Generally considered the first Submariner, although there is a debate, the Rolex Submariner was a hit and shares most of the same attributes as the Fifty Fathoms. The dial is black and features the same dots and batons as hour markers, with an inverted triangle at 12 o’clock that can be seen on current production models. All models are filled with a lot of luminescence (or radium in this era). The hands had not yet evolved to the Mercedes style found on most replica Rolex sports models today but were instead plain stick or pencil-shaped.
As for the bezel, it was marked with a 60-minute scale as usual but lacked the diagonal lines for the first 15 minutes. These markers were added in later versions to help the wearer keep more accurate track of the end of the dive when the precise time of the safety or decompression stop became more important. However, this watch also has an inevitable minor drawback.
Blancpain has a patent for a unidirectional bezel. The idea was the brainchild of the brand’s CEO, Jean-Jacques Fiechter, who was also an avid diver and serves as a basic failsafe. The unidirectional bezel ensures that in the event of accidental movement of the bezel underwater, it will only over-read the so-called underwater time, thus helping divers avoid the potential dangers of decompression sickness. Because the copyright belongs to Blancpain, the Submariner had to remain in use with a bidirectional bezel until the 1980s.
Rolex did, however, have the rights to an arguably more important innovation, which the brand extended specifically for the Submariner. From the mid-1920s onwards, part of the Oyster case construction was a special winding crown system fitted with a gasket that screwed into a tube inside the case. It provided impressive protection against moisture. But for the new dedicated diving model, it was clear that it had to be significantly improved.
The end result is the Twinlock crown, an arrangement that uses two sets of O-rings to create a pair of watertight seals within the winding stem assembly, making the Rolex Submariner replica the first dive watch to be water-resistant to 100 meters.