Seiko Diver’s Watches
Seiko Cronos Sea horse J13032
The first fully fledged waterproof Seiko watch appeared in 1959 in the form of the Seiko Cronos Sea horse fitted with the 21 jewel hand-wind Cronos 54/54A movement. That watch was equipped with a two part screw down case back and was rated water proof to 50m. Although it was actively marketed in some sense as a divers watch, in reality its use would have been limited at best to swimming or snorkeling. Nevertheless, it arguably represents the nucleation point in the development of the modern-day Japanese divers watch, in spite of the fact that it is clearly not one. What it was though, was a watch with genuine water proof credentials, to the extent that the wearer could reasonably expect to be able to wear it whilst swimming.
For the full account of the restoration of this 1961 example, please click here.
Seikomatic SilverWave J12082
If the Cronos Seahorse was the twinkle in the eye of Seiko’s future aspirations as the producer of professional diver’s watches, the SilverWave marks the point of Seiko not only dipping their toe in the water, but slipping beneath the surface. The introduction of the 50m Seiko SilverWave in 1961 marked a number of firsts for Seiko: it represented their first semi-serious diver’s watch (although not iso-rated and therefore not qualifying as a professional divers watch by today’s standards); it was their first watch with an inner rotating timing bezel; and it was their first automatic watch with a screw-down case back.
The earlier incarnations of these lovely watches were identified with the model number J12082, a numbering convention preceding the familiar eight digit system currently used by Seiko. The naming conventions for the movement calibres was similarly different, with the 20 jewel automatic 603 calibre fitted to these earlier watches essentially the same as the 6201.
For the full account of the restoration of this rare 1962 example featuring a star-burst dial, please click here.
Seiko Sportsmatic SilverWave 69799
The Seikomatic SilverWave 50 Proof was produced for about three years until 1964 when it was joined/replaced by a budget version marketed as the Sportsmatic SilverWave, with model number 69799. This new watch was superficially identical in appearance but featured a more workmanlike 17 jewel 2451/6601 movement and, by virtue of its press-fit case back, a reduced 30m water resistance. This watch was produced until 1966 at which point its model number had been upgraded under the new numbering convention to 6601-7990. In terms of progress towards a pukka diver’s watch, this watch did not represent an advance but it is nevertheless an interesting and collectable watch.
For the full account of the restoration of this 1964 example, please click here.
Seiko 6217-8000 ’62MAS’
Seiko’s first ISO-certified diver’s watch was released in early 1965. Rated to 150m, the 62MAS appeared in two subtly different incarnations, the original small-crown 6217-8000 being produced for just two months from April 1965, with the larger-crowned 6217-8001 taking over from July 1965 and sustaining until early 1968 when it was replaced by the Seiko 6105-8000 (see below). The 62MAS nickname derives from the first two digits of the calibre reference number, 6217, with the MAS, a contraction of ‘autoMAtic Selfdater’.
The water proof credentials of this new watch derived from a combination of its thick armoured, domed acrylic crystal, a substantial gasketed crown and its screw-down case back. The watch was fitted with a bi-directional, non-indexed count-down diver’s bezel. At 37.8mm in diameter it is small by today’s standards but all the more wearable as a result.
The 62MAS was fitted with a robust 17 jewel 6217A automatic movement with quickset date date complication. Its dial features substantial rectangular framed hour markers filled with luminous compound.
An account of the restoration of this very early 1965 example of the 6217-8000 will appear in due course at adventuresinamateurwatchfettling.com
Seiko 6217-8001
The original small-crown 6217-8000 was produced for only two months from April 1965. In July 1965, a revised version featuring a larger crown replaced the early incarnation, a change marked by a new model reference number, 6217-8001. The mildly revised 62MAS remained in production until 1968. Most of these watches were produced in the Suwa factory in Nagano but later on in its production life, production was moved to the Daini factory in Tokyo. These later watches are distiguished by their horseshoe case backs and a different luminous compound formulation that ages quite differently to that used in the Suwa-produced watches.
For an account of a recent restoration of a 1967 example of the 6217-8001, please click here. A number of other examples of 62MAS projects can be found here.
Seiko 6105-8000
In 1968, Seiko replaced the 62MAS with the 6105-8000, a watch that marked a significant change in terms of styling and engineering whilst retaining some of the characteristic features of their original iso-certified diver’s watch. The larger 62MAS crown was retained in the new watch but its position shifted from the 3 o’clock to 4 o’clock position. The countdown diver’s bezel was again bidirectional and non-indexed and secured to the case using the same retaining wire design as the 62MAS. However, the crystal in the new watch was a double-domed tempered ‘Hardlex’ mineral glass sitting in a profiled L-shaped rubber gasket, and held in position using a steel bezel sitting beneath the turning ring. The case dimensions also increased in this new watch to 40.8mm at its widest point across the case.
