How Do Mechanical Automatic Watches Work? What does Complications mean? What types of automatic watches exist?

Having discussed the essential components of a watch in our post here, let’s dive a little deeper and talk about what really drives the interest in luxury mechanical watches: complications.

Let's start by clarifying some definitions here. A mechanical (manual-wind) watch is not the same as an automatic watch, although an automatic watch is a type of mechanical watch. Think technology and how it advances. In the past you had to actually wind your watch every day if it wasn't battery operated, but with advancements in watchmaking, watch movements are able to wind themselves using body movement and storing the power from that body movement into a power reserve that lasts days, how many days depends on the watch features.

Essentially, a complication is any function that a watch performs beyond the basic telling of time. The most common one you’ll see is a date, but they range all the way up to sophisticated mechanisms that track all kinds of fascinating timekeeping elements.

As with anything, let’s start simple and work our way up.

Date

When most think of watches, the date is often a foregone conclusion. Its ubiquity makes it seem like something that comes along with the standard functions, but it is nonetheless technically a complication.

Fairly easy to implement, the date is a reliable and common complication that, at this point, needs little introduction.

Day and Date

Slightly more complicated than the date, the day and date combination is less common to see but still not surprising to encounter. It is often a welcome addition to the display, and many common models have day wheels that do double-duty, displaying the days in two different languages.

GMT

Getting into the somewhat more esoteric territory, this is often somewhat abstract to some users, especially those that rarely leave their home time zone. The simplest way to explain it is that watches with a GMT function have the capacity to track a second time zone, with some such as Rolex’s GMT model able to even do so with a feature to quickly calculate a third.

This is another one that is fairly simple to implement, with the most basic versions simply adding an extra hand that completes one rotation per day instead of two. They can get more complicated, as with the rotating disc set within the dial on the Rolex Sky-Dweller.

We should also note at this point that a number of complications such as this one are rarely seen alone, as they are often paired with a date if nothing else.

Chronograph

One of the key features that added usable day-to-day functionality to watches was the chronograph, or stopwatch. There were mechanical chronographs that were not linked to continuous timekeeping at all, but those are few and far between now, with precise timing of things like races and athletic events giving precedence to more accurate digital alternatives.

Nonetheless, the feat of creating a stopwatch synergistically melded with a timekeeping function was a huge deal in the watch world. Even today, mechanical chronographs are some of the most popular models, with many such as the Audemars Piguet models being incredibly desirable.

In many cases, the chronograph function is synonymous with the identity of the model; the Rolex Daytona, for example, wears its racing lineage on its sleeve with the very name it took.

Dual Time

This is where things get a little more abstract. There are a number of different ways that dual time mechanisms can be applied to watches, with some individual nuances.

Technically, GMT would fall under a dual time function, but it is popular enough that it can be given its own category. But outside of that, there are some other applications.

The simplest would be two synchronized displays, often offset by a variable number of hours. This can take the form of one additional dial or a second hour hand on the main dial, or some watches such as Franck Muller’s Master Banker have two subdials that can display a total of 3 time zones simultaneously.

Related to this is the related “world time” complication. This often comprises the aforementioned extra hour display, but often also incorporates a display around the dial that gives the name of key cities in different time zones, allowing times to be set without necessarily knowing the hour offset for that area.

Alarm

This is another one that needs no introduction, but it is surprisingly rare to find in wristwatches. In a world of digital alarm clocks and smartphones, it makes some sense that there is not a strong drive to expend the resources and time to manufacture watches with the function.

That said, it is fascinating to see how the challenge of creating these mechanisms has been tackled by watchmakers in the past, as few complications are quite as necessarily aggressive in their functionality.

Repeaters

By contrast, repeaters are still considered to be very desirable. A repeater is a complication that, in the case of “hour repeaters” strikes the number of hours in the current time, “quarter repeaters” the hour and 15-minute increments past the hour, and “minute repeaters” unsurprisingly strike the hour and minute.

Due to the complicated nature of their design and the corresponding value that they command as a result, watches with repeater functions tend to be limited runs and exclusive to buy.

A related mechanism would be a “grande sonnerie”, which differs from a repeater in that it will strike the hours and quarter hours on schedule, rather than the repeater’s doing so when prompted by a button press.

Annual and Perpetual Calendars

Thought of as some of the highest expressions of watchmaking art, these are some of the most prestigious pieces.

An annual calendar consists of a mechanism that tracks the time, day, month, and has parts aligned to compensate for the different number of days in a month. An annual calendar is so named because, if kept running full-time, it only needs to be adjusted once per year, compensating for the 28 or 29 days in February.

A perpetual calendar, on the other hand, actually compensates even for this detail. Perpetual calendars, so named because they will never need to be adjusted if kept running, add to the annual calendar an additional tracker for the leap year cycle.

Some perpetual calendar watches simply use a subdial display with four quadrants–three standard years and one leap year–but some go so far as to display the year itself.

The good news is that as long as the watch never stops, it requires no intervention at all (other than regular service intervals). The bad news? Due to a calibration in the Gregorian calendar, the year 2100 will not be a leap year, so the watch will have to be recalibrated after that.

Is that the end of the list? Not by a long shot. The Vacheron Constantin 57260 tips the scales at a maddening 57 separate complications, some of which were designed exclusively for that piece. But this covers the basics that you are likely to see in the market. Beyond this, you get to novelty, commission, and special concept pieces…so keep an eye out and see how many others you can spot.