Dual Time vs GMT

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Dual Time vs GMT

Post by jkbarnes »

Are these terms synonyms or is there a difference between a dual time watch vs. a GMT complication? Perhaps there was a difference at one point but they’re now used interchangeably? Or are they NOT used interchangeably? Or maybe the difference in terms reflects how the second time is presented?

The question is prompted by browsing a watch brand’s site and seeing some watches labeled “dual time” while another was “GMT.”
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Re: Dual Time vs GMT

Post by Amor Vincit Omnia »

I have often wondered about this too, Andrew. I think that in a lot of people’s minds the differences are shrouded in mystery, especially when we add in the world timer description.

My basic understanding (and forgive me if I am wrong here) is that a dual time might be something as simple as an adjustable bezel such as the internal one which the Magrette Dual Time has.

As far as I know a GMT can be a watch such as the ones produced by CW, where the third hand is independently adjustable. This is distinct from what tends to be called a True GMT, such as the ones produced by Rolex, where there is an independently adjustable hour hand.

To my mind a world timer seems to suggest that there should be a ring of time zones with prominent cities to identify them. I think in other respects the CW world timer (at least the C65 variant) is just a standard GMT movement with that addition.

The two CW world timers with JJ movements are a bit different. I have also seen watches (including vintage) with a completely separate subdial that operates as a second time zone in miniature.

Clear? As mud, I suspect! :lol:
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Re: Dual Time vs GMT

Post by nbg »

I take the view that a watch described as a GMT would typically have the time in the 2nd time zone indicated by a hand pointing to a 24 hour scale, depicted on either an external bezel, or an internal rehaut. I.e. designs that are a nod to the original Rolex GMT Master that was designed for Pan Am pilots.

A dual time watch tends (but not always) to have the 2nd time zone on a simple 12 hour scale, either by use of a sub dial, or occasionally another hour hand on the main dial, that is only visible when a different time zone is being selected. The so called dual time complication often has an AM/PM indicator for the 2nd time zone. Pushers, rather than use of a position on the crown are sometimes used to set the 2nd time zone.

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Re: Dual Time vs GMT

Post by tikkathree »

My experience has proven the two terms to be used synonymously and that watchmakers usually go for the catchier GMT moniker.
When I talk about a GMT watch I really mean dual time zone because my interest is in tracking the actual time with my siblings, 7 hours behind London time.
There are watches which simply have a 24hour bezel, often but not exclusively in "pepsi" fashion or have a 24 hour subdial. Within my experience these cannot be set independently of the main hands.
Let's see now...

C65 Anthropocene: I use both the pointer and subdial to represent "Wyoming time"
20200714_164906.jpg
My C60 GMTs I leave the bezel alone and rely on the pointer

20200714_164934.jpg
Sorry about the dust....
20200714_165659.jpg
Ditto the Great White
20200714_165012.jpg
Or you could have subdial Second Time Zone
20200714_165113.jpg
20200714_165105.jpg
Then Omega does the 24hour marker in a subdial
20200714_165635.jpg
Or, howabout an independently set GMT/Second Time Zone hand? The watch runs down and stops and you lose the differentiation.
20200714_165351.jpg
Bet you wish you hadn't woken me up now.... :lol:
C60 MKI, MKII, MKIII: "some",
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Re: Dual Time vs GMT

Post by jkbarnes »

Amor Vincit Omnia wrote: Tue Jul 14, 2020 4:46 pm I have often wondered about this too, Andrew. I think that in a lot of people’s minds the differences are shrouded in mystery, especially when we add in the world timer description.

My basic understanding (and forgive me if I am wrong here) is that a dual time might be something as simple as an adjustable bezel such as the internal one which the Magrette Dual Time has.

As far as I know a GMT can be a watch such as the ones produced by CW, where the third hand is independently adjustable. This is distinct from what tends to be called a True GMT, such as the ones produced by Rolex, where there is an independently adjustable hour hand.

To my mind a world timer seems to suggest that there should be a ring of time zones with prominent cities to identify them. I think in other respects the CW world timer (at least the C65 variant) is just a standard GMT movement with that addition.

The two CW world timers with JJ movements are a bit different. I have also seen watches (including vintage) with a completely separate subdial that operates as a second time zone in miniature.

