(2/3) BACK TO THE FUTURE, Seiko divers review – 6105-811x and comparaison with the SLA033 / SBEX031 reissue


Previoulsy :

Reminder :I cannot guarantee that this article is 100% complete or accurate. If you spot any issues, missing copyrights in the article, please add comments.

Note: I’m French, so my English is unfortunately not a Shakespeare/W.Churchill/B.Obama/R.Parks one. But I did a lot of efforts!

PART 2a –  6105-8110 Review

Mine is a model from February 1973, serial number 321202. It is in a pretty good condition.

6105-8xxx history and models

The Seiko 6105 is a real iconic diver watch in the Seiko history. It has been the third generation of the divers for the brand, following the 62MAS and the slimmer 6105-8000/9. During the Vietnam War, pilots used to buy Glycine Airman watches and 6105 was a very popular choice for Marines.

It was easily found in U.S. Army PX’s (Post Exchanges - Retail stores found on United States military installations). It cost about 1 or 2 months of a regular soldier pay (75$ - 95$).  Today, it corresponds to 510 equivalent $ - 650 equivalent $ including the inflation from 1970 to 2020.

If four Seiko 6105 models have been produced from 1968 to 1977, two of them were just designed for marketing reasons:

  • 6105-8000: Symmetrical cushioned case, no hacking 6105A and 6105B hacking movement depending the build date, non-locking crown, bi-directional bezel with a spring surround which provides friction and doesn't click.
  • 6105-8009: Same features as the 6105-8000. 9 is for the US market.
  • 6105-8110: Asymmetrical cushioned case, 6105B hacking movement, turn/lock crown mechanism, bi-directional bezel with a click ball mechanism.
  • 6105-8119: Same features as the 6105-8110. 9 is for the US market.

According to the catalogs, the transition between the 2 versions has been made in 1969-1970. So, the 6105-811x (the second generation) was made from 1970-1977.

6105-800x (Image courtesy a friend of mine)

The reference of the 6105-8110 models is 61MC 022 in the Japan Domestic Market (JDM) catalogs. In 1975, the reference is changed to YAH028.

In 1972 US catalogs, the reference is 55029.

61MC 022 with the XGL-731 aka “Tire tread” strap (Extract of 1974 JDM Seiko catalog V2)

YAH028 with the XGL-731 aka “Tire tread” strap (Extract of 1975 JDM Seiko catalog V2)

55029 with the ZLM01 aka “waffle strap (Extract of 1972 Seiko catalog)

6105 models were replaced by the Seiko 6309 “Turtle”.


The original model is often referred as “Captain Willard” as it was worn by the character Captain Benjamin L. Willard, Airborne Army Ranger played by Martin Sheen in the movie Apocalypse Now from Francis Ford Coppola (1979). Another surname, often used in France is, for the same reason, “Apocalyse Now”.

Apocalypse Now  (Image courtesy Internet)

In Japan, the watch has the nickname of “Uemura”, a reference to the Japanese explorer Naomi Uemura who wore the watch during his 12,000km solo dog-sled journey from Greenland to Alaska in 1970s.

Naomi Uemura 6105 (Copyright Seiko)


 6105-811x models has a unique case and crown protection. You cannot miss it! To my mind, this asymmetrical and curvy shape is the key point of the watch and the reason for this model is a “must have”. This is clearly difficult for me to express my feelings. I simply fell in love with this amazing case! 


The watch size without crown is 44mm, 13mm thick, 48mm lug to lug and 48.5mm from the crown to the opposite side. Pretty large!

The manufacturing quality and finish are impressive and can be successfully compared with contemporaneously Omega and Rolex divers.

The top case finishing is a brush circular one and a polishing one on the side. A sharp curved edge demarcates the both areas. The bottom case is brushed too. The case back is polished.


One unusual item to notice: the lug width is 19mm. This is largely uncommon and, to be honest, this is not very helpful for strap switching!


As already notified, all models are rated to 150m.

Early asymmetric 6105-811x Proof models had a different crown cut out area compared to the later Resist versions of the same generation. This is a very subtle change of case manufacture.

Crown and gasket

 The oversized crown is about 6.3mm wide, with ridges combined in groups to help you grip it. It is at 4 o’clock and a huge crow protection.


