Quick facts
- Caliber
- 6105(automatic)
- Jewels
- 17
- Beat rate
- 21,600 vph
- Hacking / hand-winding
- — / NoPending verification
- Water resistance
- WATER RESISTANT
- Crown
- 4 o’clock
- Production
- 1968–1977
- Modern equivalent
- SPB151 / SPB153
Variants
The 8110 and 8119 share the case and movement and differ by market. The earlier, slimmer 6105-8000 is compared below.
| Reference | Market | Day wheel | Status |
|---|---|---|---|
| 6105-8110 | — | — | Pending verification |
| 6105-8119 | — | — | Pending verification |
Serial decoder
Enter the six-character serial from the case back. The 6105 was made from 1968 to 1977, ten years, so each serial points to a single year.
Possible production date, not a guaranteed date or an authentication. Production date is not the purchase date.
Full decoder with caliber and case codePrice guide
Prices appear after our first sampling of sold listings in November 2026.
| Condition | Low | Median | High |
|---|---|---|---|
A · Collector | — | — | — |
B · Serviced original | — | — | — |
C · Running, unserviced | — | — | — |
D · Project or suspected franken | — | — | — |
Sampled —, n = —, eBay sold listings viewed manually.
Checks before you buy
Replaced dials, hands, bezel inserts and whole movements all turn up on 6105s. Check the case back, the dial and the movement together; no single detail settles it.
Case back, serial and dial wording The back reads 6105-8110 or 6105-8119. A PROOF dial goes with a WATERPROOF back, a RESIST dial with WATER RESISTANT, and the serial year fits.
A PROOF dial on a mid-1970s serial needs explaining. Sources put the switch to RESIST in 1970 (Worn & Wound) or 1971 (Seiko staff), so either wording can be original on a 1970 or 1971 watch.
Sources: webChronos interview with Seiko staff; Worn & Wound. Our own photo comes with our first shoot.
Dial printing Flat-topped marker surrounds, crisp printing, a Suwa symbol and JAPAN 6105-8009T at the bottom.
Rounded, shiny marker surrounds, a stuck-on look, rough printing or bright green lume.
Sources: Adventures in Amateur Watch Fettling; Fratello. Our own photo comes with our first shoot.
Hands Rectangular faceted hour and minute hands; a seconds hand with white lume and a red section.
Relumed or replacement hands, or hands from another Seiko. Faded red on its own is normal.
Sources: Fratello; Adventures in Amateur Watch Fettling. Our own photo comes with our first shoot.
Bezel Black insert with a triangle lume pip at 12 under a small clear window; turns both ways in 60 clicks.
An undersized pip, a missing window or an insert that doesn't sit flush.
Sources: Worn & Wound; Fratello. Our own photo comes with our first shoot.
Crystal Dual-curved Hardlex. A lower-profile Seiko service crystal is a replacement, but a genuine Seiko part.
Sapphire or a modern anti-reflective coating with no record of the change.
Sources: Seiko's 1970 re-creation page; Fratello; Adventures in Amateur Watch Fettling. Our own photo comes with our first shoot.
Crown and lock pin A crown marked with an arrow and LOCK that hooks onto a pin in the crown guard; crisp lines between brushed and polished surfaces.
A worn or missing pin, a crown that won't lock, or rounded edges from heavy polishing. A crown that locks still isn't proof the watch is water-resistant.
Sources: webChronos; Worn & Wound; Adventures in Amateur Watch Fettling. Our own photo comes with our first shoot.
Movement A 17-jewel 6105B with a seconds stop and a date-only calendar.
A 6119 or 6306 inside, a day-date dial, or a 6105 rebuilt with donor parts. Ask for a movement photo.
Sources: Seiko 6105B parts catalogue; Adventures in Amateur Watch Fettling. Our own photo comes with our first shoot.
Common faults and service
The problems repairers document on 6105s come with age: the crown seals, the rotor bearing and the crown's lock pin.
