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A Brief Guide on How Do GMT Watches Work?

A Brief Guide on How Do GMT Watches Work?

A GMT watch would typically feature additional hour hand to indicate other timezones. But, how exactly do GMT watches work? Check here!
May 02, 2024

When we consider the origins of global air travel, we recall the GMT watch. When airplanes were built directly from World War II bombers, their powerful rotary engines propelled them through the air, whipping the nacelle and its contents along several intermediate stops before arriving at the passenger’s final destination. Those were somewhat daring times for civil aviation.

Of course, a lot has happened since then; with the rise of contemporary low-cost carriers, air travel is now practically a commodity. But, the meaning and function of our GMT watches have not altered, and neither has their unique attraction, which we will examine together.

What is a GMT Watch?

A GMT watch is simply one that has a GMT complication, with complexity being any feature that the watch may perform in addition to telling time (in one time zone, that is). As a result, the Rolex GMT-Master adds a second, arrow-shaped hour hand to the dial and a rotating 24-hour bezel in addition to keeping 12-hour time. 

The second-hour hand was complicated underneath to only revolve once daily, as opposed to twice. Traditional GMT watches typically have mechanical movements that are essentially indistinguishable from conventional watches, with the exception of the inclusion of the incredibly minute extra hand that tracks the hours.

There are numerous different sizes, styles, and designs of GMT watches, and many of them use two-hour hands to keep time. The bulk of them operates with a double-hour hand that is set to two different time zones.

Some of them, like the 1953’s Glycine Airman, the first GMT watch ever made, includes a handy 24-hour dial indicator instead of the traditional 12. This eliminates the need for us to make any mental calculations to identify whether it is day or night where we are interested.

How Do GMT Watches Work?

A standard GMT watch uses a regular watch movement and has two hands for telling the time. The typical one rotates the dial once every twelve hours. To span the entire dial in 24 hours, however, the GMT indicator is set to move at half the normal speed. As a result, we can easily tell if it is day or night in the time zone we have selected as our “base.”

The most frequent exceptions to the rule that time zones should be separated by an hour are India and Sri Lanka, whose time zones differ by 30 minutes. The minute hand is required in this scenario in order to maintain accurate time. Certain GMT timepieces have a “tail” that is connected to the hand in order to indicate the exact minutes.

With a regular GMT watch, it is difficult to compute some time zones, such as Nepal, the Chatham Islands, and Eucla, because their time zones are separated by 45 minutes.

Some GMT watches may compute a third-time zone due to a spinning bezel with a 24-hour reference that may be configured to reflect the reference time for the time zone of interest.

The GMT watch comes in two varieties: those with an independently adjustable local time hand and those with an independently adjustable GMT hand. We must make this clear to you before we continue. Although it might seem like a small distinction, it is not.

The Rolex “true” GMT allows you to change the hour hand to reflect the time in your location. The top brands, like Rolex and Omega, frequently provide these, which are more expensive and harder to get.

For that keeping track of someone else’s time zone, the second form is more practical. They are frequently provided by ebauche manufacturers like ETA, Soprod, and Sellita, and as a result, are less expensive.

Additionally, you may purchase a quartz analog watch with the GMT feature from brands like Citizen and Luminox, which will perform just as well as a classic mechanical movement while costing much less.

Why GMT Watches Are Special?

For people who appreciate sporty-looking watches who frequently travel, whether, for work or pleasure, a GMT is a suitable option.

The aforementioned Glycine Airman and, most significantly, the Rolex GMT Master, whose initial model had the renowned red and blue “Pepsi” bezel, are among the most recognizable GMT watches.

Funny side notes: Although the latter may sound like it is related to the well-known beverage, “Pan Am” airlines, whose colors were red and blue, actually commissioned it.

Of course, there are exceptions to this rule, such as the dress watches produced by Jaeger LeCoultre and Grand Seiko with the GMT feature.

The world timer may be for you if you prefer a more exquisite appearance to the athletic watch because it performs similarly to GMT watches but has a more opulent design.

Louis Cottier invented world timers in 1932, which are typically dress timepieces with spinning discs for tracking time zones. The illustrious ref. 3372, the first world timer watch, was ordered by Patek Philippe in 1932.

Final Thought

We are taken back in time to a period of exploration and amazement thanks to the interesting history of the GMT watch. In the modern world, when space travel is becoming more common, we can’t help but smile when we think about time zones.

Read more: Watch Movement Types Explained: How Do They Work?

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