All brands featured on Mainspring have one key element in common: they were created by people who have a passion for horology, self-expression, and storytelling. Whether their creations are elegant rectangular timekeeping devices or tough-as-nails tool watches made to survive an apocalypse, they were all driven by a profound need to tell a story whether about themselves or you. An invitation of sorts to embody someone you yet aren’t but aspire to be, or to embrace who you already are. As Sophie Scott-Lewis explained, watches are means of self-expressions and—to us watch folks—the one item we can wear on our body which can say to the world who we are. Because you can work for the fanciest of Swiss banks and wear a 1,000-meter diver with a sandblasted case, just like you can sport a 30mm gold watch whilst flipping burgers. That is the power of watches and that’s what we’re going to talk about (again) today. 

Of course, all of the watches I decide to write about resonate with me on one level or another. (I hope they do for you as well.) And you might have realized that I have a thing for tool watches—I do write about them a lot—and so you won’t be surprised to read yet another review about yet another utilitarian timekeeping device—the MKII Fulcrum 39. This one is a special one as I’m a big fan of Bill Yao’s work (he also runs Tornek-Rayville) and that he had the boldness and courage to bring to life his vision for a modern American military diver, drawing inspiration from the 1970s Rolex Mil-Sub which, to many, is a sacrilege to even base anything on. A silly thought of course which emanates from the highest levels of horological snobbery. Because the Fulcrum 39 is mainly two things: (1) a superb tool watch; (2) the purest form of the very human behavior of building up from what came before us. 

Specifications

Being a diver and an instrument destined to the military—a domain of our history and activity Bill has a passion for—the MKII Fulcrum 39 comes with two sets of specifications which we’ll discuss separately. One that is more or less commonplace for dive watches, and another that is more geared towards those who serve. (But you and I can enjoy both and benefit from both even though we don’t dive or serve.) So the first set includes 200 meters of water resistance, which is plenty and some for 99.99% of humans who have an affinity for underwater exploration; nighttime legibility guaranteed by way of generous applications of BGW9 on the hands, printed hour markers, and lumed pip on the bezel; a precise and well-machined 120-click unidirectional bezel; a robust and serviceable caliber, the regulated Miyota 9015* (4Hz/42 hours of power reserve); a legible and monochromatic color scheme; and drilled lugs for easy strap change.

*The Fulcrum 39 also comes in a no-date version with the Miyota 90S5. 

The second set of specifications—which sets the Fulcrum 39 apart from many other divers—includes a few key elements: a deeply-set anodized aluminum bezel insert, held firmly in place by way of a lip resting against the crystal, built this way to be more resistant to shocks and made of this tried-and-true material as it is also more resistant to shocks; a thick double-domed sapphire crystal instead of ever-so-popular box-shaped crystals as they are easier and cheaper to service and replace; a super grippy and functional screw-down crown semi-protected by crown-guards**; a bead-blasted 316L stainless steel case for increased resistance to shocks and corrosion (as well as providing tactical advantage); shoulder-less spring-bars for the single-pass nylon strap, which are less likely to pop out in action—whatever action that may be; and the latter was created, I believe, following the design of the first military dive watch issued straps (TR-900) based on the MIL-S-46383 specification from 1963. 

**The crown-guards have just the right height to prevent the crown from being knocked-off sideways whilst making it easy to operate wearing gloves. 

In terms of dimensions, the MKII Fulcrum 39 has a lovely profile which, perhaps it was made to be so, perfectly fits my French wrist of 6.50”/16.5cm: a diameter coming in at 39.50mm at the bezel (and 37.7mm at the case,) a lug-to-lug of 47mm, a thickness of 14.10mm, and a lug width of 20mm. Because Bill Yao does things with purpose and to match the unique vision he had for his horological creations explains why, as you should know, he purposely made the Fulcrum thicker than it could have been in order to give it a more distinct muscular, and somewhat more vintage, profile. (And the aforementioned bezel inlay construction contributes a couple of millimeters.) A thicker case weighs a little more and so lodges itself more easily on the wrist, and is more resistant against shocks which makes sense to find here since the Fulcrum 39 is a de facto military dive watch. Again, this model was designed with great purpose and it shows in the way it was spec’ed. 

Design

I often say that the design is what makes a watch and I generally stand by this statement. However, in today’s particular case, the specifications play an equal part in making the Fulcrum 39 a unique tool watch. And there are elements of its design which can appear surprising at first but which make sense upon closer inspection. For example, Bill Yao added chamfers to the case not necessarily to give the Fulcrum 39 a vintage feel—though the Rolex Mil-Sub 5517 had polished chamfers—but to elegantly narrow the appearance of the massive lugs—with which the bezel dominated the look of the old—and to make it possible to endow this model with a standard 20mm lug width instead of going for a 19 or 21mm lug width. (Adding chamfers on a bead-blasted case is unusual.) Seen from the sides, these muscular lugs have a claw-like profile with filed lower sections so that the Fulcrum 39 sits perfectly flat on the wrist. Bonus point: I appreciate the modest height and roundness of the crown-guards. 

