San Martin SN0109 GMT Review: Tudor Black Bay Homage

So, I somehow missed one of San Martin’s most praised GMT homages. However, that little or not so little Sei I o NH35 movement crisis - and, by extension, the NH38 and NH34 - finally brought this San Martin onto my radar.

And strangely enough, after two weeks while preparing for this review, I’ve been wearing it almost daily. And that doesn't happen very often. There are a few things that I found surprisingly appealing. And the new movement isn’t the only surprise: the bezel action for example, is nothing like I expected. So what’s changed, and how good can this homage really be? We have it here. Let’s take a closer look.

Design

The design inspiration here is obvious, and while sticking to the script so to speak, San Martin has made it a very versatile, refined and attractive watch. One of my favourite details is the blue-grey colour on the bezel. It’s an unusual shade, and they also offer a colourway with a dial in a similar colour. As well as the warm, almost creamy white dial, which, I think looks absolutely fantastic. Honestly, I had a hard time choosing between them.

And not only this thing is very good looking - it’s very practical too. We get a screw-down crown, sufficient water resistance and the kind of lume I’ve come to expect from San Martin. I’ll put it through my usual 15-minute test so you can judge that for yourself.

The movement in this upgraded version is part of the appeal as well. Like the NH34 it replaces, it’s a caller GMT, with an independently adjustable GMT hand. But it actually delivers a better performance and smaller dimensions, which may have helped San Martin reduce the case height. We’ll look at it properly in a moment.

What surprised me most though was the bezel. Quite a few manufacturers take a lazy design shortcut and reuse a diver case for their GMTs, leaving us with a unidirectional dive bezel. San Martin hasn’t done that here. This one is a proper bidirectional GMT bezel, with 24 distinct clicks, and each position settles into place really nicely. The bezel action really feels far better than I expected.

Now the bezel insert is aluminium. I’d personally have gone for matte ceramic, but I know many of you prefer aluminium on a watch like this for that more period-correct look. So on that front, San Martin has definitely delivered.

Now as we, of course, have hereall the premiummaterials: a boxed sapphire crystal, stainless steel construction and a bracelet with inverted end links. And we also get something here that only a year or two ago, I’d have been complaining about if it wasn’t there; now we almost take it for granted. I'm talking about San Martin’s robust on-the-fly clasp. Always an welcome feature.

So, songs of praise all round? Well, almost. However there is well at least one thing I’d like San Martin to change, and I’ll show you when we get to it. First, let’s look at the movement.

Dimensions

No major surprises with the dimensions. The coin-edge bezel measures spot-on 40 millimetres across and overhangs the case slightly, which comes in at around 39 millimetres. Lug width is 20 millimetres, so you’ll have plenty of strap options.

Lug to lug, my calipers show about 48.5 millimetres. Thanks to the inverted end links, that’s close to the watch’s full span on the wrist. I think it should work comfortably on wrists from around six inches upwards, and possibly a little smaller.

Case height is around 12.4 to 12.5 millimetres, including the slightly raised boxed sapphire crystal. That’s a good result for an automatic GMT. The bracelet tapers from 20 millimetres at the lugs to just under 16 millimetres at the clasp, and putting it on the scale the watch weighs comes to around 150 grams on the bracelet.

Overall, a set of very versatile proportions that to some extent help explain why I’ve kept reaching for it.

Case

The case has a slender, classic shape. The lugs curve down slightly, but there’s no elaborate sculpting. Satin brushing covers the tops and sides, separated by a thin polished chamfer that runs from one lug tip to the other. It’s a small detail, but it gives the case a nice, clean and elegant outline.

There are no crown guards, which suits the vintage styling, and the signed screw-down crown is well proportioned. Around the back, we get a plain screw-on caseback. I’m getting used to these—Rolex gets away with it, after all—but I wouldn’t mind a little engraving around the edge. A model number and a few specifications would do nicely. Would I pay more for it? Probably not. More useful though is the stated 100 metres of water resistance. With the screw-down crown and caseback, this feels like a watch I can wear every day and happily take swimming.

