Dive Watches – Unique Ability To Withstand Pressure

Dive watches are remarkable devices. Their unique feature is an ability to withstand the enormous pressure at two hundred meters or more under water. They can operate at a pressure much greater than that capable by the human body. Specialist online retailers like eWatches are a godd source of information about these products.

Authentic dive watches comply with ISO 6425, an internationally recognized testing standard. Watches that satisfy this standard are certified so divers know they are acquiring a genuine dive watch capable of operating to defined depth limits.

Normal atmospheric pressure on the surface of the earth at sea level is 101,325 pascals, 1,013.25 millibars or 101.325 kilopascals (being or 14.7 pounds per square inch). This pressure is known as one standard atmosphere. When diving under water, pressure increases at the rate of 1 atmosphere for every 10 meters of depth. Pressure at 50 meters is 6 atmospheres (1 atmosphere of air pressure plus 5 of water pressure). The pressure at 100 meters is 11 atmospheres.

A dive to a depth between 18 to 30 meters (60 to 100 feet) is considered a deep dive for a recreational diver. Deep diving using air alone, as opposed to a special gas mixture, is extreme and very dangerous.

The deepest so-called open circuit scuba dive is to a depth of 330 meters (1,083 feet) by Frenchman Pascal Bernabé on 5 July 2005 near Propriano on the west coast of Corsica. He used a special gas mixture known as Trimix. However his dive is not recognized by the Guinness Book of Records. The fatality rate is so high that the publication has discontinued recording this activity since it does not want to encourage attempts at the title.

The challenge posed by deep diving is not the pressure it poses on our skeletal structure, but on the oxygen in our respiratory system. The air we breathe is a mix of nitrogen (80%), oxygen (19%) and other gases (1%). This mix that keeps us alive on the surface of the earth
becomes toxic and can kill us when it is placed under high pressure. Oxygen becomes toxic at a depth of about 70 meters (230 feet or 1.6 bar partial pressure). This depth is a maximum safe diving depth using classic, ordinary scuba gear with unmixed air. It is also an extreme depth and not recommended for divers without special training and fitness.

By comparison, dive watches are designed to operate well beyond depths of 70 meters. The first dive watch to be rated capable of operating at 100 meters was the Rolex Submariner launched in 1953. It set a depth benchmark of 100 meters for dive watches. Since then, dive watches have grown tremendously in popularity and some are now capable of operating at depths of 500 meters.

That depth represents an enormous amount of pressure, equivalent to 21 atmospheres. Some dive watches can withstand pressures beyond a depth of 300 meters. Even though very few divers will ever dive to these depths, a rating to that level is important since fast hands movements underwater, like swimming strokes, add considerable pressure on a watch.

Divers looking to buy a new watch might consider eWatches, one of the world's leading online watch retailers. It has a fine reputation as a reliable supplier that offers firm warranties and attractive prices on its products. A recent check of its site showed eWatches had more than sixty dive watch models in stock. The site also has a range of handy articles about watches and how they work, including an interesting article on dive watches.