The crown comes with an arrow and the word "lock," which does not appear on any other of the Seiko diver range of watches. The reason for is that the 6105 divers use a mechanism named “turn and lock” (or “turn/lock”) that is unique to this model. In consequence, this is not a screw-down crown.


When the crown is pushed, you can slightly turn it. It locks one of the crown grooves into a pin located in the case. To be clear, the crow does not really lock.

It only stops the crown for rotating but does not prevent it to pull it in and out.

Instructions manual - Crown-locking device (Image courtesy Internet)

Notice that the gasket is integrated within the crown, so you can’t replace it unless you change the whole crown.

For sure, this is not secure as a proper screw-down crown and of course do not seal very well. It’s the reason Seiko improved these items in the 6309 models.

Unfortunately, this seal weakness has a direct impact on the dials and hands condition of the vintage 6105 we can retrieve on the market (see the chapters dials and hands).


Seikolic corner

Often this locking-pin is missing due to corrosion. The lock is not possible anymore. Restoring is possible but expansive.

Missing pin (Copyright Merlin699 on SCWF)


Fake recognition

The crown is a very important item to check when you’re looking for an authentic 6105-811x watch. Original 6105-811x crowns have 6 groups of “teeth” (or “ribs”). Each group has six to eight “teeth”. Fake crows have only five “teeth” per group and probably needed to cut off or modify the crown tube.
Most probably, crowns with 6 “teeth” per group are coming from early productions models (1970 to mid-1970s).

Fake crown teeth picture (Copyright Nikidasi on

Dial and case back

 I need to merge these 2 items because there is a relation between the dial and the case back markings.

The dial is matt black with flat-topped frame markers, nickel plated and filled with a lot of lume using promethium (Pm147) material. It seems that the markers were embossed from the rear in the first models and applied after. 



The Seiko logo is applied and is matted silver finished.


The fine print below the 6 should notify “Japan 6105-8009T”.


There is the date window at 3 o'clock with a nice metallic frame.


The finishing of the dial is impressive and emphasizes the shape of the case to my mind.

“WATER 150M PROOF” or “WATER 150M RESIST” dial marking? This is the question and an important one!

The “WATER 150M PROOF” printing on the dial was associated with a “WATERPROOF” printing on the case back. The case back is simple, with an engraved horseshoe like drawing. The text inside is straight: “STAINLESS STEEL”, “6105-8110” (no 6105-8119 found in this configuration) and “WATERPROOF”. The worlds “WATER” and “PROOF” are placed side by side without space. “SEIKO” and the “Suma” logo are engraved in the center of the back. The serial Number and “JAPAN A” are below. “JAPAN A” is the country and case manufacturer mark.

The “WATER 150M RESIST” printing was associated with a “WATER RESIST” printing on the back. The horseshoe is still present until 1973/74 when it has been replaced by a plain back. The rest of the information did not change.

The “PROOF/PROOF” models are rare.

The back case is screw down.


Seikolik corner

The dial (and hands) are difficult to find in decent condition. As explained previously, the crown protection and its seal are the main reasons. Majority of 6105 have moisture inside. The lume, the hands and finally the dial turn grey or black due to moisture.

Moisture (Image courtesy Internet)


a majority of 6105 on the market are sold with replacement dials. Fortunately, they are easy to recognize. Although, they provide a sanitized dial, they do not reach the quality of the original one and to my mind, downgrade the whole watch interest.

On replacement parts, the markers have very sharp corners, a flat top with weak lume. The lume color is a shiny green. The “8009T” marking is not preceded by a dash “-“. The printing of the text is thinner or bigger and the applied Seiko logo is rough and shiny. The date window inner coins are sharp.

Aftermarket dial (Copyright Adventures in Amateur Watch Fettling)


The hour and minute hands are faceted steel baton style with beveled edges. 6105-8xxx and 62MAS models have the same hands and are lume filled. The sweep hand is a dedicated “stop light” style with two lume filled holes. The outer hole has white lume like the hour, minute hands and indexes and the inner hole has a kind of red salmon color.



A particularity to notice: 6105-811x (and may be 6105-800x) has 2 types of sweep hand. A long one and a shorter one. It seems that the shorter one replaced the long one in 1972. The longer sweep hand reached the markers.

Seikolic corner

A lot of aftermarket hands exist. They are easy to differentiate but of course they will reduce the value of the watch.

 I tried to list the different permutations in the following chart.




