The mechanical diva on the stage of the Oris Big Crown ProPilot X Calibre 115 movement is the big kahuna itself: the extremely large mainspring visible at 12 o’clock, which provides more than 10 days of power reserve. And a fair bit more, which I will get to.

Oris Big Crown ProPilot X Calibre 115 (photo courtesy Anders Modig)

A common strategy for achieving extremely long power reserves – a really user-friendly feature for people who own several watches – is to have two spring barrels. But Oris opted for one big one instead.

And with the development of Caliber 110 first presented in 2014 in honor of the company’s 110-year anniversary, the Hölstein-based brand is now going “Full Monty.”

Back of the Oris Big Crown ProPilot X Calibre 115 (photo courtesy Anders Modig)

However, Oris’ “nudity” is a distinctly contemporary expression of skeletonization, an art form thought to have started with watchmaker André-Charles Caron around 1760.

“The object is not to achieve as much transparency as possible,” says Beat Fischli, Oris’ chief operating officer, regarding this twenty-first-century, hand-wound creation. Caliber 110 features a patented non-linear power reserve at 3 o’clock and small seconds between 7 and 8 o’clock.

“If maximum transparency was the goal, we would have made it, for instance, without the indications for the power reserve. No, what we wanted to do was to show the essentials and create a strong effect of depth and three-dimensionality.”

Oris Big Crown ProPilot X Calibre 115 front and back (photo courtesy Anders Modig)

The first challenge was to ensure structural stability after materials were removed. Early on in the two-year research-and-development process, Fischli and his team realized that they had to completely reinvent the mainspring itself.

“In the other [movement] versions –  Calibers 110 to 114 – we also have additional functions such as date disk and GMT, and in the skeletonized version with fewer wheels the mainspring was simply too strong,” he explains.

So he went back to the mainspring supplier, which he prefers not to mention by name. But a qualified guess would be that it is one of the two main suppliers to the Swiss watch industry, Generale Ressorts or Schwab-Feller.

In the end, the mainspring became the same length as in the movement’s previous versions – 1.8 meters – but a reduction of the thickness has lowered the torque by 15 to 20 percent.

Still, the movement, whose diameter measures 34 mm, gained in power reserve. “The official power reserve is still 10 days, but until the watch stops it is somewhere between 11 and 11.5 days,” Fischli says.

Oris Big Crown ProPilot X Calibre 115 on the wrist with the Matterhorn in the background (photo courtesy Anders Modig)

Chronometric performance diminishes after the 10 days. Within the first 10 days, precision is within C.O.S.C. chronometer realm, albeit not certified, and there is also anecdotal evidence of even better performance.

Fischli tells me of a colleague’s watch, which deviated by only 30 seconds after three months on his wrist. “Of course that doesn’t go for each and every watch, but it says something,” he proudly admits.

The supporting role to the mainspring is played by the patented, non-linear power reserve indication at 3 o clock. This 240-degree indication’s display is more even than one might think as the power reserve winds down, showing greater accuracy than a usual power reserve display would toward end of its winding period. This is thanks to two worm gears at the back of the movement, which are unusual mechanisms in a mechanical wristwatch.

Big Crown ProPilot X Calibre 115: a new expression for Oris

Not only is this skeletonizing expression new for Oris, so is the price tag above CHF 7,000 (CHF 7,200 to be exact).

Despite that, it has been extremely well received and according to the company is selling like hotcakes.

One of the reasons for that, aside from the product’s desirability, is that Oris has never made such a big effort on marketing. Oris does not aim to leave its core territory, one that has always been aimed at people who work and spend, but think before buying; this type of consumer likely must save to buy a mechanical watch.

I also imagine that this price tag attracts a segment of the market new to Oris – one that includes people who may think along the lines of “if it ain’t expensive, it ain’t worth it.”

Titanium clasp and bracelet of the Oris Big Crown ProPilot X Calibre 115 (photo courtesy Anders Modig)

Last but not least, the contemporary feeling of the Big Crown ProPilot X Calibre 115 also gets a boost from the materials: the case and well-integrated bracelet with double deployant clasp are made of titanium. An elegantly perforated leather strap is also available.

Oris Big Crown ProPilot X Calibre 115 (photo courtesy Anders Modig)

For more information, please visit www.oris.ch/en/watch/oris-big-crown-propilot-x-calibre-115.

Quick Facts Big Crown ProPilot X Calibre 115
Case: 44 mm, titanium
Movement: manually wound Caliber 115, 10-day power reserve, 3 Hz/21,600 vph frequency, patented non-linear power reserve display
Functions: hours, minutes, seconds; power reserve display
Price: CHF 7,200 / €6,900

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