Movement based on the Swiss invention patent No. 101 652, delivered on September 30, 1922, to Vacheron Constantin, Geneva, for a “Raquette de montre” (watch index-regulator).

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Deck watch, deck chronometer and precision counter-clock by Vacheron Constantin

A “deck watch” or “deck chronometer” is a precision timepiece used on the deck of boats for navigational purposes (point reading) to avoid disturbing the proper functioning of the marine chronometer, which remains in a specific area of the ship (chronometers room or captain’s cabin).

Vacheron Constantin produced a few marine chronometers and deck watches that were mainly used on ships of the military or merchant fleets. The movements of these large timepieces had to be extremely precise and were built since 1905 with Guillaume balances and hair-springs with terminal curve (Breguet-type). Very often these movements are submitted to the tests of astronomical observatories and can obtain a Bulletin de marche.

The Genevan manufactory also used these same movements, intended for civilian use, to be fitted into table clocks enabling the brand’s retailers to have a precision timekeeper that would allow them to monitor the proper functioning of the watches they sold in their boutiques.

These clocks are occasionally referred to as “horloge de comptoir” or “counter-clock” and may be labelled “Heure exacte” (Exact time).

All these timepieces can be equipped with a subsidiary or central seconds hand and can have a power reserve indicator. They are much more rarely found with a regulator-type dial. They can be housed in silver, stainless steel or chromed metal cases or incorporated into mahogany boxes.

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The Guillaume balance is a compensated bimetallic balance, made of anibal (an alloy of steel and nickel) and brass, after the works of Dr Charles-Edouard Guillaume (1861-1938), with which the middle-temperature error is practically eliminated.

The middle-temperature error (or Dent’s anomaly), is the difference between the rate of a chronometer at the mean temperature and the average of the rates at extreme temperatures.

This type of balance was used by the horological manufactories since 1904.