The Rolex GMT embodies the classic definition of a tool watch –a watch designed for a specific purpose in mind. In the early 1950’s as jet propelled flight and the ability to cross multiple timezones in one sitting was becoming more ubiquitous and accessible, Pan American Airlines asked Rolex to produce a wristwatch that could track multiple timezones simultaneously.  Unveiled at Basel in 1954, the Rolex GMT brought functionality to the watch market that no other brand considered.  Utilizing a rotating bezel similar to the Submariner and the Turn-O-Graph, and a fourth hand that made a complete circle around the dial over a period of 24 hours rather than 12 hours, Rolex unveiled a technically simple yet clever way to track multiple timezones.

 

To understand how the Rolex GMT functions, one need to understand how Greenwich Mean Time (and hence “GMT”) works.  The earth is divided into 15 meridians, or one-hour timezones. As one travels east or west, local time differs.  Since 1767, the Greenwich Observatory in London acted as the starting point of world time, commonly referred to as the Prime Meridian, and in 1884 was referred to at Greenwich Mean Time or GMT.   First for ocean vessels, then military, and now air and spacecraft travel, GMT time is used world time such that 1200 GMT is the same globally without reference to local time.  Early sailing ships used GMT time to track latitude (or east / west travel) while circling the globe.  Using GMT as a starting point, timezones were created such that one did not need to change their clock or wristwatch for every 15 degrees of travel east/west.  The moniker GMT is now updated to Universal Time Coordinated (UTC) recognizing that the Prime Meridian spans several countries rather than one city in Europe.

 

 

The way the Rolex GMT functions utilizes a combination of the rotating bezel and the fourth 24-hour hand. The rotating bezel has 24 gradations signifying the 24 hours in a day.  The 24-hour hand points to the outer bezel and shows local time in a 24-hour format (eg. 1:00pm = 1300 hours). The original bezel was colored blue between 1800 and 0600 hours to signify nighttime hours, and red for the remaining daylight hours.  The red-blue bezel also signified Pan-Am’s corporate colors at the time. For pilots traveling among timezones, they would rotate the bezel triangle to the timezone they are in to indicate UTC/GMT time.  For example, Pacific Standard Time (PST) is UTC minus 8 hours, the pilot would rotate the triangle back 8 hours and the 12 hour hand would point to UTC time on the out bezel.

 

 

Rolex improved upon this design with the introduction of the GMT Master II by making the 12-hour hand independent of the 24-hour hand.  Making the 12-hour hand independent from the 24-hour hand brought the ability to track a third timezone, and allowed the pilot/traveler to adjust the 12-hour hand to local time, while keeping the 24 hour hand on UTC time.  Rather than using the 24-hour bezel to track UTC, the bezel could now be used to easily calculate a third timezone.

 

 

The Rolex GMT combines a rugged tool watch with elegance and refinements found in a boardroom or in a first class cabin. For years, the Rolex GMT was available with either a refined Jubilee bracelet found on the dressier Rolex DateJusts, or the a Oyster bracelet with expansion clasp found in the Rolex dive watch, the Submariner.  Current Rolex GMT models do not offer a bracelet option, but rather is fitted with a brushed Oyster bracelet with a polished center link found on the DateJust line.  Rolex developed a method to color their latest ceramic bezel inserts as homage back to the original GMT.  The Rolex GMT is a great watch with a fantastic pedigree worn by pilots, astronauts, movie stars, and CEO’s.  Strapping on a GMT is more than wearing a Rolex, but also is a visual testament to the history and provenance of a great tool watch.

– Sheldon Smith