One of the most exotic Breguet watches in production today, the Marine Tourbillon Équation Marchante 5887 combines a tourbillon regulator, perpetual calendar, and running equation of time. Complexity aside, the watch is mechanically fascinating: the traditional complications within are executed in a modern and practical way.

The equation of time, for instance, relies on an open-worked cam produced via the high-tech LIGA photolithography technique. And the tourbillon cage is lightweight titanium with a silicon escapement, while the automatic winding is equipped with a peripheral rotor.

Breguet has now introduced a new version of the grand complication, in pink gold with a slate-grey dial. While it is mechanically identical to the two earlier versions – in platinum with a blue dial or pink gold with a silver dial – the new watch is striking and harmonious, shedding a bit of the sports-watch aesthetic of the Marine by way of the richer colours.

Being a facelift, the dimensions of the watch remain unchanged. It is still a massive 43.9 mm in width, though a svelte 11.75 mm high, thanks to the ultra-thin movement inside.

Like the movement, aesthetics across the case and dial are very much a blend of new and old. The case has the traditional fluted band, but is paired with modern integrated lugs.

Similarly, the dial is solid gold and decorated with traditionally-executed guilloche engraved with a rose engine, but in a modern, stylised wave motif.

In a nod to the age-old Breguet tradition of asymmetric dials, the chapter ring for the time sits slightly off-centre, and features applied pink gold numerals, matched with pink-gold hour and minute hands in a reimagined Breguet style, with the tips filled in Super-Luminova.

The perpetual calendar indicates the day, month and leap year in twin apertures, along with the date on a retrograde scale. But the core complication of the watch is the running equation of time – which means it shows apparent solar time in real time – indicated by an additional minute hand with a Sun-shaped tip. This is much more convenient as apparent solar time can be read instantly on the dial, instead of having to add or subtract the time difference shown on a conventional equation of time scale.

A special cam

While a regular equation-of-time watch operates with a cam and feeler, a running equation of time integrates a differential gear system, so the equation of time hand functions as a secondary, independent minute hand that shows the time according to the Earth’s movement around the Sun, which is not exactly 24 hours throughout the year. In fact, the apparent solar day varies by as much as 30 minutes from the conventional, 24-hour day.

The kidney-shaped cam attached to a sapphire disc

The secret behind the equation of time display is visible at five o’clock, together with the tourbillon. Within the aperture, the cam for the equation of time is mounted on a sapphire disc engraved with letters representing month of the year.

The current month is indicated by a jewel-tipped feeler that traces the inner perimeter of the kidney-shaped cam as it makes one revolution a year. The kidney shape of the cam approximates the elliptical orbit of the Earth around the Sun, so the motion of the feeler results in the equation of time display.

Right behind the cam, mounted on the same axis, is the tourbillon with its titanium cage that contains a silicon hairspring, escape wheel and pallet fork. Thanks to these lightweight components, the movement manages an 80-hour power reserve despite its relatively high frequency of 4 Hz.

The bridges, barrel and peripheral rotor are all hand-engraved

The movement inside is the automatic 581DPE, which is derived from the ultra-thin tourbillon movement found in the Tourbillon Extra-Plat 5367.

Its height is made possible thanks to various features, including a barrel mounted on roller bearings instead of a traditional pivot as well as the narrow, peripheral rotor with a platinum weight, rather than a conventional full rotor on the top of the movement.

The peripheral rotor with its inner toothed edge and engraved platinum weight

Key facts and price

Breguet Marine Tourbillon Équation Marchante 5887
Ref. 5887BR/G2/9WV

Diameter: 43.9 mm
Height: 11.75 mm
Material: 18k rose gold
Water resistance: 100 m

Movement: Cal. 581DPE
Functions: Hours, minutes; equation of time; power reserve indicator; perpetual calendar with retrograde date
Frequency: 28,800 beats per hour (4 Hz)
Winding: Automatic
Power reserve: 80 hours

Strap: Alligator leather with folding clasp

Availability: To be announced
Price: US$215,000, or 309,000 Singapore dollars