Calibres 17-13 and 16-15 are two closely-related watch movements from Minerva. All measure about 17 ligne, though the modern Minerva changed their naming from “17” to “16”. This was also the base for chronograph Calibre 16 or 17, number 29.
Minerva created a series of 17 ligne calibres early in the 20th century. All measure 5.3 mm high.
This series varied mainly in their adjustments 6, 7, 9, 15, 23, and 24 had between 2 and 5 adjustments.
Calibre 17-13 was an ultra-thin hand winding calibre from Minerva, measuring just 4.15 mm tall. The basic design of Calibre 17-13 was also used in the other 17 ligne calibres, mentioned above. At 37.9 mm, Calibre 17 was large for a wristwatch at the time.
Cal. 17-13 was used in many famous watches, including Minerva's own 140th Anniversary model, as well as Sinn dashboard clocks and the limited-edition Chronoswiss Pocket Regulateur. It was the basis for Calibre 16-15 (see below) as well as chronograph calibre 17-29.
A 5-bridge variant of calibre 17-13, Calibre 17-22 was the highest standard for Minerva pocket watch movements.
On taking control of Minerva from the Frey family in 2000, the Minerva technical staff concluded that, although the old calibre design was still usable, it could not be produced with modern equipment. For this reason, the calibre was scanned and reconstructed in CAD for modern CNC machining.
Calibre 16-15 is a completely new version of Calibre 17-13 with little parts reuse. It has a diameter of 38.4 mm, has 18 jewels, and consists of 158 handfinished parts. It was used by Panerai (modified for small seconds at 9 00) as OP XXVII in their PAM 322, PAM 398/399, and PAM00521/22.