Deep Dive: The Blancpain Fifty Fathoms

Some of the most innovative inventions in the world come after a near-death experience, and the Blancpain Fifty Fathoms is one example. In the early 1950’s, Blancpain’s then CEO and avid diver Jean-Jacques Fiechter nearly drowned during a dive off the French coast. His watch couldn’t track how long he’d been underwater, and he ran low on air without realizing it. He barely made it to the surface. That scary moment gave him an idea: divers needed a better watch, and one that could help keep them alive.

Fiechter designed this watch himself based on his vast experience in diving. The result is a timepiece that had a rotating bezel to measure dive time, glow-in-the-dark markers, and a tightly sealed case to survive deep water. But Swiss watch sellers weren’t impressed. They said it was too bulky and that people only wanted dress watches.

Then two French Navy divers, Bob Maloubier and Claude Riffaud, came across the Fifty Fathoms after struggling with unreliable watches that broke or got magnetized in the depths. Fiechter’s design had everything they needed: water resistance, anti-magnetic protection, and a safe, easy-to-use bezel.

 

 

By 1953, the Fifty Fathoms became part of the French Navy’s essential equipment. Later, the U.S. Navy and other elite forces followed. One near-death experience turned into a game-changing invention for divers around the world.

Origin of the name

The name “Fifty Fathoms” wasn’t just for show, although it was inspired by a play. When Jean-Jacques Fiechter picked it, he wasn’t trying to sound cool (or maybe he was), but he wanted to make a point. A fathom is a unit sailors use to measure depth (about six feet), and the phrase "full fathom five" comes from Shakespeare’s The Tempest. But this watch went much deeper at 50 fathoms, or 91 meters/300 feet which was the limit of safe diving at the time.

Other brands were still selling fancy waterproof dress watches. But Blancpain’s Fifty Fathoms was something completely different and with a very specific user base in mind, and the French Navy were the first to recognize the brilliance he had created. It was a turning point where watches were not just accessories for styling anymore, but started becoming serious tools for survival. It has been dubbed as the first archetypal dive watch, preceding the Submariner.

Combat experience

And the Fifty Fathoms doesn’t fake its resume. In 1953, the French Navy’s combat divers, led by Bob Maloubier, became the first to officially use it on dangerous underwater missions. Its strong performance quickly got attention worldwide. The U.S. Navy’s early SEAL teams used a modified version rebranded as the Tornek-Rayville, featuring glowing tritium dials for night ops. Germany’s elite Kampfschwimmer divers also used it.

This watch had the means to survive in an actual battlefield. It had screw-down casebacks to handle pressure, anti-magnetic shields to avoid setting off underwater mines, and a special disc inside that turned color if moisture got in. It went beyond the labs and was tested in real life conditions - in combat and in murky waters, as well as high-stress missions. And it passed those tests and earned its figurative stripes. It was so good that other militaries had to get a piece of the action.

Notable models

When Cold War trade rules blocked Blancpain from supplying the Fifty Fathoms to the U.S. military, New York-based jeweler Tornek-Rayville stepped in. The end result is the TR-900 which is a rebranded, military-spec version of the legendary dive watch. Fewer than 1,000 were made, and most were destroyed after service, making surviving pieces some of the rarest and most sought-after vintage tool watches in existence.

One variant, the “No Rad,” became another standout. As concerns grew over radioactive luminous paint, Blancpain introduced a new dial marked with a crossed-out trefoil and the words “No Radiations.” It was meant to assure divers of safety, but the symbol stood out and the warning sign accidentally became iconic. Its bold, almost rebellious look turned a safety label into a collector’s piece.

 

 

By the 1970s, the Fifty Fathoms nearly disappeared. The quartz crisis hit the watch world hard, pushing mechanical watches to the sidelines. Blancpain itself even shut down in 1980, and it seemed like their story was over. But in 1983, Jean-Claude Biver and Jacques Piguet brought the brand back to life, giving the Fifty Fathoms (and their other historical pieces) a second chance.

In 2003, it made a bold return with a special 50th anniversary reissue: three limited runs of 50 watches each, combining military roots with luxury watchmaking. Twenty years later, Blancpain proved the watch still had more to say. The 70th anniversary release featured the cutting-edge Tech Gombessa, built for deep saturation dives with a 3-hour bezel. It launched alongside modern “No Rad” editions and vintage-inspired models using new materials.

Making your own Fifty Fathoms Seiko Mod

 

The Fifty Fathoms, being the legendary watch that it is, has been a modding staple for years now. The most popular interpretation is of course, the “Fifty Five Fathoms” which combines the vintage FF look with the Seiko 5’s sportier design. Now we at namoki are releasing our own version of the FF case and giving it a much more wearable size of 40.5mm compared to the usual 45mm. This will make it more suitable for desk-diving, as opposed to the original’s more hardcore purpose. Don’t take this as a toning down though; we’re also releasing matching dials, hands, bezels and inserts so you can recreate this icon of a watch as faithfully as possible, or give it your own spin.

The namoki FF case will also be released in three finishes - Polished finish, Black, and Rose Gold, so you can make it more subtle and utilitarian or make it a bit dressy. Stay tuned to our social channels and subscribe to our newsletter to get notified once it’s available on the store!

Wrap up

As the first true diving tool watch, the Blancpain Fifty Fathoms was one of those heavy-hitting watches that helped shape history. Up to this day its influence lives on in both reissues and custom builds by Seiko modders around the world.

At namokiMODS, we give you the means to recreate your favorite watches at home or build something that’s entirely unique and personal. From dive watches to skeleton dress watches, you can build it all with our premium quality parts. Be sure to check out our expanding catalog for your next Seiko mod.

Happy modding!