The crown seals sit inside the crown and were never meant to be replaced on their own, so an old or new-old-stock crown can have hardened gaskets (The Watch Spot)
Rotor bearings can rust solid and then damage the automatic winding parts, even on a watch that still runs (The Watch Spot)
On 6105-811x cases the crown's lock pin can wear down (Adventures in Amateur Watch Fettling)
Hardened crown seals; they sit inside the crown, so the usual fix is a new crown
A rusted rotor bearing that has damaged the automatic winding
A worn or missing crown lock pin
A cracked or corroded crystal retaining ring
Hardened case back and crystal gaskets
Seiko USA doesn't list the 6105 among calibers it won't service, but warns that other old calibers may be returned unrepaired and that water resistance can't be guaranteed on older divers. Its estimate for mechanical calibers like this one is $359.
Not on Seiko USA's list of calibers not to send (checked 2026-10-26). Seiko USA notes other old calibers not listed may also be returned unrepaired.
Where to look
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6105-8000 vs 6105-8110: which one is it?
Look at the right side of the case. The 6105-8000 of 1968 is a slim, symmetrical cushion case about 41 mm wide, with a signed Seiko crown set into the case at 4. The 6105-8110 that replaced it in 1970 is wider and asymmetric, with a crown guard that sweeps out around the crown. Seiko’s product planners told webChronos that the company only distinguishes these two cases; the “mid-case” some collectors talk about isn’t an official version.
| 6105-8000 / 8009 | 6105-8110 / 8119 | |
|---|---|---|
| Made | 1968 to 1970 | 1970 to 1977 |
| Case | Slim, symmetrical cushion, about 41 mm | Asymmetric cushion with a crown guard, 44 mm without the guard |
| Lug to lug and lugs | 48 mm, 19 mm lugs | 48 mm, 19 mm lugs |
| Crown | Signed push-pull crown at 4 | Arrow-and-LOCK crown held by a pin at 4 |
| Bezel | Turns both ways; Fratello says without clicks | Turns both ways in 60 clicks |
| Movement | Usually the 6105A | The 6105B, with a seconds stop |
The 8009 and the 8119 are the North American versions. Plus9Time’s copy of a 1981 Seiko USA cross-reference lists the 8119 as model 55029 for the USA and Canada.
6105A vs 6105B
Both are 17-jewel automatics beating at 21,600 vibrations per hour, with a date and no day. Neither can be wound by hand. The difference is the seconds stop: Seiko’s 6105B parts list adds a second-setting lever, so the B stops the seconds hand when you pull the crown and the A doesn’t. Mizeni lists hacking for the 6105B only.
Expect a B in an 8110 or 8119 and usually an A in an 8000. Seiko hasn’t published the date it switched, and The Watch Spot documented one 8119 with an A inside, so treat a mismatch as a question to ask, not as proof of a swap. Our 6105 movement page covers the parts the 6105 shares with the 6106 and 6119.
PROOF or RESIST on the dial?
Both are original. Early dials read WATER 150m PROOF with WATERPROOF on the case back; later ones read WATER 150M RESIST with WATER RESISTANT. Seiko’s planners say the company started using RESIST in 1971, ahead of the ISO standard that followed in 1972; Worn & Wound puts the change in 1970. Watches from 1970 and 1971 can carry either.
What needs explaining is a mismatch with the serial. A RESIST dial on a case back that decodes to 1968, or a PROOF dial on a mid-1970s 8110, points to a replaced dial or back. Fratello flagged exactly that kind of mix, a 1968 back with a RESIST dial, on an auction watch.
The dial code is JAPAN 6105-8009T on both the 8110 and the 8119, as Worn & Wound records. Don’t read the 8009 in it as a mismatch with the case.
Is the crown a screw-down crown?
No. The 8110’s crown pushes in and hooks onto a pin in the crown guard, which is what the arrow and LOCK on the crown are for. Seiko’s planners told webChronos they used a stopper pin because screw-down crowns were still being developed. The seals sit inside the crown and weren’t designed to be replaced on their own, so a worn crown is usually replaced whole (The Watch Spot). A crown that locks isn’t proof the watch is still water-resistant.
