Marcus Hanke[PuristSPro Moderator]
11515
Sinn should know better: 10 bars does not correspond to a depth of 100 meters ....
May 11, 2019,08:39 AM
... since the air pressure on the sea surface already is 1 bar. So 10 bar corresponds to a depth of 90 meters, not 100.
It is typical for so many erranous information given areound water tightness. The pressure resistance rating for a specific case is given for the time of production, similar to the chronometer certificate, that also is a report about a movement's performance at the time of testing. Depending on time and storage conditions, the pressure resistance can change, if the gaskets are degraded, for example for years in a shop window in bright sunshine and directly under hot halogen spotlights.The manufacturer cannot be held responsible for such a folly.
Additionally, experience shows that the average watch wearer (which excludes the crazy watch nut that is the rule on sites like PuristSPro) does not spend any thought on keeping his or her watch serviced and in good condition. These watches are seeing a watchmaker when they fail, and not earlier. Give them 100 meters of water resistance, and they believe that to be valid for decades, without any replacement of gaskets. Just ask a good watchmaker how many sports watches, including Rolexes, with completely corroded movements, caused by water immersion, they had on their tables. I am sure they will have plenty to tell.
Consequently, I see a tendence to downscale the pressure resistance rating, jut not to be made responsible for any user-initiated humidity problem. Just an example: When I bought my first expensive mechanical watch, this was a Zenith chrono, then called Class 4, later Class El Primero. This had shaped pushers, a non-screw down crown and a snapback, all features normally not connected with high water resistance. Nevertheless, it was rated to 100 meters:
A bit later, the very same watch, without any constructional changes, was rated to 50 meters only. Apparently, it were legal considerations rather than technical ones that caused that change.
On the other hand, Ulysse Nardin was the first manufacturer rating its watches with repetition to 30 meters, while all others did not give any water tightness rating, due to the slider used for releasing the chimes. Apparently, they trusted their construction enough.
A different example of a non-understandable depth rating is the Seiko Marinemaster 300, featuring a massive monocoque case and tiny crystal diameter, which normally would indicate a depth rating in the four digit range, and officially offers only 300 meters. Apparently, it should be able to withstand much higher pressures, but the manufacturer does not want to risk any claims resulting from failure at high pressure situations. And, to be honest, even after degrading of the gaskets, the Marinemaster should withstand a 300 meter water column anytime.
A different approach is the regulation of the warranty. Whhile modern movements often get a longer warranty, period, its validity is connected to the condition of a regular water tightness test at the manufacturer's service center. Sometimes, this condition is barely mentioned before the purchase. Breitling, for example, gives 5 years warranty for all B1-equipped chronographs, but only, if the watch is sent in for water tightness testing every two years. If you buy such a timepiece pre-owned, without proof of that testing, you only have two years warranty from original purchase. Omega, in the opposite, does not demand such a testing and gives a prolonged warranty.
Marcus