What makes a GMT a 'proper' GMT?

[ArghZombies]

I recently discovered the Longines Conquest GMT which caught my eye as a nice sub £1,000 watch:



However, I've heard people say that this, and other similar watches aren't 'true' GMT watches, unlike the Rolex GMT Master.

As far as I was aware a true GMT had a GMT hand that makes one revolution for each 24 hour period, with 24 indicies indicated around the dial, whereas there are cheaper ones that just have an extra hour hand that allows you to set a second timezone, but still rotating every 12 hours. But this Longines has a 24 hour indicator near the chapter ring, making me think it is indeed 'proper'.

Where am I wrong (if indeed I am) in my understanding of this complication, and is this watch a proper GMT?

[andrew]

It depends on what you want. If an independently settable 24h hand is desirable because it allows you to track (and change) a second timezone from where you're sitting, then it's more "proper" than one which you have to hack in order to change the 24h hand.

If you travel a lot (which was the point of the first GMT watch*) then you will probably be better off with one whose 12h hand is independently settable.

* The first GMT watch with an independent 24h hand did not allow any adjustability at all; the alternative timezone was displayed using a rotating bezel. That would not be a "true" GMT by some people's definitions, nor the original and slightly earlier Glycine Airman, which had only a 24hr hand and a rotating bezel to display a second timezone.

Generally speaking, people define as "true" the operating method of the GMT watch they own, or prefer. It's nothing to do with universal agreed definitions (little is, in the watch world!)

[DB9yeti]

I'd imagine any watch that allows you to set an independent hand to monitor a second timezone could be called a GMT watch.

The original Explorer II (1655) just had a hand that went round once every 24hrs, not independently adjustable - effectovely a day/night indicator. So it looked like a GMT function, but wasn't (happy to be corrected, have never handled one, was just told this).

[java]

I have a few and they pretty much all annoy me. They annoy me because they offer second time zones that are in whole hours. There are many timezones which are not separated by whole hours. Therefore they are not really world time, they are part of the world time.
There are very few which offer full manipulation of the second timezone.

My Parmigiani Hemispheres will allow completely independent setting of the second timezone as well as Night/day indicator for both.

[erwin]

I travel for business all a round the world; so the gmt function is very important for me.
From all gmt watches that I have, which the best served for me is the Pam 320 with 12 hours GMT function.
24 hours has no sens for me.
Only if you're in Usa and works in asia have over 12 hours of diference.

[Tokyo Tokei]

The original Explorer II (1655) just had a hand that went round once every 24hrs, not independently adjustable - effectovely a day/night indicator. So it looked like a GMT function, but wasn't (happy to be corrected, have never handled one, was just told this).

You are right, the original Explorer II was marketed for spelunkers, where knowing whether it was day or night was important. A small market perhaps. The same movement was in the original GMT Master, but this had a rotatable bezel ( unlike the Explorer II ) which meant the 24hr hand could be used to indicate any arbitrary time zone. Later, the movement was modified to allow independently setting the 24hr hand, so even without a rotatable bezel, it could be used as a "true" GMT in the Explorer II. To answer the OP's question, I think this is what makes a "true" GMT - an additional hour hand that may be set independently from the main hour hand. You may lose the quick-set date facility in such a movement, it's worth checking if this is important to you.

Paul

[ArghZombies]

I think this is what makes a "true" GMT - an additional hour hand that may be set independently from the main hour hand.
Paul

So, if you can't set it independently from the main hour hand, how do you set it? I have heard this sort of thing as criticism of some GMTs, this Longines included - but I don't really understand what it means.

[Tokyo Tokei]

So, if you can't set it independently from the main hour hand, how do you set it? I have heard this sort of thing as criticism of some GMTs, this Longines included - but I don't really understand what it means.

You don't set it, it just rotates around the dial at half the speed of the hour hand, rather like the date wheel. If you have a rotating bezel, you use the bezel to line up with the 24 hour hand at any offset you like. If you don't have a rotating bezel ... you have an am/pm indicator.

