Dive Watches in Depth - FAQ

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Dive Watches in Depth - FAQ

Postby koimaster » June 19th 2018, 9:31am

We answer your FAQs about water resistance, dive bezels, depth gauges, and more about divers’ watches in this feature from the WatchTime archives.

How water resistant should a dive watch be?
Some manufacturers say that their watches with a water-resistance rating of 300 meters or more are suitable for recreational scuba diving. Others say the watch need have a rating of just 200 meters; still others say it can be 200 meters as long as it is specifically labeled as a dive watch. The International Standards Organization (ISO), on the other hand, stipulates that a dive watch must be water resistant to 100 meters.

All these depth ratings are significantly higher (or lower, if you will) than the depths to which a non-professional diver can dive. Recreational divers don’t go deeper than 40 meters (130 feet). Beyond that, they enter the realm of technical diving, which requires extensive training, special mixed gases to breathe, long decompression stops and special equipment.

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Re: Dive Watches in Depth - FAQ

Postby bedlam » June 19th 2018, 11:01pm

OMG...the dynamic pressure furphy again.

The reason for the discrepancy: when tested for water resistance in the factory, the watch is in an artificial environment that is much different from what the watch will face during an actual dive. For the test, the watch is perfectly stationary, the gaskets brand new, and the case newly assembled, so that nothing will compromise its water resistance. The testing machinery does not account for such phenomena as additional pressure from the impact of the wearer’s jumping or diving into the water; or for temperature and pressure changes as the diver ascends and descends, which can cause the case to shrink or expand.

Also, temperature variations are not specifically depth related - thermoclines occur at all depths. On average it tends to be a bit cooler the further you go from the sun...but the difference between 10m and 40m is usually only a couple of degrees. Not really an issue for the confusion related to WR ratings.
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