Given the interest in vintage Seiko divers, I thought it was worth posting about their modern descendents, especially the one in the most direct line in descent from the 6309 that people have been looking at. This is the SKX007 - also known as the SKX09 when it has a bezel with a "pepsi" red quadrant - and the SKX013 when in a slightly smaller case sized for women:
The 7 evolved from the 6309 in a an extremely simple way - Seiko modified their standard mechanical watch mechanism to be even more reliable than it already was, and copied what jewellers in Asia had been doing for clients in machining away the "excess" metal from the 6309's large cushion case to make it slightly lighter. Otherwise Seiko stuck with already worked for them - an ultra clear face and hands, and a crown at 4 instead of 3 to make it less likely to stick in your wrist. Earlier versions of this process were called the 7002 and replaced the 6309 in 1988, and the final SKX007 was introduced in 1996.
The result was a huge success. These watches are true ISO rated divers (meaning they have to meet standards for drop resistance and water resistance, and that they have to be tested more thoroughly than normal watches) and became a standard on dive boats, because they're widely reckoned to be the tougest mechanical watch in existence, they enormous "lume" (i.e. they glow really brightly in the dark) and because, as ISO divers go, they are so cheap - buying an SKX007 is cheaper than getting a Rolex Submariner serviced. (About $200-$250.)
The SKX007 was also a big hit aesthetically, so much so that Seiko's $2000 and $4000 "Marine Masters" use a variation on its case design. At the same time, a modding industry grew up around the watch, and it's probably unique in the ready availability of replacement faces, hands, bezel rings, and crystals.
Other things worth knowing:
- The watch doesn't automatically "hack" (ie freeze the seconds hand) when re-setting, but if you are fussy then you an give the winder a little "back pressure" to freeze the seconds
- The SKX007 uses oversize spring bars. Not every strap can accept these, but you should never use smaller bars - they waggle in the receiving holes, grinding the edges of the bars and the holes.
- The worst case repair for an SK007 is that you replace the entire mechanism. You can do this yourself with a few tools bought off ebay, and "mechs" can be bought for about $50
- Standard accuracy is about 20 seconds a day, but watches often tweak to 5-10s a day if you have a jeweller tune them or do it yourself. However, once you've opened the case you have let dirt in, which reduced the time between services.
- If you leave an SK007 sealed, the life between services is reckoned to be about 20 years. So you should probably leave it sealed - unless you are diving, in which case you should have the watch seal serviced regularly and then pressure tested. At least in theory - because there are divers (I am *not* a diver!) who just use a G-Shock or an SK007 or whatever until it dies, with no seal servicing, and people do seem to get away with it...
- As standard the SKX007 comes on a steel "jubilee" bracelet or a rubber strap called a "wave vent" Z22. Most people would say that you are better replacing both of these: an online company called "Yobokies" and an ebay seller called "wjean" sell exceptional "oyster" style bracelets designed for the 7; a better (more comfortable) rubber strap would be the Seiko B22 (do NOT buy Seiko rubber straps on ebay - most are fakes and can tear very easily, leaving you with a dropped watch) or possibly a "flat vent" Z22. Nylon NATO straps are probably the most popular choice (the pattern of the one shown is called a "Bond" because Sean Connery wears a similar strap in Dr No - so free visual pun!):
..Notice the guards on each side of the winder to keep it from harm.
And this is an SK007 on a wjeans/yobokie (they look identical and probably come from the same factory) oyster bracelet:
- You can also find variants of the SKX007/9 with different model numbers and weird face colours and odd bezels if you trawl ebay
- Seiko-made faces are outstandingly bright; non-Seiko faces sold by modders will have much less lume.
- There is also a slightly smaller women's version, the SK013, which is still an ISO rated diver:
(These are on stcok wave vent Z22's: I like the Z22 and think it is comfortable, but a lot of people do not - so it's probably a good idea to pick up a NATO as well when you order the watch.)
- All versions are autowinding only - ie you can't wind them by hand. But the autowinder is arguably the most efficient in existence - 7's usually start ticking when you pick them up. To wind one before wearing, you just swirl it around for 10-20 seconds before putting it on.
- The glass is a high graded of toughened borosilicate glass. Seiko never put sapphire onto working diving watches because it shatters too easily. You can easily get the glass replaced with artificial silicon, which is theoretically more scratch resistant, the Seiko boro is so scratch resistant itself that it almost certainly isn't worth doing.
- SK007s are produced in both Japan and Korea, and have a J or a K after the model number to tell you which. No one has ever detected a quality difference between the two, and the production lines are believed to be almost entirely automated anyway! So you won't gain anything by looking around for one of the less common J's, which are usually sold at a premium.
- The bezel rotates (one way) for timing purposes.
This review shows far more model variations and dozens of mods:http://quartzimodo.com/seiko-skx007j-review/