Dr. Ito's thorough analysis of mechanical watches!! Vol.25 ~ What is the correct way to use a GMT Master? ~

Good evening everyone!

This column talks about mechanical watches from an engineer's point of view. This is the 25th installment.

"What is the correct way to use a GMT Master?"

I will be talking about this topic.

It is no exaggeration to say that the Rolex GMT-Master is as popular as the Daytona .

Its biggest feature is that it has the ability to display a second time zone (GMT function), and the successor to the GMT Master, the GMT Master II, can even display a third time zone.

However, we often hear people say, "I can set the second time zone, but what about the third time zone?" and it is true that many people do not know much about it. I also looked at the operation method again and thought that it was indeed complicated.

So, this time we will be using images to provide a detailed explanation of how to operate the GMT Master, so if you are considering purchasing the GMT Master or GMT Master II, be sure to read this as a reference.

How to use the GMT Master

First, let's talk about the GMT Master. The GMT Master has the following features:

• It has a hand called a "GMT hand" that indicates a second time zone or serves as a 24-hour hand.
• The "GMT hand" moves in conjunction with the hour and minute hands and cannot be moved independently.
• The bezel can be rotated either left or right.
• Equipped with a quick date change function (for model numbers with 5 digits or more).

With that in mind, let's dive right in!

The time in two countries will be displayed using Japan and New York (14 hour time difference) as an example.

Let's assume that the time in Japan is 10:00 a.m. In that case, it is 8:00 p.m. in New York (the previous day). First, align the ▼ on the bezel to the 12 o'clock position.

In this state, the GMT hand functions as a 24 hour hand.

Then set the hands to New York time.
New York is 14 hours behind Japan, so we will set the time back 14 hours.

The date went back to 8pm the previous day.

Then rotate the bezel by the amount of time difference.
Japan is 14 hours ahead of New York, so turn the bezel 14 hours "to the left."

It is important to note that the bezel rotates once every 24 hours, not 12 .

The hour and minute hands show the time in New York (8pm), while the GMT hand and rotating bezel show the time in Japan (10am).

Also, if you want to read the time in Japan using the hour and minute hands and the time in New York using the GMT hand, simply turn the bezel 14 hours to the right.

How to use the GMT-Master II

Next, we will explain how to use the GMT-Master II.

The GMT-Master II has the following features:

• It has a hand called a "GMT hand" that indicates a second time zone or serves as a 24-hour hand.
• Only the hour hand can be moved independently.

• There is no quick change function for the date. The date is adjusted by rotating the hour hand.
• The bezel can be rotated either left or right.

As before, we will use Japan and New York (time difference 14 hours) as an example to display the time in two countries. Japan time is 10:00 AM and New York time is 8:00 PM.

Align the bezel ▼ at the 12 o'clock position.
Next, check that the hour hand and the 24-hour hand (GMT hand) are pointing to the same time.

*In the photo above, the hour hand is pointing to 10 o'clock, and the GMT hand is also pointing to "10" on the bezel, which is the same time.

If they are not showing the same time, set the GMT hand to the 24 o'clock position, then rotate the hour hand to 0:00 a.m. Then advance the time to the current time to synchronize the time.

Next, set the hands to New York time. Since New York is 14 hours behind Japan, pull the crown out one notch to set only the hour hand 14 hours behind.

The hand points to 8pm and the date reverts to the previous day. The GMT hand points to "10" on the bezel, indicating the second time zone, Japan.
　
In addition, the GMT Master II can display a third time zone by rotating the bezel . Let's try displaying the time in Hong Kong in addition to the time in Japan and New York.

Hong Kong is one hour behind Japan, so turn the bezel one hour to the right.

Then you can read three times.

• The hour and minute hands indicate that it is 8pm in New York.
• If you look at the "GMT hand" in 24-hour format, it is 10:00 AM in Japan (read this from the position of the GMT hand, not the numbers on the bezel).
• Furthermore, the "GMT hand" and "24 hour bezel" tell us that it is 9:00 AM in Hong Kong.

It may have been a little difficult, but what did you think? I don't think you'll see the third time slot very often, but if you know how to use it like this, you'll be able to feel safe no matter where you go.

summary

What did you think?

The GMT Master and GMT Master II are difficult to understand when explained in words, but I hope that the explanation with images helps you understand. I hope you will take this opportunity to read this article over and over again and learn how to use them!

We hope that this article has been useful to you and has piqued your interest in luxury watches! If you have any questions, please feel free to contact us directly and we will answer them thoroughly. We look forward to your visit and inquiries.

Look forward to the next one! See you next time!