Why is it called the Captain Willard?
Because Martin Sheen’s character, Captain Benjamin Willard, wears one in Apocalypse Now (1979). Fratello identifies it as a 6105-8110. We haven’t found a record of the film watch’s case back, so whether it was an 8110 or an 8119 can’t be confirmed.
What goes wrong, and what a service costs
The documented problems come with age. The Watch Spot found hardened crown seals, even in a new-old-stock crown, and a rotor bearing rusted solid that had damaged the automatic winding on a watch that still ran. Adventures in Amateur Watch Fettling records worn lock pins, cracked crystal retaining rings and hardened gaskets.
Seiko USA doesn’t list the 6105 among the calibers it no longer services, but it warns that other old calibers may be returned unrepaired and that it can’t guarantee water resistance on older divers. Its estimate for mechanical calibers like this one was $359 before tax and shipping in October 2026. Weigh that against what the watch is worth once serviced, which our price guide will show after sampling.
Modern Willards
Seiko has re-made the 1970 diver several times: the SLA033 re-creation in 2019 (2,500 pieces), and the SPB151 and SPB153 re-interpretations in 2020. None of them was in Seiko USA’s catalog when we checked in October 2026. Our 6105-8110 vs SPB151 comparison sets the specs side by side.
Sources
- Worn & Wound, Affordable Vintage: Seiko 6105: case, crown, dial code, PROOF and RESIST.
- webChronos, Uncovering the Evolution of the So-Called “Seiko Second Diver”: interview with Seiko planning and design staff; dimensions, crown, RESIST in 1971.
- Plus9Time: the Seiko USA cross-reference and the GL721 and XGL-731 strap histories.
- Fratello, #TBT Seiko 6105-8110 and the Bonhams auction review.
- Adventures in Amateur Watch Fettling and The Watch Spot: restoration notes. Seiko: the 6105B parts list and Seiko USA’s service page.
FAQ
What is the difference between the Seiko 6105-8000 and 6105-8110?
The case. The 6105-8000 of 1968 is a slim, symmetrical cushion case about 41 mm wide with a signed push-pull crown at 4. The 6105-8110 replaced it in 1970 with a 44 mm asymmetric case, a crown guard and a crown that locks on a pin. Seiko's own records only distinguish these two cases.
What is the difference between the 6105-8110 and the 6105-8119?
The market. Plus9Time's copy of a Seiko USA cross-reference lists the 6105-8119 as the USA and Canada model, number 55029, on the ZLM01 waffle strap. The case, movement and dial are the same as the 8110.
What are the dimensions of the Seiko 6105-8110?
44 mm wide without the crown guard, 48 mm lug to lug and 12.5 mm thick, with 19 mm lugs. Those are the numbers Seiko's design team measured on an original when it re-created the watch in 2019.
Does the Seiko 6105 hack or hand-wind?
It never hand-winds. Hacking depends on the version: the 6105A has no seconds stop, while the 6105B, found in the 8110 and 8119, stops the seconds hand when you pull the crown.
Is the 6105-8110 crown a screw-down crown?
No. It's a push-in crown that hooks onto a pin in the crown guard, which is why it's marked with an arrow and LOCK. Seiko staff say screw-down crowns were still being developed at the time.
Why is the Seiko 6105 called the Captain Willard?
Martin Sheen's character, Captain Benjamin Willard, wears one in Apocalypse Now (1979). Articles usually identify it as a 6105-8110; we haven't found a record of the film watch's case back, so the exact reference can't be confirmed.
How much is a Seiko 6105-8110 worth?
It depends on originality and condition more than on the dial wording. Our sampled sold ranges appear on this page after our first sampling in November 2026. They cover original 6105s only; the modern re-interpretations are priced separately.
Is there a modern version of the Seiko Willard?
Several. Seiko re-created the 1970 diver as the SLA033 in 2019 and re-interpreted it as the SPB151 and SPB153 in 2020. None of the three was in Seiko USA's catalog when we checked in October 2026. Our comparison page sets them side by side.