Seiko’s first range of truly submersible sports watches came in the form of the Seikomatic 50m SilverWave in 1961, which marked a number of firsts for Seiko – it represented the Japanese company’s first dive watch; their first watch with an inner rotating countdown bezel; their first use of the tsunami wave symbol; and it was their first automatic watch with a screw-down case back.
Fast forward to the ever more refined serviced 1977 Seiko 6306-807A SilverWave automatic diver here, which has lost some of the early diver’s rough edges yet retained all (and then some) of the charm.
Between 1965 and 1975, Seiko brilliantly conceived, designed, and produced three generations of classic ISO-certified 150 m divers’ watches, in chronological order - the 62MAS, 6105-8000/9, and the 6105-8010/9. Then 1976 arrived...
That year, Seiko debuted its replacement for its 6105, conceived in two different specifications - one of which was the 6306 for the domestic Japanese Domestic Market and the 6309 for the international market; the JDM variant - the Calibre 6306 - was fitted with a more advanced 21 jewel 6306A movement, with hacking and an English/Kanji Japanese day wheel.
The 6306 lived a rather short life in between the 6105 and down-jeweled and less complex 6309, and was produced from 1976 to 1981, when Seiko would favor the 6309 until it too was replaced with the 7002 diver in 1988. The 6306 calibre was a successful effort by Seiko to improve the 6105 movement, which allowed for greater lifespan, robustness, and ease of maintenance.
This Seiko 6306 automatic diver comes on its original Seiko-signed bracelet, and with nylon strap, rugged travel case, and springbar tool.
1977 Seiko 6306-807A SilverWave Automatic Dive Watch
DIAL: White Suwa and Silverwave-signed dial, with Kanji Japanese/English day variants and date at the 3 o'clock position working as designed. Correct handset includes "stoplight" seconds hand very familar to Seiko aficionados - it's the same used on the famous 1970s Seiko 6105 "Captain Willard" diver!
CASE: Stainless-steel case measures 38mm x 43mm; matching caseback. Crown screws down, as designed.
CRYSTAL: Seiko Hardlex crystal, no deep scratches or cracks.
BAND: This Seiko diver comes on a vintage stainless-steel Stelux bracelet, which will fit up to an approx. 8.25 inch wrist; this 6306 also comes with black nylon strap.
MOVEMENT: 6306A Seiko 21-jewel automatic movement, manufactured in October 1977, which beats at 21,600 bph an hour. This watch performs as if it has been recently serviced (albeit not by us).
CROWN: Unsigned stainless-steel crown, which screws down as designed.