To the moon and back - iwc’s moon phase watches

 

Displaying the current phase of the moon on the dial of a mechanical watch may not sound like a big challenge. But in practice, it is complicated. The main difficulty lies in the fact that the moon does not follow an exact 24-hour rhythm. Generations of watchmakers have tried to display the moon’s orbit of 29 days, 12 hours, 44 minutes and 2.9 seconds as realistically as possible on the dial of a watch. The first moon phase watch at IWC was developed by Kurt Klaus as part of a calendar mechanism that was featured in the IWC pocket watch (Ref. 5500) of 1977, and was highly appreciated among watch aficionados. As a consequence, more pocket watches with moon phases followed. Later, Klaus developed the famous Da Vinci Perpetual Calendar (Ref. 3750), which also featured a moon phase, and became one of the Swiss manufacturer’s horological milestones. Since then, the moon phase display has held a fixed place in IWC’s perpetual calendar watches. In recent years, the charming complication has also been the star of IWC’s Portofino 37 watches, and of new ladies’ models in the Da Vinci family.

 IWC Da Vinci Perpetual Calendar moon phase watch (Ref. IW3750)

Première in the perpetual calendar

The Da Vinci Perpetual Calendar (Ref. 3750) from 1985 owed a large amount of its enormous success to its high-precision moon phase display. When working on his perpetual calendar mechanism during the 1980s, Kurt Klaus came up with a solution for the moon phase display involving a special wheel train. Thanks to an extremely precise reduction rate, it only needed a manual adjustment once every 122 years. The moon phase complication has had a permanent place in IWC’s perpetual calendar watches ever since. It has also progressed to new and even higher levels of precision; current models of the perpetual calendar have a moon phase display that uses a special wheel train with a reduction rate so accurate that it needs adjustment just once every 577.5 years – theoretically speaking.

Doubling up

Most moon phase watches display the moon as seen in the Northern Hemisphere. But what about watch wearers living in the Southern Hemisphere? This question motivated IWC’s engineers to develop a double moon display that was first presented in the Portugieser Perpetual Calendar (Ref. 5021) in 2003 – another first in the world of Haute Horlogerie. It depicts the moon as it appears in both the Northern and the Southern Hemisphere – so whether you are in London or Cape Town, in New York or Rio de Janeiro, your timepiece will always show you the correct phase of the moon. Today, this complication can be found exclusively in IWC’s perpetual calendar watches like the Portugieser Perpetual Calendar (Ref. 5034).

IWC Portugieser Perpetual Calendar moon phase watch (Ref. IW503401)
IWC Da Vinci Perpetual Calendar Chronograph moon phase watch (Ref. IW392101)

Simply unique

Before the launch of Kurt Klaus’ Da Vinci Perpetual Calendar, the moon phase watch had already made its first grand appearance in a wristwatch in the early 1980s: as a feature in the Portofino Reference 5251. With a case height of just 8.5 mm, it was the only wristwatch to offer a moon phase display as well as a pocket watch movement – the IWC-manufactured 9521-calibre, which was visible through a sapphire glass back. This "pocket watch for the wrist", with its outstanding horological features, was regarded as a successful symbiosis of excellent engineering and a bold yet unpretentious design.

Today, the moon phase is featured in a variety of timepieces for both men and women. The Da Vinci Automatic Moon Phase 36 (Ref. 4930) is one of two dedicated ladies’ models introduced in the 2017 Da Vinci collection, while the Da Vinci Perpetual Calendar Chronograph (Ref. 3921) resonates particularly well among watch complication aficionados. A moon phase star is the Portofino Automatic Moon Phase 37 (Ref. 4590), which primarily speaks to female clients. Combining poetry and aesthetics on the wrist, it shows the daily changing shape of the moon against a glittering, star-studded sky. The latest addition of a moon phase watch to IWC’s portfolio is the Portofino Hand-Wound Moon Phase (Ref. 5164), which pays homage to the first Portofino from 1984.

 

Learn more about IWC’s moon phase watches made in Schaffhausen and discover the full collection