When we think of the GMT watch, we think back to the early days of international air travel. Those were somewhat daring days for civil aviation, when aircrafts were designed directly from World War II bombers with their powerful rotary engines blasting through the sky, whipping the nacelle and its contents along several intermediate stops before reaching the passenger’s ultimate destination.
Of course, the world has changed dramatically since then; air travel is now almost a commodity, with the growth of modern low-cost carriers. But the significance and purpose of our GMT watches have never changed, nor has their distinctive allure, which we’ll explore together.
What does GMT stand for?
GMT is a name given to the time zone that covers all or part of the globe and is based on English time originally established in 1884 by Greenwich Mean Time (GMT), which was derived from observations at the Royal Observatory in Greenwich, England. The boundary passing through Greenwich is used as a reference for determining all other time zones across the world, breaking the Earth into 24 “sections” that are more or less extensive (as some large countries use a single time zone, such as China).
The most prominent advocate of the importance of time zones and clock synchronization, however, was not an Englishman but a Scot. Sir Sandford Fleming, born in Scotland but a Canadian citizen, proposed a global system of time zones at several world conferences between 1879 and 1883, which was eventually authorized.
The Wright brothers’ first flights were still a long way off, but establishing a uniform, accurate timekeeping system was essential to keep the long-distance trains that linked North America’s cities running on schedule.
What is a GMT watch?
A GMT watch, unlike a regular timepiece, is a “tool watch”. It is designed to fulfill a certain need, such as divers watches intended to operate underwater. However, the aim of a timepiece with a GMT feature is to present you with the date in different time zones at the same time using the same dial and movement, which is extremely useful for international travelers, pilots, and aircrews.
Traditional GMTs are generally automatic timepieces with a mechanical movement that is nearly indiscernible from a regular timepiece, except for the presence of the extremely modest additional hand tracking the hours.
GMT watches come in a variety of shapes, sizes, and styles, with many versions using a dual hour hand for timing. The majority of them utilize a double-hour hand for their operation, which is adjusted to two separate time zones.
Some of them include a useful 24-hour dial indicator rather than the conventional 12, such as with the Glycine Airman, the first GMT watch ever produced in 1953. This helps determine whether it’s day or night where we’re interested without having to perform mental calculations.
How does a GMT watch work?
A typical GMT watch has two hands for measuring hours, but is driven by a traditional watch movement. Every 12 hours, the normal one makes one revolution of the dial. In contrast, the GMT indicator is set to move at half speed in order to cover the entire dial in 24 hours. This allows us to quickly determine whether it is day or night in the time zone we have set as “base.”
There are some exceptions to the one-hour separation between time zones, the most common ones being India and Sri Lanka, which diverge by 30 minutes. In this case, the minute hand is needed in order to keep the right time. Some GMT watches feature a “tail” attached to the hand in order to indicate the exact minutes.
Some time zones, such as Nepal, Chatham Islands and Eucla, are tough to calculate with a standard GMT watch because their time zones are separated by 45 minutes.
Due to a rotating bezel with a 24-hour reference that can be set to show the time zone of interest’s reference time, certain GMT watches may calculate a third-time zone.
Before we go on, we must inform you that GMT watches exist in two types: those with an independently adjustable local time hand and those with an independently adjustable GMT hand. It may appear to be a minor distinction, but it is not.
The “true” GMT, created by Rolex, lets you adjust the hour hand to your location’s time. These are more difficult to come by and are costlier, and are often offered by the biggest brands like Rolex and Omega.
The second type is more useful for those tracking someone else’s time zone. These are commonly offered by ebauche-makers such as ETA, Soprod and Sellita, and thus are cheaper.
You may also buy a quartz analog watch with the GMT function from companies like Citizen and Luminox, which will serve you as well as a traditional mechanical movement and are considerably less expensive.
Is a GMT watch worth it?
A GMT is a good choice for those who travel often – for work or leisure – and who like sporty-looking watches.
Some of the most iconic GMT watches include the aforementioned Glycine Airman and, most importantly, the Rolex GMT Master, whose original version sported the famous red and blue “Pepsi” bezel.
A funny side note – the latter may sound like it is linked to the famous drink, but was actually commissioned by “Pan Am” airlines, whose colors were red and blue.
There are, of course, exceptions to this rule, like the dress watches offered with the GMT function by Jaeger LeCoultre and Grand Seiko.
For those who prefer a more refined look over the sporty watch, the world timer might be for you- it has a similar function to GMT watches with a more elegant exterior.
World timers are usually dress watches, created in the 19302 by Louis Cottier, who developed a time zone-tracking system through rotating discs. In 1932, Patek Philippe commissioned the first world timer watch, the historic ref. 3372.
How to use GMT watch?
It is not difficult to change or use a GMT watch, but you must follow a specific set of procedures.
Here is a step-by-step for a “Rolex-style” GMT:
- Pull the crown out to the outer position
- Set the GMT time zone reference
- Set the crown to the first position
- Adjust the date
- Turn the crown to the second position
- Set the time to the present time zone
If you have the choice of tracking a third time zone, simply work out how many hours away from the indicator’s reference time zone (i.e., GMT hand), and turn the bezel starting at 12 o’clock. If the extra time zone is East of the reference time, turn the bezel counterclockwise for the number of hours. If it is on the West side, rotate the bezel clockwise for the same amount of time.
For example, if the GMT hand indicates the time in Berlin and you want to calculate the time in Hong Kong (GMT +8), turn the bezel counterclockwise for eight hours.
It’ll be simple to figure out the different time zones’ timings at this point. The GMT hand will indicate the reference time zone, which will have a 24-hour indication; the time zone in which we are now located will have a “standard” 12-hour display; and the third time zone, if any, will be shown on the bezel.
The GMT watch has come a long way, and through its fascinating history, we’re transported back to a time of discovery and wonder. Today, in a world where space travel is becoming a norm, we can’t help but think about time zones and smile.