I am afraid I don't have the answer to your question. I tend to rest my 8900 AT dial up when I take it off at night and it is generally around +0.5-1 spd.

How long have you had your watch and has it been mostly everyday wear? Did the hour hand issue start after you began resting it on the crown? I can't imagine the minimal extra force on the crown would make a difference--especially if it is screwed in. But that's just my guess.

I must say it always freaks me out hearing about the hour hand issues on the 8900 movement. Shouldn't happen on such an expensive watch!

 

I’ve had it since Dec 2020. Got it grey from Joma. It’s mostly weekend wear and I swap between it and my VHP when I’m too lazy to wind. So, infrequently on the weekends. I have used it to date change when it’s been behind. I honestly can’t remember if the hour hand issue came like that and I didn’t realize it or if it developed after I got it.

I do know though that I stripped the crown’s threading early on (first time with a screw down crown).

I agree on the hour hand issue. Has left me a little miffed. I still maintain it’s close to a perfect watch!

 

In reading other threads about this topic I have noticed that it tends to be people who swap watches frequently who have this issue, since they often have to scroll through multiple dates. See this thread: https://www.watchuseek.com/threads/aqua-terra-hour-hand-getting-stuck.4647801/page-3 -- in there people speculate that this issue is due to wear on the hour wheel from excessive use of the jumping hour hand. So you can help prevent the problem by minimizing use of that function to only when necessary (this is easier when you wear it everyday and only have to adjust for the occasional short month).

Maybe it is possible that stripping the crown threading early on jostled something in the movement leading to the problem. I have a hard time imagining that resting a watch on top of a properly screwed down crown would cause any problem at all.

It is a perfect watch for me so far! Crazy accurate, great looking, and dependable (knock on wood).

 

I can't speak for the positions, but I can't imagine resting it with the crown in a downward position would be a problem. It's screwed into the case.

However, I don't think your hour hand being off is due to that. My AT did the exact same thing. I have pics of mine where the hour hand was perfectly aligned. Then I noticed that it wasn't aligned anymore, so I know it wasn't always that way. I honestly don't know why, but my GUESS is that it would be more due to having to cycle around so many times to set the date. I'd much rather this movement have a quick-set date as opposed to being able to independently move the hour hand. YMMV.

I sent it in for servicing under warranty. It's back and doing just fine...for now.

 

Most put their watches in the dial up position.

 

With the majority of my watches I timegraph them to find out which positions run fast and which run slow, then use this position overnight to compensate any inaccuracy incurred during the day. However, my 8900 series AT, which consistently runs at +2 on wrist does not have a position where it actually loses time so I keep it dial up overnight which keeps the +2 accuracy. Oh, and I seriously doubt there would be any damage to the crown in the resting position you're talking about, OP.

 

I leave my 8900 AT resting on it's crown overnight all the time, and that keeps it consistently about +1spd. I've had it nearly 4 years and haven't noticed any issue whatsoever.

 

Perhaps I'm missing something, OP, you're not physically resting your watch on it's crown, right? If you are I'd prop it up on something so as to avert any pressure on it.

 

? Seems like a stretch that resting on the crown would cause harmful pressure. I do this with 2 watches and have been for many years, zero issues or problems. Are you saying most watch heads are heavy enough to cause harmful pressure? Until I read your warning I have never given this practice one thought in terms of possible damage or any negative impact at all. One of them was an AT 8900, the other is a speedmaster 9906 movement.

If anyone can expand on this please do, if it's harmful I'll change my ways!

 

I am resting it on its crown.

 

Why in the world would you do that and needlessly put pressure on it? At least put a soft cloth underneath it.

 

Sunny side up is safer......

 

Crown down gets me the best accuracy results. Maybe that will change after service.

 

I use a small padded zipper travel case that allows me to put mine crown down too but it is extremely well protected and it’s not actually resting on the crown even though it is crown down… if that makes any actual sense.

 

My AT (top left) tumbles when not worn:

 

Send it in for service and create a record of any defects in the watch. If it needs more repair in the near future then you have a record of a not so brilliant experience with the watch or the service department. The watch should function just fine in any position you leave it in. The 8900 is one of the most advanced watch movements you could buy, and it is a premium spec movement from Omega. With two barrels, 60 hours of power reserve, magnetic resistance to 15,000 Gauss, a silicon balance spring, and METAS Master Chronometer certification. This watch will be accurate upside down on the moon. Question is going to be how did you manage to strip the crown threads?

 

First time with a watch with a screw down crown. The AT is my second ever mechanical watch (first was a Tissot Le Locle). So I applied too much force I think.

 

every one of my watches have a misalignment (hands, bezel, rehaut etc some degree) but 16mins is too much...

 

If you want to rest it crown-down then put it on something the case/bracelet are in contact with but the crown is not. For example, the cubbies in my 8-place watch box allow for me to do this with my Speedmaster Pro, which I rest in a couple of different positions to manage its accuracy (loses a bit dial-up and gains a bit crown-up).

I wouldn't rest it on the crown just to get a rate 1 second/day better than dial-up, but if you can rest it crown-down but not actually on the crown then that's different.

