Seiko’s 701x series – including the 7018-6000 here – arrived to the market two years later than Seiko’s famed 6139 series, with both featuring a similar single-register 30-minute layout and day/date complication; however, the two movements shared no components, and the 701x had its own rather unique feature - certain models, signed “Time-Sonar” on the dial, were the first automatic chronographs available with display backs, a rarity for any watch at the time.
Although similar to the 6139 series, the 701x series was arguably the more technically advanced of the chronograph movements. The 7015 has an additional flyback functionality (which allows the user to immediately restart the chronograph without having to first stop and reset, akin to the popular vintage Citizen 8110 bullhead).
Of note, the 701x series was the thinnest vertical clutch column wheel chronograph during a portion of the 1970’s, existing from 1970 through ’77. The movement has a diameter of approximately 27mm and is only an astounding 6.4mm tall, which is significantly thinner than the 6139. Finally, the 701x line had some of the most attractive variations of any early Seiko chronographs, including the square cased 7016-5001 “Seiko Monaco.”
This Time Sonar comes with an ostrich strap, NATO strap, Pelican travel case, and springbar tool.
1970's Seiko 7018-6000 Time Sonar Automatic Chronograph
DIAL: Original Seiko-signed black dial, with original minute, hour, and second hands – including the matching color chrono hands and 12 o’clock marker (these came in three colors: yellow, red, and a funky green). Date and day function - with Kanji Japanese and English day variants - at 3 o'clock positions work as designed.
CASE: 38mm x 43mm stainless steel case in pre-loved condition, with original tinted see-thru caseback.
CRYSTAL: Hardlex crystal, with no blemishes or scratches.
BAND: This 7018 comes with a light brown ostrich strap, with subtle dark brown accent stitching. It also comes with a red and cream NATO strap, replete with stainless steel hardware – a great complement to the sporty nature of this automatic chrono.
MOVEMENT: Seiko 13-jewel 7018B flyback automatic movement.
CROWN: Recessed unsigned stainless-steel crown.