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 idea occurred to him when his gaze fell across an ESP-01 module next to a watch on his bench. Figuring the two needed to get together, he ordered a BMP280 pressure sensor board, tiny enough itself to fit anywhere. Teamed up with a small LiPo pack, everything was stuffed into an Invicta dive watch case. A little code was added to log the temperature and pressure and transmit the results over WiFi, and [Kristopher] was off to torture test his setup.

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.

Hats off to [Kristopher] for doing the work here. We always love citizen science efforts such as this, whether it’s hardware-free radio astronomy or sampling whale snot with a drone.

24 thoughts on “Torturing An Instrumented Dive Watch, For Science

  1. Sealing at deep depth but leaking at low depth is plausible, even if it wasn’t the case on this particular watch. Sometimes if the case is flexible, it may have a mediocre seal and slow leaking condition until you lower depth and the water pressure compresses the case together. If you test products intended for deep depths only at the maximum pressure rating and never test at low pressure and other pressure levels in between, you can miss failing conditions.

    1. Yes, but such a behavior would be useless for a dive watch. You can not just magically emerge in greater depths. You have to dive down in a controlled way and even more important: you have to dive up slowly to avoid decompression sickness or even death.

      1. True, just worth mentioning that the harder waterproofing test very often is the spray test or sticking the watch for 6 hours in 1 inch of water rather than putting in a pressure chamber. Compression makes seals better up to a point.

  2. Why did you guys use an Invicta? They are not ISO certified dive watches, in fact they have been shown to have crap water resistance even in shallow swimming. Get a Seiko SKX or a Citizen Promaster next time.

    1. Yep – tried – sensor wifi package wouldn’t fit. We didn’t test the max depth rating, but it was fine at 70m. Also – you could infer that if an Invicta will survive, a certified watch would do even better.

  3. A meaningful question here is – is this the same watch brand from the same manufacturer or just comparing a case he put together carefully, and of high quality, with a ??? knockoff from ???

    See my point? Are all dive watches the same, built with the same design and care as one another? Testing the wrong thing might not be such a meaningful test.

    1. It’s really odd that he chooses to put a pressure sensor instead of a humidity and temperature sensor. Screw down the case back compresses the air in the case is really expected and his experiment doesn’t tell a whole lot. Also watch case / crystal compresses (which is the working principle of dry leak testers) and there’s just too many factors that would influence pressure. Humidity (along with temperature) would only be affected by leakage. If you got a leak the absolute humidity would just go up.

      1. Why not humidity and temperature and pressure sensor (bme280)? They are cheap now. I made my watch pressure tester with a water bottle, schrader valve and magnets. I prefer yours to mine but seeing bubbles come out is satisfying. BMP280 is better than the datasheet, I use mine in a vacuum gauge.

    2. Hi! The construction and seals for most dive watches are the same. You have a rubber gasket on the edge of the back of the case and 1 or more on the crown. I have experience with mechanical watches, and I guess I failed to mention that’s what I’m specifically discussing. This is a real Invicta case which has a claimed manufacturer rating of 300m.

  4. I’ve always loved the BME280, but now I love it even more.

    Glad that the test used the case of a real dive watch, and not something of questionable origin which claims “5 ATM” on the dial but it’s 30 day warranty is void if you shower or swim with it. ;-)

  5. I guarantee your demo didn’t convince anyone to whom it wasn’t already obvious that a dive watch can handle a shower just fine. Those are not people for whom logic, reason, and measurement mean anything. Can we stop indulging idiots by taking their nonsense seriously?

    What’s next- putting motion sensors and cameras in the closet and under the bed to prove there are no monsters there?

    1. While I agree there seems to be a bigger subset of people like that running around right now, I know a few people that need to see things with their own eyes to understand even after an explanation. I approached this as a teaching opportunity.

      I think you described a baby monitor. Which is a small % for keeping the baby safe, and a large % of reassuring Mom that there are no monsters in there.

  6. Measuring pressure inside the case tells you nothing especially if you are exposing it to a non constant, non uniform pressure. Water/moisture can leak in from one edge and air can leave from another with the pressure inside being irrelevant. You can also have small amounts of water enter and not detect it because of large changes in temperature. What would be more useful is detecting humidity in the case. Pack in a sensor while in a dry atmosphere and seal the case. Any moisture means a seal failure.

    1. You propose a valid test. I would consider this for a watch of a lesser depth / water resistance rating. In this case though – this is a tiny pressure vessel and humidity is not seeping into the case if 100psi of air is not getting in there.

      1. It is possible for the 100 PSI pressure to drive in a small amount of moisture without the pressure inside the case changing a to detectable level. That’s because the pressure might not increase much, especially if the moisture condenses out of vapor, a temperature change might mask a small vapor volume change, and the flex in the watch case itself would cause an increase in pressure that would likewise mask the moisture seepage.

  7. The issue with wearing a watch in the shower isn’t the pressure, that has never been the issue. The issue is how the temperature affects the seals inside the watch. Most all dive watches are designed to operate within a normal temperature range not much higher than about 100 some odd degrees. Any higher, and you risk the fluctuation of size and fit of gaskets and seals, which then compromises the seal.

    1. I put this in an oven and got it over 110F degrees inside – outside temps were 170F+ It was still totally water proof. A watch at the beach in the Sun could see the same temps as a hot shower. I would argue that this is exactly the environment that dive watches are designed for.

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