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DoctorEvil
·B bgkbckWell, I can tell you from personal experience to ALWAYs screw down your crown. In waist deep water my ceramic PO was destroyed!
https://thewatchmaker.com/water-resistance-101/
Water resistance with unscrewed crown?
https://thewatchmaker.com/water-resistance-101/
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Leviathan
·B bgkbckWell, I can tell you from personal experience to ALWAYs screw down your crown. In waist deep water my ceramic PO was destroyed!
Was this restored? We’d love to hear a follow-up on how this was dealt with (and at what cost). Hope it’s back on your wrist and in good shape.
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Archer
··Omega Qualified WatchmakerOMG, so sorry for you. Were you able to salvage it? However, this would be consistent with my understanding of water resistance ratings. So, 50m water resistance with crown unscrewed means splashes of water from rain showers and hand washing only. See table below and my reference link:
https://thewatchmaker.com/water-resistance-101/
Jack and his son should know better, but let's just say that is a "generic" chart that may apply to cheap fashion watches, but for actual information on the Omega, consulting the manufacturer is a better way to understand their ratings.
For Omega, the rules cited in that chart do not apply - 50 m means it can go down to 50 m.
I can't say what happened to the ceramic PO, but it appears there was a defect - this is not because the watch was subjected to too much pressure.
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Leviathan
·Jack and his son should know better, but let's just say that is a "generic" chart that may apply to cheap fashion watches, but for actual information on the Omega, consulting the manufacturer is a better way to understand their ratings.
For Omega, the rules cited in that chart do not apply - 50 m means it can go down to 50 m.
I can't say what happened to the ceramic PO, but it appears there was a defect - this is not because the watch was subjected to too much pressure.
Or is it redundant for, say, a brand new unaltered 300M+ rated Omega diver? Thanks.
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p4ul
·
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DoctorEvil
·Jack and his son should know better, but let's just say that is a "generic" chart that may apply to cheap fashion watches, but for actual information on the Omega, consulting the manufacturer is a better way to understand their ratings.
For Omega, the rules cited in that chart do not apply - 50 m means it can go down to 50 m.
I can't say what happened to the ceramic PO, but it appears there was a defect - this is not because the watch was subjected to too much pressure.
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josiahg52
·If my profession resulted in frequent wetting of my expensive watch or multiple decompressions, I would undoubtedly consider yearly pressure testing and maintenance a requirement.
I understand the screw-down He valve on the Seamaster watch only allows the auto-valve to operate in a decompression event when unscrewed. Otherwise, it positively ensures that the auto-valve will not open regardless of internal case pressure. The auto-valve is one-way.
When screwed down, the screw-down crown ensures that the stem remains centered within the stem tube which maintains the water resistance rating of the assembly. When screwed down, it also transmits any forces to the case proper which will make for a more resilient assembly. Some crowns have a secondary gasket that seals against the case.
I understand the screw-down He valve on the Seamaster watch only allows the auto-valve to operate in a decompression event when unscrewed. Otherwise, it positively ensures that the auto-valve will not open regardless of internal case pressure. The auto-valve is one-way.
When screwed down, the screw-down crown ensures that the stem remains centered within the stem tube which maintains the water resistance rating of the assembly. When screwed down, it also transmits any forces to the case proper which will make for a more resilient assembly. Some crowns have a secondary gasket that seals against the case.
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Archer
··Omega Qualified WatchmakerWhen screwed down, the screw-down crown ensures that the stem remains centered within the stem tube which maintains the water resistance rating of the assembly. When screwed down, it also transmits any forces to the case proper which will make for a more resilient assembly. Some crowns have a secondary gasket that seals against the case.
Again this depends a great deal on the design. A well designed crown system doesn't need to be screwed down to either keep the stem centered, or to transmit side forces on the crown to the case via the case tube. I think when people imagine these things in their mind, it doesn't always reflect the reality of what these crowns actually look like.
This point about stem centering and side forces is often brought up in the screw down crown discussion, and it implies that if a crown doesn't screw down, that the crown is free to flop around and be displaced with the slightest force, but this really isn't the case. Even in a crown that doesn't screw down, like on a Speedmaster, the crown is always in contact with the case tube. The clearance between the opening of the crown and the case tube is very small, so the lateral movement that can happen is extremely small - here's a photo to illustrate:
This is a Speedmaster case with a crown fitted to the case tube, and you can see that the case tube nearly fills the opening of the crown. There's not enough of a gap around the case tube to move the crown far enough that the seal inside the crown could ever lose contact with the case tube, or enough to cause the stem to go "off center" somehow.
Ironically screw down crowns in general have more of a gap than you see here, so when unscrewed they tend to be more vulnerable than non-screw down crowns in this regard. However the gap is still small enough on most designs that a side force on the crown isn't going to cause the seal inside the crown to lose contact with the case tube. This is particularly true for case tubes that are internally threaded like Omega uses.
Cheers, Al
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nnhoang
·
Oh hey that was me!
Even after Archer confirmed a watch would still be water resistant after unscrewing the crown, I was still curious about why. All his informative posts in this thread definitely fulfilled that curiosity.
I'm counting down the years before my SMPc needs servicing.. can't wait to send it to Archer.
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PATRICK JP
·Hello! I also have a doubt, if for example you forgot to screw the crown and go into the sea or take a shower with unscrewed crown, can something happen? Or does it have extra protection? I am referring to the Omega Seamaster 300m.
Crown unscrewed and having a shower or going to swim in the sea ?! This will result in flooding your watch, no doubts.
PS: I stand corrected after reading Archer’s very instructive post.
Edited:
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PATRICK JP
·So, this question comes up frequently, so here's some photos for the you. Starting with a freshly serviced watch:
Standard pressure test using vacuum and pressure. -0.7 bar vacuum, and +10 bar pressure:
With the crown screwed down, of course it passes easily:
Let's unscrew the crown now:
Test it again, and it passes:
Here you can see that the crown is unscrewed:
Now let's pull the crown all the way out to the time setting position, so pulled out as far as it can be pulled out:
Test it again, and it passes:
The gasket that is inside the crown doesn't leave contact with the case tube, no matter what position the crown is in. No one is suggesting that you should intentionally leave the crown unscrewed on the watch, but if you do and the seals are in good condition, then most likely you will be fine.
There are some people on watch forums (this one included) for whom water resistance is a topic that can't be thought about in any rational fashion. They will tell you that getting your watch wet will result in doom and chaos, but these watches are designed to resist water, and if they are in good condition (this is the key) then they will be fine.
Cheers, Al
Excellent illustrations and explanations ! Thanks !
Here I have a question: Some people recommend that waterproofness be checked once a year as a precaution. Now, I have collected my brand new Seamaster 300M in 05/2022 and saw on the outer box that it was manufactured 07/2021. Soon we shall get into August, does it means that I should get my new watch checked ? This watch was never immersed either in the sea, fresh water, shower, etc…
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Evitzee
·Never could understand why owners with watches with screw down crowns seem to forget to secure them and then jump in the water. When on your wrist the crown should be screwed down, period.
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Cosmin Robert
·That's right, every time you have it in your hand, the crown must be screwed to the maximum. I've jumped in with him a few times so far, not the slightest problem! After I swam with him I took a "shower" with clean and fresh water! I was more curious, that's why I asked in this topic.
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