Combustion engine devotees love to talk about the incredible ingenuity of the rotary engine. The interesting shape and motion of the rotary system are to visually-minded designers just as fascinating as a rotary engine’s advantages over standard piston-operated combustion ones. Fascinated by quirky yet circular movement patterns, this Behrens Rotary wristwatch is not the first time a mechanical watch display has been inspired by a rotary engine — though it is a particularly interesting and, for the style, affordable, manifestation of a rotary engine watch. Behrens originally released the Rotary watch in 2020.
I believe that the display of the Behrens Rotary is inspired by that of the C3H5N3O9 watch from 2013. Those are exceptionally rare (though I did get to wear one, and it was cool) and were produced as a collaboration between MB&F and URWERK. The Behrens Rotary continues this visual legacy with a high-end, but much more accessible, rotary engine dial from the innovative Chinese watchmaker.
The mechanism of the Behrens Rotary includes a base Swiss Made Sellita SW200-1 automatic movement. On top of that, there is a bespoke module produced by Behrens that creates the rotary engine time display. It even includes a date indicator window (that is easy to miss if you aren’t looking for it) and rotary engine-style hands for the hours and minutes. Even though the hands operate in full circular motions, the time is told on semi-circular scales at opposite ends of the dials. The three triangular tips of the hands are painted with luminant and serve as the indicator hands.
The quality and finishing of the dial components are impressively good and the mechanics seem to work well. Behrens uses all the same materials as similar watches from Switzerland including synthetic ruby palettes. The dial looks very cool, and reading the time this way is fun and not too difficult. One of the odder things on the dial is the style of the applied Arabic numerals. They are legible, and I love how they look, but for a watch that, to me, is at least contemporary, even futuristic, I feel a tinge of cognitive dissonance at the somewhat festive and ornate font.
Turn the watch over, and you can see the automatic movement through the sapphire crystal window. Keeping on theme, Behrens includes an automatic rotor that looks like the triangular rotary engine segment. The movement operates at 4Hz and, I believe, still has about two days of power reserve even with the added module system.
For the Rotary watch, Behrens chose a polished steel case that has a formal, but not boring, design. More so, it has a modern visual language, as opposed to a more retro-style case. I think I would have also liked to see a sportier or more “industrial” case to go with the “engine” theme of the watch. That said, there is still a lot of fun to be had wearing this watch. Especially since it is a very intentional artistic and mechanical expression by Behrens.
The finely polished and brushed steel case is 42mm-wide and about 14mm-thick. Much of that is thanks to the box-style sapphire crystal which also replaces most of the bezel. Without the crystal, the case is only about 8mm-thick, so when wearing it, it doesn’t actually look all that thick. The case is also water resistant to 50 meters and a lug-to-lug distance of about 51mm. Places on quick-release spring bars, the Rotary case has a black crocodile skin (nicely made with a soft calfskin liner) strap. Clearly, Behrens was going for a dressier look for this timepiece.
The C3H5N3O9 watch that this Behrens Rotary is based on is not only unavailable for the most part but also cost just under $200,000 USD if I recall correctly (and that was 10 years ago). Behrens creates a high-end and exclusive mechanical experience, but one that is not so stratospherically-price that it immediately alienates the majority of consumers. For that reason alone I appreciate that companies like Behrens are doing the very interesting work of democratizing some of the world’s more distinctive mechanical time displays and mechanisms out there. Behrens offers a satisfying answer to their question of “what if we made a rotary engine dial watch,” with this timepiece, and I think it deserves a strong look – especially by those who are particularly interested in the story of the rotary combustion engine. Price for the Behrens Rotary reference BHR022 watch is $4,955 USD. Learn more at the Behrens watches website here.