 

Resting the watch on its crown is not going to cause any damage. Your hour hand misalignment has nothing to do with that.

 

Since too many of the answers here are just feeding the madness, let me say this: you can rest the watch any way you please. As long as it's not in a running oven or under a heavy rock, it's gonna be fine. The crown is not tiny and the watch is not heavy. Ideally don't drop it on the floor or bang it against a wall. If you do, chances are it will be fine even then.

Just enjoy life man, that watch is tougher than you are!

PS: The hand misalignment should be fixed under warranty if it's that far off the mark.

 

If you are saying that the hour hand does not come up to the proper hour mark until the minute hand is on the 16 minute mark during normal operation, that has nothing to do with the watch gaining or losing time. It needs to be serviced and the hands removed and realigned. At noon or midnight all three hands should align together at 12, if they don't service is required.

It does not matter if you rest the watch with the crown down, the crown stem is not engaged with the movement when the crown is screwed down. I would say to rest it on soft so not to scratch it.

 

I the crown is screwed down, it is hard to see damaging the movement. Depending on the surface, you might damaging the Omega inscribed on the crown. As for the hour alignment problem, there are stories of issues with jumping hour movements. Although I thought that was more with the last generation.

 

My initial comment was that this novement is not one of the best. Do you you think this movment is one of the best? Is it in the top 3...?

You are the one that made the claims - it's not up to me to prove or disprove your claim. But this seems like a very naïve way to look at things. In order to even begin answering this question, we would have to define and agree on what parameters are being judged to determine what "best" means. You obviously value very specific things that many others would not, and are bothered by things that others are not bothered by, so this is a rather fruitless exercise.

It's very simple, Regarding the thickness, the Aqua Terra 41mm is 13.3, the Sinn U50 is 11.2, but whith a superior eater resistance (350 meters more than the Aqua Terra).

Yes, the SW300-1 used in the Sinn is based on the ETA 2892A2, and it's 3.60 mm thick. For a cheap off the shelf movement it's quite good. But it's not equipped with the anti-magnetic technology that the 8900 is, and it doesn't have a silicon balance spring. It isn't a chronometer, and the power reserve is 50 hours. So if your main criteria is that it's thin and cheap, it would be the winner. But on many other parameters it falls behind the 8900.

The 8900 is not a particularly thick movement at just 5.5 mm thick - this is for a twin barrel 60 hour power reserve movement. In comparison the Rolex 3035 is 6.35 mm thick, and the 3135 is 6.00 mm thick, yet the 8900 has a far longer power reserve than either of those two movements.

Regarding the date change I find it quite annoying the setting, it takes too much time.

Then don't buy one. All watch movement and watches are a series of compromises. If you can't live with it, then that's fine. But to declare it as inferior because it's annoys you seems a little juvenile.

There are definitely pros and cons to a quick change date v a quick change hour wheel. Again it's all what you value, and those decisions don't apply to everyone else.

Regarding the rotor and the misaligned hands, that's pure anecdotical evidence and I don't have any evidence to even try to argue. When the evidence is anecdotical, we cannot know if the affected watches represent 0.000001% of the total production or 1%.

If you can find hard data like you are asking for on any watch movement, please post it here. You won't, because no watch company publishes this sort of information.

There are no issues with the rotor on this movement, so not sure where you are seeing this.

As far the misaligned hands, there was a problem with the hand fitting early on where the hour hand in particular would drift over time - go out of sync with the minute hand. This was all about how tight the hands were when they were mounted on the movement, so it was not a movement related issue - it was hands that were not correctly manufactured. The repair that Omega put out was to replace the hands...not change anything in the movement.

So you are even attributing things to the movement that have nothing to do with the movement. Before you make declarations in the future, you might want to research the issues a bit more thoroughly.

Cheers, Al

 

You are the one that made the claims - it's not up to me to prove or disprove your claim. But this seems like a very naïve way to look at things. In order to even begin answering this question, we would have to define and agree on what parameters are being judged to determine what "best" means. You obviously value very specific things that many others would not, and are bothered by things that others are not bothered by, so this is a rather fruitless exercise.



Yes, the SW300-1 used in the Sinn is based on the ETA 2892A2, and it's 3.60 mm thick. For a cheap off the shelf movement it's quite good. But it's not equipped with the anti-magnetic technology that the 8900 is, and it doesn't have a silicon balance spring. It isn't a chronometer, and the power reserve is 50 hours. So if your main criteria is that it's thin and cheap, it would be the winner. But on many other parameters it falls behind the 8900.

The 8900 is not a particularly thick movement at just 5.5 mm thick - this is for a twin barrel 60 hour power reserve movement. In comparison the Rolex 3035 is 6.35 mm thick, and the 3135 is 6.00 mm thick, yet the 8900 has a far longer power reserve than either of those two movements.



Then don't buy one. All watch movement and watches are a series of compromises. If you can't live with it, then that's fine. But to declare it as inferior because it's annoys you seems a little juvenile.

There are definitely pros and cons to a quick change date v a quick change hour wheel. Again it's all what you value, and those decisions don't apply to everyone else.



