Bulova 23 Jewel 10BPAC auto L5/L4 ss
Case Dimensions and features:
- Width w/o Crown: 33.85 mm
- Length: 40.95 mm
- Depth: 7.95 mm wo/crystal, 12.10 mm w/crystal
- Lug Width: 17.35 mm
- Crown: 4.50Dia mm, unsigned
- Crystal: 27.85Dia mm, in bezel. Shallow Domed Acrylic
- Bezel O.D.: 33.30 mm
- Case Back O.D.: 28.95 mm
- Case Back thread O. D.: 27.50 mm
- Inside case back inscriptions: Bulova Watch Co.; Stainless Steel; Swiss; Brevet; a “Swiss Cross”; 260126; Perlage finishing; faint watchmaker engravings
- Outside case back inscriptions: Bulova; Stainless Steel; Shock Resistant; 6013564; L6; Anti-Magnetic; Self-Winding; Waterproof
- Movement: 10BPAC 23 Jewel Automatic, No Date
- Engraving on Movement: On Rotor BULOVA WATCH CO; 10BPAC; U.S.A.; 23 Jewels. On Bridge: L5
Notes: The MyBulova database (that is available to me) has three examples of models with this case. Other than the black dial, this would appear to be a “23R”, one example seen here: https://mybulova.com/watches/1956-bulova-23-r-12247
At first glance, this an understated design and something of a departure for Bulova in this era. Under closer inspection it becomes evident that this is one of Bulova’s earlier forays into “dive watch” specifications, at exactly the timeframe that Blancpain, Rolex, Doxa (and to a lesser extent, Squale) were all introducing their now iconic divers. The case, though not quite as serious as an EPSA “compressor”, is none-the-less rather impressive for it’s time. From the compressor-like internal springs in the case back, to the super stout build and protected crown, it is obvious that it was purpose- built to withstand significant water pressure. I would speculate that, with servicing and new case and crown seals, this watch could test to 50 meter easily. The minor wear that this watch exhibits would suggest that replacing the crown would not be required to pass such a 5 ATM water pressure test. The inscription “Brevet – Swiss Crown – 6013564” is the Swiss Patent Number for this case design. Overall, this configuration closely follows the direction Omega was taking for “waterproof” watches in this era, and even outdoes the “beefy lug” Seamaster in respect to case thickness and sealing technology. The drilled lugs are just the cherry on top of this ultra vintage design.
Well, today I got the call I knew was coming…my boss said I have to end my extended vacation tomorrow. I did, however, spend my last couple of idle weeks getting a few more of my Bulovas that aren’t in the database listed. My thanks to the esteemed Panel for selflessly identifying these for me. I learned much, and maybe made a small contribution to this enthusiasm of so many. It is only fitting that I conclude this growth spurt with an obscure Bulova, which just happens to be a personal fave.
In reply to Thanks for the heads up… by mybulova_admin
I think generic Bulova 23 is probably right. In hindsight, I am not sure why a dive oriented watch would have the somewhat ornate dial that this one has. What threw me was that instead of being deep black, like my "A", this one has a silvery dark dark grey appearance. Since I made this post I have combed the database more thoroughly and seen "A" versions that appear in photos to also have this mirror-like effect.
This case has a substantial o-ring in the crown, and also one in the case back, along with the "compressor spring". I have hundreds of watches, mostly Swiss. When I see the Swiss patent number prominently displayed inside the caseback it usually means that the manufacturer has convinced the Swiss patent office that they have come up with a unique method of achieving either super water-proofing (in later years downgraded to water-resistance), or exceptional shock resistance. The actual patent documents are available from the governmen, by number. I have read a few. When granted, they are highly technical, very detailed, and make express claims that the Swiss accept as true. I personally have never seen another Bulova before the 80's with the brutish build of this case. Around 1954-56 was when the serious players decided to throw their hat in the ring to catch up with the Submariner and 50 Fathoms, and this falls right in that time line. I mentioned before the similarities to the "beefy lug" Seamaster. Google just those three words and you will see why I make the comparison. This case is actually more substantial.
In reply to I agree with Ken, the case… by Geoff Baker
In reply to Geoff, do you think the… by mybulova_admin
In reply to Sorry, no, I mis-read the… by Geoff Baker
I have been back to this one a few times and am still perplexed. Case is Swiss as marked, but movement is marked USA with no apparent import code stamp. This may indeed be a marriage, but I don't think we have enough info to call it non-conforming. The USA on the rotor is confusing. Is it possible this is a USA in house movement sent to Switzerland to complete a watch we have yet to see; or a swiss case sent to the US?? I'm leaning towards calling it a generic
1960 Bulova 23 with the hope we can one day ID more accurately.
In reply to I have been back to this one… by neetstuf-4-u
Hi NS4U
Your point was well taken, and made me spend another hour going through the database, seeing if I could find the USA movement with the Swiss back on other "23" models. What I learnbed is that less than half of submitters posted an inside case back shot. However, I did find numerous examples of that combination, enough that I gave up after about three pages of "23"s. Here are some with Swiss backs that I found: https://mybulova.com/watches/1957-bulova-23-r-6554 ; https://admin.mybulova.com/watches/1955-bulova-23-b-10500 ; https://mybulova.com/watches/1956-bulova-23-4330 ; https://mybulova.com/watches/1956-bulova-23-11411 ; https://mybulova.com/watches/1956-bulova-23-a-12204 ; https://mybulova.com/watches/1957-bulova-23-a-14087 . I am sure there are at least that many more with the USA/Swiss connection. The positive aspect is that your question is one that would have logically been asked in the future, and now it is answered. Certainly didn't intend for the panel to devote so much of their valuable time on this, but know that the efforts to keep a tidy archive are appreciated, and it plays an important role in preserving the sparse history of Bulova. By the way, I think the correct call was made.
Jimmy