Uncovering the Evolution of the So-Called "Seiko Second Diver" / The Adventures of Uemura Diver Part 3

Naomi Uemura is an adventurer with a dazzling array of accomplishments, including the first person to climb the highest peaks on all five continents, a 12,000km solo dog sled across the Arctic Circle, and a 3000km crossing of Greenland. It's well-known that on his adventures he carried a 1970 model of the Seiko Second Diver, a diver's watch released by Seiko in 1968. However, there are no records that reveal which Second Diver he was taken on, or which model it was, and various anecdotes are circulating. To find out, motor journalist and self-confessed Second Diver enthusiast Hiroki Yamada conducted an original investigation. This is the story of the adventures of "Uemura Diver."

Following the footsteps of Naomi Uemura after acquiring the so-called "Seiko Second Diver" / The adventures of Uemura Diver Part 1

FEATURES

Visiting Seiko Watch Headquarters to find out about the so-called "Second Diver" worn by Naoki Uemura / The Adventures of Uemura Diver Part 2

FEATURES

Looking back on the adventures of Naomi Uemura

　The Seiko 61MC (6105-8000, then 6105-8110 from 1970) gained fame as the watch used by the legendary adventurer Naomi Uemura during his Arctic expedition, and was later nicknamed the "Uemura Diver." (As the name changed from Seiko 61MC after 1975, this article will refer to this watch by its nickname, "Second Diver.") The adventures surrounding this watch, which had long remained obscure, have been revealed in the interviews up to this point, from when it was given to Naomi Uemura by Seiko in 1971, to when it was taken on an Antarctic inspection trip, and finally to when it was taken on a "12,000km solo dog sled journey around the Arctic Circle."

　To elaborate further, Naomi Uemura stayed in South America from December 1971 to the beginning of the following year, inspecting the Belgrano Station in Antarctica (Argentina). After this, he attempted to climb the south face of Aconcagua (6960m), the highest peak in South America, which he had previously summited in February 1968, but due to rockfalls and other obstacles, he only managed to reach 5400m before returning to Japan (he later achieved a second ascent via the normal route in the winter of 1980).

　Then, in September 1972, he traveled to Greenland for dog sled training and polar acclimatization. He spent about a year there, and on February 4, 1973, he completed a solo 3000km dog sled journey, which could be considered a rehearsal. He returned to Japan in July of the same year. It was around this time that he met his wife, Kimiko, and they married in May of the following year.

　そして1974年11月22日に日本を発ち、再びグリーンランドへ。西部の村「ケケッタ」で準備を整えたあと、12月29日～1976年5月8日の期間を経て、カナダ北西部を経てアラスカ ・コツビューへ到着、「北極圏1万犬ぞり1万2000km単独行」を完了させた。

　What's interesting here is that if we count the first solo dogsled expedition to Greenland, a 3000-km trek in 1973 as a practice run for the 12,000-km trek, the Second Diver was carried on two adventures. It may also have been carried on the Himalayan Expeditionary Reconnaissance Team's reconnaissance of Dhaulagiri V in Nepal, which took place from March 8 to May 12, 1974.

　From 1971, when it was given to him by Seiko, until 1976, when he completed his 12,000km solo expedition, the watch was used for approximately six years. It seems that the "Second Diver" was more than just a promotional tool or instrument; it was a watch that Naomi Uemura cherished. Although there are no official records of the "Second Diver" being taken on any further adventures, it is preserved at the Uemura Adventure Museum in Itabashi Ward as a tool carried during his "12,000km solo dog sled expedition to the Arctic Circle."

　Now, in this article, I will share the questions I posed to Shotaro Hanamura of Seiko Watch's Product Planning Department 2 and Junpei Matsue of the Product Design Department, as a true enthusiast, and their answers regarding the Second Diver itself.

　Furthermore, I would like to systematically organize the evolution of the "Second Diver" under the supervision of Seiko Watch.

Uncovering the history of the so-called "Seiko Second Diver"

Hiroki Yamada (hereinafter Yamada): The so-called "Seiko Second Diver" is divided into the "early model" released in 1968 and the "later model" from 1970 onwards. Furthermore, since the later model underwent minor modifications, it is commonly divided into the "mid-period model" and the "late model." Could you please tell me if there is an accurate distinction?

Shotaro Hanamura (hereinafter Hanamura): Seiko only distinguishes between "8000" (6105-8000) and "8110" (6105-8110) by case number, with "8000" being the early model and "8110" being the late model. In other words, there is only the early and late model, and no mid-model classification. The name of the watch itself has changed over time.

Is it the same even if the design is different?

Yamada: The dial and case back designs are significantly different between the commonly recognized "mid-model" and "late-model" models. Even so, as long as the case number is the same, is there no particular distinction between them?

Hanamura: No, it hasn't been changed. It's simply treated as a "minor change within the same model." However, we are certainly aware that there have been subtle changes in specifications and that fans distinguish between the two models.

