Discover the charm of Sinn's pilot watches, the true essence of the "903" and "103"

Since its founding, Sinn has focused its development on pilot watches, and they are an important part of the brand's identity. Recently, new versions of the iconic 903 and 103 series were released, but what kind of evolution have they undergone? Let's explore the appeal of Sinn's pilot watches, the true essence of the brand, while answering these questions.

The ever-evolving navigation chronograph

　Sinn is a German watch manufacturer whose origins lie in the Helmut Sinn Spezialuhren (Helmut Sinn Specialty Watches), which was founded in Frankfurt, Germany in 1961 by Helmut Sinn, a pilot and flight instructor for the German Armed Forces. One of their most important and long-selling models is the "903."

　When this model was born in the 70s, the watch industry was undergoing a period of great change with the advent of quartz watches, and many watch manufacturers, especially in Switzerland, went bankrupt or were forced to sell their operations to other companies. The Sinn 903 was one model that was at the mercy of this changing times. Its origins lie in a classic pilot's watch, born in the 50s with an aviation-use circular slide rule on the bezel. When the Swiss manufacturer that developed it fell into financial crisis, Sinn purchased the design rights and the rights to supply parts such as the movement, allowing it to continue producing the 903.

　A rotary slide rule is an analogue calculator used by pilots and navigators when creating flight plans. As it is commonly called a "slide rule" in English, it is known for its style of performing various calculations by sliding two graduated plates, but in fact, the first slide rule developed in the 17th century was a rotary slide rule that performed calculations by rotating two graduated disks.

　The idea of ​​incorporating a circular slide rule on the outer periphery of a watch for calculations was first realized in pocket watches. Eventually, the era of wristwatches arrived, and in the 1940s, models incorporating circular slide rules into standard three-hand watches appeared. Next, models incorporating similar circular slide rules into chronograph wristwatches were developed, and these further evolved into full-fledged pilot watches in the 1950s, featuring high-performance three-dial chronographs with 30-minute and 12-hour counters and incorporating aviation circular slide rules. In other words, the Sinn 903 is the legitimate successor to the full-fledged pilot watches that were born in the 1950s.

　Since then, Sinn has continued to produce the 903 without interruption, but as it is a long-selling model that has been produced for many years, it has undergone changes such as changes to the movement and minor changes to the exterior. Among these models, one that is particularly memorable is the model equipped with a manual-wound Lemania chronograph movement manufactured in the 90s.

　A distinctive feature of the hand-wound models of this era is that the three subdials are located close to the center. This is a feature derived from the structure of the movement. Moreover, in addition to the standard 12-hour models, 24-hour models were also produced. A key feature of these models is that the top of the dial is at 12 o'clock noon, rather than 24 o'clock. This resulted in a unique style in which the hour hand indicated the daytime hours on the upper half of the dial and the nighttime hours on the lower half.

　The 903 later evolved into the 903 St. Auto, equipped with an automatic chronograph movement manufactured by La Joux-Perret, a movement manufacturer based in La Chaux-de-Fonds, Switzerland. This model featured a date window between the 4 and 5 o'clock indices and a rotating slide rule system that allowed calculations to be performed by rotating the inner bezel with the crown at the 10 o'clock position.

　Then, in 2024, the 903 underwent a major renewal, or rather a complete redesign, and was reborn as the "903.St.II" and "903.St.BEII" introduced here.

　The movement is the La Joux-Perret caliber LJP L110. The crown at 10 o'clock that was present in the previous model has been abolished, and the original style of operating the bezel ring itself for calculations has been restored. As a result, the bezel notches of the previous model were somewhat gentle, but the notches of the new version are deeper, making it easier to operate even with gloves on.

　It is also worth noting that the bezel can be operated smoothly while also achieving a high level of water resistance of 20 bar, making it safe to wear not only in everyday life but also in outdoor situations.

　Furthermore, the Arabic numeral at 12 o'clock, the bar indexes, and the hour and minute hands are made of hybrid ceramic containing a high concentration of luminous material. The three-dimensional indexes on this new dial emit a strong light as a whole, making them clearly visible not only from the top but also from the side, even at night or in the dark, achieving high visibility.

　The new 903, with its high level of functionality, faithfully inherits the genes of the base model that Sinn inherited from the 1970s, while aiming to step up to a higher level, making it a pinnacle of pilot watches.

The History of Sinn and the Pilot's Chronograph

　The "103 St. Ty. Hd" is a contemporary model that embodies the classic chronograph style that Sinn, founded in 1961, has been producing since its founding. This model features a "tri-compax" dial layout, with a 30-minute chronograph counter at 3 o'clock, a 12-hour counter at 6 o'clock, and a small seconds at 9 o'clock. Even in an age where automatic movements are commonplace, this model employs a manual-wind chronograph movement, a stubborn design in some ways. While automatic movements are certainly convenient—the mainspring is automatically wound and continues to operate upon wearing—the unique appeal of a manual-wind movement is that it allows for a stronger sense of connection between the wearer and the watch. Winding the mainspring with the crown before wearing a watch is an important ritual in the process of enjoying a watch.

　The attractively curved reinforced acrylic crystal further enhances the classic look of the 103.St.Ty.Hd, but upon closer inspection, you can see significant improvements in the new 103.St.Ty.Hd. One such improvement is the crown guard. Guards to protect the crown, arguably the most vulnerable part of a watch, were not available in the 1960s. Furthermore, the watch's specifications, including a power reserve of approximately 56 hours and water resistance and pressure resistance of 20 bar, meet modern demands.

　It's been about 20 years since Sinn last released a 103 series model with a manual-winding movement, so the 103 St. Ty. Hd, limited to 1000 pieces worldwide, fills that gap with a classic chronograph equipped with truly fascinating cutting-edge features.