Set for the next 500 years - the perpetual calendar watch

 

IWC’s perpetual calendar displays the date, day of the week, month, moon phase, and year in four digits – and it will continue running perfectly with virtually no corrections until 2499. Developed by Kurt Klaus during the early 1980s, it made its debut in the iconic Da Vinci Perpetual Calendar in 1985. This ingenious mechanism developed under the code name “Operation Eternity” took IWC to the peak of haute horlogerie, and is regarded as a milestone in the art of watchmaking even today. Over the years, IWC’s engineers have continuously enhanced the original mechanism, developing perpetual calendar watches, for example, with a digital display for the month and day, or a double moon phase display. 

Drawing of Kurt Klaus’ Da Vinci Perpetual Calendar mechanical watch, 1983

Finding a new source of power

 

The Gregorian calendar is a hurdle for any young child: besides counting months of various lengths, the calendar adds a leap day every four years. A challenge for generations of watchmakers who have worked tirelessly to develop a mechanical calendar. The first such mechanisms that began to appear in wristwatches around 1930 were either unique pieces or produced in very small series. Moreover, they were quite complicated to operate because each display had to be set separately. These imperfections bothered IWC’s head watchmaker Kurt Klaus in the 1980s. At a time when electronic quartz watches flooded the world’s markets, he decided to push forward with the development of a mechanical perpetual calendar that would set new standards in terms of engineering, practicability and operation. His basic idea was to use the date mechanism integrated into the basic movement as a source of power, which at night would activate an entire gear chain and advance all the displays at once. A true revolution in the world of haute horlogerie. 

Progress through simplicity

 

The perpetual calendar was ready just in time for the presentation of the Da Vinci Perpetual Calendar (Ref. 3750) at the Basel watch fair in 1985. Its most striking new feature was the possibility to manually synchronize all its displays - which means that if the watch has been idle, the calendar can be advanced simply by turning the crown. No other perpetual calendar in history was so easy and convenient to operate. And for the first time ever, a perpetual calendar came with a four-digit year display. Another feature of the original perpetual calendar mechanism was the precise moon phase display which only needed manual adjustment after 122 years.

 

The perpetual calendar complication was featured in a number of iconic IWC haute horlogerie timepieces. The Grande Complication for the wrist (Ref. 3770), launched in 1990, is the 'smallest' and easiest to operate Grande Complication in the world. The development began in 1983 and lasted seven years. The result combines the perpetual calendar, the classical wristwatch automatic mechanism, the mechanical chronograph, a precise lunar phase display, an integrated striking mechanism, and the minute repeater, in one superlative watch: the Portugieser Grande Complication (Ref. IW377602). 

The Portugieser Grande Complication features a perpetual calendar  (Ref. IW377602)

Continuation of a legacy

 

In 1975, Kurt Klaus was entrusted with his first project. His task was to develop a calendar module for a pocket watch. The first prototypes followed. In 1977, the result was presented at the Basel watch fair, Reference 5500, a Lépine pocket watch with a calendar and moon phase display. Within its 18 kt gold case there was a 17 ligne gilded brass movement caliber 9721 with hand engraved bridges. Even at this time, Kurt Klaus had his own idea and deep desire: he wanted to create the “perpetual calendar” for the wrist.

 

The famous Il Destriero Scafusia (Ref. 1868), launched in 1993, is considered the 'warhorse from Schaffhausen'. In a movement with a diameter of just 35 mm, 750 individually manufactured and meticulously processed parts are at work. 76 jewels guarantee minimal friction and abrasion. 21 complex functions and displays are the result. The automatic wind-up was consciously omitted so that the exceptional beauty of the movement - protected by sapphire crystal - can be admired. All inscriptions and decorations on the case and movement are engraved by hand.

 

As the basic functional principles of the perpetual calendar have remained virtually unchanged since 1985, the mechanism itself can be found in a wide selection of current IWC timepieces that include further technical additions. For example, a digital display for the date and month can be found in the Aquatimer Perpetual Calendar Digital Date-Month Ed. “50 Years Aquatimer” (Ref. IW379403) and Ingenieur Perpetual Calendar Digital Date-Month (Ref. IW381701). Moreover, the further developed double-moon complication which allows for a view on the moon from both the northern and southern hemispheres are featured in the current models of the Portugieser Perpetual Calendar (Ref. IW503401 and IW503404).

 

Learn more about perpetual calendar watches made in Schaffhausen and discover the full collection.