The Rolex GMT is one of the most popular watches right now, with demand for them soaring sky-high. But not everyone knows how the GMT function actually works, nor how to use it.
We’ve already talked about the history of the Rolex GMT in a 3-part series (Part 1, Part 2 and Part 3 available using these links), but today we’ll go into detail on the technical side of things, how to regulate it, and how to use the modern GMT function.
Setting the time
With a Rolex GMT on your wrist – or any other GMT equipped watch for that matter – you can keep track of 3 different time zones. Although, if you don’t want things to get too complicated, you can also monitor just two.
First things first, let’s go through all the components that go into the GMT function:
- The crown
- The bezel
- Hour hand
- GMT hand
- The date
By pulling the crown out by gradual progressions, you can regulate and adjust the date, the hour hand (independently from the minute hand), and the hour, minute and GMT hand, respectively. This last crown position is the only setting which allows us to regulate the position of the GMT hand (normally in a different colour to the other hands for improved legibility).
Two Time Zones
Monitoring two separate time zones on a GMT is very straightforward.
With the fully-extracted crown (position 3), the first step is to set the GMT hand to the local time. This is to be done on a 24-hour format, so for example: if it’s 5pm where you are, set the GMT hand to the “17” position by using the graduated bezel for reference. Then, push the crown in by one click (position 2) and set the regular hours hand to the same position as the local time, but using the regular 12 hour scale.
Now, all that’s left to do is to rotate the 24-hour bezel by adding or subtracting the number of hours your different time zone is in. For example:
If the second time zone that you want to keep track of is 5 hours behind your local time, you will need to rotate the bezel clockwise by 5 “clicks”. Now, the GMT hand should point to the time in your desired second time zone.
Pretty easy, right?
Three Time Zones
The first step is to set the GMT hand to the “true GMT”, or the actual time in Greenwich, England. In fact, GMT stands for precisely this: Greenwich Mean Time (if you’re in London, I highly suggest you go check out the museum there!).
Then, using the second crown position, adjust the regular hour hands to the local time. Using an example: the local time in Rome is 5pm (1:00), so in order to keep track of 3 time zones, you will want to first adjust the GMT hand to 4pm (16:00) and then set the local time.
After having adjusted the GMT and local time, we rotate the bezel the same number of clicks as you did before (or however many forward or behind as you please), so that the GMT hand is now your second time zone. Now, you can read:
– Local time (with the regular hour hands)
– Second time zone (by reading off the hour on the bezel that the GMT hand points to)
– GMT time (by remembering how many clicks forward or back you have done you have done)
You can also set the GMT hand to another time zone, which we can use as your “home” time zone, and not the local time, but it’s less common. In doing this, the bezel will indicate the time in the “third” time zone, and would need to be adjusted accordingly.
Using the GMT hand as your “home” time and the regular hour hands as the local time, it might occur that the date displayed is different to the date in your “home” time. This all depends on the different combinations of time zones!
Bonus: GMT as a compass?
If you position both hands (regular hour and GMT) to the “same local time” (as in: if it’s 5pm where you are, set the regular hour hands to the 5 o’clock position and the GMT hand to the 17 o’clock position), you’ll be able to use it as a sort of compass!
By setting the watch as described above, place it flat (so that it’s “parallel” to the ground). Then, line up the regular hour hand to where the Sun in shining, and the GMT hand will point towards North!
Now that you know how the GMT function works, there just one small little detail that we have to make clear: the use of the GMT function win the context of Daylight Saving Time and Solar Time. Unfortunately, the GMT complication doesn’t know the difference between these two forms of timekeeping, so you’ll have to remember to adjust for them when you’re travelling. For example, you might find yourself in a time zone which is using “Summer” time, so you adjust for it. But, make sure you know whether or not the secondary time zone you want to monitor is also using that format, and then adjust accordingly.
All that’s left for you to do now is to have a go yourself! Take your GMT watch, set the time, and go explore!
Don’t have one? Well, there’s only one way to make that right….
-Translated by Patrick R.