The invention of the waterproof Oyster case in 1926 and a self-winding mechanism via a perpetual rotor in 1931 enabled Rolex to offer watches whose functions included those of marine instruments.
Their performance were proven by pioneering sailors, such as Sir Francis Chichester, who made history by being the first man to single-handedly circumnavigate the globe from west to east between Aug 1966 and May 1967. His voyage on the Gipsy Moth IV was accompanied by a chronometer-certified Rolex Oyster Perpetual that stood up to the stormy seas.
Today, Oyster Perpetual timepieces are designed to brave the open ocean as well as the underwater world, with new renditions of Yacht-Master and Sea-Dweller launched at Baselworld 2019.
Similarities between the two models are the dial layout, Chroma light display with blue luminescent material, and sapphire crystal fitted with a magnifying Cyclops lens at 3 o'clock.
For the first time, the Swiss brand uses white gold for the Oyster case of the Yacht-Master 42, recognisable by a bidirectional rotatable bezel with a raised 60-minute graduation.
Matching the black lacquer dial, the bezel's Cerachrom insert is in corrosion-resistant and scratchproof matt black ceramic.
The 42mm sailing watch is waterproof to a depth of 100m whereas the slighty larger Sea-Dweller can plunge to 1,220m, thanks to the helium escape valve.
Patented by Rolex in 1967, the safety valve allows excess pressure built up in the case to escape during a diver's decompression phase in a hyperbaric chamber, while preserving the waterproofness of the watch.
The Sea-Dweller was designed in collaboration with professional divers, who spent extended periods underwater. Its unidirectional rotatable bezel is also fitted with a 60-minute graduated Cerachrom insert in black ceramic while knurled edge gives a good grip when setting dive time.
The new interpretation has the name of the watch inscribed in yellow instead of red on the black dial.
The bezel, winding crown and centre links of the bracelet gleam in yellow gold while the case and bracelet's outer links are in Oystersteel.
The middle case is crafted from a solid block of Oystersteel, an alloy with anti-corrosion properties commonly used in aerospace and high-technology industries.
The combination of gold and steel, called Rolesor, has been a signature feature on a Rolex watch since 1933.
Carrying the Superlative Chronometer certification, the yellow Rolesor version of the Sea-Dweller and white gold Yacht-Master 42 are driven by an in-house developed and manufactured movement providing a power reserve of approximately 70 hours.
