A dive watch is a timepiece specifically designed to be worn by someone who dives. Dive watches are typically water-resistant to at least 50 meters (150 ft.) and may include features such as depth gauges. They tend to offer more robust protection against water pressure than other watches due to their robustness and seal between the case back and crystal.
The diver’s watch includes a self-starting dive timer function together with real-time decompression calculation and other watch features.
Diving watches are primarily tool watches, and some manufacturers offer versions that may be classified as jewelry or fine mechanical watches. It may be analog or digital. Some diving watch versions include both digital and analog components and pure analog and digital models.
ISO 6425: Standard Diving Watches
The International Organization for Standardization (ISO) regulates the standards and features for diving watches through the ISO 6425 standard; the following are some examples:
- Waterproof watches shall be equipped with a diving time indicator (e.g., rotating bezel, digital display, or other) that allows the reading of the diving time with a resolution of 1 minute or better over at least 60 minutes.
- Minute markings on the watch face that are recognizable.
- The readability and visibility were good enough in total darkness at 25 cm (9.8 in).
- The presence of an indication that the watch is working in total darkness. A running second hand with a luminous tip or tail is usually used to indicate this.
- Magnetic resistance is tested by exposing the watch to a strong magnetic field. The watch must keep its precision of ± 30 seconds per day when exposed to a 4,800 A/m direct current magnetic field three times.
- This type of resistance is evaluated by immersing a steel sample in a 30 g/l NaCl solution for 24 hours to determine its rust resistance. This test water has a salinity comparable to normal seawater.
- The presence of an End-of-Life (EOL) symbol on a battery-operated watch.
ISO 6425 compliance is optional and has costs, so not all manufacturers submit their watches for certification.
Diving watch movements must be built more robustly than standard dress watches to endure a seawater environment at depth. Because of this, the watch case is significantly heavier and larger than a dress watch constructed from similar materials. Stainless steel case was previously the only material used to make diving watch cases. However, stainless steel is still widely utilized as a case material in a modern dive watch.
A rotating bezel is a common feature of analog diving watches, allowing for easier reading of the elapsed time of less than one hour from a specific location. Rotating bezel watches are the most common choice for scuba diving and snorkeling. Lockable bezels are available on some diving watches to reduce the risk of unintentional bezel operation underwater.
The Bezel Markings
Most diver watches have markings on the bezel that allow the calculation of time remaining (on the assumption that no decompression stops are required during a dive). The international standard is called BCD (Beginner’s Combo. Dive computer and watch) code, but many manufacturers have their coding system; for example, Rolex uses a mix of the BCD code and its coding.
The Rolex Submariner watch model 6538 was a very early example of a dive watch, introduced in 1954. It also became the first wristwatch to have a water resistance exceeding 100 m (330 ft). The actual depth achievable by the 6538 was 200 m (660 ft).
Some watches have a fixed metal or plastic bezel, which cannot be adjusted. This is because it would be difficult or impossible to make the bezel secure enough at any position other than where it is locked.
A GMT or “Dual Time Zone” dial is helpful to a traveling diver. Some analog dive watches are available with a GMT hand, making it possible to read two time zones at once using rotating bezels marked in 24-hour and conventional time, or else by two separate scales.
Divers Watch Crown
The glass on many divers’ watches is thick and curved inward to prevent shattering. A crown is essential for analog diving watches and avoids or reduces irritation from the crown touching the wearers’ (left) wrist or back of the hand. Some versions have the crown installed in unusual places such as 4, 8, or 9 o’clock.
However, models with crowns function similarly to non-divers analog watches’ crowns. Screw-down crowns or other locking crowns and traditionally operated water-resistant crowns cannot be utilized underwater.
Helium Escape Valve
A helium release valve, also known as a decompression valve, is an automatic valve controlled by pressure. It releases helium gas trapped inside the watch during decompression or at depths beyond no-decompression limits.
Dive watch straps
Dive watch straps are usually made of rubber or synthetic material due to their flexibility and comfort on the wrist. Rubber watch straps are popular with scuba divers. The strap must be durable enough to withstand repeated contact with water.
Related: How Watches Are Made
Water can weaken or damage many materials; therefore, most have rubber straps fitted with extra reinforcement to prolong their lifespan further. Although supplied by most modern manufacturers, replacement straps are easily found in retail stores due to their popularity.
