Deconstruction Vintage Blancpain Fifty Fathoms by The Naked Watchmaker

An example of the original Fifty Fathoms divers watch manufactured in the early 1950’s.

(This watch was restored & photographed at Blancpain in their restoration workshop.)




The original Fifty Fathoms carried the trademark “LIP Blancpain”, LIP was a watch retailer in Paris and manufacturer in Besançon. Jean-Jacques Fiechter, Blancpain’s CEO from 1950 until 1980, a diver himself, developed the Fifty Fathoms model.



Incabloc, ie shock protection for the balance pivots of the balance staff was developed in the late 1940’s. This was a considerable evolution in practical watchmaking. Prior to Incabloc, when watches received shocks, the balance pivots could be easily broken and the watch would stop. This was such a phenomena that the military would employ watch technicians to repair the watches that were being damaged in action. Antimagnetic/waterproof & shockproof, even automatic, as engraved below were all technological advances of the period and used as strong selling points.



The original Fifty Fathoms carried the trademark “LIP Blancpain”, LIP was a watch retailer in Paris and manufacturer in Besançon.

The fully assembled movement  

The Movement with the rotor weight removed

The rotor weight. The milled out section below the pivoting point for the rotor creates a spring section in the rotor to allow the rotor to flex avoiding the rotor axel to be broken in case of shocks.


The dial, with luminescent indexes printed onto the surface. The original luminescent materials used, specifically for the military due to their norms, were highly radioactive, more so than for models which were made for the public.


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The hands were stamped from brass, painted white and filled by hand with luminescent materials.



Under dial view of the mainplate.



The balance cock and balance wheel assembly. The spring above the red end-jewel is part of the Incabloc shock protection.

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Profile views of case



Bezel removed with its friction spring to the left



The soft iron cover (cage) protecting the movement from magnetism. The pip, or button in the centre would push against the inner case back holding it in place.



Explosion of the calibre excluding the rotor weight


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Article by The Naked Watchmaker 

Text and photos are the property of The Naked Watchmaker©

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