In 2015, the large digital date and month display becomes a dominant feature of the IWC Portugieser watch family. Limited to just 25 watches in platinum and 75 of each of the red gold editions, the new Portugieser Perpetual Calendar Digital Date-Month Edition “75^th Anniversary” is equipped with a wealth of sophisticated complications that are available in this combination only from IWC Schaffhausen.

The digital perpetual calendar is one of the outstanding technological advances made by the Schaffhausen-based watchmaking company. With the new Portugieser Perpetual Calendar Digital Date-Month Edition “75^th Anniversary” (Ref. 3972), the Portugieser watch family now includes a model featuring a digital display for the date and month. This exclusive timepiece packs a wealth of IWC watchmaking expertise into its 45-millimetre case: perpetual calendar, large digital date, leap year display, chronograph with flyback function and the IWC-manufactured 89801 calibre with its quick-action switch and efficient double-pawl winding mechanism. On the occasion of its relaunch to mark the 75^th anniversary of the Portugieser family, the watch is fitted with an arched-edge front glass and Santoni alligator leather strap and has an attractive new calibre design. The watch is limited to 25 pieces in platinum and 75 pieces each in 18-carat red gold with either a black or silver-plated dial.

The Portugieser Perpetual Calendar Digital Date-Month Edition “75^th Anniversary” makes allowances for the different ways of seeing things that have developed over the centuries: the dial combines two striking, highly legible analogue displays (time and chronograph) with three digital ones (date, month and leap year). Today, most people prefer to read the time with the help of hands but are happy if the date is shown in figures. This was not always so, as can be demonstrated by the example of the time of day. In 1884, IWC unveiled its first Pallweber-style pocket watches with a jumping digital display showing the hours and minutes. The watches were an enormous hit, but then, after just 3 years, the craze was over. When digital time displays were embraced on a massive scale with the quartz watches of the 1970s, the watchmakers in Schaffhausen stuck to their guns and continued to use hour and minute hands. And for a good reason: on a digital display, the abstract information contained, for instance, in “11:45” first needs to be mentally processed, whereas the spatial arrangement of the hands on an analogue watch is understood quickly and intuitively. It is, simply, “quarter to twelve”.

Just how intensively the designers in Schaffhausen have thought about our habitual ways of seeing things can be seen from the chronograph display on the Portugieser Perpetual Calendar Digital Date-Month “75^th Anniversary”. While considering whether there was a way to make the figures in the various subdials of a conventional chronograph easier to process, they hit on the idea of displaying the stopped hours and minutes in a totalizer – just like the time of day. The stopped seconds continued to be shown by the central seconds hand. From a design point of view this may seem ingeniously simple, but technically speaking it is very difficult to implement. To turn the “watch-within-a-watch” concept into reality, a team at IWC worked for 4 years on the in-house 89360-calibre chronograph movement with its particularly efficient double-pawl winding mechanism. In this assembly, four pawls arranged diagonally to the pawl wheel – in other words two sets of double pawls – convey the push-and-pull motion from the rotor to the barrel. This solution eliminates dead spots during winding and boosts the system’s efficiency by a significant 30 per cent. The further-developed in-house 89801 calibre is now used in the Reference 3972. Like its predecessor, it features an integrated flyback function that enables the user to reset the running stopwatch hands to zero simply by pushing the button, and to start another timing sequence immediately.

It is said that some proud owners of an IWC timepiece equipped with the Perpetual Calendar Digital Date-Month movement put the complex mechanics of their watches to the test on New Year’s Eve by starting the chronograph just before midnight. Precisely at the moment that the new year begins the entire dial is set in motion: six hands advance slowly while two large display discs and a smaller one also move forward with a distinctive and (due to the commotion caused by celebrations) barely perceptible click. Despite this tour de force of precision mechanics, the interplay between the complications does not affect the precision of the movement, even if there is hardly any more tension in the spring. Where does the IWC-manufactured 89801 calibre get all this power? The secret is a second source of energy, the so-called quick-action switch. Every night, when the date display moves forward, the switch siphons off a little of the energy, stores it and then discharges it precisely at the end of the month or year when, in addition to the date and month disc, the leap year disc also needs to be advanced. The perpetual calendar can be set easily using the crown. It will not require correction until 2100, a year that breaks with the conventional 4-year cycle and will not be a leap year. The see-through sapphire-glass back provides a view of the meticulously finished movement consisting of 474 individual parts. Following further development, the IWC-manufactured 89801 calibre now has a number of new features: the rotor and the inset “Probus Scafusia” medallion are now slightly more delicate in design and made of solid red gold. Other new highlights include the decorative blued screws, which together with the red jewels and the Geneva stripes on the plate constitute an attractive ensemble.

Movement	:	IWC-manufactured
Calibre	:	89801
Frequency	:	28,800 A/h / 4 Hz
Jewels	:	51
Power reserve	:	68 h
Winding	:	Automatic
Glass sapphire	:	Arched edge, antireflective coating on both sides
Water-resistant	:	3 bar
Diameter	:	45 mm
Case height	:	16.5 mm
Features	:	Mechanical chronograph movement Perpetual calendar Large, double-digit displays for the day and month Leap year display Stopwatch function with hours, minutes and seconds Hour and minute counters combined in a totalizer at 12 o’clock Flyback function Small hacking seconds See-through sapphire-glass back Rotor made of 18-carat red gold
Materials
Ref. IW397201	:	Case in platinum, silver-plated dial, blackalligator leather strap by Santoni, folding clasp in platinum
Ref. IW397202	:	Case in 18-carat red gold, black dial, dark brownalligator leather strap by Santoni, folding clasp in 18-carat red gold
Ref. IW397203	:	Case in 18-carat red gold, silver-plated dial, dark brownalligator leather strap by Santoni, folding clasp in 18-carat red gold
Limited edition	:	25 watches in platinum 75 watches for each of the two red gold references