Watch Complications: The Dual Time Zone
The dual time zone allows the wearer of a watch to see at a glance the time in another part of the world. Generally, both displays are powered by the same movement, but there are still variants within the genré, a few of which I will explore here.
Watches with a true GMT function have two hour hands. The first hand is the regular hour hand which travels twice around the watch face in 24 hours and is used to tell the time in the normal way. It can be adjusted independently of the second hour hand. The second hour hand is the GMT hand and this hand travels around the watch face only once in 24 hours. When the regular hour hand is adjusted to reflect an alternative time zone, the GMT hand remains pointing at Greenwich Mean Time. Alternative time zones can be calculated by adding or subtracting hours from this GMT hand. (In reality, most people set the GMT hand to a time zone of their choice other then GMT.) Many GMT watches also have a rotating bezel which, when marked correctly with a GMT scale, can be used, with a little calculation, to track a third time zone. An example of such a watch is the Rolex GMT Master.
Although this variant is called different names by different watchmakers, I think that the term Hometime describes it particularly well. With these watches, the second hour hand travels twice around the face in 24 hours just like the regular hour hand, but it can be hidden beneath the regular hand when not in use. When the wearer travels to another time zone, the regular hour hand can be adjusted independently to reflect the new time zone whilst the second hour hand, or hometime hand, remains where it is in order to track the time zone the wearer calls home. Examples of this watch include the Patek Philippe Aquanaut Travel Time and the Jaeger-LeCoultre Reverso Squadra Hometime.
World Time Zone
These watches allow the wearer to view the time across all of the world’s 24 time zones at a glance. Generally they feature two bezels – an outer bezel listing the major cities in each of the 24 time zones and an inner bezel marked with a 24 hour display. The outer bezel is set by the user whilst the inner bezel rotates once in 24 hours. An example is the Girard Perregaux Traveller WW.TC, the Financial version of which is illustrated above.
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