Screw Down Crown vs Push/Pull Crown: What Actually Keeps Water Out
A watch case is a sealed box. The case back is gasketed and screwed shut, the crystal is pressed into its own gasket, and the case body is machined from a single block of steel or titanium. Once those joints are closed, they stay closed. However, there is the crown. It has to turn, it has to pull out and it has to push back in. It is the one part of the case that moves in normal use, and it is the one place where water has an obvious route in.
Watchmakers deal with this in one of two ways. Either the crown threads onto a tube and clamps itself shut, or it sits in that tube on a rubber O-ring and is held there by friction. That is the entire difference between a screw down crown and a push/pull crown. But if you are looking for a dive watch or a waterproof watch, which one performs best at depth?
What a watch crown actually does
The crown is the knob on the side of the case. Behind it sits the winding stem, a thin shaft that runs through a tube in the case wall and into the movement. Pull the crown out and the stem changes position: one click to set the date, two to set the time. Turn it in and you wind the mainspring.
That stem passes straight through the case wall. Unlike the case back or the crystal, it is not a fixed joint that can be sealed once and forgotten. It is a moving shaft in a hole, and the only thing standing between the movement and the water outside is a small rubber gasket seated in the crown tube.
A watch has four sealing points:
- The caseback gasket
- The crystal gasket
- The pusher gaskets, on a chronograph
- The crown gasket
Three of those never move. The fourth moves every time you set the time. Everything that follows is about how you keep pressure on it and stop water getting into the internals of your watch.
How a threaded crown seals
A screw down crown, also called a locking crown or a threaded crown, has a fine thread cut into its inner face. The crown tube on the case carries a matching thread. Push the crown in, turn it clockwise, and it winds down onto the tube until it stops hard.
The crown tube and the threading
The tube is usually a separate component, pressed or screwed into the case wall and sealed with a gasket of its own. The threads are shallow and fine, and it takes only two or three turns to go from open to locked.
That fineness is also why cross-threading is the most common way people damage a crown. A small-diameter thread does not tolerate being forced, and a crossed crown always feels like it is nearly catching when it is not.
Why the gasket is the most important part of a crown
Because the threads do not seal anything. If you thread a bolt into a nut and hold it up to a light, you will see air gaps. The threads are not a barrier. What they do is generate clamping force. As the crown winds down, it compresses an O-ring inside the tube against a flat mating surface. The rubber deforms, fills the microscopic gaps, and that is your seal.
This is why a locking crown is not automatically more waterproof, but it is more reliable. It is also why it does not matter if your watch is rated down to 250 meters if the gasket is perished, because it will get ruined. And it is why you should service your watch regularly.
How a push/pull crown seals
A push/pull crown uses the same gasket without the clamp. The crown is a friction fit in the tube. The O-ring is very slightly oversized, so pushing the crown home compresses it just enough to seal. It is a good system, and it is fitted to far more watches than the threaded version, including plenty rated to 100 meters.
What you get from a push/pull crown
- One movement to set the time, with nothing to unscrew
- No threads to cross or strip
- Fewer wearing parts
- A slightly slimmer case
Where a push/pull crown falls down
- The crown can be pulled out accidentally by a cuff, a strap or a pocket
- Nothing holds the gasket under compression when external pressure rises
- The seal depends entirely on the condition of one O-ring
- In practice it tends to cap out around 100 meters
The real differences between the two
| Screw down crown | Push/pull crown | |
|---|---|---|
| How it seals | Threads clamp the gasket | Friction holds the gasket |
| Typical rating | 100 to 500+ meters | 30 to 100 meters |
| Accidental pull-out | Not possible when locked | Possible |
| Wear points | Threads and gasket | Gasket |
| Setting the time | Unscrew, set, screw back down | Pull, set, push |
| If neglected | Fails at the gasket | Fails at the gasket |
| Built for | Water, pressure, impact | Everyday wear |
If you are looking for a good dive watch, what you should consider is this: a push/pull crown is a good seal that depends on being left alone, and a screw down crown is a good seal that stays clamped whether you leave it alone or not. If you are regularly down to 200 m in search and rescue operations, or even if you are a recreational diver, sometimes that can be the distinction between a reliable watch you can wear for many years, and one that gets destroyed the first time you wear it.