Yamada: So why did the dial inscription change from "WATER 150m PROOF" to "WATER 150M RESIST" in the 1971 model?

Hanamura: In 1964, the ISO (International Organization for Standardization) established a watchmaking technical committee, and from the late 1960s to the early 1970s, there was a movement to establish international standards for wristwatches. This included consideration of watch water resistance, which culminated in the issuance of the international standard ISO 2281 in 1972 (Editor's note: International standard for the water resistance of wristwatches. ISO 6425 was established for professional-use diver's watches). Based on the committee's deliberations at the time, Seiko began using the "WATER RESIST" marking in 1971, without waiting for the ISO to be issued. This was probably because they judged it to be advantageous for overseas exports, which were expanding at the time. Nowadays, it's commonplace for the model number to change if the markings on the dial are changed, but I think it was a more lenient era.

"61MC" isn't the only "Second Diver" name!

Yamada: Looking at the Purchasing Handbook, a catalog for retailers and wholesalers, the name of the 61MC changed later on. Why was that?

Hanamura: Up until the 1975 catalog Vol. 1, it was 61MC, but in the 1975 catalog Vol. 2, it changed to "YAH028". Before that, there was no concept of a reference, and it is thought that after 1975, it was systematized, and the excessive number of references were organized as needed.

Yamada: That means the model I own was manufactured in 1976, so it's "YAH028"!

Hanamura: That's what it says in the catalog!

The "Second Diver" was numbered 8110 and released as a "new watch."

Yamada: Did users at the time understand that the 8110 was the successor to the 8000?

Hanamura: I think it was probably generally perceived as a separate model. Seiko also introduced the 8110 as "a new diver's watch."

Yamada: What position did the 8110 hold among Seiko watches at the time?

Hanamura: Compared to the higher-end "6159" series released around the same time, this model was generally more affordable. Or rather, at that time, there were only two reference numbers for diver's watches: the 6159 series and the 6105 series (which was the "second diver"). Also, the term "diver's watch" wasn't yet common, and in catalogs, it was listed under the category of "special watches."

The 8110 was a transitional model for Seiko's diver's watches.

Yamada: Why did the 8110 model use a crown lock pin?

Hanamura: Seiko first adopted a screw-down crown with the 6215 series "Seiko Diver 300m Water Resistant (released in 1967)". At that time, screw-down crowns were still in the trial-and-error stage, and push-in crowns were easier to manufacture. Therefore, the more affordable 8110 series had a push-in crown, and I think a crown rotation stopper pin was used to fix the crown's movement.

Yamada: After that, the crown became screw-down type starting with the "Diver 150m" (the so-called "Third Diver"), which was released in 1978.

Junpei Matsue (hereinafter Matsue): I suspect that the case of the Second Diver took this form because it was necessary to lock the crown with a brazed pin to prevent malfunctions during diving.

Yamada: I see!

Matsue: I think the designer at the time came up with this design because he wanted a shape that would allow for a pin that also served as a crown guard to be attached.

Yamada: So without Pin's idea, it wouldn't have taken this form!

Matsue: I think so (nods deeply).

Yamada: So the reproduction design follows this crown design, even though it is a screw-down type.

Matsue: Yes. However, the direction of the arrow has been changed to match the structure, specifically to indicate the direction in which the screw should be tightened.

Urethane bands have also undergone changes!

Yamada: Speaking of the "Second Diver," it's famous among fans for its two-groove band, which they call the "tire tread," but were there any other variations?

Hanamura: The 8000 series used the same pyramid-shaped band as the "6159" series (Seiko Diver 300m 6159-7000/6159-7001). The 8110 series features a design that fans call the "waffle" band, but photos of it with the pyramid-shaped band can also be found in overseas catalogs. Therefore, it's possible that different bands were being used in parallel at the same time. The type known as the "tire tread" band appeared in 1972 when the dial and case back designs were changed (the so-called later model). That's why the band on the reissue design model of the "1970 Mechanical Divers" released in 2019 is also the pyramid-shaped type. I heard this from a designer at the time, but apparently, Seiko's bands in the past were selected by the product planning department from proposals made by band manufacturers. So, they weren't designed to match the watch, but rather chosen from existing options.

Is this the official size?

Yamada: Please tell me the official case size of the 8110 in accordance with modern measurement standards.

Matsue: The case has a total length (12-6 o'clock) of 48mm, a diameter (3-9 o'clock) excluding the crown guard of 44mm, and a thickness of 12.5mm (actual measurement 12.54mm). Incidentally, when planning the reissue design model, we measured the size of every part of the original. In the reissue design model, the movement has been changed to Cal.8L35 and has been revised to conform to current diver's watch standards, so the diameter, thickness, and position of the crown have been changed from the original model. However, although not all of them, the original drawings for the 8110 still exist, and the original wristwatch was also preserved in working condition, so it was relatively easy to proceed.