If you can find hard data like you are asking for on any watch movement, please post it here. You won't, because no watch company publishes this sort of information.

There are no issues with the rotor on this movement, so not sure where you are seeing this.

As far the misaligned hands, there was a problem with the hand fitting early on where the hour hand in particular would drift over time - go out of sync with the minute hand. This was all about how tight the hands were when they were mounted on the movement, so it was not a movement related issue - it was hands that were not correctly manufactured. The repair that Omega put out was to replace the hands...not change anything in the movement.

So you are even attributing things to the movement that have nothing to do with the movement. Before you make declarations in the future, you might want to research the issues a bit more thoroughly.

Cheers, Al

I asked you if you consider the 8900 movement as one of the best because you know a lot of the subject. Among the movement that you know, do you consider it top 3 or maximum in the top 10?

The power reserve in the movement used in the U50 is 56 hours, not 50. The doble barrel argument for just 4 hours more of power reserve is flimsy. And thanks for the comment about the hands, I didn't know it and you're rigth, I will research more thoroughly and clearly the same applies to you. Mind you, I'm not a watchmaker. I only like to be informed about the things that I buy.

I'm not defending the SW300, which is clearly an inferior movement. In fact, my main complaint with the U50 is precisely the movement, next that there is no date option and finally the lume.

And you're rigth, just because the date changing I didn't buy the 41 mm.

 

I asked you if you consider the 8900 movement as one of the best because you know a lot of the subject. Among the movement that you know, do you consider it top 3 or maximum in the top 10?

Sorry, I don't try to come up with lists ranking watch movements. I leave that sort of thing to collectors to argue.

The power reserve in the movement used in the U50 is 56 hours, not 50.

Not really. Sellita is playing some games with the numbers they publish...so here's a copy of the image from the technical guide for the movement right from the Sellita web site:

DocTec_SW300-1.pdf (sellita.ch)

You will notice they list 2 numbers for power reserve. The minimum is 50 hours - this minimum number is what the industry uses when the give you a power reserve. It is true that watches will often run longer, in particular if new or right after a service. So an ETA 2824-2 that is rated for 38 hours will "typically" run for 43 or 44 hours.

The ETA 2892A2 that the SW300 is based on, has a rated power reserve of 42 hours, will "typically" run well over 50.

This is true for almost all watches - the published (minimum) power reserve is often far less than what the watch will actually run. Sellita is the only maker I know of that uses this "typical" number as a published power reserve, and quite honestly it's misleading because people inadvertently use it to make inaccurate comparisons as you have.

So just like the 2824-2, the 2892A2, and the SW300, the 8900 will also run longer than it's rated 60 hours. So this idea that it's "only 4 hours more" is false. You are comparing two different measures.

Cheers, Al

 

Sorry, I don't try to come up with lists ranking watch movements. I leave that sort of thing to collectors to argue.



Not really. Sellita is playing some games with the numbers they publish...so here's a copy of the image from the technical guide for the movement right from the Sellita web site:

DocTec_SW300-1.pdf (sellita.ch)

View attachment 17946183

You will notice they list 2 numbers for power reserve. The minimum is 50 hours - this minimum number is what the industry uses when the give you a power reserve. It is true that watches will often run longer, in particular if new or right after a service. So an ETA 2824-2 that is rated for 38 hours will "typically" run for 43 or 44 hours.

The ETA 2892A2 that the SW300 is based on, has a rated power reserve of 42 hours, will "typically" run well over 50.

This is true for almost all watches - the published (minimum) power reserve is often far less than what the watch will actually run. Sellita is the only maker I know of that uses this "typical" number as a published power reserve, and quite honestly it's misleading because people inadvertently use it to make inaccurate comparisons as you have.

So just like the 2824-2, the 2892A2, and the SW300, the 8900 will also run longer than it's rated 60 hours. So this idea that it's "only 4 hours more" is false. You are comparing two different measures.

Cheers, Al

I measured the power reserve of the U50 long time ago when someone said in a comment in this forum that Sinn updated the movment used in the U50. Thereby I wanted to know if my watch was within the updated batch or if it was the previous iteration.

I measured and left the watch alone and exceeded the 56 hours. I have those numbers in a note, but go you to know where are the numbers. The only thing that I member is that exceeds the 56 hours if I'm not mistaken and because of that I knew that my watch was the updated version. So the 56 hours is something that is easily verifiable.

And for sure it's good that companies exceeds the numbers, if I'm not mistaken the U50 is tested to 650 meters or 750, I don't remember the exact number.

I don't want to look like if I were fighting, sometimes i don't express myself properly. I'm here to learn and if I have the opportunity to cross words with some as knowledgeable as you are, believe me it's great. I'm taking it as a great opportunity to learn more and I appreciate very much your comments.

As I mentioned before, Omega is my favorite brand and I find the Aqua Terra in the top three watches. For sure there are many watches that could be more expensive and within my budget, but I will take the Aqua Terra any say of the week. And for sure there are almost uncountable more expensive options out there that are out of my budget and that I will never consider due to my limitations, but I don't care, I'm happy with what I have.