New Model Press Release – Portugieser Perpetual

First off, let me state my personal thanks and those of all Timezoners to Messrs. Kern and Friedberg who so graciously allowed us access to these images and text well before the show launch.

Portuguese Perpetual Calendar

Pure craftsmanship in the Portuguese family

Around 70 years after the launch of the first Portuguese watch, and ten years after its reincarnation, IWC Schaffhausen has added a real highlight to the model range: the Portuguese Perpetual Calendar, Reference 5021. This watch uniquely embodies the manufacturing capability of IWC. It combines the company’s own 5000 calibre movement, which gets its energy from the renowned Pellaton winding mechanism, with the perpetual calendar and an entirely new moon phase display, the latest world-first to be patented by IWC.

Ingeniously simple, simply ingenious: the combination of two top designs

Once again, the watch designers at IWC Schaffhausen have brought the whole of their specialist knowledge to bear in the latest highlight from the factory in the East of Switzerland. Two outstanding designs are combined in the Portuguese Perpetual Calendar. The basis for the drive is the same large IWC automatic movement, with its Pellaton winding mechanism, seven-day power reserve and date, that does service in the Big Pilot’s Watch. Added to this is a perpetual calendar module, the principle of which is already familiar to watch lovers from the Grande Complication, the Da Vinci family of watches and the GST Perpetual Calendar.

The calendar functions are almost identical with those of the aforementioned models. The mechanisms have been increased in size, however, in line with the large Portuguese automatic movement. This also has a positive influence on the readability of the individual displays. Three hands tell the wearer the date (at 3 o’clock), day (at 9 o’clock) and month (at 6 o’clock), and these are kept company by the four-digit year display in a window between 7 and 8 o’clock.

Moon phase display: accuracy with

scarcely any room for improvement

It goes without saying that a moon phase display also belongs in an IWC with a perpetual calendar. Until now, this display has appeared in a crescent-shaped window in the dial, beneath which a disc with two yellow moons rotates. The moon is represented as it can be seen in the sky in the earth’s northern hemisphere. The designers at IWC were no longer content with this, however. They developed an entirely new representation of the moon phase, which now shows the position of the moon in both hemispheres. Of course, no time was lost in patenting this world-first.

This innovative type of moon phase display is made possible by a wristwatch design feature that is still unique to IWC. A disc with two opposing circular windows rotates above a yellow surface with two black circular areas of identical size lying in the horizontal plane. The result is two moon phase displays, which are not situated at a single fixed point, but are constantly in motion. Above the centre, the position of the moon can be seen as it appears to an observer in the night sky of the northern hemisphere, and below the centre, inhabitants of the southern hemisphere can find a true-to-side representation of the moon’s position.

This is not the only special feature of the display, however. The edges of the moon could be made larger thanks to the increase in available space, and improved accuracy was achieved by calculating new numbers of teeth The deviation in the Portuguese Perpetual Calendar amounts to one day in 577 years. This is unbeaten by any other mechanical wristwatch at the present time. As a comparison: the display often deviates after only 32 months in other current moon phase watches.

Astronomers have calculated that the moon requires precisely 29 days, 12 hours, 44 minutes and 3 seconds for one complete orbit of the earth. We know from experience that the moon disc in the majority of wristwatches has 59 teeth and two moons situated opposite one another. A watch of this kind accordingly takes precisely 29 days and 12 hours to complete a moon phase. The deviation of plus 44 minutes and 3 seconds adds up to one day over 32 months and is then reset, usually with the help of a correction button. IWC has dispensed with a button of this kind. The company is proud that its perpetual calendar is operated exclusively via the crown. Descendants who inherit a Portuguese Perpetual Calendar will only need to visit a watchmaker after 577 years, therefore, to have the moon phase display corrected.

Evolutionary stage number two:

the date disc drives the calendar

You will recall that IWC introduced the Portuguese Automatic 2000 to mark the change of the millennium, powered by the factory 5000 calibre movement. 1000 examples were produced in stainless steel, 750 in 18 ct. rose gold and 250 in platinum. These have all been in the hands of watch collectors for some time now. More than four and a half years of design and development work went into the 5000 calibre. The basis for further developments was established. The first evolutionary phase was presented by Schaffhausen two years later: the Big Pilot’s Watch with the 5011 calibre developed from the automatic 5000 calibre movement, which was modified from a decentral to a central second display and in addition received a date.

The date ring played an important role in the second evolutionary phase. Concealed under the dial, it gives the impulse every evening for the perpetual calendar to advance by one more day. It does this, as already mentioned, according to the same principle as in the Da Vinci. The two calendar modules are not completely identical, however. Whereas 82 individual parts are responsible for the correct calendar displays in a Da Vinci, a Portuguese requires 109. This additional expense is explained by the larger diameter of the watch, which among other things requires the use of a greater number of intermediate wheels.

Power plant: 50611 calibre with

a seven-day power reserve

The calendar requires extremely little power. The effects on the power reserve are negligible. The 5011 calibre is in fact more than capable of taking the load in its stride, as the extra-long mainspring stores energy for more than 200 hours. Nevertheless, the self-contained power reserve was restricted to 168 hours or seven days to avoid a fall-off in energy towards the end of the spring force curve and to maintain the escapement accuracy as constant as possible for the entire period. The necessary accuracy is also taken care of by, among other things, the escapement regulator with a screw balance, two adjusting snails and a Breguet balance spring borrowed from the legendary Pilot’s Watch Mark XI.

A design that has been in the patent file at IWC for a number of years ensures a steady energy supply. It was invented by Albert Pellaton, Technical Director of the factory from 1944 to 1966. The Pellaton winding system was used in such legendary watches as the Yacht Club or the Ingenieur and is today experiencing a renaissance in three models. The efficiency of this system remains unmatched to this day. The mainspring is tensioned by even the smallest movement by the wearer, because the mechanism transforms every movement of the rotor into energy, regardless of the direction of rotation. The movement is fully wound after exactly 1960 rotations of the rotor.

This is indicated externally on the power reserve display at 3 o’clock. The date display is also in this position in the calendar module, and both displays work concentrically. The remaining power reserve is indicated in the inner ring by a short hand, and the date can be read in the outer ring. Thanks to the large diameter, all the displays could be made larger and the readability improved.

The limited series of 250 watches in platinum is as elegant as the 18 ct. yellow gold variant with a silvered dial. The variant in 18 ct. rose gold with a black dial presents a rather more strongly contrasting appearance. The dial is protected by a slightly convex sapphire glass, which is retained by a mirror-finished, lightly stepped bezel. Real crocodile leather straps and closures in the same precious material as the case ensure that the watch stays securely on the wrist. If you take off the watch and examine the fascinatingly refined movement through the glass back, you will be aware immediately of what you are holding in your hand. The golden medallion in the rotor says it all: Probus Scafusia, craftsmanship made in Schaffhausen.

The watch is 44 mm wide and 15.3 mm high, and has sapphire glass on both the front and back due to a slightly different case design.