My initial experience with the SD43 is very parallel to the experience that Jake Ehrlich of RolexMagazine.com had three years earlier.  Jake’s review and experience (and photo shown left) with what he calls the Single Red SeaDweller is found here.  Jake's experience and description are the same uncanny experiences I had, but I did not stumble across Jake's article until after I owned the SD43 for a month.

I did have some trepidation of moving to a larger watch after wearing a 40mm SD4000 and 40mm GMT BLRO, but there are some design differences that gave me some confidence that the watch would wear well.

When looking at the SD43, the first thing I noticed is the balance and how it is evenly distributed. There is no Maxi case found on the ceramic bezeled GMT Ref 116710 and Submariner Ref 116610, the bracelet width is proportional to the case, and there is enough weight making the watch feel robust.

The SD4000, although released for 3 short years, was an indicator for future Rolex design language. The SD4000 has the proportionally tapered lugs reminscent of the 5 digit Rolex references of the 1990's and later seen in the Rolex Explorer II Ref 216570.

The SD 43 takes the same design cues of the SD4000 but the case and bracelet are proportionally larger. Comparing the SD 43 (right) and the SD4000 (left), the lugs of the SD43 have greater taper and greater case thickness as the 40mm SD4000.

As Jake points out in his article, the casebacks are the same diameter, height, and bevel taper.

Another design difference is the lug shape. The SD4000 (top) has flatter lugs than the SD 43 (bottom). When compared to any of the GMTs that have a very flat case, the SD4000 lugs do curve.

But as experienced on larger watches such as the Explorer II Ref 216570, the lugs of the SD43 curve to fit the wrist. This is one of the reasons why the SD43 works on modestly sized wrists.

The SD43 is also traditionally tapered from the endlink to the bracelet, but is just 1mm wider on each side. Viewing the SD43 bracelet (bottom) and the SD4000 bracelet (top) the taper matches Rolex's proportional design language.

Additionally, the SD43 Glidelock clasp is proportionally larger than the SD4000 Glidelock clasp. The SD43 clasp is a bit larger, and I noticed a bit more play in the sliding mechanism inside the clasp than on the SD4000. Nothing serious with the amount of play, but enough to notice a difference in the the sliding action between the two sized clasps.

One surprising component that was not made larger are the springbars that hold the SD43 bracelet to the case. The SD4000 springbars (left) are much thicker than the springbars of the SD43 on the right. The SD4000 springbars are the same springbars used in the 116660 DSSD.

Although the SD43 springbars are thinner, there appears to be more spingbar that inserts into the case. The diameter of the springbar end is the same diameter as the section that slides into the springloaded sleeve. The SD4000 springbar tip steps down in diameter than the section that slides into the springbar sleeve.

Obviously, Rolex engineers discovered something with the springbar's design. Structural or metalurgical engineers please chime in.

As both Jake and I discovered, the larger size does not mean the watch is automatically too large or to too heavy. Aside from the curved case and the curved lugs, the trick to wearing 40mm+ watch on a 7 inch-ish wrist is making sure that the bracelet is snug which makes the Glidelock clasp a critical element of the watch. Unlike the Oysterlock clasp found on the GMT's and other Rolex models whereby they have to be worn a bit loose to allow for wrist expansion, the Glidelock has plenty of adjustment. The beauty of the Glidelock is that the wearer can make realtime adjustments throughout the day. I found the same is true when wearing the DSSD, SD4000, and the Explorer II Ref 216570.

How It Compares

Weight measured on an inexpensive electronic scale; your milage may vary....

The table above is comparison on size/weight of the Rolexes that I have owned over the few decades. The heavier watches (above 150g) that had Glidelock clasps were easy to wear. The lighter watches (eg. GMT 16710) were light and comfortable, but they had a particular set of fitting-isms such as the winding crown sliding into the back of the hand, or the watch sliding around along the wearer's wrist I have not experienced with the SeaDwellers. The combination of the Glidelock clasp, combined with the thicker caseback lifting the watch a few millimeters off the wrist makes a significant difference in wearability.

The Accuracy

The SD43 utilizes Rolex's updated 3235 movement that boasts 14 new patents and a 90% redesign from its 3135 predecessor including the Chronergy escapement and 70 hour power reserve complete with a +2/-2 Rolex timing certification. The COSC -4/+6 timing certification is a feat for most mechanical watch movements which underlied my skepticism for Rolex tighter specification and certification, but I discovered that out of the box, both the GMT 126710 and SD43 were on the mark.

Utilizing Tom Kerrington's (roamingtrek@gmail.com) fantastic iOS app, Watch Tracker, tracks timekeeping over the long term. Over the course of 120 days, the +1 continues over relatively deskdiving days, mixed in with some bikerides.

I did notice that after a month, the watch did seem to run at -1 sec / day. I knew that -1 would be a simple adjustment which I made utilizing the steps I discuss here. Performing slight regulation adjustments is not for the faint of heart, but with the right tools and equipment, is not too tough to do.

The chart on the right and the chart above show how the watch went back to +1 after the slight adjustment.

Since the adjustment, the SD43 has run pretty consistently over these last two months.

Tom Kerrington's Watch Tracker iOS app is available here.

After wearing the SD4000 I realized that it was missing something that made the watch mine versus a generic SD4000. Subsequently, I personalized the watch with a red date wheel because I felt the watch needed a touch of red, as well as needed caseback engraving that was not typical.

With the SD43, there are no available red date wheels available as the date mechanism is an entirely different design than what is found on the 31xx movements. Despite the unabailibility of a red date disk, the SD43 already has a touch of red on the watch face so a red date disk would be over the top.

The wider links on the SD43 seemed like a good place for a Minus4Plus6 logo. Knowing that laser engraving is precise at any size (just look at the laser etched Rolex crown on a Rolex crystal), I knew that it was possible. Working with LA Watchworks on the concept, they sent the SD43 bracelet to their laser engraving subcontractor who did an amazing job. Laser engraving does not stamp the material and thus is very precise and the coloration makes the logo visible without any weird reflections or metal displacement.

Needless to say, my feeling about SeaDweller 43 is "whatta watch." The SD43 combines the utility, durability, and accuracy while staying within the traditional Rolex refined and sleek design language. The fully brushed bracelet links, subtly black matte dial, and the single red SEA-DWELLER on the dial make this watch a definite keeper.

PS. Notice that I did not mention anything about date cyclops on the crystal. Needless to say, I like it. I feel that the date cyclops on my SD4000 is one missing element on that watch.