What you should also consider is that both designs will fail the same way, at the rubber.
Does a locking crown make a watch more waterproof?
Actually, no, it does not. It does make the watch more reliably sealed, which is not the same thing. If you are a scuba diver and you only go down to 50 m, that is probably not going to make much difference to you. If you are looking for a serious dive watch, then this is something you should pay attention to.
The gasket is doing identical work in both designs. A screw down crown does not create a better seal. What it does is guarantee the seal stays compressed, and guarantee the crown cannot be knocked or dragged out of position while you are wearing it.
Which means a well-maintained watch with a push/pull crown and a fresh gasket will outperform a neglected watch with a locking crown and a ten-year-old one. The mechanism only helps if the rubber underneath it is still doing its job.
Where the threaded design is genuinely better is under sustained pressure and under impact: diving, or any field use where the watch will take knocks with sand or grit in the mix.
What water resistance ratings mean
The number stamped on a case back is probably the most misread figure in watchmaking. It is not a depth you can go to.
Water resistant is not waterproof
No watch is waterproof, and in most markets a manufacturer is not permitted to use the word. Water resistance is a rating established under specific laboratory conditions, and it degrades from the day the watch leaves the factory as the gaskets age.
Why a 50 meter watch is not a swimming watch
Ratings are established in a pressure chamber with the watch stationary. Real water is not stationary. Diving into a pool, swimming a stroke, or standing under a shower head all generate momentary pressures far above the static equivalent of the depth involved.
In reality, this is what you can do with a watch depending on what it is rated to:
- 30 meters / 3 ATM. This is for splashes and rain. It is not for swimming.
- 50 meters / 5 ATM. This is for brief accidental immersion, say if you drop your watch in the sink. Still not for swimming.
- 100 meters / 10 ATM. This is the minimum depth you can take a watch swimming and snorkeling.
- 200 meters / 20 ATM. This will work for hard swimming, surface water sports, and recreational diving.
- 300 meters and above / 30 ATM+. This is for scuba or recreational diving, and you will be able to go down to serious depth.
- 500 meters and above with a helium release valve. This is for saturation diving, where the watch is held at pressure for days.
ISO 22810 vs ISO 6425
There are two standards that dictate whether a watch is waterproof or not. ISO 22810 covers water-resistant watches generally and sets out how the rating is tested. ISO 6425 is the diver's watch standard, and it is considerably stricter: a minimum of 100 meters, a time display legible in darkness, a unidirectional bezel or equivalent elapsed-time control, and resistance to shock, magnetism, salt water and thermal shock, with every individual watch tested rather than a sample from the batch.
A watch marked "diver's 200m" has met ISO 6425. A watch marked "200m water resistant" has not. If you take one thing away from this article, it should be this. If you need to do serious diving, make sure you know what you are buying.
Which crown do you actually need?
For most people the honest answer is that a push/pull crown is probably enough. If your watch will see rain, hand washing and the occasional swim, and you have it serviced on schedule, it will be fine.
However, if you go into the water regularly, down to any kind of serious depth, or if it goes somewhere it will be knocked about (field, military or tactical use being the obvious use cases here) or if you simply do not want to think about whether the crown is sealed or not, you need a locking crown. Below are our top four picks for some of the best dive watches from MTM, and all of them have a locking crown.
Our top pick for everyday wear and travel
The Hypertec Chrono 2A is one of our entry-level watches. Constructed and crafted from solid 316L stainless steel, it's rated to 200 meters (so it's excellent for swimming) and has a 44 mm case diameter. We use the exceptionally reliable Miyota 0S11 quartz chronograph movement - of course, with a locking crown.
