Here on Fratello, we’ve covered just about every vintage diver from one of our favorite brands: Seiko. The 6215, the 62MAS, the Grandfather Tuna, and each of the 6105’s has been documented, just to name a few. So, imagine my surprise upon seeing that the Seiko 6159-7000 and its -7001 companion have never been treated to a full feature here. It was time to end that.

Perhaps the Seiko 6159-7000 needs a little introduction, but I think it deserves one. Things officially kicked off in 1965 with the Seiko 62MAS, a 150-meter diver. From there, Seiko went in two directions. They decided to serve both the professional and recreational set with unique dive watches for each. The sporting crowd received the 150-meter 6105 with its c-case shape and later in the guise of the “Willard.” The professionals, in 1967, received the 6215-7000 with its 300-meter case. After what became a short single year of production, it was time for the 6159-7000.

Seiko 6215-7000 9

The Seiko 6159-7000 followed the 6215-7000 in 1968

We’ll never know why the 6215-7000 only lasted for a single year, but there’s no doubt that it’s one of my favorite watches of all time. For me, it is the watch that set a design standard for so many Seiko watches we have today. More directly, it provided the basis for the Seiko 6159-7000 in 1968 and its -7001 follower in 1969. If you’re keeping track of all these successive years, yes, it’s clear that Seiko wasn’t happy and was in the midst of a lot of meddling.

One theory as to why the 6215-7000 lasted for such a brief period is that Seiko wanted to have something on the market for professional divers, but that its 6159 movement wasn’t quite ready for showtime. That makes sense because the 6159 movement was a properly innovative unit. In the 6215, the design was the primary highlight. With the Seiko 6159-7000, the looks are still remarkable, but the movement takes (and deserves) center stage.

Seiko 6159-7000 Watch 5

The 6159 has serious technical chops

In Swiss watch collector circles, Seiko doesn’t get the credit it deserves when it comes to technical chops. I guess most are still cranky about its quartz revolution that led to the demise of so many companies. Still, Seiko was a force to be reckoned with back in the day and came with its 36,000vph “Hi-Beat” movement in 1967. That’s just a touch after Girard-Perregaux and in the case of Seiko, it was an all in-house affair. The 6159 movement is unique and I suppose that it took a little longer to ready for the market.

Seiko 6159-7000 Watch 5

Differences versus the 6215 are subtle but there

The Seiko 6159-7000 brought some other differences with it versus the old 6215-7000. The dial is very similar, but the indices changed as well as the hour and minute hands to some degree. The 12:00 marker is bisected and the 6/9:00 markers change from squares to elongated rectangles. More importantly, though, Seiko moved away from the warm tones of tritium to some sort of white luminous material. The effect is dramatic under the highly reflective Hardlex mineral crystal because the watch is clearly old but looks almost new in the lume department. Notably, the hands are a bit chunkier.

Whether it’s the Seiko 6159-7000 or its -7001 follower, both use a 44mm case with 50mm of lug to lug, a 19mm lug width, and a height of 14mm. The watches use a front loader case design and for whatever reason, the later -7001 has an inscribed ring on its case back. It almost makes it look like a traditional case back, but trust me, it’s not.

Seiko 6159-7000 Watch 2

Large, but great on the wrist

These watches are legendary for a reason. They wear really well and feel as if they’re built like a tank. Much like a Submariner from the same timeframe, these feel as if they can be worn on a regular basis. There is a slight concern with that, though. Would-be buyers of a Seiko 6159-7000 might hope for commonality across other watches including the prior 6215. Sadly, that’s just not the case. Despite nearly identical looks, the 6215 and even both 6159 models you see here on these pages use different crowns and crystals. As I said, Seiko was truly meddling in attempts to improve these watches year over year.