Paul

[ArghZombies]

You don't set it, it just rotates around the dial at half the speed of the hour hand, rather like the date wheel. If you have a rotating bezel, you use the bezel to line up with the 24 hour hand at any offset you like. If you don't have a rotating bezel ... you have an am/pm indicator.

Paul

Ouch. So for the Longines pictured if I want to set it to a different timezone I have to wait for the watch to stop, then when the actual time in the 2nd location matches the (now stationary) GMT hand, restart the watch and then set the normal hands to the current time? Damn, that sounds awkward. Surely I'm misinterpreting something here?

For instance, if the watch has stopped, it's currently 15:30 in my home location and 12:30 in the 'GMT' time, how do I get the GMT hand to show that time?

[Tokyo Tokei]

You can't, unless the GMT hand is independently settable.

Paul

[mindforge]

I suppose that's why it is called a gmt hand rather than a second time zone hand.

[patrick]

This thread makes me appreciate my G shock even more.

[hako]

But do people really use zulu time? Or just home tz?

Of course this would not apply to people happening to live on the island(s)...

[rob-vicar]

But do people really use zulu time? Or just home tz?

Of course this would not apply to people happening to live on the island(s)...

The military does

- - - Updated - - -

You can't, unless the GMT hand is independently settable.

Paul

Which it is on the Longines, from their blurb "Function: Hours, minutes, seconds and date. 24 hours hand with time zone mechanism."

[Fords]

It's a bit more bang for your buck the extra hand an all.

[Captain Morgan]

Ouch. So for the Longines pictured if I want to set it to a different timezone I have to wait for the watch to stop, then when the actual time in the 2nd location matches the (now stationary) GMT hand, restart the watch and then set the normal hands to the current time? Damn, that sounds awkward. Surely I'm misinterpreting something here?

For instance, if the watch has stopped, it's currently 15:30 in my home location and 12:30 in the 'GMT' time, how do I get the GMT hand to show that time?

Working on memory here but, only Rolex and Omega gmt watche allow you to make the following adjustment via crown.

Position 1 after winding position allows independent adjustment of main hour hand, second position adjust both gmt and main hour hand.

You set the gmt hand to "home time" and then when traveling you change the main hour hand to "local time" gaining you time in your local location and keeping your home time on the gmt hand.

Simples.....

Other manufacturers offer similar systems but not generally via crown adjustment, they may have a second crown or adjuster buttons.

I think Seiko quartz are an exception I think and also use a single crown system.

Hth

[fiddler69]

Working on memory here but, only Rolex and Omega gmt watche allow you to make the following adjustment via crown.

Position 1 after winding position allows independent adjustment of main hour hand, second position adjust both gmt and main hour hand.

You set the gmt hand to "home time" and then when traveling you change the main hour hand to "local time" gaining you time in your local location and keeping your home time on the gmt hand.

Simples.....

Other manufacturers offer similar systems but not generally via crown adjustment, they may have a second crown or adjuster buttons.

I think Seiko quartz are an exception I think and also use a single crown system.

Hth

The Longines movement will be based on the ETA 2893 (actually a sized-up version - see http://www.ablogtowatch.com/longines...-watch-review/). The difference between this and the Omega/Rolex solution is that in the latter, as described above, the main hour hand can be moved (in hour increments) without hacking the movement, when traveling - i.e. you can keep the seconds running and the GMT hand on your home time while you adjust the main hour hand, maintaining accuracy. In the ETA solution, the GMT hand is adjustable in hour increments (not the main hour hand) which means that when travelling, if you want to use the main hour hand for your local time, you have to hack the movement (losing seconds' accuracy) and adjust all hands, before re-setting the GMT hand to the correct time zone differential. It is therefore less elegant as a travelling solution, but can be very handy (excuse the pun) when not travelling, as a way to track a second time zone (an office in another country for example). For this reason, the ETA solution watches tend to be referred to as "office" GMTs not "true" or travelling GMTs.