Still looking at the case, we can see why and how the bezel is slightly larger, so that it’s easier to grip and turn wearing gloves (or simply being underwater and turning the darn thing with your bare fingers,) something made possible by an undercut which separates the bezel from the mid-case. The bezel has a superb profile as the aluminum insert is shaped at an angle and creates the perfect bridge between the slope of the domed crystal and the deeply grooved, serrated-like knurking of the bezel. Moreover, the bezel has a fully graduated count-up scale where all (most) minutes are represented by individual hash-marks, larger at the 5, 15, 25, 35, 45, and 55 markers, and spelled out with numerals printed in a bespoke typeface for the 10-minute increments. All markers are printed in a pearlescent silver paint which adds to the vintage aesthetic of the bezel and perfectly matches the matte tones of the anodized aluminum insert. 

And the dial, and I don’t know whether I prefer the dial or case + bezel combo or both equally—a superb exercise in simple and effective design. The broad sword hour hand is astonishing and highly legible, so is the long pencil-style minute hand, both polished and both hearkening back to military divers from the 1970s—of which the Rolex Mil-Sub wasn’t the only example as Omega, during the same time period, issued the Seamaster 300 ref. 165.024 to the British Royal Navy. A thin and polished seconds hand, complete with a lumed arrow-shaped element, finishes the handset which contrasts in an unusual way with the matte black dial and printed hour markers. The latter come in two shapes and two sizes—small batons and larger ones at the 3, 6, and—as well as an inverted triangle at the twelve. Obviously, the Fulcrum 39 is the epitome of superlative utilitarian horology and it’s easy to understand why. 

A special note goes to the 4:30 date aperture, a placement I for one have no problem with as it preserves the dial symmetry whilst adding an extra bit of functionality, which Bill Yao went as far as getting a custom date disc printed to further ensure legibility. (I have no issue reading the date whether it is in single or double digit.) 

The Heart of the Matter

At the heart of the matter are two things. First is the fact that the MKII Fulcrum 39 is indeed a modern U.S. military dive watch—a singular one—on account of its specs and particular design elements. Bill Yao, I believe, struck the perfect balance between legibility and character, adding what was necessary and appropriate to tie this model to 1970s military-issued divers he was inspired by to create the Fulcrum, whilst creating a logical continuation to dive watch designs as they were codified in the 1950s. As indicated in the introduction, it is perfectly human to build upon what came before, and I guarantee you that the majority of watch brands do the same thing, some with more or less success than others, and many with a profound lack of taste or even respect for what did come before them. And whatever is generally absolutely unique doesn’t always make sense. Trust me. 

The second heart of the matter is this: Bill Yao is unique in our niche world of horology as he manages to both draw inspiration from the past and create something from it that is absolutely unique. And to understand the uniqueness of his creations one has to look at them from both micro and macro perspectives—design wise—and from both historical and contemporary perspectives. Imagine, for example, that the MKII Fulcrum 39 is what a Ford Mustang could have looked like in 2025 should the car manufacturer have not strayed too much from the original design. What the Bullet Journal is for analog planning, a Tactical Turn for handwriting, and a single-pass FKM rubber strap is for tool watches. In other words, the Fulcrum 39 is not a copy of the Rolex Mil-Sub or Omega Seamaster, neither is it an homage, but instead is its own thing—and as Bill Yao put it, what the Rolex could have looked like should the Coronnet brand had taken a different route. 

Conclusion 

So the MKII Fulcrum 39 is a blend of what made the Mil-Sub beautiful with things that Rolex never—and would never—dared or been able to do. For example, beadblasting a case or issuing watches to the U.S. Military, which it never did, and which would have resulted for example in the use of the 12-hour bezel which is only found, originally, on watches made by American brands or destined to American soldiers. (Bill Yao first designed the Fulcrum with a 12-hour bezel and added the 60-minute one to please folks like yours truly.) At the end of the day, the Fulcrum 39—as well as its predecessor from 12 years ago—is a unique tool watch which proves that there is beauty in utility and in doing the simple things well. (Quoting from the master himself.) 

From a more practical standpoint, the MKII Fulcrum 39 will be back in stock this month and will set you back $995 for which price you will have a beadblaster stainless steel bracelet, an FKM rubber strap, and a single-piece black nylon strap. A very good deal in my book. So check out the brand’s website and sign up to their newsletter to get information on the upcoming restock.

Thanks for reading.