The other signficant change was in the movement: the 6105-8000 was fitted with a brand new 17 jewel automatic calibre, complete with quickset date complication. As with the 62MAS though, the watch did not incorporate hand-winding and had no stop-seconds hacking facility.
For the full account of the restoration of this 1970 example, please click here.
Seiko 6105-8110
In 1970, Seiko replaced the first generation 6105 with a heavily revised version packaged in a much larger, curvier 44mm asymmetric cushion case. The dial and hand designs were retained from the earlier watch, as was the double-dome crystal but a number of engineering improvements accompanied the changes in external appearance: the bidirectional bezel was now indexed with 60-clicks, metered by a sprung ball bearing mechanism; the crown was prevented from freely rotating in its inner-most position by a locking pin; the movement was upgraded to the 6105B variant which now included a stop-seconds hacking function.
The 6105-8110 gained some notoriety in having featured on the wrist of Martin Sheen in Francis Ford Coppola’s Apocalypse Now and for this reason is commonly referred to as the Captain Willard. The second generation 6105 was produced from 1970 to 1977.
For the full account of the restoration of this late 1974 example, please click here.
Seiko 6306-7001
Officially, the 6105 disappeared from domestic Seiko catalogues in 1976 but the model continued to be produced until 1977. With a notional 5 year production span under its belt, in 1975 Seiko charged a young engineer, Ikuo Tokunaga, with the job of designing a replacement. Tokunaga’s new more rounded cushion case design would incorporate many of the features of the older watch, such as the sprung ball-bearing 60 click bi-directional bezel and case construction philosophy, but with a screw-down crown replacing the locking crown design of the out-going model.
Out too with the embossed dial and coin edge bezel turning ring, replaced with a printed dial and a new, deeper, grippier turning ring. The double-domed Hardlex crystal of the 6105 was also dropped in favour of a beveled flat Hardlex. The lifetime of the 6105B movement had also run its course and the new watch would feature a brand new 21600 bph movement, the 6306A featuring both date and day complications.
The new watch was conceived at the outset in two slightly different specifications, one for the domestic Japanese market and the other for overseas. Where the overseas version would be fitted with the 17 jewel 6309A fitted with bilingual day wheels appropriate for the target market, the Japan domestic version was fitted with the higher specification 21 jewel 6306A that added seconds hacking and which was fitted with English/Kanji day wheel.
An account of the restoration of this 1979 example of the 6306-7001 can be found here.
Seiko 6309-7040
The 6309A-equipped version of Seiko’s fourth generation 150m diver’s watch spanned an 11-year lifetime from 1976 to about 1987 when it was replaced with a slimmer profile case model. For the first five years of its production life, the 6309-7040 was produced at the Suwa factory in Nagano prefecture and these watches are distinguished by the presence of the Suwa symbol beneath the 150m on the dial. From late 1981, production, or at least assembly, was shifted to Singapore and Hong Kong and the Suwa symbol disappeared from the dial.
An account of the restoration of an example dating from July 1981 can be found here.
Seiko 7548-700B
By the time of the introduction of the Seiko 6309-7040 and 6306-7001, the quartz revolution was in full swing and it was inconceivable that Seiko would not recognise the potential application of this new technology in a diver’s watch. In 1979, they released a quartz-powered version of their fourth generation diver’s watch fitted with the 7548 calibre which itself shared much of its architecture with the 6306/9. This new quartz 150m diver’s watch used a slimmer slightly asymmetric case with a flared crown guard extending around the lower right quarters of the case. Other than the styling of the case, the engineering was identical to the 6306/6309 mechanical versions.
An account of the restoration of this mid-1981 example of the Pepsi colour-schemed 7548-700B can be found here. Examples of other 7548 projects can be found here.
Seiko 7549-7010
In 1968, Seiko established a new project team who were tasked with producing a watch that was to be designed from the outset for saturation diving rather than simply an adaptation of an existing design. The design brief was to produce a shock-resistant, corrosion proof, anti-magnetic watch with a case that was impermeable to helium gas. In 1975, after seven years of research and development, the first Seiko Professional 600 m diver’s watch emerged and the Tuna dynasty was born.
The exotic high beat GS movement fitted to those first watches was subsequently ‘upgraded’ in 1978 to the five jewel 7549A quartz movement in the celebrated 7549-7009 Golden Tuna, named for its distinctive gold-coloured titanium nitride coated titanium case. The Tuna model line continued to evolve through the 1970’s, 80’s and beyond spawning in the late 1970’s the slightly more modestly proportioned 300m-rated 7549-7010, forgoing monocoque construction for a more conventional two piece 45mm steel case.
An account of the restoration of this 1983 example can be found here.
