One of the coolest things about divers watches, is that they are amongst the toughest watches on the planet. These highly specialized sports watches are designed with functionality first on the watchmaker's priority list. This is because as a watch is subjected to greater depth, the tougher it has to be to guarantee safe operation in a pressurized environment.
How Divers Watches Are Tested
There is a strict international standard that a true divers watch must satisfy in order to be a certified diving watch. Watches must pass a series of tests laid out in ISO 6425, to earn the right to print the words "DIVER'S WATCH" on the case. Any watch bearing this marking will have satisfied the ISO 6425 testing procedure that is a special type of guarantee that the watch will hold up under submarine conditions.
The first test in the ISO 6425 procedure is a condensation test. The test involves heating a plate to around forty to forty five degrees centigrade, the watch is then placed on the plate and left for a period of ten to twenty minutes. Over this period the watch will heat up to this specific temperature. Onto the watch's crystal face, a drop of water at room temperature is placed and left for one minute and then wiped off.
If there is any condensation seen to be forming beneath the crystal face, then the watch fails the testing. No further testing is conducted from that point on.
Another test in the procedure requires that watches be tested at depths that are 25% below their rated depth in still water conditions. Slight weather variations can cause the density of seawater to differ from between two and five percent and it is also well established by science that seawater is denser than fresh water.
Thermal shock testing is also applied to the dive watch as part of the testing procedure. The testing involves rapid temperature changes. For a period of an hour, the watch is first placed in forty degree water, then when the time expires, is rapidly transferred to five degree water. The watch is left for a further hour before being moved back to the fourty degree water again for a final hour.
By far the longest test in the ISO procedure is to test the watch's resistance to the corrosiveness of seawater and involves the diving watch being submersed in thirty centimeter water for a period of over two days. This is why most diving watches are manufactured from stainless steel, titanium, plastics or ceramics as these materials do not rust.
Using A Diver Watch Under Water
Diving watches are also tested for the practical application of using a sports watch underwater. It is mandatory that all diving watches have some mechanism for keeping track of the total amount of time since the start of the dive.
Most analog diving watches use a unidirectional rotating bezel to track dive length, the bezel can only be rotated one way and as part of the standard is required to have distinctive markings at five minute intervals and a scale of sixty minutes. The watch is required to have its 60/0 minute mark be legible at twenty five meters below the surface and the reading of the time legible itself. Analog diving watches achieve this with luminescent watch hands, whereas most digital diving watches implement this with a back lit watch screen.
Divers watches must also indicate that they are working, both at 25 meters and in complete darkness. Analog watches have a running second hand with luminescent tip. When the battery runs out they must present an "EOL" (end of life) indicator.
Divers watches are among the most rigorously tested sports watches on the planet, meaning a good one will likely last you for many years and be completely safe to use in and around seawater, whether you are scuba diver or not.
