These two complications essentially perform the same function but while the dual time, as the name suggests, allows the wearer to tell the time in two different time zones, the GMT can accommodate multiple time zones using a 24-hour rotating bezel. Both are perennial favourites with people who travel a lot and, indeed, it was the birth of the jet age that led to their development.
While no particular watchmaker is credited with the dual time complication, Rolex was the first to produce the GMT in 1954.
The dual time complication features two hour hands (a main and sub dial) to indicate the time in different time zones, which are displayed using the same movement. The second hour hand often runs on a 24-hour clock rather than 12 to improve ease of use. This usually involves adding two extra wheels to the mechanism. Alternatively, the second time zone is displayed using a 12-hour indicator paired with a day/night dial.
Patek Philippe Calatrava Travel Time 5134R
However, GMT watches, which come from Greenwich Mean Time (known today as Coordinated Universal Time, or UTC), always use a 24-hour scale to indicate the second time zone. They typically comprise a 24-hour track located along the bezel or outside of the dial, which can be fixed or rotating.
In both cases, the time zones are referred to as current time (where the wearer is) and home time (where the wearer is based). In order to tell a third time on the GMT, the bezel can be rotated however many hours difference between home time (or GMT +0, depending on its owner’s usage) and any given time zone to determine the exact time in that destination without having to set the watch.
Both complications hark back to the 1940s and 50s, when the need for such models was brought about by the rise in commercial air travel. As flying distances increased, and more flights traversed several time zones, pilots required a timepiece that could track GMT along with local time. Responding to this gap in the market, Rolex worked in partnership with Pan Am Airlines to create the original GMT watch. Launched in 1954, the Rolex GMT-Master featured a long hour hand that made one revolution around the dial every 24 hours and pointed to a bezel marked with 24 hour increments, as well as a short hour hand which could be independently set on a 12-hour scale to follow local time. This format was known as ‘true GMT’. For the first two years of production, the timepiece’s distinctive two-tone bezel was made of Bakelite. However, this cracked easily, so Rolex switched to aluminium instead.
Further improvements were made to the GMT-Master and it was eventually replaced by the GMT-Master II, which is still in production today. A simple arrow-tipped hand rotates around the dial once a day and points to home time, which is read off the 24-hour bezel. In the 1980s, the GMT-Master II 16760 became an instant smash with Rolex fans when an extra hand was introduced, so that the wearer could read three different time zones at once. It remains a firm favourite with pilots, frequent fliers, the US Air Force and NASA astronauts.
Each GMT-Master has its own nickname, taken from the 24-hour bezel’s different colour options, and has a loyal following of collectors, serious travellers and celebrities. The red and blue ‘Pepsi’ model, the inaugural GMT-Master, counts actors Orlando Bloom, Sylvester Stallone and 007 himself, Daniel Craig, among its famous fans. Its attractive two-tone bezel also comes in handy for telling day and night-time apart. The ‘Rootbeer’, which comes with a gold and brown bezel, is a favourite with David Beckham, Clint Eastwood and Ellen DeGeneres, while tennis legend Roger Federer favours the blue and black ‘Batman’ edition.
When choosing between a dual time or GMT watch, it’s important to know if the 24-hour hand can be set independently to a second time zone. And, if it doesn’t have a 24-hour hand, check if the second time zone is accompanied by an am/pm or day/night indicator because, if not, the watch cannot be reliably used to ascertain the time of day in a remote location. These watches may be dual times, but they do not qualify as GMT in the technical sense because Greenwich Mean Time respects a 24-hour format.
Patek Philippe ref. 5134R Calatrava Travel Time – A David Duggan favourite, this exceptional model is ideal for the people who have an aversion to conventional-looking travel time watches. At first glance it looks like a simple, straightforward Calatrava, until you press one of the two integrated pushers on the side to reveal a skeletonized third-hand which can be used to mark a second time zone (and then can be hidden again when superfluous to requirements).
Rolex GMT II Master – It would be wrong to exclude this iconic model from our list. Not only is this one of Rolex’s most popular model series for its fascinating heritage and sheer practical functionality, but the customisability of each model, with differing bezel editions (black/red ‘Coke’ dial blue/red ‘Pepsi’ for example) gives each one a sense of individuality and pride for those who wear them.
Tudor Black Bay GMT – Albeit a newcomer to the GMT scene, Tudor’s GMT offering was released at Baselworld in 2018 and caused quite a stir. Despite pulling from its older sibling Rolex’s GMT reference, the snowflake hand is a welcome departure – as is the more affordable pricing – while maintaining superb quality that you can expect from Tudor.
Find out which series GMT Master David prefers in your free copy of the David Duggan 35thAnniversary Guide to Complications.