03.09.2024
ISO 6425 or DIN 8306
What must a dive watch be able to do?
Not every watch ...
The most important thing is that the watch can withstand the water pressure at the desired diving depth. To ensure that a dive watch can also be used as a backup for a dive computer if necessary, it must meet certain requirements set out in the DIN 8306 dive watch standard and the international ISO 6425 standard.
DIN 8306 or ISO 6425
The features of a dive watch
The dive watch standard DIN 8306 and the international standard ISO 6425 cover the following points:
- Pressure-resistant to 20 ATM (≈ 200 m), which means that the dive watch must remain at this water depth for two hours and then another three hours at a depth of three meters - the dive watch must still function during and after 20 minutes of water pressure at the specified depth.
- Rotating bezel, which for safety reasons can only be turned counter-clockwise and can still be operated at a depth of 30 centimeters.
- Continuous minute markers and a clearly legible, stepped line marker every 5 minutes as well as a luminous triangular marker on the bezel (or, depending on the design, on the dial) to indicate the dive time.
- Clear legibility of the dive watch from a distance of 25 cm in the dark, which is why the markings on the bezel, hands and indices are fitted with luminous material.
- Luminous second hand to show that the watch is running.
- Anti-magnetic in accordance with DIN 8309 (accuracy of ±30 seconds per day in three positions under a direct current magnetic field of 4,800 amperes per meter). Shockproof in accordance with DIN 8308 (the deviation must not exceed ±60 seconds per day after a shock of 4.43 m/s).
- Rust-resistant in seawater (the diver's watch must survive 24 hours in warm salt water without damage).
- Firmly mounted bracelet (nothing must come loose or bend when the bracelet is subjected to a load of 40 kilograms for one minute).
- The average rate deviation may only be between -4 and +6 seconds per day (only applies to DIN 8306).
- Pressure-resistant crown (for this purpose, the crown is loaded with 0.5 kilograms for ten minutes at 25 percent above the specified pressure resistance (at 20 ATM this is 25 ATM)).
- Resistant to temperature fluctuations (the watch is first brought to 40 degrees Celsius for ten minutes at a depth of 30 centimeters, then to five degrees Celsius for ten minutes, then back to 40 degrees Celsius for ten minutes).
- Resistant to pressure (the dive watch must be able to withstand 25 percent above the specified depth for one hour, then one hour at 0.3 bar negative pressure).
Further features
beyond ISO 6425 or DIN 8306
To ensure that a dive watch is easy to read underwater, even from the side and in the event of reflections, the cover glass should be anti-reflective, at least on the inside. Dive watches usually also have a screw-down crown so that it cannot be accidentally pulled out while diving and water ingress damages the movement.
Rubber watch straps have also proven their worth in diving practice, as they adapt perfectly to the changing pressure conditions under water. However, metal watch straps and textile straps are also very popular on diving watches. A helium valve, on the other hand, is only necessary if the watch is to be taken on dives to several hundred meters and the diver is in a pressure chamber during the decompression phases. This usually only applies to professional divers, but a helium valve is not necessary for hobby divers. On the contrary: a helium valve is just an additional opening that poses a risk of leakage.
Rubber watch straps have also proven their worth in diving practice, as they adapt perfectly to the changing pressure conditions under water. However, metal watch straps and textile straps are also very popular on diving watches. A helium valve, on the other hand, is only necessary if the watch is to be taken on dives to several hundred meters and the diver is in a pressure chamber during the decompression phases. This usually only applies to professional divers, but a helium valve is not necessary for hobby divers. On the contrary: a helium valve is just an additional opening that poses a risk of leakage.
Circula diving watches
& ISO 6425 and DIN 8306
The Circula diving watches (AquaSport II and SuperSport) comply with almost all points of the ISO 6425 and DIN 8306 standards - however, they are not certified. Only the points "Anti-magnetic according to DIN 8309", "Shockproof according to DIN 8308" and the average rate deviation of -4 and +6 seconds per day (DIN 8306 only) do not apply. However, both watches are still suitable for diving and the wearer can enjoy them for a long time after the dive.
