The Patek Philippe 5372 split-seconds chronograph and perpetual calendar, presented in 2017, follows on from the 2015 Patek Philippe 5370, a split-seconds chronograph with two conventional chronograph pushers. Like that model, the 5372 has a circular platinum case. The dial is completely different, with simple Arabic numerals applied onto a gold dial with blue sunburst pattern. The watch is compact, with a diameter of 38.3 mm. Patek Philippe haven’t specified the thickness but it looks to be about 13.3 mm. Water resistance is 3 atm. Even though the movement is based on the CHR 27-525 PS, which is the world’s thinnest monopusher split-second chronograph movement with column wheel (5.25 mm thick), the CHR 27-525 PS Q calibre powering the new 5372 is 7.3 mm thick as a result of the additional perpetual calendar module. Patek Philippe’s movement designers minimized the thickness of this module, introducing certain technical innovations, two of which have patents pending.
Clarity and symmetry
Like the 5370, the 5372 is superb in the clarity of the dial. The extra space gained by abandoning the tachymeter scale was used to increase the diameter of the subdials. A brief tour: moon phase at 12 o’clock, accurate to one day’s deviation every 122 years, continuous seconds at 9 o’clock, and a 60 minute chronograph counter at 3 o’clock. This is large enough to make readings of elapsed times feasible. At 6 o’clock, a subdial for the date. The rectangular window at 9 o’clock shows the day of the week, the window at 3 o’clock shows the month. At 4.30 there is a small circular window showing the leap-year cycle with numbers from 1 to 4, 4 being the leap year, and at 7.30, another circular window with a day/night indicator. The dial is symmetrical around the vertical axis.
Monopusher chronograph, plus split-second pusher
The chronograph pusher on the crown is used to start, stop and reset the chronograph. The pusher at 2 o’clock is for the split-second function, which can be used for intermediate measurements such as a lap time. When the chronograph is running, pressing the pusher at 2 o’clock stops the split-second hand, while the chronograph hand keeps running. Once you have recorded the lap time, pressing the split-second pusher again returns the split-second hand to the chronograph seconds hand and they continue running together. The process can be repeated any number of times. It is important to reset the chronograph only when the chronograph seconds and split seconds hands are superposed. The crown is used just to wind the watch and to set the time, and the movement provides the stop-second function.
Care required in calendar correction
The platinum case has a distinctive concave bezel. The strap is in alligator leather with gloss finish, and a foldover clasp. Recessed pushers on the caseband are used to correct day of the week (8.30), moon phase (10.30), date (12.00), and month (12.30). A stylus is provided with the watch to make corrections. The leap year cycle is set by working on the months correction pusher. The date change operates between 10pm and 2am, while the moon phase changes between midday and 2pm. It is important not to adjust calendar and moon phase settings in those two time brackets. To avoid damaging the movement, Patek Philippe recommend setting the watch at a safe time such as 9am, and they also say that it’s best to wind it at the same time every day, taking care not to overwind.
The CHR 27-525 PS Q movement is hand-wound, with 476 components, 12 bridges and 31 jewels. The balance is relatively large, with just 2 arms and 8 poising weights. It runs at 21,600 vibrations per hour, 3 Hertz. Power reserve is minimum 38 hours, maximum 48 hours, without the chronograph running. The chronograph is operated by two column wheels, and new tooth profiles that reduce wear – so presumably it has a horizontal clutch. The movement can be viewed through the sapphire caseback.
The movement has the Patek Philippe Seal, a quality mark, which guarantees that the watch meets the brand’s own criteria regarding quality and performance. In terms of precision, it specifies an accuracy with a maximum deviation of -3/+2 seconds per day. This is double COSC and close to Rolex’s Superlative Chronometer certification.
The Patek Philippe 5372 split-seconds chronograph and perpetual calendar in platinum is a prodigious complication, with a price to match: 460,000 Swiss francs inclusive of 8% VAT. It is also available in a version with beige dial and glossy brown alligator strap. Same price. More information from the Patek Philippe website. Follow this link for a selection of perpetual calendar chronographs.