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When you looking into Japanese Diver watches, The Seiko SUMO is very likely to be one of the watches that you will come across. Simple, reliable, and robust, this Japan-made Diver watch is one of the best quality-to-price ratios timepieces you can get with a budget within USD$600.
The SUMOs is one of the newer addition to the Seiko Diver series. The 1st Generation SUMO, SBDC001 (Black) / 003 (Blue) / 005 (Orange) was first rolled out in 2007. It was the first Seiko divers that was fitted with the relatively new manual winding and hacking 6R15 automatic Seiko caliber. In 2015, the 2nd generation of SUMO was introduced and are now called the SBDC031 (Black) and 033 (Blue). Not much upgrade was introduced in the 2nd generation. The only difference is that the SUMO now belongs to the "Prospex" Diver series, which give it a more professional personality (Prospex stands for Professional Specification...if you ever wonder).
In 2019, Seiko gave the SUMO a huge makeover. The 3rd generation SPB101 and 103, not only have a upgraded 6R35 movement, but also a Sapphire Crystal glass, and a new bezel insert upgrade. Let's look at the major differences.
The first major upgrade for the SUMO is the change in movement. The Seiko 6R15 movement is a 23/24 jewels automatic movement, with 21,600 bph vibrations. It has a maximum power reserve of 50 hours, and has hacking and handwinding functions as well. It is fitted with Seiko's Dia-Shock anti-shock system.
The 6R35 movement fitted into the new SUMO SPB101 and SPB103 is also a 24 jewel movement that vibrates at 21,600 bph, and has hackign and handwinding functions. But the new movement how stores up to 70 hours of power, a 40% upgrade!
Hardlex is used on the 1st and 2nd generation of SUMOs. It is a mineral-based clear glass that is used by Seiko for its watches. Hardlex is not that scratch resistant compared to sapphire crystal, but it is comparatively more shatter-proof.
Seiko has upgraded to use Sapphire crystals on the SPB101 and SPB103. No one is sure why Seiko has made the decision to use sapphire instead for their new models, but it for sure upgrades the overall value of the watch because most Swiss expensive divers (Rolex, Panerai, etc.) use Sapphire crystals on their watches.
The 3rd Generation SPB101/103 has a thinner font on the bezel insert compare to the previous models. The numbers on the SPB103 is 2.5mm wide, while the previous models are 3.0mm wide. The width of the aluminium bezel insert is the same size at 4.5mm. The lume pip is also slightly different in size. The SPB103 is 2.4mm in diameter, and the older versions are 2.6mm. Another difference is the triangle on the bezel insert. The old versions have a perfect triangle, while the SPB101/103 has one of the angle cut off.
It is a weird decision that I do not understand from Seiko. They had the "S" engraved on the crowns of the SBDC001 and 031, which I think is very iconic for the SUMO. However, Seiko decided to cancel the "S" engraving and just leave the crown blank (No, not even the Prospex "X" logo). I feel it awkward personally, but I leave it for you to judge. Other than the "S" logo, the crown designs did not change much, there is still 8 teeth on the crown.
I was guessing that the SPB103 would be a little heavier because it has an upgraded Sapphire crystal glass, and a slightly heavier movement because of the upgraded power reserve, but it was not the case. I weighted the three watches with 10 links installed. The SPB103 weights 176g, the SBDC031 is 181g, and the SBDC001 is 178g. The newest SUMO is actually the lightest of the three! I guess Seiko has also considered the comfort of the watch owner, and reduced the weigh of the watch a little so it sits more comfortably on the wrist.
The hands on the SPB101/103 is a bit different to the previous generations. The pentagon lume on the second hand is slightly bigger on the SPB101/103 than the previous generations. On the minute hand, the SPB101/103 has a thinner design, and has lost the pointy end on the non-luminous side. On the hour hand, SPB101/103 has a new vertical stroke that went half way into the lume, while the SBDC001/031 a horizontal roof-shape line that divided the lume into two parts. The hour hand has also lost the pointy design at the end of the non-luminous side, compare to the previous generations.
Seiko redesigned the dial for the SPB101/103. The hour marks at 6 and 9 is a thin trapezoid design, and it is a bit thinner than the one on the SBDC001 and 031. The iconic flipped triangle hour mark at 12 o'clock has also been redesigned. on the SPB101/103, it is now a trapezoid instead of a triangle. The date window at 3 o'clock position is left unchanged.
The SPB101/103 has a new chapter ring. The hour marks are bigger, and the minute marks are longer.
The case finishing leave pretty much the same for the 3 generations - Polish combines with line-brushed finishing. The bracelet is also the same.
The SUMO is one of the best value-over-price wristwatch you can find in the market. The new SPB101/103 is a diver watch with 70-hour power reserve, hacking and handwinding functions. For under $1,000, there isn't much competitors that can match this specification of its class. If you have never owned a SUMO, then the new SPB101/103 will not deceive you for its value. It will certainly be a watch that you won't regret owning.
For those who already owned a SUMO, is it worth to upgrade to a SPB101/103? there is a drastic upgrade on the movement. It is now 70 hours of power reserve, compare to the 50 hours for the previous 6R15 movement. Other than the movement upgrade, the watch feels pretty much the same on the wrist as the previous models. One thing I like about the new SUMO is that there is a Green color version (SPB103) that was not available in the previous versions. If you go back to the 6R15 SUMO, there is a special edition SZSC004 (Jade SUMO) that is becoming harder to find these days. So I'd say, if you are considering upgrading to the new SUMO, get a SPB103 green one, otherwise the SPB101 will look very similar to your SBDC001 or 031.
Enjoy : )
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