Urban Jürgensen & Sønner Chronometer P8 Automatic - How Do You Solve A Problem Like .... The Detent?

The Urban Jürgensen & Sønner Chronometer P8 Automatic is a worthy nomination in the "Complicated Watch" category for the upcoming Grand Prix d'Horlogerie de Genève, yet face-on it is classical by design, more than a little Breguet-esque and exquisitely innocent.  But - this piece is powered by a highly unusual movement, one which features a Pivoted Detent Escapement, an arrangement which has no business being in a wristwatch at all, because it was devised to fit into something much bigger, and much more sedentary.  In fact, despite all the other technical advances, throughout modern-day wristwatch production, to place a Detent escapement inside the case of a wristwatch was considered to be impossible, futile even.


One impulse, less friction.

The Detent escapement was designed for use in ship chronometers, which, before modern navigation aids were invented, needed to be accurate and durable enough to last voyage after voyage.  You may be familiar with the Lever escapement, which does two things - it stops the escape wheel then it transmits the energy on to the balance using a little two-pronged fork - two actions, two impulses per oscillation.  The Detent escapement has one purpose - stoppage of the escape wheel - one impulse per oscillation,  given directly on to the balance.  So was the Detent in fact an escapement simplified?  Perhaps so.  One action meant less friction so less lubrication would be required and the end result would be enhanced accuracy and durability.  But - the Detent was delicate, quite happy to tick along nicely so long as it was safely anchored in it's habitual Marine Chronometer environment whose gimbals offered its frangible nature refuge from any nasty shocks, and therefore a construction quite unsuitable to play any part in the construction of a wristwatch..... until Urban Jürgensen & Sønner stuck their necks out and thought they might just have a go...


So - How do you solve a problem like the Detent?


....by using the best that the industry has to offer.  Jean-François Mojon, director of Chronode SA, GPHG Best Watchmaker 2010 and collaborator on the Opus X was given the responsibility for developing what would become the UJS Calibre P8, and its production and finishing were the responsibility of the remarkable Kari Voutilainen, AHCI member, meticulous craftsman and perfection-seeker.


Naturally this is a highly technical calibre, created to be both accurate and durable.  The Detent itself is diminutive in size and is protected with a patented plate which was created to guarantee it's safety. The complexities contrast with simplified elements - this is a calibre created by watchmakers for watchmakers - a three screw fixing system ensures ease of access and even the winding system is incomplex,  but durability is a priority and the components are designed and assembled where possible in such a way as to reduce friction.  The pivot and spring barrel bridge connect in such a way as to avoid all but necessary wear and tear.  The large free sprung balance - 12mm - has variable inertia, even micro components have been re-designed, such as the teeth on the escape wheel which are profiled to reduce momentum and promote stability.  Attention has been given to the winding system too, the gold rotor has been mounted on a jewel bearing, the teeth in its ratchet wheel have been optimized and five jewels in the bridge aid the overall shock-absorbing construction in the finest way possible. Is it accurate? You bet it is.  The brand state that during COSC bootcamp it performed better than 300 other brand watches, despite its unique intrinsics.


Peter Baumberger, the man who instigated the UJS P8 adventure and who inspired Messrs. Voutilainen and Mojon to achieve the nigh on impossible died in 2010 leaving his good friend Helmutt Crott to continue the undertaking and overcome the next confounding project for Urban Jürgensen & Sønner- just how do we follow that.....?


The 2012 Grand Prix d'Horlogerie de Genève takes place on November 15th.