As Java points out, very few multiple time zone watches allow for half hour (e.g. India) time differences (unless via a moveable bezel) as the hands are linked or can only move in hour increments - although his rather marvelous Parmigiani example does and is therefore nigh on perfect.

Hope I got that right!

[andrew]

Working on memory here but, only Rolex and Omega gmt watche allow you to make the following adjustment via crown.

I think IWC's pilot watches do, too, although they display the second zone using a number dial or more recently a city "ring", not a separate hand - which may be ways dodging the Omega/ETA patent death-grip. Others still - UN, Tudor, Oris - use pushers to activate a subdial or number dial.

[ArghZombies]

The Longines movement will be based on the ETA 2893 (actually a sized-up version - see http://www.ablogtowatch.com/longines...-watch-review/). The difference between this and the Omega/Rolex solution is that in the latter, as described above, the main hour hand can be moved (in hour increments) without hacking the movement, when traveling - i.e. you can keep the seconds running and the GMT hand on your home time while you adjust the main hour hand, maintaining accuracy. In the ETA solution, the GMT hand is adjustable in hour increments (not the main hour hand) which means that when travelling, if you want to use the main hour hand for your local time, you have to hack the movement (losing seconds' accuracy) and adjust all hands, before re-setting the GMT hand to the correct time zone differential. It is therefore less elegant as a travelling solution, but can be very handy (excuse the pun) when not travelling, as a way to track a second time zone (an office in another country for example). For this reason, the ETA solution watches tend to be referred to as "office" GMTs not "true" or travelling GMTs.

As Java points out, very few multiple time zone watches allow for half hour (e.g. India) time differences (unless via a moveable bezel) as the hands are linked or can only move in hour increments - although his rather marvelous Parmigiani example does and is therefore nigh on perfect.

Hope I got that right!

Ah that's a great write-up, thanks. I think I have my head around it now! Perhaps I need to go to an AD of Rolex and Longines to have a play with both types to see how they all work from there.

[Piemuncher22]

I have a few and they pretty much all annoy me. They annoy me because they offer second time zones that are in whole hours. There are many timezones which are not separated by whole hours. Therefore they are not really world time, they are part of the world time.
There are very few which offer full manipulation of the second timezone.

My Parmigiani Hemispheres will allow completely independent setting of the second timezone as well as Night/day indicator for both.

If I remember rightly you were wearing that Parmigiani at the drink up in London, a truly lovely thing.

I very rarely travel anywhere, and have no need what so ever for a duel time zone, however as a lifelong fan of the Rolex GMT (and owner of two) I still remember being pissed off that it isn't a true GMT after it was explained to me........ Cheers Java.

[thenikjones]

Blancpain also uses the OMEGA/Rolex system.

Traveller and Office GMT are as good terms as any - I like the Omega Traveller version because I travel a lot. Fortunately not to India or Australia, where AFAIK the 30min time zones would mess me up.

If you don't travel that often then really, just get the watch that you like the look of. You won't set it THAT often.

[ArghZombies]

If you don't travel that often then really, just get the watch that you like the look of. You won't set it THAT often.

This is true. It's the history of these complications, the engineering
and the style that I like, rather then purely being for a certain purpose. Hell, I've never even dived deeper than maybe 10 metres in my life; doesn't mean I don't still like dive watches!

[Alfredo Doricchi - AD des]

You're Longines it's a proper GMT

[gunner]

Working on memory here but, only Rolex and Omega gmt watche allow you to make the following adjustment via crown.

Position 1 after winding position allows independent adjustment of main hour hand, second position adjust both gmt and main hour hand.

You set the gmt hand to "home time" and then when traveling you change the main hour hand to "local time" gaining you time in your local location and keeping your home time on the gmt hand.

Simples.....

Other manufacturers offer similar systems but not generally via crown adjustment, they may have a second crown or adjuster buttons.

I think Seiko quartz are an exception I think and also use a single crown system.

Hth

Seiko spring drive GMT does the same.

[NenoS]

But do people really use zulu time? Or just home tz?

Of course this would not apply to people happening to live on the island(s)...

