As the winding crown is gently pressed in and turned, the thread engages. After just another few turns, the system locks, and the case is now perfectly waterproof and dustproof. Sealed tightly by the Triplock winding crown, the Submariner is ready to descend to depths of up to 300 metres (1,000 feet).
Offering a point of entry to the movement inside the case, the winding crown has always posed a challenge for waterproofness in watches. The Triplock winding crown equipping the Submariner today is the most up-to-date and highly developed version of the original screw-down winding crown, invented by Rolex in 1926 to make the Oyster waterproof. The Oyster was the first watch in the world to be wholly protected from the elements. A miniature masterpiece of engineering, the Triplock is made up of some ten different components manufactured from the most resistant materials and includes three waterproofness systems. Its design is so efficient that, more than 40 years after its initial development, the crown could be used, as is, for the Rolex Deepsea, Rolex’s latest-generation divers’ watch, waterproof to the extreme depth of 3,900 metres (12,800 feet).
SCREW-DOWN SYSTEM AND
The first waterproof crown patented by Rolex in 1926 established the basic principle: the crown, fitted with a gasket – made of metal at the time – screwed onto a tube which was part of the watch case. When the crown was screwed down, the gasket was compressed against the tube, creating a perfectly waterproof barrier. The wearer had only to unscrew and release the crown in order to adjust the functions of the watch and wind the movement. The sole weak point was that the case could only be waterproof so long as the crown was screwed down. Rolex improved the mechanism in 1953 by developing the Twinlock winding crown, with a double waterproofness system which it introduced on its first divers’ watch: the Submariner. The metal gasket at the base of the crown was replaced by two O-rings in a synthetic material. The first, inside the crown, presses against the top of the tube, as previously, to lock the case when the crown is screwed down. The second is positioned inside the tube, around the winding stem, to offer protection even when the crown is unscrewed. It offers another advantage in that it stabilizes and provides secure support for the stem when it is moved. The Twinlock crown is fitted today on most Rolex watches and guarantees their waterproofness to a depth of 100 metres.
The third-generation waterproof winding crown named Triplock, is fitted with a triple waterproofness system. It was introduced in 1970 to equip the Sea-Dweller, the model designed for professional deep-sea divers. To further reinforce the waterproofness, even if the crown should remain unscrewed under water, Rolex engineers added a second O-ring inside the tube. This acts as a kind of airlock, safely keeping out even the minutest particles. The Triplock system was fitted in the Submariner starting in 1977. Today, it equips all the brand’s divers’ watches as well as a number of other Professional models.