The dials and hands of a dive watch must be straightforward to read in adverse conditions, such as during a nighttime diving operation. Therefore, the numbers on the dial should be large enough for an untrained diver to read underwater. Some manufacturers use extra-high brightness waterproof luminous paint for better legibility. In normal light, this type of paint appears frosty white or grey. Underwater, however, it becomes exceptionally bright.
A diver may need to know the remaining oxygen supply left in an emergency. A “safety stop” can be necessary, either after a dive or before surfacing.
Some watches’ EOL (End Of Life) Indicator is designed to change color from white to red if the watch has not been used for 36 hours. A power reserve indicator is a small, round display that displays the current state of charge for some electric and mechanical movement types.
The ISO issued a standard for water-resistant watches that prohibits using the word waterproof with such watches. The ISO 6425 international standard regulates the requirements for diving watches. The straps are examined in static or still water at 125% of the stated (water) pressure, so a watch with a 200 m rating will be water-resistant if it is stationary and submerged up to 250 m under static water. Water-resistance testing is somewhat different from non-dive watches since every watch must be thoroughly tested.
According to ISO 6425, the water-resistance standards include:
- A diver’s watch is water-resistant to 1,650 feet (500m), which can resist chemicals and saltwater for up to 50 hours.
- The watch must be submerged in water at a depth of 125% of the rated pressure with a force of 5 N perpendicular to the crown and pusher buttons (if any) for 10 minutes.
- The watch should be immersed in 30cm of water at the following temperatures for 5 minutes each: 40°C, 5 °C, and 40°C before being dried again (temperatures do not exceed 1 minute between changes). No sign of water ingress or condensation is allowed.
- The watch is immersed in a pressurized vessel and exposed to 125 percent of the predicted pressure for 2 hours. Within 1 minute, the pressure must be applied. The overpressure shall be reduced to 0.3 bar within 1 minute and maintained at this level for 1 hour after that.
- The watch must be immersed in a suitable pressure container and exposed to 125 percent of the rated pressure for 15 days in a (helium-enriched) breathing gas mix. Within three minutes, the overpressure must be reduced to normal pressure. No evidence of water intrusion, condensation, or other issues caused by internal overpressure is acceptable.
- The ISO 2281 test is an optional test that may be used to assess the water-resistance of a watch (but not required for obtaining ISO 6425 approval). It exposes the watch to a pressure of 2 bar; no more than 50 mcg/min of air is permitted to enter the case.
Why are dive watches so popular?
It is popular because they offer the features that deep diver wants. Due to the construction, their appearance is considerably more durable. It frequently includes security or safety features that make diving watches stronger than other watches. Different brands have done various things to upgrade their watches to resist demanding environments where watches typically shouldn’t be worn. A dive watch’s aesthetics may be pretty subtle, but they can also be rather loud.
How are dive watches different?
Dive watches can have a rubber strap, metal bracelet, or any combination of these materials. Rotating bezels and dive computer capabilities can give them a sharp appearance that is difficult to match with standard wristwatches. It may also offer barometers or compasses that other dive watches typically don’t provide.
Do divers actually use dive watches?
Not all professional divers wear them. Many divers will opt for dive computers if their diving activities are primarily recreational or scientific in nature. Some avid scuba aficionados prefer a diving watch that can aid with navigation underwater or have a unique aesthetic design to suit their own personal preferences.
Why do Marines wear their watch backward?
Marines wear their dive watches backward to keep the dive watch’s rotating bezel from hindering their ability to grip equipment. They also do this because when they are in a diving environment, it’s much easier for them to have all of that information on the backside of the dive watch instead of trying to twist around or turn over their watch to see the information they need.
Do people actually dive with a Rolex?
Yes! Rolex is water-resistant and therefore is safe to dive with. However, a Rolex is not dive-proof, despite many people believing this. The fact of the matter is that no luxury watch can be truly diver-proof. In 2007, a well-known dive watch tester took five luxury dive watches to depths of pressure equivalent to their stated dive capabilities. All had water ingress issues at depths below 200 feet (60m) and would not pass the ISO 6425 standard for dive watch certification, proving that no dive watch is truly diver-proof.