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GMT Watch manual
1-anatomy of a GMT
2-watch reading a GMT
3-watch setting a GMT
4-watch tipsINTRODUCTION
Wrist watches with a dual-time reading are often linked with the military of the commercial field. They provide a convenient mean of coping with time zone change. Certain watches and chronographs do simply display time on a 24 hour scale, whilst other combine both 12 and 24 hour reading.
In the nineteen fifties, Rolex designed the GMT Master, which was the very first watch to feature a dual time complication showing home time on a 24 hour display and local time on an independent 12 hour display. The feature proved out to be very convenient and allowed the pilots of PanAM to keep track of their home time while flying across time lines.
Since then, established watchmakers such as Citizen, Seiko, Omega and Blancpain have adopted this display, making it the standard for dual-time wristwatches.
This page aims at explaining the benefits of the 24 hour watch with independent 12 hour reading. The few user tips can also be applied to any other 24 hour watch or chronograph.
ANATOMY OF A GMT WATCH
(1). SECOND HAND
(2). MINUTE HAND
(3). INDEPENDENT 12 HOUR HAND: like a conventional watch, displays AM and PM local time
(4). 24 HOUR HAND: usually arrow-shaped and red, displays 24 hour home time
(5). DATE WINDOW
(6). SETTING CROWN, three positions: screwed in/out, setting position 1, setting position 2
(7). BIDIRECTIONAL ROTATING BEZEL: when present, either features 24 hour markings, 360 degrees bearing, 60 minutes divisions or major cities namesThe watch pictured left is the GMT from Blancpain’s Trilogie, a remarkable shot by fellow watch enthusiast Mike Margolis
Similar watches are
-Without bezel: Rolex Oyster Perpetual Explorer II
-With bezel: Omega Seamaster GMT, Rolex Oyster Perpetual GMT-Master I, Rolex Oyster Perpetual GMT-Master II, Seiko Kinetic/AGS Flightmaster, Seiko Kinetic/AGS Landmaster, Seiko Kinetic/AGS Landmaster Southpole, Seiko Kinetic/AGS Landmaster Sagarmatha, Seiko Kinetic/AGS Pipin Ferreras, Seiko Kinetic/AGS Scubamaster, Seiko perpetual calendar
READING A GMT WATCH
This is the diagram we are going to use. The minutes hand, the 12 hour hand, the 24 hour hand and the date window are represented. (The second hand has been left out to keep the dial less busy)
Like on a conventional watch, the 12 hour hand rotates twice a day, displaying AM and PM time on the dial.
On a conventional watch, the hand would be showing 10:10. But one would not be able to tell if it were AM or PM time
The 24 hour hand rotates just once a day, pointing at the outer ring, or bezel. And by doing so, it helps to differentiate between AM and PM time.Here, the 24 hand points at 10:10 (10:10 AM), and not 22:10 (10:10 PM)
Reading the display might turn out to be quite tricky at the beginning, yet once one gets the hold of it, it becomes a child’s play:
As one can see, the 24 hour hand completes a single revolution, whilst the 12 hour hand rotates twice, successively displaying AM and PM time.
SETTING A GMT WATCH
Here lies the particularity of the independent 12 hour complication first used by Rolex, and now Blancpain, Omega and Seiko:
Pulled in setting position 1, the crown makes the 12 hour hand jump forward or backward without affecting the rest of the mechanism.
When crossing a time zone, the wearer can simply adjust the 12 hour hand to local time, whilst the 24 hour retains home time.
The date indication is also for local time, so it only changes when the 12 hour hand has completed two revolutions
Pulled in setting position 2, the crown moves the whole 3 hands forward or backward and hacks the second (except on the Blancpain, where the second doesn’t hack)TIPS (les trucs et astuces)
Using a GMT watch like a professional
It has been brought to my attention that aviation professionals and licensed amateur radio hobbyists use their 24 hour hand to display UTC time, or Zulu Time:
They set the whole watch on Greenwich Mean Time (GMT 0), and then set the independent 12 hour hand on local time
In our example, if it is 10:10 AM in New York (GMT -5), the whole watch must be set 5 hours forward to display the Greenwich Mean Time (GMT 0)
The independent 12 hour hand can then be set 5 increments backwards to display local New York time (GMT -5)After this operation, the independent 12 hour hand is no longer synchronized with the 24 hour hand, unless it is being set 5 increments forward
Using a third time zone
It is possible to use a rotating bezel with 24 hour subdivisions to indicate a third time zone:
Simply rotate the bezel by one increment, per hour or time zone.