Radio amateurs (HAM) only use UTC or Zulu time . As far as I know , the pilots in long distance flights too.

[pacchi]

in my understanding a GMT watch has the ability to show GMT or Zulu time. So needs to be 24hrs hand not 12hrs hand. No need to be adjustable to be called GMT....IMHO

[hako]

Personally I have used UTC quite a lot, with some military experience and a HAM license, but very, very few of my fellow wristwatch wearers seem to really care. So, a traveller's watch it is.

I tend to use 12hr dials for home tz reference, but could not be bothered to set any more complicated setups. Unless on duty, of course.

[Leif]

On a few of the Sinn watches (for example the 756 Diapal), there's an extra hour hand which can be set independent of the ordinary hour hand. When it's not needed, the extra hand can be hid behind the ordinary hour hand. Not a traditional GMT arrangement but IMHO very easy and convenient to set without hacking the watch and thus perfect for travel. And I think I can tell whether it's day or night without looking at the watch.

But as always, from a purely functional point of view, a G-shock beats them all, also as a GMT watch, at a fraction of the cost of a mechanical GMT watch.

[andrew]

On a few of the Sinn watches (for example the 756 Diapal), there's an extra hour hand which can be set independent of the ordinary hour hand. When it's not needed, the extra hand can be hid behind the ordinary hour hand. Not a traditional GMT arrangement but IMHO very easy and convenient to set without hacking the watch and thus perfect for travel. And I think I can tell whether it's day or night without looking at the watch.

I like that arrangement too.

The only downside (aside from the limitation shared with most mechanical GMT watches when it comes to part-hour zones) that I perceive is that with large offsets you will still have to remember whether the zone is forward or back. E.g. if you have a 756 UTC and set the "ghost" hour hand to +13 for the time in Auckland and it's 3 pm in the UK, the ghost hand will show 4 pm - the same time as it would for Paris. And if you're going to add 12 each time, you may as well add 13 :). But that's being picky, because for smaller time differences it's great for an instant read, and as you say being able to hide the spare hand when not in use is pretty neat.

[HappyJack]

Fortis do/did a couple of GMT Chronos, where the hour hand is quick set, and there's a separate sub dial showing 24 hours time, linked to the date mechanism. So, for example, if you set the 24 hour time in London tonight then flew to Sydney, you could easily reset the main hour hand in Sydney (which is useful) without hacking the movement, but the date will change 11 hours later, at midnight GMT. Confusing.

Citizen do some GMT watches where the date is quickset one way and the running hour hand is quickset the other. So when you fly one way you can jump the hour hand by an hour without hacking, but the other way, you have to move it by 23 hours, then reset the date, to get to the correct local time. Weird.

I've had one of each and didn't get on with either. I now have a Seiko GMT Perpetual with the 8F56 movement, which apart from being quartz, functions like the Rolex or Omega movements, allowing the GMT hand to remain unchanged whilst you reset the running hours without hacking (after all, GMT/UTC time doesn't change, just because you travel). If I were buying now, I'd focus on Omega, Rolex, Seiko or, possibly, on the Blancpain, but probably not IWC though - I don't like the hour window but prefer a GMT hand.

Or go anadigital and try an Omega X-33.

[gunner]

Citizen do some GMT watches where the date is quickset one way and the running hour hand is quickset the other. So when you fly one way you can jump the hour hand by an hour without hacking, but the other way, you have to move it by 23 hours, then reset the date, to get to the correct local time. Weird.

I've had one of each and didn't get on with either. I now have a Seiko GMT Perpetual with the 8F56 movement, which apart from being quartz, functions like the Rolex or Omega movements, allowing the GMT hand to remain unchanged whilst you reset the running hours without hacking (after all, GMT/UTC time doesn't change, just because you travel). If I were buying now, I'd focus on Omega, Rolex, Seiko or, possibly, on the Blancpain, but probably not IWC though - I don't like the hour window but prefer a GMT hand.

Or go anadigital and try an Omega X-33.

Same here, had the Citizen but found the arrangement annoying, now got a spring drive seiko.