Although Abraham-Louis Breguet is best remembered today for inventing the tourbillon, he also helped to advance nautical navigation, with two milestones marking his work in this area. The first was his appointment to the Bureau des Longitudes in 1814. This French scientific body was interested in various practical applications of astronomy, including solving the Longitude Problem (like its English counterpart the Board of Longitude) by using accurate timekeeping to determine one’s position at sea. The second occurred the following year, when Louis XVIII issued an ordinance recognising Breguet as the chronometer maker of the French Royal Navy.

Breguet’s namesake brand today honours its founder’s place in nautical navigation with the Marine collection, which consists of sporty timepieces that hark back to the robust marine chronometers of yore. The brand has decided that the collection is due for an overhaul, and kicked this off with the Marine Équation Marchante 5887, which sets the aesthetic codes that future Marine timepieces will follow. Two major updates have been made: the case is now slimmer, although it retains features such as the bezel design and fluting on the case middle, and the lugs have been changed to central ones.

Breguet Marine Équation Marchante 5887

The Marine Équation Marchante 5887 sports multiple complications backed by an intricate design and superlative finishing, and kicks things off with the quintessential three-armed bridged tourbillon at five o’clock, inside an aperture that contains several other components (more on this later). Meanwhile, the timepiece also has a perpetual calendar, with a somewhat unusual display format that uses a window for the day of the week, a separate window for the month and leap year, and a retrograde indicator for the date. There’s also a power reserve indicator at seven o’clock.

Breguet Marine Équation Marchante 5887

Although the sapphire disc at five o’clock has the months of the year printed on its edge, it isn’t part of the calendar display. Rather, this component is for correcting the running equation of time display, and also bears the kidney shaped cam responsible for the complication. The equation of time shows the difference between a mean solar day, which is exactly 24 hours long, and an apparent solar day, which is defined by the time from one noon (when the sun is highest in the sky) to the next. The length of the apparent solar day varies due to the Earth’s tilted axis and eccentric orbit around the sun, and the apparent solar noon can arrive 16 minutes faster to 14 minutes slower than what a clock shows, depending on the time of the year. This variation is fairly constant though, and computing the kidney shaped cam to display this difference is easy.

Instead of merely using a sector that shows this difference in minutes, however, Breguet has opted to use the running equation of time here – the additional minutes hand, tipped by the stylised sun, tells the apparent solar time, and is read just like the main minutes hand. To create this, the solar minutes hand is driven by two sources linked via a differential gear. One is the main minutes hand, which drives the secondary solar minutes hand with its own rotation. The other is the lever that “reads off” the cam at five o’clock, to translate the “reading” into either an acceleration or retardation of the hand.

In terms of finishing and decoration, there’s also much to say. The dial features two types of guilloché – the “waves” pattern on the outer edge of the dial is a familiar sight, while the new pattern in the central portion of the dial, which Breguet also calls “waves”, is an entirely new development. The bridges and main plate on the back also feature extensive engraving, with a windrose motif on the barrel, and the Royal Louis, a vessel in the French Royal Navy, on the bridges. Other subtle details abound, such as the “Marine Royale” inscription on the flank of the tourbillon bridge. This is clearly the flagship for the refreshed collection.

Breguet Calibre 581DPE Specifications

Movement Self-winding Breguet Calibre 581DPE with tourbillon regulator, running equation of time, perpetual calendar, and power reserve indicator; 80-hour power reserve
Case 43.9mm in platinum; water resistant to 100m
Strap Alligator with gold deployant clasp

This article was originally published in WOW.