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posted by Fnord666 on Wednesday July 24 2019, @03:45AM   Printer-friendly
from the is-it-impact-resistant? dept.

Submitted via IRC for Bytram

Torturing An Instrumented Dive Watch, For Science

The Internet is a wild and wooly place where people can spout off about anything with impunity. If you sound like you know what you’re talking about and throw around a few bits of the appropriate jargon, chances are good that somebody out there will believe whatever you’re selling.

Case in point: those that purport that watches rated for 300-meter dives will leak if you wiggle them around too much in the shower. Seems preposterous, but rather than just dismiss the claim, [Kristopher Marciniak] chose to disprove it with a tiny wireless pressure sensor stuffed into a dive watch case.

[...] The first interesting result is how exquisitely sensitive the sensor is, and how much a small change in temperature can affect the pressure inside the case. The watch took a simulated dive to 70 meters in a pressure vessel, which only increased the internal pressure marginally, and took a skin-flaying shower with a 2300-PSI (16 MPa) pressure washer, also with minimal impact. The video below shows the results, but the take-home message is that a dive watch that leaks in the shower isn’t much of a dive watch.


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  • (Score: 3, Informative) by martyb on Wednesday July 24 2019, @08:03AM (2 children)

    by martyb (76) Subscriber Badge on Wednesday July 24 2019, @08:03AM (#870602) Journal

    In general, I would agree with your assessment, but things are not quite as dire as suggested.

    I refer to https://en.wikipedia.org/wiki/Water_Resistant_mark [wikipedia.org] — specifically to the sections on "ISO 2281 water-resistant watches standard" and "ISO 6425 divers' watches standard".

    In the former, only a sample of watches from a lot need be tested. Specifically:

    ISO 2859-2 Sampling plans indexed by limiting quality (LQ) for isolated lot inspection and ISO 2859-3 Sampling procedures for inspection by attributes – Part 3: Skip-lot sampling procedures

    In the latter, just to make sure we are talking about the same thing:

    "Watches conforming to ISO 6425 are marked with the word DIVER'S WATCH xxx M or DIVER'S xxx M to distinguish diving watches from look-a-like watches that are not suitable for actual scuba diving. The letters xxx are replaced by the diving depth, in metres, guaranteed by the manufacturer."

    Here is just one of the many qualifications a diver's watch must pass:

    Diving watches are tested in static or still water under 125% of the rated (water) pressure, thus a watch with a 200-metre rating will be water resistant if it is stationary and under 250 metres of static water. ISO 6425 testing of the water resistance or water-tightness and resistance at a water overpressure as it is officially defined is fundamentally different from non-dive watches, because every single watch has to be tested.

    The force of the spray in a shower is incredibly small compared to the pressures that every dive-rated watch is tested to. Imagine suggesting that a submarine may be able to dive to a depth of 200 meters, but might suffer water intrusion during a heavy rain. Yeah, it's about that silly.

    Not satisfied to test his instrumented watch case in a simple shower, he also tested the water resistance under a power washer:

    Close enough to strip paint…

    This is my gas powered 2800psi pressure washer way too close to a 300m dive watch. I’m using the white nozzle here to simulate a proper soak. I was only able to change the pressure inside the watch 0.14psi or about half of our 70m dive of 0.3psi. If water was somehow able to seep into the case we would have seen a much higher change in pressure, and the pressure wouldn’t revert back to where it was when we stopped hitting it with the spray. If taking more than 2000psi of shower to the case is like diving 35m, then I’m sure that your 50psi home shower will not hurt your dive watch.

    Bad car-ish analogy time. Imagine an industrial warehouse where forklifts regularly transport metric-ton-sized loads around, and claiming that if you jump up and down you can get the concrete flooring to crack. How many times are you gonna have to jump?

    If you purchased a dive watch and it leaked while you were taking a shower, then there is something definitely wrong with the watch. (Assuming, of course, that the watch is relatively new -- i.e. the seals have not dried out -- and it has not suffered a major impact; just every day wear and tear.)

    Background: I have over a dozen years' experience selling watches... probably well over 500 watches in any one of those years. I have had numerous people tell me (who had watches with the, lesser, ISO 2281 rated resistance of 30 meters): "Oh, I swim and shower with my watch all the time; never had a problem!" I don't recall ever seeing a diver's watch with water intrusion.

    tl;dr: "If your diver's watch stopped because of water, then you probably did, too." =)

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  • (Score: 2) by AthanasiusKircher on Wednesday July 24 2019, @06:56PM

    by AthanasiusKircher (5291) on Wednesday July 24 2019, @06:56PM (#870810) Journal

    Thanks so much for all this detailed info.

    On a sort of related topic, I do think that such a test posted online might be useful for some people. We live in an age of increasing doubt. (And in many cases consumers often have very good reasons to doubt manufacturers' claims.)

    I agree with your assessment here, but the sort of misinformation about watches spreads quickly on the internet -- "You can't even shower with them on!" And sometimes citing specs isn't enough to convince anyone, but seeing a video is. Weird, but most people don't really have a scientific mindset. You can cite numbers and statistics, but they see a video of a guy testing it, and suddenly they believe it. (Sometimes.) Of course, an online video could be doctored. Websites have sponsors all the time who do "generous" reviews. I'm NOT saying that happened here, but people also have a valid reason to question such things too.

    And I'm sure some of those folks are arguing somewhere on the internet right now -- "Obviously, this guy is a paid shill!" Or, "obviously this is what they want you to believe, but you see how he did this in the video? That's fishy..." Etc. We live in an era of both doubt and conspiracy theory. I don't know how to change that in general. But to the question at hand -- some people will believe this online "experiment" more than they believe specs. Others will still shout about conspiracies. 'Tis the way of the world these days it seems.

  • (Score: 1, Funny) by Anonymous Coward on Thursday July 25 2019, @04:19AM

    by Anonymous Coward on Thursday July 25 2019, @04:19AM (#870939)

    The Internet is a wild and wooly place where people can spout off about anything with impunity. If you sound like you know what you’re talking about and throw around a few bits of the appropriate jargon, chances are good that somebody out there will believe whatever you’re selling.

    Background: I have over a dozen years' experience selling watches... probably well over 500 watches in any one of those years. I have had numerous people tell me (who had watches with the, lesser, ISO 2281 rated resistance of 30 meters): "Oh, I swim and shower with my watch all the time; never had a problem!" I don't recall ever seeing a diver's watch with water intrusion.

    ...