The reproduction design model is a high-end model

Yamada: Why did you print the "SEIKO" logo on the dial of the reproduction design model instead of applying it to match the original?

Matsue: That's because, even if it's a reissue design model, it needs to meet the current Seiko diver's watch standards as a diver's watch. The hour markers on the dial are embossed to prevent them from coming off when the watch is subjected to impact.

Hanamura: It's a dilemma whether to stay true to the original or prioritize modern standards, but by reviewing the details of the design in line with current diver's watch standards and combining that with the processing techniques we've cultivated with high-end products, the "1970 Mechanical Divers Reissue Design" has become a "high-end timepiece."

Matsue: If we were to create new molds specifically for the reissue design, the price would inevitably go up. The 8110 is a practical instrument, but its price ends up being high. Therefore, we had very thorough discussions about "how to make a practical instrument look like a high-end instrument." So, for the reissue design, we added finishes that are commensurate with the price, such as applying Zaratsu polishing to certain parts.

The reason for the 19mm lug width

Yamada: The lug width of the 8110 seems a little too narrow for the size of the case. Now that's one of its distinctive features, why did you choose 19mm?

Hanamura: That was a popular size at the time, so the reissue design is also 19mm.

Matsue: In modern times, it's not very versatile, so it might be a little inconvenient if you want to change the belt. But with the复刻 design, we deliberately focused on the balance between the head and the band!

Yamada: Why did Naoki Uemura choose a metal bracelet instead of the original band?

Hanamura: The band material at the time was PVC, which would crack in extremely cold climates, so it is thought that people were forced to wear metal bracelets. The material was changed to urethane in 1975, which makes it less likely to harden in cold places.

There are no official records

Yamada: I've seen many stories online about Mr. Uemura giving advice based on his experience using the 8110 under harsh conditions, and how Seiko incorporated that feedback into their watch improvements. What specific advice did he give? And how was that reflected in subsequent watches?

Hanamura: There are no official records of that. (From the development log of the Seiko Diver Professional 600)https://museum.seiko.co.jp/seiko_history/milestone/milestone_08/As you can see from this, the Seiko development team was conducting very detailed and thorough development even back then, so I would like to think that there was some kind of information sharing.

Specifications of the so-called "Second Diver" by era

　As you can see from reading this far, the interview was extremely informative. I would like to express my gratitude once again to the two of them for researching the details, so detailed that it would be impossible to write them all here.

　Finally, the specifications for each model are listed below. The basic descriptions are based on the catalogs issued to dealerships at the time. However, I have also added specifications based on my own research.

● Early model (called)
Released in 1968
Official name: 61 Seikomatic Calendar 17 jewels

*61MC is indicated.

Automatic, 150m water resistant, rotating ring, Hardlex crystal, luminous paint
SS・WP・LB (Stainless Steel, Water Resistant, Leather Band)

Price at time of release: 14,500 yen

Remarks
Movement: Cal.6105

Seiko News further states that the new diver's watch features a "click-type rotating bezel" and a "fixed crown."

-Mid-term model (first appearance of the so-called "Uemura Diver")
Released in 1970
Official name: 61MC 17 stones 022
Seiko Diver (From now on, it will be called a diver's watch)

Automatic winding, hacking seconds function, 150m water resistance, rotating bezel, Hardlex crystal, luminous hands and markers.
SS・WP
Price at time of release: 14,500 yen

Remarks
Movement: Cal.6105 (with hacking function)
Dial logo: WATER 150m PROOF
The case back features a horseshoe design with the words "WATERPROOF" (continuous font).
The crown in the catalog photo is not a pin-lock type, likely because it was not ready in time for the photo shoot.

*Seiko does not distinguish between "mid-period" and "mid-period" models, so some of the information that would normally be included in the remarks section of the retailer's catalog is not included.

Mid-term minor change model (no official name)
Released in 1971
Official name: 61MC 17 stones 022
セイコーダイバー
Automatic winding, hacking seconds function, 150m water resistance, rotating bezel, Hardlex crystal, luminous paint.
SS・WP　
Price at time of release: 14,500 yen

Remarks
Movement: Cal.6105 (with hacking function)
Dial logo: New notation in line with ISO standards: WATER 150M RESIST.
Back cover specifications: Water resistant (one corner open)

●Later model (the model referred to as the later model)
Released from 1975 to 77
Official name: 61MC 17 jewels 022 Seiko Diver *Changed to "YAH028" midway through.

Automatic winding, hacking seconds function, 150m water resistance, rotating bezel, Hardlex crystal, luminous paint.
SS・WR
Original retail price at launch: 2 yen (since 1975)

Movement: Cal.6105 (with hacking function)
Dial logo: WATER 150M RESIST
Back cover specifications: Changed to simple back WATER RESISTANT (one corner open).
Partway through the process, the model name was changed to a part number name. There were no mechanical changes.