Inside IWC Schaffhausen’s record-breaking Portugieser Eternal Calendar

In the realm of luxury aviation watches, IWC Schaffhausen has earned itself quite the reputation, thanks to its use of ceramic and titanium, functional calendar complications and the iconic moon phase calendar.

As one of IWC Schaffhausen’s landmark features, moon phase calendars have been in circulation since 1985. Back then, the Da Vinci Perpetual Calendar Chronograph enjoyed a moon phase accuracy of 122 years, quite the feat. The brand would end up debuting its successor in 2003, the Portugieser Perpetual Calendar with a moon phase display, having an impressive accuracy of 577.5 years.

IWC Schaffhausen, nevertheless, continued to innovate. Hence, the recent introduction of the Portugieser Eternal Calendar with a double moon display. What makes this piece especially impressive is its moon phase accuracy, clocking in at a staggering 45,361,055 years. The mark would break the Guinness World Record for the ‘Most Precise Lunar Phase Wristwatch’ in the world, beating the previous world record by 43 million.

“The moon phase of the Portugieser Eternal Calendar exemplifies the culture of engineering and innovation we live every day at IWC,” Stefan Ihnen, associate director technics at IWC Schaffhausen, says of the recognition.

So how did the Maison achieve such a number for the timepiece’s moon phase accuracy? The answer lies in the Portugieser Eternal Calendar’s reduction gear train, which is placed between the base calendar module and the moon phase disc. This allows it to reduce the duration of one calendar month to the duration of one synodic month or the length of which the moon completes its revolution around the Earth.

There are also three intermediate wheels that make the timepiece formidable, effectively extending its functionality for longer periods of time. IWC engineers use a required precision manufacturing called the LIGA process. Here, they managed to create the wheels from unconventional manufacturing capabilities. Collectors, of course, can appreciate the movement through the sapphire crystal case back.

“From our apprentices and trainees to our most experienced watchmakers and engineers, we are continuously pushing the boundaries of what is possible in fine watchmaking,” Ihnen adds. “This record is a great recognition of their hard work and our watchmaking expertise.”

Take a closer look at this record-holder timepiece and visit IWC Schaffhausen for more information.

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