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Before really digging into this review, I think there’s something I need to address, especially if you’re new to watches and watch enthusiasm in general. In a lot of watch media today, you’ll hear stuff like “There’s nothing like a Rolex on the wrist” or something along those lines. Sprinkle in phrases about how “timeless” or “iconic” a watch is, package it together with a passively condescending tone, and you’ve got a prime example of what watch journalism is like in its current state. Now, while I won’t deny the appeal of something like a Rolex Sub on the wrist, it’s disheartening to hear people that come from all walks of life express how disenchanted they’ve become with the watch world when encountering this kind of intimidating language.

As someone that has spent time with some more “high-end” pieces, I’m confident in saying that really, there’s actually nothing like a Seiko* on the wrist. If I didn’t trust my own words before, the fact is really set in stone now – all thanks to my time with the Seiko SBDC027 Sumo 50th anniversary watch. Thank you to @thewristfund for loaning us the watch – these have become pretty tough to find. So, let’s take a look at what makes this limited, “higher-end” Seiko diver special.

The Seiko SBDC027 Sumo 50th anniversary was produced to commemorate the 50th anniversary of Seiko’s first line of professional dive watches released in 1965. If you aren’t familiar with the Sumo line overall, it falls in a segment between Seiko’s entry level divers (like the SKX007) and watches like the Seiko Marinemaster SBDX017. While this watch is essentially identical to the standard, current production Seiko Sumo (SBDC031) in many ways, there are several visual and technical refinements that set it apart.


Ideally, I think I’ll start with the one characteristic of this watch that just blew me away right off the bat. The case of the Seiko SBDC027 is unlike anything I’ve seen in Seiko’s other divers. Measuring in at 45mm in diameter and 52.6mm lug-to-lug, it proves itself as one of those watches that looks scary as hell on paper. But, as is the case with other watches like the Seiko Samurai, the dimensions result in something far more pleasing on the wrist.

Naturally, you have a range of brushed and polished finishes, but the bevelling gets really out of hand here (in an awesome way). The case exhibits four different alternating brushed and polished surfaces. It’s a characteristic of the Sumo’s twisted lugs and something I never really paid much attention to until I had the watch in person. It’s the kind of attention to detail you’d expect from Seiko but not necessarily in the sub-$1000 category. Finally it offers 200m of water resistance and the case is 13mm thick but very manageable in my opinion.


Here’s where things get interesting. The dial of the Seiko SBDC027 is actually a pretty cool mash-up of some classic references. As a result, the dial is what really left me smitten. Unlike the SBDC031, the 50th anniversary Sumo is actually fitted with a dial reminiscent of the 6217-8001 (62MAS), Seiko’s first pro dive watch. The hands, however, follow the design of the of the 6105 series (minus the stop light coloring on the seconds hand). It’s what I’d consider a cleaner look overall and something I really appreciate in a diver that aims to pay tribute to Seiko’s dive watch heritage. Also, the 120 click unidirectional bezel has a glossy (almost ceramic looking) effect to it and is probably one of my favorite visual features.


Perhaps the most widely criticized aspect of any Seiko Sumo model is the bracelet. So really, I wanted to take a detailed look at what gets people up in arms about it. The bracelet is 20mm wide and while some may disagree with me, I find that it actually works pretty well with the 45mm case size. The center links are only polished along the edges and that entire portion of the bracelet appears slightly raised, which results in what I’d consider a pretty unique look. It also features solid end links and easy adjustment points. If I’d have to critique anything here, it would be the clasp. For a watch that is meant to pay tribute to Seiko quality, it would’ve been nice to have a milled clasp. A secure flip lock system keeps it all together along with dual release push buttons.


Inside the Seiko SBDC027 is Seiko’s own 6R15. An evolution of the sturdy 7S26, the movement operates at 21,600 vph and allows for an acceptable daily variation of -15/+25 seconds a day. There’s also a 50 hour power reserve courtesy of the SPRON 510 mainspring. SPRON 510, according to Seiko, is a Co-Ni alloy that allows for “high elasticity, durability, corrosion resistance, and heat resistance.” While the acceptable daily rate may seem like a pretty wide range, I really found that the watch would only lose about 2 seconds a day. Additionally, the movement hacks, offers hand winding, and supports a nice, simple date display at 3 o’clock.

Final Thoughts

Before this watch was sent to me, its owner proudly referred to it as a “Sub Killer.” I read the message, chuckled, and went about my day. Now, after spending some real time with the watch, I can totally see what he meant. The Seiko Sumo has earned its cult following and is a watch that has really turned my attention toward Seiko’s higher end dive watches. At the expense of being called naïve or ill-informed, I have to say that this watch can really hold its own against something like a newer maxi case Submariner. Tear me down in the comments, whatever. But, I feel that the Seiko Sumo succeeds in satisfying the urge for a tool watch on the wrist and at the same time, achieving the look and feel of something more “luxurious.” If you’ve ever had any doubts about pushing beyond Seiko’s entry-level models, let them go. I say it’s worth it and the Sumo is a pretty great place to start. Seiko


  1. Nice review. I have the Blumo versions, and after having this one, I wonder what a MM300 would cost with a 6R15 movement? These Sumos are just that nice in my opinion (and I have had a MM300 on the wrist before)! I just have a hard time getting excited over the 8Lxx movement.


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