Case back

Horseshoe / Plain back

Sweep Hand

Few months in mid-1970


(no 6105-8119 found)







Possible mix









Around 1972






1973/74 -> End






Mine is a 6105-8110 RESIST/RESIST model from Feb.1973 model with a horseshoe and short sweep hand.



The bezel is quite different between 800x series and 811x models. The 800x bezels are bi-directional without clicks because they featured a friction O-ring for tension.The 811x bezels are bi-directional too with 60-clicks in a full rotation. This is the first time that a Seiko diver featured a click ball mounted in the case.

A rubber O-ring gasket increases the tension of the mechanism.

It is a coin-edge bezel with aluminum insert and a glossy and reflective lack grained finish.




A reversed triangle is at 12 o’clock with a concave lume pip. The triangle has a grained finish too. In an original insert, there is a small gap between the triangle and the outer edge.  The point of the triangle usually turns under the inner edge of the insert.  It looks cut viewed from the top of the watch. 


Fake recognition

Aftermarket replacement bezels have distinctive points:

  • Uniform texture (not grained).
  • The silvered triangle makes flush the edge of the insert (no gap) and its point exactly enters the inner edge.
  • A bump lume pip is often present.


The crystal is a Seiko patent named “Hardlex”. This is a hardened mineral glass. Mine is dual curved but it can differ. The Seiko reference is 320W10GN00.

The reference 320W10GN00 means:

  • 320: Nominal diameter (32mm wide)
  • W: Plain, no tension ring
  • 10: 10th design added to 320W series
  • G: Material is tempered mineral glass (i.e Hardlex)
  • N: Unknown
  • 0: Unused digit
  • 0: Unused digit

 I really appreciate the optical effect caused by the crystal.


Seikolic corner

The usage for the 320W10GN00 reference has been studied by several persons and their conclusions differ (Sources: Jonathan Koch “Swedefreak , “SeikoPsycho” and Spencer Klein).  Let’s try to summarize the options below: Everyone agrees that the crystal reference is divided to at least 3 types: “I”, “II”, “III” and another “Type IV” or a second variation of “Type III”.

“Type I” is the first edition and the oldest one and perfectly fits for early 1970s/pre-1972 models including the earliest 6105-800x models. It has a flat top and a single inner dome. It measures about 3.85mm deep, 1.5mm thick at center with frosted sidewall and polished bevel. The sharp edge was very vulnerable to chips because it was above the bezel. It’s the reason for Seiko fixed the problem with a slightly lower profile dropping the height by about 0.20mm.

The conclusions differ on the “Type II” and “Type III” usage.

First possibility: “Type II” has been used from 1971 to early 1976 models and “Type III’ (profile more dropped again) was made from approximately 1976 to the mid-1980s. First variation of “Type III” is a flat top model and the second variation is a down top type. First variation has been more intensively used.

At the opposite, “Type II” was very uncommon and quickly replaced by “Type “III”. On both sides, “Type II” and “III” are double dome crystals.  According this last source, “Type III” has a top shallow dome to decrease the reflective effect and a more pronounced inner dome. Its edge will be nearly flush to the insert. Therefore, in this situation, this type is considered as the most common variant and after 1972, became correct for both OEM and service replacement parts meaning that a 1970 watch with a “Type III” crystal is considered as a genuine combination.



6105-8110 and 6105-8119 models use the cal. 6105. The 6105 movement came in 2 variations: 6105A and 6105B. They were both 17 jewels and run at 21,600 bph (3Hz) and a power reserve of 46h. The movement had a quick date set and an automatic, self-winding mechanism. The automatic winding mechanism was particularly efficient even from a stopped position.

Manual winding was not possible, mainly due to Seiko’s Magic Lever System (or Pawl level in some Seiko documentations). This mechanism is part of the automatic winding mechanism. The Magic Lever winding system uses pawls ather than direct gearing between the rotor and barrel. This helps isolate the gear train from shocks. Magic Lever has one pawl to "pull" and another to "push" the transmission wheel (Read the Seiko Museum article for detail).

Instructions manual – No manual winding (Copyright Internet)

The real difference between 6105A and 6105B was that 6105B hacked, meaning the second hand stopped when the crown was pulled out. The 6105-8110 and 6105-8119 models fitted the 6105B.
As always, no embellishment on the movement, but let’s say this is not a key point for a diver!