Clear? As mud, I suspect! :lol:
Haha! I didn’t even think about a world timer! I’ve never fully understood exactly what a world timer is.

As for the rest of your response, I think you’ve captured the difference perfectly! To paraphrase Winston Churchill, the difference appears to be a riddle wrapped up in an enigma?

On a serious note, I was wondering if perhaps GMT implied an 24 hour central hand with an adjustable bezel, while a dual time suggested a subdial with either a 24 hour hand or 12 hour hand?
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Re: Dual Time vs GMT

Post by jkbarnes »

nbg wrote: Tue Jul 14, 2020 5:04 pm I take the view that a watch described as a GMT would typically have the time in the 2nd time zone indicated by a hand pointing to a 24 hour scale, depicted on either an external bezel, or an internal rehaut. I.e. designs that are a nod to the original Rolex GMT Master that was designed for Pan Am pilots.

A dual time watch tends (but not always) to have the 2nd time zone on a simple 12 hour scale, either by use of a sub dial, or occasionally another hour hand on the main dial, that is only visible when a different time zone is being selected. The so called dual time complication often has an AM/PM indicator for the 2nd time zone. Pushers, rather than use of a position on the crown are sometimes used to set the 2nd time zone.

Neil
That’s what I was thinking when I posed the question.
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Re: Dual Time vs GMT

Post by Amor Vincit Omnia »

jkbarnes wrote: Tue Jul 14, 2020 5:13 pm On a serious note, I was wondering if perhaps GMT implied an 24 hour central hand with an adjustable bezel, while a dual time suggested a sundial with either a 24 hour hand or 12 hour hand?
As in, “What’s the current time in Byzantium, Publius?” :lol:
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Re: Dual Time vs GMT

Post by jkbarnes »

Amor Vincit Omnia wrote: Tue Jul 14, 2020 5:23 pm
jkbarnes wrote: Tue Jul 14, 2020 5:13 pm On a serious note, I was wondering if perhaps GMT implied an 24 hour central hand with an adjustable bezel, while a dual time suggested a sundial with either a 24 hour hand or 12 hour hand?
As in, “What’s the current time in Byzantium, Publius?” :lol:
STUPID AUTOCORRECT! :lol: :lol: :lol:

I literally laughed out loud at this!

I’ll go back and fix that...
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Re: Dual Time vs GMT

Post by jkbarnes »

tikkathree wrote: Tue Jul 14, 2020 5:07 pm Let's see now...

Bet you wish you hadn't woken me up now.... :lol:
Not at all! I think all those examples serve to validate my question.

And I really wish that Anthropocene came in a non-LE version. That’s a beautiful watch.
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Re: Dual Time vs GMT

Post by 0uatiOW »

I’m a little late to this but I have a small collection of travellers watches & they are my most used variety because I travel a lot for work, or at least I used to.

When I hear “dual time watch”, I think of a watch with a rotating 12-hour bezel or a chapter ring, which is offset so the main hour hand points to a different timezone. The Magrette Dual Time mentioned by AVO is an example, but any watch with a moving 12 hour bezel will do the same thing. I’ve blagged one of Gary’s pictures below (credit where it’s due).

Image

GMTs usually have an extra “GMT” hand - usually red, orange, yellow, even blue, which can be set independently to point to any hour, but moves at half speed (1 full rotation per 24 hours), therefore tracking a second timezone. Many GMTs, including the CW C60 & C65 versions, and the Zelos below, use ETA or Sellita movements, which allow the GMT hand be set independently.

Image

A better design, in my opinion is to allow the main hour hand to be set independently, which is how the Rolex GMT Master (I think) & the Tudor BB work. This is a lot more practical if you are on the move. I use the Tudor when I travel long haul with connections in different places, because I can easily set the main hour to local time.

Worldtimers are different again - they are meant to easily show the time in any timezone in the world. They usually have a rotating inner bezel showing the names of different (sometimes relatively little known) cities around the world. By setting the GMT hand to, errr, GMT, & aligning the target city on the inner bezel to 12, the GMT hand should show the time in that city. On this Bremont you can see that it’s just after 9pm in the UK, and just after 3pm in Chicago (this watch also operates as a traditional ETA GMT).

