jason_recliner wrote: ↑
November 9th 2021, 4:54am
3Flushes wrote: ↑
November 9th 2021, 4:03am
jason_recliner wrote: ↑
November 8th 2021, 5:04pm
conjurer wrote: ↑
November 8th 2021, 12:59pm
koimaster wrote: ↑
November 8th 2021, 11:06am
Was not aware that "dive" watches had Exhibition Casebacks. Perhaps Omega should rename the watches as something like Black Bay desk diver, the perfect watch for wanting to look like a man.
That's the thing, isn't it. It doesn't make sense to put an inaccurate fragile mechanical movement in a dive watch. But it's in there and it's beautiful so you want to see it. The 'luxury dive watch' is a bit silly. I loved my PO and SMP to bits. Would I wear one today? No.
But oh my LORD, that dial. Come on Omega, put the zircon dial in an Aqua Terra already.
The notion that dive watches with mechanical movements are unsuitable for diving is nonsense.
Nah, a mechanical movement is good enough
in most instances. But it's far from the best engineered. Quartz movements are significantly (i.e. measurably) more durable, rugged, and shock resistant. Not to mention more accurate and more reliable.
Sapphire is hard and strong but it's brittle. But again, it's good enough
. The real risk is adding another join between two pieces (sapphire caseback and metal caseback surround) that must be sealed. Sealing isn't hard, and it almost always won't fail. But if one was looking to design a reliable, functional caseback, would it comprise one or two pieces?
Agreed that analog quartz watches are somewhat more durable given the absence of, particularly, a balance and escapement, and much of their accoutrements, however, to aver that mechanical movements are therefore too fragile and not suitable for diving, particularly without supporting documentation, is nonsense. The degree to which mechanical dive watches are utilized by professional and sport scuba divers, including our own resident diving expert, speaks for itself.
As to greater reliability of quartz, I'm not sure how true that actually is even if the electricity doesn't go out for whatever reason.
As to accuracy, a good quartz movement is somewhat more accurate than a good mechanical movement, however, that the difference is substantial enough to be critical to scuba diving is nonsense. In the case of Tudor, pre Master Chronometer Omegas, Bremont and other top shelf divers, the COSC cert of -4 to +6 seconds per day equates to - .167 to + .25 seconds per hour. The METAS cert of 0 to + 5 seconds per day equates to + .208 seconds per hour. At a hypothetical +/- 25 seconds per day accuracy spec, worse than any Seiko (arguably the most popular dive watches) mechanical movement, equates to 1.042 seconds per hour.
While the typical dive generally lasts about an hour or so depending on depth, even assuming a four hour dive, well beyond the non decompression limit of 205 minutes at a depth of 35 feet, if
a diver could carry enough air, and assuming, of course
, that a proper pre-dive synchronization of the subject watch with a calibrated time source like an atomic clock, or a computer, has been performed, it hardly seems necessary to say the notion that a mechanical dive watch is not accurate enough for scuba diving is not only nonsense, but is utterly ridiculous.
As to sapphire, again the thicker the material, the less brittle in tension, and the more likely to survive most typical impacts, and is certainly hard enough to withstand far greater than the pressure at the specified depth rating of any dive watch.
Regarding the water resistance and reliability of a screw down open back, they are indeed two pieces; the way they are assembled in a fully automated process is the key. The sapphire lens is slightly larger than the threaded piece of the caseback, between .33mm, and .53mm or somewhere between 1 and 2/100ths of an inch or so. The lens is held by a vacuum over the reverse of the threaded piece, and a gasket is placed on a lip machined around the inside just above the male threads. The sapphire is then press fit into place onto the gasket making for a secure fit. The gasket is then fully compressed when the unified caseback is flipped over and screwed into the case during assembly, assuring a watertight seal. Many solid and open casebacks have a double gasket design.
There is no way for the fit of the sapphire to fail. An exhibition caseback is no more subject to leakage or failure while being worn than is a solid caseback; in the case of the failure of the gaskets, that is. Such a failure is less likely than trump being voted Pope if the gaskets are refreshed and the watch pressure tested on schedule by a watchmaker who knows what they're doing.
While closed casebacks on tool and dive watches was a longstanding watchmaking tradition, open casebacks have been around since the sixties, and have become a ubiquitous presence in watch design, and will be sooner than later in what is perhaps the last frontier, dive watches with mechanical movements, that is.