Seikolic corner

In fact, this is difficult to verify if your movement is a “A” variation or a “B” variation. The reason is that the both calibers are intensively interchangeable, even in the 61xx family itself (some bridges could be 6106 or 6119 too). The easiest way is to find the hacking level using its inspection hole or remove a bridge to revealed it.

Hacking Lever (Copyright DrSeiko)

Hacking Lever (Copyright Adventures in Amateur Watch Fettling)


Originally, 6105-8110 came fitted with a 19mm rubber strap released in 1969 ref. GL721. The nickname of this strap is “Chocolate Bar” due to his specific pattern on the top side.

GL721 (Copyright plus9time)

In the 1972 Catalo supplement, another original rubber strap for 6105-8110 was the XGL-731 aka “Tire tread”. It has been only supplied on this model and probably released in mid or late 1972.

XGL-731 (Copyright plus9time)

It seems that 6105-811x export model was only fitted with the ZLM01 for duration of product life. The ZLM01 aka “waffle” was Seiko’s first in house designed dedicated to divers and has been released in 1967.

ZLM01 (Copyright plus9time)

Previous 6105-800x models came fitted with ZLM01 reference.

Seikolic corner
Finding an original strap is a sinecure because they are very rare, expensive and often in bad condition. Fortunately, several manufacturers - easy to find on Internet - produce realistic "Chocolate Bar", ZLM01 and XGL-731 straps copies if you want a vintage and genuine look.

If you prefer solid end-link bracelet, you can find too a “H-link” bracelet that is genuine too from a period perspective. As an alternative, you can also use a Marine Master strap.



To be honest, I did not retrieve a lot of information about the box. The E-BM45 box seems to be used for 6309 and 6306 divers. A long box is often seen on the Internet for 6105-811x models, but I do not know the reference.

Here an example of a “square” type box:

Copyright GuyJ on Wrist Sushi

Papers and instructions

Documents were composed by the Instructions manual and a worldwide guarantee. At least two different Instructions manuals have been edited. One of them covers the calibers 6159, 6105 and 2205. The second one just covers the calibers 6105 and 6159.

Covers of the Instructions manual – Cal. 6159 & 6105 (Image courtesy Internet)

Front cover of the Instructions manual – Cal. 6159, 6105 & 2205 (Image courtesy Internet)

The both Instructions manual covers these functions:

  • How to use your Seiko Automatic Diver’s watch
  • How to start the watch
  • How to set time and calendar
  • How to set the second hand
  • Hi-beat watches (This chapter is dedicated to 6159 calibers).
  • Unique crown-locking device
  • Rotating bezel (to exactly calculate elapsed time)
  • To preserve the water-resistant quality of your Seiko watch


Despite an important size, the watch is extremely comfortable even with my “chicken” wrist. You should even wear it under any shirt sleeve.  

From a design perspective, I will summarize to just one sentence: ASYMMETRY IS AESTHETIC! This is my last opinion. Clap end.

Hieraklion 01/2020


Some interesting readings, videos and references

Adventures in Amateur Watch Fettling: m
Fratello Magazine : /
Horology Crazy: m
Keep the Time Blog: /
Plus9Time : /
Seiko & Citizen Watch Forum (SCWF): /
Seiko Club Singapore: /
Seiko Corp: /
Seiko Diver Blog: /
Seiko Museum: /
Seiko Shizuku-Ishi Studio : l
Spencer Klein: m
The Grand Seiko Guy : m
The Seikoholics Forums: /
The Sping Bar : m
Vintage Time Australia: Haut du formulaire

Worn & Wound: /
Wrist Sushi, A Japanese Watch Forum: /

Drjaytripod January 29th, 2020-06:58
Excellent, thank you!  
Bill January 29th, 2020-17:38
Excellent Seiko 6105 review and reference material. Three generations of Seiko Divers. ... 
hieraklion January 30th, 2020-02:23
Superb !  
Jay (Eire) February 12th, 2020-04:23
What a great triple Bill.  
Bill February 12th, 2020-22:43
Addicted by every measure. Love the divers.  
Jay (Eire) February 12th, 2020-04:22
This is an excellent post, thank you for putting this together and I look forward to no.3. I still need to reread these two posts, lots of information to digest. I have the other 6105 (-8000) which I posted about here I’ve been on the lookout for a Captain Willard for some time but as you say, they are not easy to f... 

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