Two hundred meters on a chronograph matters more than it sounds. A chrono has two pushers piercing the case alongside the crown, which means more moving seals. If you want one watch that handles a commute, a holiday and a pool without a second thought, this is the one for you.
Our top pick for lightweight daily wear
The Black Falcon Titanium, $1,235, has a 44 mm titanium case rated to 100 meters, with sapphire crystal and our proprietary 8J81-M4 quartz movement with a recharging system.
This is the pick if weight is the deciding factor. Titanium runs roughly forty percent lighter than steel, which is the difference between a 44 mm watch you forget you are wearing and one you notice all day. The 100 meter rating is the lowest of the four here, and that's the honest trade you're making. This isn't really a dive watch, and it's a watch to be worn constantly rather than dived in - the locking crown is there so that constant wear never puts the seal at risk.
Our top pick for field and tactical style
The Black Warrior, $1,235, is 44 mm in solid 316L stainless steel or titanium, rated to 200 meters, using a Swiss Ronda 715Li quartz movement behind anti-reflective K1 tempered glass. This has a locking, O-ring sealed crown.
It shares its 200 meter rating with the Hypertec, so it is worth saying plainly what the extra money buys. The Warrior's crown assembly is specified with its own O-ring seal, the movement is Swiss rather than Japanese, and the case is offered in titanium as well as steel. This is a watch designed to be knocked about with grit in the threads, and the crown is built to match.
Our top pick for diving and extreme depth
The US-744X, $3,225, is a beautifully engineered watch, designed for serious divers. A 45 mm case machined from Grade 5 titanium with forged carbon fiber, rated to 500 meters and fitted with a helium release valve, behind 5.5 mm of sapphire, driven by a Grand Seiko 6R20 automatic with 29 jewels and a 45-hour power reserve. This is a serious piece of kit.
The helium release valve is the detail that tells you what this watch is for. Saturation divers live in helium-rich atmospheres for days at a time. Helium molecules are small enough to work their way into a sealed case, and on ascent they need somewhere to go or they push the crystal out. A valve is only fitted to watches expected to be used that way. On a 500 meter case the locking crown is a structural requirement.
Frequently asked questions
Not necessarily, but it is definitely more secure. It clamps the gasket rather than relying on friction, and it cannot be pulled out accidentally. For a watch that goes in water regularly or takes impacts, that is important. For everyday wear, a push/pull crown with a healthy gasket is typically perfectly adequate.
Almost all of them. ISO 6425 does not mandate a threaded crown outright, but in practice it is very difficult to meet the standard's pressure and reliability requirements without one.
Yes, if the watch is rated to at least 100 meters, the crown is fully pushed home, and the gaskets are in good condition. If you want to go deeper than 100 meters, you will probably find your watch is ruined by the time you surface.
The watch runs normally and looks fine, but its water resistance is effectively zero. An unlocked crown on a 200 meter watch is less sealed than a properly seated push/pull crown on a 50 meter one. Make sure the crown is fully home before you dive.
Usually cross-threading, where the crown has caught at an angle. Back it off completely, push it straight in with light pressure, turn counter-clockwise until you feel it drop into the thread, then wind it clockwise. It should turn with almost no resistance. If it does not, stop. Grit in the threads or a bent stem needs a watchmaker, and forcing it will strip the tube.
Finger tight, and no more. The gasket is fully compressed as soon as the crown seats. Extra force does nothing for the seal and wears the threads. Do not go at it with pliers, it is just not necessary.
No. The crown has to be unscrewed before the winding mechanism engages. On an automatic that is rarely an issue, since the rotor does the work, but a watch left unworn for a few days will need unscrewing and hand-winding to restart.
That the watch passed a pressure test equivalent to 20 atmospheres under static laboratory conditions. In practice it means swimming, surface water sports and recreational diving are fine, provided the crown is locked and the gaskets are current.
Not really. Fifty meters covers splashes, rain and brief accidental immersion. Swimming generates dynamic pressure well above the static figure. One hundred meters is the sensible minimum.
