The Omega Marine Chronometer was the first quartz wristwatch ever to be awarded certified status as a marine chronometer. The watch was made by Omega SA and developed by John Othenin-Girard and is one of the most accurate non thermo-compensated production watches ever made, keeping time to within 1 second per month Introduction The watch was introduced to the market in 1974 under calibre 1511, having an unrivalled accuracy of 12 seconds per year thanks to the revolutionary 2.4 MHz quartz circuit. in 1976 the calibre 1516 Marine Chronometer was introduced with smaller case dimensions and altered movement, although performance remained the same, sales began in 1974 and the watch remained in Omega line up until 1978. Famous owners of Omega Marine Chronometers have included Jaques Cousteau and Eric Tabarly. Early development The first prototypes of the ‘1500 family’ quartz watch (which later developed into the Marine Chronometer) were presented at the Basel Fair in 1970 as calibre 1500, developed by Omega and the Battelle Geneva Research Institute. Known as the ‘Elephant’, there are rumored to have been only five examples of this watch made by Omega. The calibre 1500 ‘Elephant’ (known so because of the design of the movement with two large battery compartments resembling large ears) boasted an accuracy of 12 seconds per year, which equated to 1 second per month, five times more accurate than the beta 21 (the first Swiss production quartz watch) introduced to the market the year previous. The calibre 1500 was Omega’s first in-house quartz movement developed under project leader John Othenin-Girard by SSIH. The development of the calibre 1500 and subsequent successors cost Omega 30 million Swiss Francs with the sole intention to produce a wristwatch of unparalleled accuracy and performance. This significantly improved performance in time keeping was to be achieved by the development of a circular quartz resonator that vibrated at 2,359,356 times per second (a frequency of 2,359,356 Hz or ≈ 2.4 MHz), by comparison the Beta 21 quartz resonator (which as a watch had an accuracy of 5 seconds per month) vibrated at 8,192 times per second. The lenticular crystal oscillator in the calibre 1500, 1510, 1511 and 1516 was developed in the UK and used solely in the Megaquartz calibre 2400 series. The five calibre 1500 watches produced achieved the required 1 second per month accuracy through a stable (non thermo compensated) quartz resonator as part of