Image

The key is that the inner bezel should rotate. If my memory serves me correctly, the CW C65 Worldtimer doesn’t have a rotating bezel, but I haven’t handled it so I’m not sure exactly how it works.

There are versions of Worldtimers which use different displays - CW makes one with a map of the world and little red dots, though I don’t really understand how it works.

I also have an Oris Worldtimer, which is not really a Worldtimer, & operates in a different way to all the others. It has a separate sub-dial at 3 for the home time, while push buttons at 4 & 8 shift the main hour hand forward & back, and for the same reason I mention above with the Tudor GMT, it fabulously practical when travelling.

Image

There may be other variants out there, and if there are, I’d be fascinated to hear how they work.
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Re: Dual Time vs GMT

Post by downer »

When I was travelling for work, the watch that always appealed tome was the JLC Master Hometime...

Image

The blue second hour hand shows ‘hometime’ on a 12 hr scale, while the main hour shows local. Hometime is also shown on a 24 hour scale on the upper subdial. When you are in your home time zone, the second hour hand is hidden behind the main hour hand.
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Re: Dual Time vs GMT

Post by jkbarnes »

downer wrote: Tue Jul 14, 2020 10:35 pm When I was travelling for work, the watch that always appealed tome was the JLC Master Hometime...

Image

The blue second hour hand shows ‘hometime’ on a 12 hr scale, while the main hour shows local. Hometime is also shown on a 24 hour scale on the upper subdial. When you are in your home time zone, the second hour hand is hidden behind the main hour hand.
That’s a real beauty, and a rather elegant execution of dual times.
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Re: Dual Time vs GMT

Post by jkbarnes »

0uatiOW wrote: Tue Jul 14, 2020 9:53 pm I’m a little late to this but I have a small collection of travellers watches & they are my most used variety because I travel a lot for work, or at least I used to.

When I hear “dual time watch”, I think of a watch with a rotating 12-hour bezel or a chapter ring, which is offset so the main hour hand points to a different timezone. The Magrette Dual Time mentioned by AVO is an example, but any watch with a moving 12 hour bezel will do the same thing. I’ve blagged one of Gary’s pictures below (credit where it’s due).

Image

GMTs usually have an extra “GMT” hand - usually red, orange, yellow, even blue, which can be set independently to point to any hour, but moves at half speed (1 full rotation per 24 hours), therefore tracking a second timezone. Many GMTs, including the CW C60 & C65 versions, and the Zelos below, use ETA or Sellita movements, which allow the GMT hand be set independently.

Image

A better design, in my opinion is to allow the main hour hand to be set independently, which is how the Rolex GMT Master (I think) & the Tudor BB work. This is a lot more practical if you are on the move. I use the Tudor when I travel long haul with connections in different places, because I can easily set the main hour to local time.

Worldtimers are different again - they are meant to easily show the time in any timezone in the world. They usually have a rotating inner bezel showing the names of different (sometimes relatively little known) cities around the world. By setting the GMT hand to, errr, GMT, & aligning the target city on the inner bezel to 12, the GMT hand should show the time in that city. On this Bremont you can see that it’s just after 9pm in the UK, and just after 3pm in Chicago (this watch also operates as a traditional ETA GMT).

Image

The key is that the inner bezel should rotate. If my memory serves me correctly, the CW C65 Worldtimer doesn’t have a rotating bezel, but I haven’t handled it so I’m not sure exactly how it works.

There are versions of Worldtimers which use different displays - CW makes one with a map of the world and little red dots, though I don’t really understand how it works.

I also have an Oris Worldtimer, which is not really a Worldtimer, & operates in a different way to all the others. It has a separate sub-dial at 3 for the home time, while push buttons at 4 & 8 shift the main hour hand forward & back, and for the same reason I mention above with the Tudor GMT, it fabulously practical when travelling.

Image

There may be other variants out there, and if there are, I’d be fascinated to hear how they work.
Excellent and incredibly informative reply. Thank you!

That Oris Worldtimer seems like the perfect travel watch. I love it.
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Re: Dual Time vs GMT

Post by downer »

Had a couple of versions of the Oris “Worldtimer” myself - back in the day...

Image
Image
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Re: Dual Time vs GMT

Post by monkeymax »

Some great examples in this thread! Here's an example that's definitely dual time rather than GMT!ImageImage
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