The Seiko 6138 "Yachtman" automatic chronograph - like this early 1970 Seiko 6138-0010 JDM SpeedTimer here, on its original SpeedTimer bracelet - has a well-known cult status, hence the nickname “UFO” (although advertised by Seiko as the “Yachtman Chronograph”) due to its flying saucer-esque case design.
The UFO features innovative and simple construction, such as a unique lug-less case, very indicative of the 1970s in which it was made, its pushers (held in place by the movement’s space ring) and crown are well proportioned for the case size.
The oddly numbered 6138 was the successor to the 6139 - the world’s first automatic chronograph - after its introduction in 1969, and the 6138 followed closely behind and was likewise produced by Seiko until 1979.
The main differences between the 6138 and 6139 is the 6138 offers hand-winding and featured two chronograph registers versus the sole one on the 6139.
Further, the Seiko 6138 contains subdial registers measuring minutes and hours, whereas the 6139 only measured minutes. Inside, the UFO features a column wheel and vertical coupling – all hallmarks of a serious chronograph movement.
The UFO’s black dial is contrasted with silver subdials and orange/red highlights on the central chronometer hand, dial and the external tachymeter bezel, and its fully integrated chronograph render it truly a landmark design, easily pitting it against the Zenith El Primero.
This Seiko UFO comes with its original Seiko SpeedTimer bracelet, nylon strap, spring bar tool, and rugged travel case.
1970 Seiko SpeedTimer 6138-0010 Yachtman "UFO" Proof Chronograph w/Orig Bracelet
DIAL: Seiko SpeedTimer proof/proof-signed black dial - reddish-orange dial accents remain particularly vibrant with zero fade, unlike on most UFO examples. Day/date - with Kanji Japanese/English day variants - at 3 o’clock position works nicely. Correct hour, minute, and chronograph handset; lume throughout handset and dial retains shine.
CASE: Stainless-steel case measures 44mm (w/o crown, 46mm with) x 47mm; matching caseback. No evidence of machine polish, and bezel insert is excellent with no fade.
CRYSTAL: Correct 6138 Hardlex crystal, no cracks nor scratches.
BAND: This UFO comes on its original Seiko SpeedTimer stainless-steel bracelet, which will fit up an approx. eight inch wrist - links are tight, and the bracelet is in overall good condition; it also comes with a red nylon strap.
MOVEMENT: 21-jewel Seiko 6138 automatic movement, manufactured in March 1970.
CROWN: Unsigned stainless-steel crown.
CHRONOGRAPH PUSHERS: Chronograph pushers depress with satisfying click, no stick. All chronograph hands reset to zero as designed.