What is a Dive Watch?
A diving watch is a specially designed watch used for underwater diving that has a minimium key feature that it is able to be water resistance to a depth greater than 10 ATM, which is the equivalent of 100 meters (330 feet).
The typical diver's watch will have a water resistance of around 20 to 30 ATM which is 200 - 300 meters (660 - 990 feet), though modern technology allows diving watches that can go beyond and much deeper. A true diver's watch is in accordance with ISO 6425, which defines test standards and features for watches suitable for diving with underwater breathing apparatus in depths of 100 m or more. Watches conforming to ISO 6425 are marked with the word DIVER'S to distinguish diving watches from look a like watches that are not suitable for actual scuba diving.
Many companies offer highly functional dive watch. Whilst a dive watch is primarily a normal watch, some companies now offer models that can in addition to this be regarded as jewellery or fine precision mechanical devices. A Dive watch can be analog or digital too.
Characteristcs of a Dive watch
ISO 6425 standard for diving watches is the standards and features for a dive watch is regulated by the ISO 6425 standard. Besides the dive watch being water resistance to a minimum of 100 meter depth rating, the ISO 6425 also provides a minimum requirement for a mechanical diver's watches, take note that a quartz and digital watches have slightly differing readability requirements such as:
- Strap/band solidity. This is tested by applying a force of 200 N to each springbar (or attaching point) in opposite directions with no damage to the watch of attachment point.
- The presence of an End Of Life (EOL) indicator on battery powered watches.
- The presence of a unidirectional bezel with at least at every 5 minutes elapsed minute markings and a pre-select marker to mark a specific minute marking.
- The presence of an indication that the watch is running in total darkness. This is usually indicated by a running second hand with a luminous tip or tail.
- Magnetic resistance. This is tested by 3 expositions to a direct current magnetic field of 4,800 A/m. The watch must keeps its accuracy to +/- 30 seconds/day as measured before the test despite having the magnetic field.
- The presence of clearly distinguishable minute markings on the watch face.
- Adequate readability/visibility the watch should be read from a distance of 25 cm (9.84 in) in total darkness.
- Shock resistance. This is tested by two shocks (one on the 9 o'clock side, and one to the crystal and perpendicular to the face). The shock is usually delivered by a hard plastic hammer mounted as a pendulum, so as to deliver a measured amount of energy, specifically, a 3 kg hammer with an impact velocity of 4.43 m/sec. The change in rate allowed is +/- 60 seconds/day.
- Chemical resistance. This is tested by immersion in a 30 g/l NaCl solution for 24 hours to test its rust resistance. The testing water has a salinity of ocean salt water.