In the era before electronic timekeeping, fighter pilots relied on mechanical navigation clocks on their instrument panels known as navigationsborduhr, or NaBo for short.
Sinn got its start making instruments and watches for pilots and planes, and one of its earliest products was the NaBo 17 ZM made for the Tornado fighters of the Luftwaffe in the 1970s (which remain in service today). Now Sinn has reimagined the NaBo 17 ZM for the wrist, creating the 717, a massive chronograph powered by the proprietary SZ01 movement.
The historical basis of the 717 is impeccable, and Sinn has managed to translate much of the cockpit clock feel into the wristwatch, right down to the details like the “pump” pushers and knurled crown that resembles those on the NaBo 17 ZM.
The 717 is impressive in the manner that most of Sinn’s “tool” watches are – it is perfectly legible and the case is virtually scratch-proof – but it also seems way larger than necessary. At 45 mm by 15.3 mm it is massive on both counts, and will probably feel extremely chunky on the wrist.
Priced at a bit over or under US$5,000 depending on the strap, the 717 sits at the high end of Sinn’s offerings, but is priced similar to other watches with the SZ01 movement. It’s fair enough, though the size will not be for everyone.
Clock on the wrist
The dial of the 717 stays faithful to the NaBo 17 ZM, most notably with the extra-large, central hand in orange for elapsed minutes. It does have the addition of a date, which surprisingly blends in well with the instrument-panel look.
One reason for the thickness of the case is the height of the bezel – almost as wide as the case middle – which is required to accommodate its steeply sloped inner flange, exactly as found on the NaBo 17 ZM. Its adherence to the original’s design is admirable, but the result is an extremely tall case.
The case is steel that’s been treated with both Tegiment and a black hard coating, creating a surface that’s scratch resistant. Better known as the Kolsterising treatment for automobile parts, Tegiment diffuses carbon into the surface of the steel, giving it a hardness of several times conventional stainless steel. The hardness is then enhanced with a black ceramic-type coating, which is itself scratch proof.
Under the solid case back is the SZ01, a movement that began as a standard Valjoux 7750 but has been transformed by Sinn to have a central elapsed minute register. Also found in the EZM 1.1, the SZ01 allows Sinn to reproduce the dial layout of historical timepieces like the NaBo cockpit clocks and EZM 1, which featured central chronograph counters to maximise legibility.
Key facts and price
Diameter: 45 mm
Height: 15.3 mm
Material: Steel with Tegiment and black hard coating
Water resistance: 200 m
Functions: Hours, minutes, date, and chronograph
Frequency: 28,800 beats per hour (4 Hz)
Power reserve: 42 hours
Strap: Leather or silicon strap
Limited edition: No
Availability: At Sinn retailers
US$4,960 or €4,650 on leather
US$5,250 or €4,950 on silicon
Prices include national taxes
For more, visit Sinn.de.
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