Reply With QuoteDoes this help http://www.gmtmasterhistory.com
Hi I tried googling but got lost so would appreciate if someone can tell me what it means ?
As in dommorton's post in white dials.
Just spotted the crown on the Seamaster GMT there sits tucked right in doesn't it Vs that of the non GMT models such as my 2254.50.
Thanks
Last edited by Robti; 24th April 2017 at 09:59.
Does this help http://www.gmtmasterhistory.com
It means a watch which can display multiple time zones simultaneously, be it through a GMT hour hand, or a GMT bezel etc
It means it has an extra hand that rotates once per 24 hours that normally tracks a 24 hour scale and can be used for following GMT time whilst the watch is set to another time zone.Originally Posted by Robti
Sent from my SM-N910F using Tapatalk
Thanks all for the helpful replies
Just for extra. Many refer to a true GMT (Rolex) and other 'not a proper' GMT (e.g. SINN UTC). The GMT has a 24h hand that you set and just leave - usually GMT but you can set as hometime - then through the crown you usually set the new time with the hour hand. A non-proper GMT has the same hand arrangements but the crown adjusts the GMT hand rather than the hour hand (in quick set intervals - not time setting). Small but subtle difference. e.g. going forward an hour - GMT, unscrew crown - pull out one position - one click and the hour hand is set, GMT stays same. Non proper - unscrew crown - set time position - wind forward an hour -set GMT hand position - then click it forward 23 hours (generally can only go forward as other direction is quick date set).
Last edited by Dazzler; 24th April 2017 at 11:17.
Great response.
Sent from my SM-G925F using TZ-UK mobile app
All good info above but I'd like to add that there's no "proper" GMT, there's one that's best for travelling (hour hand quick set) and one that's best for non travelling where you want to keep track of time in another country (GMT hand quick set). Each had their benefit depending on requirement.
Also, the extra hour hand can be 24 hour or 12 hour, the latter can be lined up with the main hour hand when not in use.
Never seen a GMT hand that can be aligned with the hour hand and stay in sync. The GMT hand by it very nature turns 360 degrees in 24 hours.
Sent from my SM-N910F using Tapatalk
GMT of course stands for Greenwich Mean Time...
Simon
The Rolex GMT Master gives you the best of both worlds, because you can leave the GMT hand on UTC (the name for the time in the GMT time zone; time zones are confusing), quick-set the hour hand if you travel, but also use the rotating bezel to track the time in some other time zone.
Which is an out-moded reference and is now referred to as UTC. I believe some also refer to Zulu time.
Sent from my F5121 using Tapatalk
I think JLC do some that rotate every 12 hours but have a day night indicator.
Indeed
Gmt is a time zone, UTC is not.
This.
"Greenwich Mean Time (GMT) is a term originally referring to mean solar time at the Royal Observatory, Greenwich where a system was first developed around 1850 for tracking time based on the rotation of the Earth. It is now often used to refer to Coordinated Universal Time (UTC) when this is viewed as a time zone.
Strictly speaking, UTC is not a time zone but an atomic time scale which only approximates GMT in the old sense. It is also used to refer to Universal Time (UT), which is an astronomical concept that directly replaced the original GMT."
Simon
And don't forget Worldtimers that show you the time in all the zones at once. If you're not familiar the blue/white 24h ring rotates overy 24 hours so just match the city to the hour next to it.
Last edited by Dazzler; 24th April 2017 at 17:29.
Most GMT watches can only handle 24 of the (current) 38 time zones although some bezels can provide adjustment for half-hour offsets. For travel to countries with a fractional offset a dual time watch can be more useful.
In reviews of the Seiko Astron , including the new LE announced after Basel, A Blog To Watch talk about the Astron being able to set to40 time Zones by GPS.
So are there now 40 time zones or are ABTW rounding up. Watchtime talks about 39 time zones.
Iran is currently on Iran Daylight Time, bringing it in line with Afghanistan on GMT +4:30 and removing a 39th time zone. At other times of the year it is on Iran Standard Time which is GMT +3:30.
I think that the Astron incorrectly lists an extra 40th time zone for Venezuela of GMT -4:30, 'Chavez Time', which no longer exists.
We had an intersting post on timezones recently - can't find it though.
It can't be easy for watches to keep up with zone changes.
Crimea, for example, is now on Russian (GMT +3) time - how does the Astron deal with such changes (if it does) where borders/zones change?
Last edited by Kingstepper; 24th April 2017 at 13:50.
They certainly do. I have a JLC with am/pm and 12 hour GMT hand. I like it because, as said, you can park the "home" hand behind the "local" hand and it looks just like a regular watch when at home.
You must have never looked at a Sinn UTC then. The GMT hand can be set to run in synch behind the hour hand to hide it when not in use.
F.T.F.A.
No I have never seen one, always willing to learn though.
Sent from my SM-N910F using Tapatalk
PP Travel Time models do that trick.
http://www.patek.com/en/mens-watches/aquanaut/5164A-001
http://www.patek.com/en/mens-watches...us/5990-1A-001
Not the best photo but you can see the skeleton hand which can be hidden behind the hour hand if required.
The Omega Seamaster GMTs of the 2000s did have a more shrouded crown, an odd quirk I find strangely endearing. Similarly they do not have a He-release valve, a huge benefit.
I have owned a black dial since 2007 and it is my favourite watch.
Didn't even spot the absence of the release valve.
I quite like that silly addition on my SMP though.
Wow so much to try and learn and I though a watch was just a watch
Now you have a handle on GMT watches next up is Sidereal Time .
Happy for you to explain this one to me after a bit of Googling as it is a bit confusing for my limited knowledge of astronomy.
"Sidereal time is the hour angle of the vernal equinox, the ascending node of the ecliptic on the celestial equator. The daily motion of this point provides a measure of the rotation of the Earth with respect to the stars, rather than the Sun."
See what I mean and that is someone's idea of explaining it !
Last edited by MarkO; 25th April 2017 at 11:54.
Try: Time zones. I never knew that..
'Sidereal' comes from the Latin word meaning star, so sidereal time is the time measured by the stars.
Imagine you want to measure one day, that is, one complete rotation of the Earth. How would you do it? One way is to fix the exact moment that a given star is directly overhead, and measure the time until this happens again. Because the stars are fixed in position relative to the Earth, on the timescales we care about, this gives you a very precise measurement for the time the Earth takes to rotate. This is called the sidereal day.
There is one star, however, which is not fixed in position relative to the Earth, because we're going round it: the Sun. Because we're going round it every 365 days or so, that means that every sidereal day, the Sun appears in a slightly different position in the sky. That means that if you chose to measure the length of the day by the appearance of the Sun at the zenith, you'll get a slightly different figure from the one you measured by the fixed stars. This length of time is called the solar day.
See Longines-Wittnauer Weems Second-Setting Watch Sidereal Model. Some more pictures: link. But you'll already know about that one, having started this thread: Weems.
Next up, the equation of time and the temporal hour system...
For the former, see here: http://forum.tz-uk.com/showthread.ph...inter-solstice
And for the latter, here: http://forum.tz-uk.com/showthread.ph...nese-Clock-Kit
Most mechanical watches can only display a second time zone providing the difference is in whole hours. Where the time zone is measured in incomplete hours eg India there generally is no way of adjusting this. I still love this complication though whether it works on a 24 hour scale like the Rolex GMT or with a second dial as with JLC Master Geographic.
You'd think the Indians would have come up with something, wouldn't you?
Good point although they might have to collaborate with Iran and North Korea :)
All wrong!!!!
GMT = 16:00 on Fridays Get Mullered Time
Posting Permissions
