Review: Edouard Koehn Legacy Rattrapante

0 0 Monday, 28 April 2025 Edit this post

Among the most fascinating complications in mechanical watchmaking, the split-seconds, or rattrapante, chronograph holds a special place. Unlike a standard chronograph, which times a single event, a rattrapante chronograph can measure two intervals simultaneously.

Two central seconds hands, stacked one on top of the other, start together, but thanks to an additional pusher, one can be stopped while the other continues running, allowing the user to record intermediate times (or “splits”).

When activated again, the split-seconds hand instantly "catches up" with the chronograph hand, hence the term rattraper in French, meaning "to catch up."

Due to the complexity of synchronising two hands so precisely, split-seconds chronographs are highly prized by collectors and enthusiasts. Historically, they were associated with timing events such as horse races, car rallies, or any situations where intermediate timings needed to be captured without stopping the overall count.

With its Legacy Rattrapante, independent watch brand Edouard Koehn presents a sophisticated interpretation of this prestigious complication, offering it in a limited edition of 50 pieces and pairing it with a Grand Feu enamel dial of exceptional visual appeal.

Following the launch at the end of September 2024 (our introductory overview can be read here), we had the chance to wear and test this captivating chronograph for a few days. We are now delighted to share our impressions and images.

Characterised by classic lines and polished surfaces, the round case measures 40 mm in diameter and 14.60 mm in thickness, including the two double-sided, anti-reflective sapphire crystals (or 13.10 mm without them).

Crafted from 316L stainless steel, the case features rectangular pushers at 2 o’clock and 4 o’clock for the chronograph functions, while a third, coaxial with the crown, activates the split-seconds function.

Thanks to its curved lugs and compact diameter, the watch sits comfortably and elegantly on the wrist.

Don’t be deceived by the numbers. Despite the 14.60 mm thickness, the Legacy Rattrapante feels notably slimmer. The rear sapphire crystal sits snugly against the curve of the wrist, preventing any increase in perceived height. From the side, the case and lugs follow the wrist's natural shape, creating a refined aesthetic.

For reference, the wrist shown in the photographs is 17.8 cm / 7 inches in circumference.

Protected by the raised glass-box sapphire crystal, the dial of the Legacy Rattrapante faithfully reproduces the layout used in a split-seconds pocket watch produced by the brand in the early 1900s. In fact, this sophisticated chronograph complication was often featured in the production of Edouard Koehn (1839-1908), a recognised master in the creation of these complex mechanisms.

Edouard Koehn 1900’s split-seconds chronograph

The instantaneous 60-minute chronograph counter, with its small red hand, is positioned at 12 o’clock and is visually balanced by the small seconds sub-dial at 6 o’clock.

Two second-hands are positioned one above the other: the red hand runs continually whenever the chronograph function is active; below it, the blue one can be momentarily halted at the push of the crown-coaxial button. By pushing it again, the split-seconds hand instantly "catches up" with the red chronograph hand.

The dial’s appeal is enhanced by the centuries-old Grand Feu enamel technique, which imparts a luminous, immaculate white surface designed to preserve its radiance and vibrancy for generations.

This traditional craft, perfected by watchmakers since the 15th century, involves meticulously applying a fine powder composed of silica, metallic oxides, and potassium onto the dial’s metal base. The two are then fused together by firing at an intense temperature of around 840 degrees Celsius (1,544 degrees Fahrenheit), creating an exceptionally resilient finish.

The term "Grand Feu" refers to the extreme temperatures, which ensure the enamel’s outstanding durability and richly saturated colour.

Once the enamel surface is complete, the Breguet numerals and inscriptions are carefully transferred onto it and permanently fixed by a final firing.

Legibility is enhanced by a clear chromatic hierarchy: black for the hours and minutes poire-shaped hands, red for the chronograph hands (central seconds and 60-minute counter at 12 o’clock), and blue for the rattrapante hand, all standing out sharply against the luminous dial.

Completing the dial’s precision-driven design, the outer minute track is divided into four segments per second, matching the 4 Hz (28,800 vibrations per hour) frequency of the movement. This layout allows for more accurate readings when stopping the chronograph seconds hand.

The 5 minute intervals are highlighted in red.

Visible through the transparent sapphire crystal caseback, the self-winding chronograph movement of the Legacy Rattrapante was developed in collaboration with Concepto, a specialist in high-end mechanical calibres.

Based on the legendary Valjoux 7750, celebrated for its toughness and proven performance, this calibre evolves the architecture by incorporating a dedicated rattrapante module.

The movement uses a cam-actuated mechanism to operate the start, stop, and reset chronograph functions, with additional cams, clamps, and levers to control the split-seconds function. Both the chronograph and the rattrapante rely on heart-shaped cams to ensure precise and simultaneous resetting.

Thanks to the strong torque of the 7750 base, the movement effortlessly drives the two large central chronograph hands while maintaining excellent timekeeping stability.

Chronograph engaged and disengaged (below)

This construction also enhances ease of maintenance, ensuring lasting reliability and performance.

Comprising 282 components, the movement features a chronometer-grade regulating organ and delivers a 48-hour power reserve. Decorative finishes include perlage, blued screws, solarised wheels, and Geneva stripes on the ball-bearing-mounted central rotor.

Paired with a Louisiana alligator leather strap secured by a stainless steel folding buckle, the new Edouard Koehn Legacy Rattrapante, ref. EK-CHR11SS-SL-WEEL-ASBK, is a limited edition of 50 individually numbered pieces (XX/50) with a retail price of CHF 15,800.

The Edouard Koehn Legacy Rattrapante is a remarkable chronograph, providing a pleasing wearing experience. Its Grand Feu enamel dial is visually captivating, blending classic elegance with rare craftsmanship. The exclusive split-seconds complication, combined with the watch's aesthetic appeal, makes the Legacy Rattrapante a standout in both design and function.

Limited to only 50 pieces, this timepiece offers compelling value, considering its high level of quality and features.
edouardkoehn.com