We all know that dive watches have excellent waterproof performance, and some people even use some watches with good waterproofing as dive watches, which is incorrect. Simple waterproofing does not mean that it is a professional dive watch.
Swiss International Standard (NIHS) stipulates that a custom diver watch must have a safety device that controls diving time. In addition, to prevent misjudgment, the device must also be equipped with a design that prevents accidental rotation. The watch is best equipped with a diving timing rotating inner ring with detailed minute graduations, and the device that controls the rotating inner ring should also have a corresponding safety start design. Generally, the unidirectional rotating bezel in the function of dive watches can meet this requirement.
The unidirectionality of the unidirectional rotating bezel is to ensure that the calculation time only counts more, not less, to prevent dangerous delays in time. The rotating bezel serves to remind the diving time. The rotating bezel is marked with graduations: 15, 30, and 45, because the oxygen cylinder for general diving can only last for 45 minutes, and now there are many markings for 60 minutes. Because divers strictly observe a 15-minute safety stop during ascent for decompression, the first 15-minute graduation is marked with color or special identification.
The indication of the time, the rotating inner ring diving timing, the operation of the movement, etc. must be clearly readable even in the dark deep-sea environment. Usually, the distance (straight-line distance between the watch and the eye) is set to 25 centimeters. Among them, fluorescence treatment is the most commonly used solution by major watchmakers.
All dive watches are equipped with eye-catching luminous hands and graduations. Usually, the hands, graduations, or surfaces of dive watches are coated with fluorescent materials, and the size of the hands and graduations is deliberately enlarged to make it easier for divers to read the time.
Early luminescent materials were radium, which was discontinued due to excessive radioactive elements. The most commonly used luminescent material now is Super-LumiNova, which is said to have a luminosity after exposure that is 100 times that of tritium luminescence. It absorbs gamma particles in light and can emit light for more than 10 hours, but its luminous intensity will decay after a certain period of time.
In order to ensure that the core components and straps of the watch do not change when soaked in salt water, the waterproof gasket, case back, and mirror components of the dive watch should be adjusted accordingly, and the common practice is to increase the thickness. NIHS standard stipulates that the case of dive watches should reach a waterproof depth of more than 100 meters. This is also one of the reasons why dive watches should have anti-corrosion and flexible straps.
When underwater, whether stroking your arms or operating instruments, we need to have flexible wrist movements, and at this time, the watch needs to be closely fitted to the wrist. Many dive watches are equipped with metal straps, but the chemical composition of seawater will still cause slight corrosion, so some dive watches will be equipped with rubber straps that are more waterproof and corrosion-resistant. Nowadays, some brands have also specially developed canvas or synthetic fiber straps.
Professional dive watches are all equipped with anti-magnetic protection devices, because the extremely sensitive balance wheel hairspring may be destroyed due to the influence of a magnetic field. The anti-magnetic protection device can protect the movement from the effects of the magnetic field, vibration, and temperature changes, thereby ensuring accurate timekeeping of the watch. In addition, the watch needs to undergo temperature change testing, and the absence of any steam condensation phenomenon is a good dive watch.