The idea behind it: diver Jayet’s patent
At the origin of this project stands the diver David L. Jayet.
He designed a dial integrating decompression tables in the form of
concentric rings and filed Swiss patent no. 312741 describing
the principle and its use in a wristwatch.
Armed with this invention, he approached Cornavin Genève.
After long technical discussions and several prototypes, the P.810 was born —
turning Jayet’s concept into a functional watch intended for professional divers.
An exceptional discovery in the workshop
When this Cornavin arrived at the workshop, it seemed to have
never been opened since it left the factory.
The case back was so tightly sealed that no standard tool could remove it
without risk — I had to fabricate a custom-made tool to open it safely.
The moment of discovery was striking: the Felsa 810 Bidynator
movement appeared in near-new condition, perfectly preserved after
decades in a drawer. The original oils had dried, but the mechanism itself
remained intact and beautifully preserved.
A respectful restoration
The movement was fully disassembled, carefully cleaned and reassembled
using modern lubricants suited to the original tolerances.
The dial, remarkably well preserved, was only lightly dusted to
maintain its original printing and subtle patina.
The hands and luminous markers were left untouched.
New gaskets were fitted, and water-resistance tested within the limits of a
vintage timepiece.
After regulation and testing, the Bidynator came back to life, beating with
remarkable precision — a testament to Felsa’s enduring engineering quality.
AMF – an unexpected partner
The AMF marking on the case back recalls the collaboration between
Cornavin Genève and the American company
American Machine & Foundry.
Known for its industrial equipment, bicycles and involvement in the world of
bowling, AMF sought to diversify its image during the 1950s by associating
with high-precision products.
It distributed several Swiss watches under the AMF Diver name, combining
American engineering with Swiss craftsmanship.
This dual signature, Cornavin – AMF, stands as a rare witness
to a time when two worlds — Swiss horology and American industry — met in the pursuit
of reliability and innovation.
Between engineering and poetry
The Cornavin P.810 reflects a moment when
watchmaking ingenuity met the early days of autonomous diving.
Its decompression dial was not decorative — it was a scientific instrument
designed to keep divers safe underwater.
The wandering-hour display adds a poetic touch: here, time
reveals itself slowly through an aperture, much like the ascent
from the depths back to the surface.
A witness to its era
Rediscovered after decades hidden away, this
Cornavin Genève P.810 is far more than a mechanical curiosity —
it is a living testimony to the collaboration between an inventive diver,
a bold Geneva manufacture, and an American industrial partner.
Restored with full respect for its authenticity, it now runs again,
giving it back its voice and its rightful place in the history of diving watches.