– Rotate the bezel counter clockwise if the third time zone is Eastern to home time
– Rotate the bezel clockwise if the third time zone is Western to home time
Example: if home time is New York (GMT -5), and third time Paris (GMT+1), move it 6 increments counter clockwise (+6)
If home time is New York (GMT -5), and third time San Francisco (GMT-
, move it 3 increments clockwise (-3) Using the GMT display as a rough solar compass
This tip also applies to practically all the other watches equipped with a 24 hour hand. The wearer can use a 24h dial for approximate navigation anywhere between the Tropic of Cancer and the Arctic Polar Circle:
Important! Both the 12 and the 24 hour hand must be synchronized to display local time
Method 1: laid horizontally, the dial will head North if the 24 hour hand is pointed towards the sun
Method 2: if the 12 hour hand is pointed at the sun, the 24 hour hand will point North
The margin of error directly depends on the difference between local official time and actual local solar time. But one doesn’t need to get too much in the technical details for approximate urban navigation
(Source : http://fejack.net/misc/gmt24/gmt24.htm)
Revue de l’OMEGA Seamaster GMT :
– Revue Omega GMT
– Revue Omega GMTtoujour dans le Japonais :
Seiko flightmaster GMT Kinetic :
Citizen PORMASTER Eco-Drive Tough GMT (montre solaire)
comme toujour les japonais prolifqiue mais pas forcément des designer à la pointe, en fait je suppose que les meilleur chez parte travailler dans Pour les appareisl électronique (sony et autres) :
Citizen Eco GMT
Etonnant ce nom de flightmaster exploité par Omega et Seiko….
Super intéressant Dynamo ! Bravo !
A+
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Contraria contrariis curantur. (Les contraires se guérissent par les contraires).- ZEN a écrit:
- Etonnant ce nom de flightmaster exploité par Omega et Seiko….
Super intéressant Dynamo ! Bravo !
A+
Etonnant, et sûrement trés embêtant pour Omega qui n’a pas dû déposer ce nom…
…ce qui leur interdira sans doute toute réédition d’un successeur du fameux chrono de pilote, car je suppose que chez Seiko, ils n’ont pas oublié de le faire…
Il parait qu’omega a failli choisir « Chronomaster » à l’époque des choix de noms pour ses collections ( Speedmaster, Seamaster….) . Coup de chance pour ZENITH…mais j’ignore si du coté de Zénith il y a antériorité ou non .
A+
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Contraria contrariis curantur. (Les contraires se guérissent par les contraires).JAPY fait également un module GMT étanche.
La « 08 » est pétrie de qualités, dommage qu’elle n’ait pas le succès qu’elle mérite.
DIDC’est vrai , Japy semble avoir du mal à décoller . Il n’est pas facile de relancer une marque.
A+
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Contraria contrariis curantur. (Les contraires se guérissent par les contraires).Aller un petit sortie de l’étargie de ce topic
Les Enicar Vintages :
Enicar Sherpa Jet
Enicar Sherpa Guide 600
Dynamo (qui a un faible pour les GMT)
A noter qu’un nouveau calibre GMT va bientôt faire son apparition chez Vostok. Il équipera la nouvelle Vostok-Europe Gaz 14.
Mouvement Vostok 2432
Aiguille des 24H
Compteur des 24H
Par contre est que le mouvement a gangné la date rapide et le stop Seconde ?
Dynamo
- Dynamo a écrit:
- Par contre est que le mouvement a gangné la date rapide et le stop Seconde ?
Dynamo
Il ne s’agit pas du 2432 mai d’un mouvement équipé d’une deuxième aiguille des heures réglables indépendamment. A noter qu’il s’agit d’une première dans l’horlogerie russe.
Par contre,pas de date rapide ni de stop seconde à ma connaissance
Moi aussi, j’attends de voir ce gros défaut des dérivés du 2416b corrigé ( et de voir une VE équipée du 2612 racheté lors de la fermeture de l’usine Poljot).
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