by 
In the 1920’s it was already popular knowledge that the Oyster case was impervious to water, which gave Rolex the edge when it came to luxury watches that could be worn daily without having to worry about the elements damaging the mechanics of the watch. In the 1940’s Panerai took notice and when approached to provide the Italian Navy with dive watches they called Rolex to supply them. Shortly after this period, in 1953 at Baselwolrd, Rolex introduced the Datejust Turn-o-graph. Essentially, the first publicly available, official “tool” watch.
With the addition of the Turn-o-graph bezel, Rolex was able to add a “tool” feature to the watch which allowed the wearer to rotate the dial in either direction in order to mark the time, essentially being able to use the watch as a basic timer without actually adding a new complication to the movement.
Taking the existing turnograph bezel and modifying the movement to include a 24 hour hand Rene-Paul Jeanneret, the Rolex executive responsible for introducing the concept that a watch should be designed for specific sports or professions, created the GMT and the Submariner, subsequently showcasing them at Baselworld in 1954.
Because the original Submariner design was based on the Turn-o-graph, early versions of the Submariner did not feature a crown guard. This lack of distinction has led many people to believe that certain prominent historical figures such as Chuck Yeager, the first pilot to break the sound barrier at a speed of mach 1 in 1947, wore a Submariner in early photos. Chuck actually wore a standard Rolex Oyster when he served in WWI and many years later was photographed wearing a 1953 Turn-o-graph followed by a Submariner and eventually a GMT. In May 1959 Rolex named a version of the Turn-o-graph (with the metallic bezel) after the special US Air unit – Group Number 3600 of Air Demonstration, otherwise known as the “Thunderbirds”, a group of skilled pilots specializing in air acrobatics and experimental flying techniques.
Often overlooked by collectors and now seldomly mentioned when referring to Rolex models, we should acknowledge that although Rolex discontinued production of Datejust Turn-o-graph in 2012 for the second time since its birth, its place in history and impact on the watch industry shouldn’t be forgotten. It can be considered the grandfather of the tool watch, directly responsible for the birth of the modern day sport watch we have all come to love.
