Sinn 903 vs Navitimer: Why It’s More Than an Homage

“Is the Sinn 903 actually a Navitimer?” I hear you cry.

Well—sort of. The full story involves a bit of a history lesson, tracing back to the original Breitling Navitimer and the dramatic twists the brand faced in the 1970s.

Back in 1952, Breitling introduced the legendary Navitimer, cementing its reputation as a brand synonymous with aviation. Not long after, the Navitimer was crafted specifically for the Aircraft Owners and Pilots Association (AOPA), helping it become one of Breitling’s most iconic models ever.

For a while, the Navitimer was basically Breitling’s golden goose. But those good times didn’t last forever. The 1970s brought the quartz crisis, hitting the Swiss watch industry hard — and Breitling was no exception. Staff layoffs followed, mechanical watch sales plummeted, and by 1979, parts of the company were liquidated, with Breitling’s doors closing temporarily.

After Breitling’s decline, the rights to the Navitimer were split between Sicura and Sinn. Sinn acquired the rights to the iconic Breitling 806 and 809 models, along with 500 cases and dials, eager to craft a pilot’s watch featuring the signature logarithmic scale and slide rule that made the Navitimer so legendary.

Meanwhile, Sicura continued producing watches under the Breitling name, holding the rights to both Breitling and Navitimer brands. Sinn, however, focused on advancing the Navitimer design with innovative technology—efforts that gained serious momentum when Lothar Schmidt took the helm in 1993.

Now, let’s talk about the Sinn 903 itself—specifically the 903 ST B E Navigational Chronograph. Since acquiring the rights to the original 806 and 809 Navitimers, Sinn has steadily refined this series, culminating in the modern 903 ST we know today. It’s an impressive piece, housed in a 41mm stainless steel case that proudly showcases the famous slide rule and logarithmic scale, packed with functions made possible by Sinn’s decades of technical innovation.

The case features a mix of polished and satin finishes, standing 14.5mm tall to accommodate the slide rule scale beneath a domed sapphire crystal with anti-reflective coating. The bezel’s grooved texture suggests it might be unidirectional, but all slide rule calculations and the internal rotating scale are actually controlled by the smoothly turning crown at 10 o’clock—a detail I discovered after poring over the detailed manual, which dedicates a whole section to mastering the slide rule functions.

But the real star is the dial. With an intricate, tool-watch aesthetic, the 903 packs the slide rule with logarithmic scale alongside three subdials designed for everything from mathematical conversions to calculating fuel consumption, speed, and distance. The chronograph function also lets you track elapsed time with precision.

Visually, the dial is a treat: a deep blue electroplated face with silver markers and counters that shimmer with a faint velvety texture. The ivory luminous coating on the hands and raised indices ensures excellent legibility and complements the blue beautifully. A date window sits discreetly at 4:30, colour-matched so it doesn’t interrupt the dial’s flow, while the seconds hand pops in white and red for quick, easy reading during calculations.

Flip the watch over, and the LJP 8000 self-winding movement is on full display through a sapphire caseback. It runs at 28,800 semi-oscillations per hour and includes a seconds stop function. The 903 ST B E also boasts anti-magnetic protection (DIN 8309) and is waterproof and low-pressure resistant to 100 metres (DIN 8310), making it as tough as it is functional.