The Case evolution of early Seiko Divers

Now, this is undertaken with "homage" watches, but I've seen quite an amount of comparisons between the "homage" and the original to be satisfied that they are pretty close to the original. Indeed from what I've seen so close that even experts are satisfied and are frustrated that "Seiko didn't do this"

So, the order of release dates of these watches is this

1. 62MAS
2. 6105-8000
3. 6105-8101

What I'm wanting to do here is show what I've observed in the design evolution of the cases of these watches, which I think actually started with the 62MAS and then jumped over to the 6105-8000 case where it then morphed along into the divers case which ended up being refined into the SKX series.

So these watches are (usually if not always) seen by budding enthusiasts from a top down or slightly off angle top down. They are seldom handled, but instead seen like this:

62MAS (Seestern)

6105-8000 (Rdunae)

6105-8110 (Addiesdive)

My view is that this presentation hides what's happened. This is exacerbated by most people only looking at YouTube  and combined with the relative naivety of what amounts to a large fresh watch enthusiast audience (coming into watches post-COVID). 

First off, I want to remind readers that none of these in the Original Seiko had a screw-down crown. The 8xxx cases had a sort of locking crown and the MAS was just relying on its o-rings to seal. This point is not insignificant in watches that will need

1. reasonably frequent time setting (because they aren't quartz and so it was likely to have worse accuracy than 30 seconds per day (that's around 3.5 minutes per week)
2. date needs to be reset about 6 times per year.

This is important (as I've mentioned in other posts) because once you damage the threads in the tube within the body (not the crown which screws into that body) your watch is no longer waterproof and the crown sticks up higher waiting to get whacked probably bending the stem (and then the watch is finally junk).

Depending on if you're a person after a daily driver "tool watch" or a KingWang follower who is the tool for the "tool watch" this may or may not matter to you.

So lets look at what I find interesting; lets line these three up...

It looks to me that the 'machining style' of the case follows an unexpected pathway. Starting from a billet of metal, machining (at first) a slim and stylish (following the fashion cues of the past but morphing them) to make the iconic 8000 case of the 6105-8000 "Slim Case" from basically the same style of case scalloping out (carving out) that the 62MAS already started. Meanwhile "The Willard is basically flat on the bottom. The Willard is just a big fat blob of metal. In contrast the 8000 is a more sophisticated turtle shell shape.

Shaping, sculpting and polishing is beautiful and as you can imagine results in a rather significant weight reduction.

Returning to the MAS and the 8000, I've overlaid the MAS onto the 6105-8000 to show how much steel is cut away from the sides of that billet (making the MAS a more refined looking case) but remains present on the sides of the 8000 case. The 8110 remains a blob with the caseback actually sunk under the level of the case (gunk collection if you ask me).

 Indeed, look at the  tips of the lugs on the cases for a familiar line.

which interestingly didn't carry over to the 8110 case, which is basically a raw blob of metal and so to me, not properly a "Turtle Shell" case, which the 8000 case was.

So lets look from the face side.

This shaving off of metal (or leaving it there instead) results in a watch which is bigger and chunkier and I suspect may have been a way to use existing machining setups while allowing a move of the crown down to the (soon to be iconic) 4O'Clock position.

Now, overlaying the 63MAS outline over the 8000 we can again see that amount of extra metal and the crown position.

The astute will notice that the dial size is actually the same and that the gap in the case for the strap is 19mm on the Rdunae while the Seestern has "modernised" to allow 20mm lugs. Personally I think that was a bit of a wise step (despite what wangers may whinge about on line) because it opens up a vast array of straps (and frankly the Rdunae is shipped with a 20mm strap anyway and its just shoehorned in there).

You can see the (smallish) amount of case shaved "off from the lugs and case" of the 62MAS it is enough to account for the weight differences found here (link) of 66g vs 72g (or the 8000 being about 10% heavier). 

This of course alters the wearability of the watch for daily use compared to the later 6105-8000 (but the Willard at 94g pushes it further). Because I didn't get long with my 8000 (see here), I perhaps need to get another one to test this out, but both of these are very wearable daily divers, more than I can say for my personal experience of the Willard.

Anyway, to me these three watches are "iconic" for different reasons. I believe that the 6105-8000 would have fallen further into obscurity if not for Apocalypse Now and the success of the subsequent 8110 case series. I mean with The Willard its Win Win for Seiko, less machining and if the clients don't care about weight  then perfect (and to be honest, back in those days "Dive Watches weren't common nor were they worn all the time by owners.

Anyway, that's pretty much all I wanted to say here.

Enjoy your day