proceed again possibly with a slightly refined error rate.

The G-shock I wear has an error rate in the -2s to -5s per week range (I haven't bothered to formally check it) so the using a quartz timepiece is similar to a mechanical one, except the error rates are somewhat smaller. While quartz time pieces are more durable, I would still treat them the same as a mechanical watch intended for this purpose (except for the winding part).

[RPZ]

Originally Posted by Adelie

With mechanical time pieces you need to do several things,
Protect them from shock
Store them in the same position always,
Protect against temperature swings,
Wind daily as near as possible at the same time.
All these are done to maintain as stable an error rate as possible.

With a known and stable error rate one can calculate the correct time from a time piece that is in error. In the long run you are going to get drift but it take a couple of months to get very far off.

If you can make landfall every couple of month and know where your are on the map, you can work a sight backwards to reestablish correct time without outside reference. Then you can proceed again possibly with a slightly refined error rate.

The G-shock I wear has an error rate in the -2s to -5s per week range (I haven't bothered to formally check it) so the using a quartz timepiece is similar to a mechanical one, except the error rates are somewhat smaller. While quartz time pieces are more durable, I would still treat them the same as a mechanical watch intended for this purpose (except for the winding part).

My experience with quartz watches is that they are generally more accurate than that.

If you have a small pocket size SW receiver you can get a GMT time check just by tuning into the BBC or any number of other SW broadcasts if you know their time zones.

[StuM]

Originally Posted by RPZ

Mechanical chronometers and watches can be very accurate. I've had at least one $300 mechanical Swiss watch not COSC certified that was accurate to about two seconds a day.

If my quartz watch was only accurate to two seconds a day, I'd replace it. My current Casio cost less than $300 and so far is accurate to a few seconds a month.

[RPZ]

Originally Posted by StuM

If my quartz watch was only accurate to two seconds a day, I'd replace it. My current Casio cost less than $300 and so far is accurate to a few seconds a month.

Yes, most quartz digitals will in fact be more accurate than even a COSC certified mechanical watch costing thousands of dollars.

[Adelie]

Originally Posted by RPZ

My experience with quartz watches is that they are generally more accurate than that.

If you have a small pocket size SW receiver you can get a GMT time check just by tuning into the BBC or any number of other SW broadcasts if you know their time zones.

At this point in history the only reason you ever have to depend on a mechanical time piece is if every piece of electronics aboard was fried in a lightning strike.

That includes quartz watches and pocket sized SW receivers.

[RPZ]

Originally Posted by Adelie

At this point in history the only reason you ever have to depend on a mechanical time piece is if every piece of electronics aboard was fried in a lightning strike.

That includes quartz watches and pocket sized SW receivers.

Electronics can and do fail without lightning strikes. As do quartz watches. Electronic gadgets are nice , convenient. But they do fail. My personal opinion is that both are a good idea. But each his own.

[Bigjim]

Originally Posted by Adelie

With mechanical time pieces you need to do several things,
Protect them from shock
Store them in the same position always,
Protect against temperature swings,
Wind daily as near as possible at the same time.
All these are done to maintain as stable an error rate as possible.

With a known and stable error rate one can calculate the correct time from a time piece that is in error. In the long run you are going to get drift but it take a couple of months to get very far off.

If you can make landfall every couple of month and know where your are on the map, you can work a sight backwards to reestablish correct time without outside reference. Then you can proceed again possibly with a slightly refined error rate.

The G-shock I wear has an error rate in the -2s to -5s per week range (I haven't bothered to formally check it) so the using a quartz timepiece is similar to a mechanical one, except the error rates are somewhat smaller. While quartz time pieces are more durable, I would still treat them the same as a mechanical watch intended for this purpose (except for the winding part).

These are all things that we did for our mechanical chronometers. Navy ships carry at least 3 chronometers. All of them lost or gained time in different manners.

If I was going to go on an ocean passage, I'd buy 3 Timexes. And, I'd keep a supply of batteries. If you were worried, you could simply change the batteries at specific intervals to ensure that the watches would never fail unexpectedly.

[hafa]

Originally Posted by RPZ

Electronics can and do fail...

Hence, the afore-mentioned redundancy.

Originally Posted by Bigjim

...Navy ships carry at least 3 chronometers.

Another example of redundancy, as applied to Mechanical devices, which also can and do fail, albeit typically with a frequency determined by maintenance. As Bigjim observed, redundancy can serve as both a fail-safe or as a means for validation/verification and is desirable no matter the system.

[Jim Cate]

And for all you wannabe celestial navos, especially those who only view it as a backup after electrical failure of some sort, well, when taking sights from a very low height of eye and from a moving small boat deck a few seconds of time error is the least of your worries!

Sure, it's good to remove as many systematic errors as you can, but in practical terms, perfect time just isn't all that important.

But it is fun to argue about time keeping, quartz failure, and carrying three chronometers, and mechanical watches are true maritime objets d'art, so carry on.

Jim

[Adelie]

I would be stunningly happy to get 5nm accuracy doing celestial under way.

[Bigjim]

Someone mentioned keeping one watch set to GMT. If you have a Timex Ironman or Marathon as well as other models, all provide for second time zone. Just press a button to view it. Hold the button for a few seconds to switch to it temporarily.

As for accuracy, as I mentioned earlier, we would do time checks every day when in port or within radio range. The Timex only lost a fraction of second a month.

[Bigjim]

Originally Posted by Jim Cate

And for all you wannabe celestial navos, especially those who only view it as a backup after electrical failure of some sort, well, when taking sights from a very low height of eye and from a moving small boat deck a few seconds of time error is the least of your worries!

Sure, it's good to remove as many systematic errors as you can, but in practical terms, perfect time just isn't all that important.

But it is fun to argue about time keeping, quartz failure, and carrying three chronometers, and mechanical watches are true maritime objets d'art, so carry on.

Jim

People should not poo poo small errors. A US Navy tugboat screwed up its celestial computations back in the 70s before all the slick digital navigation appeared. They missed Hawaii. They didn't realize it for over 48 hours when their dead reckoning track told them they should have long arrived. The skipper of the boat was relieved of duty and the navigator sanctioned. The Navy frowns on such errors.

[Jim Cate]

Originally Posted by Bigjim

People should not poo poo small errors. A US Navy tugboat screwed up its celestial computations back in the 70s before all the slick digital navigation appeared. They missed Hawaii. They didn't realize it for over 48 hours when their dead reckoning track told them they should have long arrived. The skipper of the boat was relieved of duty and the navigator sanctioned. The Navy frowns on such errors.

Small time errors such as we have been discussing are not sufficient to cause one to miss Hawaii... by a long shot.

Your apocryphal story seems related to poor practice, not poor timekeeping, so I'll continue to "poo poo" the importance of hyper-accurate timepieces for small boat navigation.

Jim