Seiko 6159-7001 Watch 2

The 6159-7001 from 1969 — my first purchase

When it comes to my two pieces, both have interesting stories. I bought the -7001 first out of Japan and, weirdly enough, I failed to notice the “Resist” dial when I won it on auction. At first, I was pretty dismayed to learn that this is actually a service dial. Some theorize that these were actually production dials if Seiko had kept making these watches into 1970 because import rules required a change away from Proof to Resist. Whatever the reasoning, it seems that Seiko used them when a 6159 came in for service. Today, they actually represent a collectible variation for 6159 fans. When I received the watch, it was actually in pretty rough shape and stopped running after an hour or so. A trip to the local Seiko boutique and a very patient watchmaker named Sandro helped mend the movement and get it back up to speed.

A tricky movement to service due to the mainspring

The 6159 movement uses a sealed barrel with the mainspring inside and it is not made to be serviced. Pictures make it look like a little flat film can. It’s possible to open that can, but it wasn’t meant to be. Still, Sandro was able to do this and somehow shorten the mainspring. Therefore, it lacks power reserve, but it keeps great time and runs for long enough to make it useable for days in a row. Here’s a nice article showing the little devil of a barrel.

Seiko 6159-7000 Watch 8

My Seiko 6159-7000 came next and also from Japan

The 1968 Seiko 6159-7000 came a couple of years later also from Japan. This was a much better watch, but also in non-running shape. You can see, though, that this was no drawer queen. The seller didn’t provide a whole lot of detail, but the mainspring was the culprit once again. This time, though, Sandro called in a favor within his parts network and he was able to source a NOS mainspring. With that in hand, the watch was brought back to full running condition.

I guess that the common theme of mainspring issues isn’t surprising. It’s a typical replacement item for all old watches and is a seriously hard-working component. The fact that the Seiko 6159-7000 is running at a crazy frequency possibly makes it even more of a wear item. When these watches are running, though, they’re magic. The way the sweep hand glides is mesmerizing. Plus, putting a Hi-Beat up to your ear is a different type of music. Still, knowing that these watches aren’t easily fixed makes it a little like wearing a ticking time bomb.

Seiko 6159-7001 Watch 1

The Hi-Beat movement was a real differentiator

We have to remember that the ‘60s still represented a serious time for innovation. A watch like the Seiko 6159-7000 was meant to display the best of what a company like Seiko could bring and a movement like the Hi-Beat was a real differentiator. In fact, Seiko still felt this because they used it six years later when they came back out with a very different 6159 in the Grandfather Tuna (today’s models apparently had crystal popping issues at serious depth which led to their cancellation). No matter what, these were meant to be precision tools, and tools are meant to be replaced one day. It just so happens that now, they’re collected.

Seiko 6159-7000 Watch 3

A hot market for a famous watch

The Seiko 6159-7000 and its -7001 sequel are wildly popular with collectors and not just those who fancy Japanese watches. Collectors, in general, realize the general importance of this watch in both Seiko and dive watch history. As a result, they’re expensive and still quite uncommon outside of Japan. Pricing varies wildly and rougher versions with undiagnosed maladies can be found in the €4,500 range. However, you’ll probably need sourcing help in Japan and a watchmaker with a hefty parts bin.

Good models with their original rubber straps can hit the five-figure mark. I’d like to think that €7,000 give or take could land a nice wearable model like the -7000 I own. Oh, collectors do seem to prefer the earlier model variant with its cleaner case back. Personally, I wouldn’t care either way. Of course, another opportunity is to pick up the SLA017 reissue from 2018 and just avoid any service issues with a vintage watch.

Seiko 6159-7000 Watch 7

Final thoughts

I’ve always felt that the Seiko 6159-7000 deserves to be considered in the same league as any of the big Swiss makers from the period. This was a seriously innovative watch that brought a peerless movement. Also, it wears like a modern watch (today’s Marinemaster 300 or whatever we call it now is very similar) and is just a bit different from the typical Subs that are so ubiquitous on everyone’s feeds. Should you decide to go down this path, and you should, owning such a watch is truly rewarding — just mind that mainspring!