Eaglemoss Military Watches Collection.

The Blancpain Fifty Fathoms is an Iconic piece and the model for the modern divers watch
In the early 1950s, the head of Blancpain, Jean-Jacques Fiechter, was a pioneer of sports diving. He understood that the life of a diver depended on a reliable timepiece and found that there was nothing suitable on the market. He tasked his watchmakers with the challenge of accurately measuring time in an underwater environment
To solve the problem of water resistance he first designed a double-sealed crown, to protect the watch from water penetration if the crown were accidentally pulled during a dive. The second internal seal ensured the water resistance of the movement. Fiechter filed a patent for this invention, and a second patent was granted for the sealing system for the case back. To prevent twisting, the "O" ring was inserted into a channel and held in position by an additional metal disk
He then addressed measuring the time of a dive. His idea was a minute scale on a rotating bezel. By placing the zero index of the bezel next to the minute hand of the watch divers could read the passage of time with the minute hand. Any accidental movement of the bezel could, however, cause a timing error. Fiechter, therefore, developed a locking mechanism to prevent accidental rotation of the bezel. For this, he received another patent. Later Blancpain developed the worlds first unidirectional rotating bezel which ensured safety during a dive
Legibility was an important factor, especially in cloudy water, so Fiechter used a large diameter watch with a strong contrast of white luminescent indexes and hands on a black background. The automatic movement was also thought to be essential to limit unnecessary wear of the crown seals



At the same period in France, Captain Robert Maloubier and lieutenant Claude Riffaud were acquiring equipment suitable for use by the newly formed French Navy Combat Diving team they led. The two officers looked for a timepiece that would be an indispensable tool for their divers. They compiled a list of specific criteria for a watch to meet their needs. The first tests they made with French watches were disastrous. They were much too small, the dials were hard to read, and the cases were far from being waterproof
In 1953, Blancpain was able to provide the French team with a watch that met its criteria. The Blancpain was outstanding in all tests and it became one of the most important pieces of equipment for the Corp. Later the same became true for naval forces around the world
Fiechter continued its quest for the safety of diving and incorporated a water-tightness indicator. If the liquid penetrated into the watch case, a circle at 6 o'clock on the dial would change colour from white to red. This indicator was on the MIL-SPEC 1, which was introduced in 1957-1958 to meet the stringent requirements of the army
In early 1958, the US Navy tested a variety of watches searching for a watch suitable for use by their Military divers in underwater missions. After these tests, the Fifty Fathoms became the standard issue for American combat divers as well as the benchmark for future watches, planned for production in the United States. Meanwhile, Blancpain was awarded contracts to equip members of the elite UDT and the Navy Seals with MIL-SPEC 1 watches

Captain Robert Maloubier, pictured below in his dive suit wearing a Blancpain, was a legendary figure of World War II and beyond, his amazing story is worthy of a read but a little long to be retold here



Case
Polished 41mm case, 43.8mm at the crown, 9.2mm deep, 49.4mm Lug to Lug, 20mm lug width
Case Interior diameter 36mm, 7mm deep. 6mm crown, 29mm glass.
Bezel is 41.5mm across with a black insert, Minutes indicated with batons at 5-minute marks, Arabic numbers at 15-minute marks and a diamond shape at the 'Zero' index
Dial
Black Dial with white printed 5th-second scale, yellow battons at five-minute intervals and 3-6-9-12 Hours indicated by Arabic numbers
trapezoid shaped hands with yellow infill and slim polished seconds hand
Strap
Black nylon strap 20mm wide polished buckle, approx. fitting 175/215mm