Crystal

The sapphire crystal is slightly domed and stands proud of the bezel, giving the watch that classic, vintage profile. You get a little distortion towards the edges, which I rather like—it adds some character.

I would welcome a stronger anti-reflective coating. Baltic, for example, seems to get a little more clarity from its crystals. This one still looks good, and I haven’t had any trouble reading the dial, but reducing those reflections would make it better.

Dial and Lume

The black dial is very nicely executed. Everything feels well proportioned, the applied indices are cleanly finished, and I particularly like the yellow GMT hand. It adds just enough colour to an otherwise black-and-white dial.

If I were to change anything, I might revisit the date window. Its placement doesn’t look quite as natural to me as the rest of the dial, although the movement and date wheel will limit what San Martin can do there. So it’s a small point.

As for the lume, the indices and hands have plenty of it, and my 15-minute test shows very good performance. It isn’t quite as bright as some of San Martin’s divers, but I have no complaints about the dial. Ok, almost no complaints. And we still talk about now when we examine the bezel.

Bracelet and Clasp

The bracelet is familiar San Martin territory: an Oyster-style, three-link design with solid links, solid end links and screws for sizing. I like how the end links sit slightly recessed between the lugs. It makes the transition into the case look cleaner.

It’s brushed across the top, sides and underside. The finishing is tidy, the gaps are consistent, and the edges are crisp without feeling sharp. It’s a straightforward bracelet, done well.

Then there’s the clasp. San Martin seems to have at least three different on-the-fly adjustment designs, and somehow they’ve made all of them feel robust. Some brands are still trying to get one right! This version has a nicely machined outer shell, a milled inner mechanism and the raised San Martin logo. It feels solid in use, and the adjustment makes it easy to get the fit just right.

Wearability

On the wrist, it’s very comfortable and nicely balanced. The on-the-fly clasp makes it easy to dial in the fit, and I’ve had no complaints wearing it for long stretches.

That comfort, along with how good it looks, probably explains why it’s ended up on my wrist so often over the past couple of weeks.

Verdict

And that brings us to the verdict. And att around $293 before taxes and discounts, I think this is a very competitive package. For perspective, San Martin Submariner homages without a GMT complication or this on-the-fly clasp is only about $80-85 less. And the actual Tudor Black Bay GMT on a steel bracelet now lists for over $5,000. And that puts the price difference into perspective.

But the strongest recommendation I can give you is that I keep wearing it. I went into this review without any particular plan to keep the watch, and two weeks later, it’s still spending an unusual amount of time on my wrist. Maybe I’m still in the honeymoon period, but it looks great, wears comfortably, and the bezel action has been a real surprise.

But that's of course my take! What do you think of this updated GMT? Do let me know in the comments. And if you’ve been watching but haven’t subscribed yet well - well It only takes a second, it’s free, and it really does help the channel.

Thank you for watching. Take care, and I’ll see you in the next one.

Bezel

Now to the bezel, and let’s get my one criticism out of the way: there’s no lume. It’s hardly a deal breaker on a GMT, but it feels like a missed opportunity when even some affordable watches now have lumed bezels.

Everything else is very good. The aluminium insert pairs a slightly radiating red with an unusual blue-grey, almost metallic tone. I think it looks fantastic.

The coin edge is easy to grip, and there’s virtually no back play or side play. It’s a proper bidirectional GMT bezel with 24 clicks, each settling neatly into position. In this price range, it’s the best bezel action I’ve handled on this style of watch.

It feels almost as though a ball-based mechanism controls the clicks—perhaps even ceramic balls—although I haven’t opened it to check. What I can say is that the action is smooth and tactile, and the alignment is spot on. This bezel is one of the things that really stood out to me.

Movement

Before we get into the calibre, a quick word about the NH34. There have been plenty of explanations for the recent supply problems and price rises across Seiko’s NH family. Seiko hasn’t confirmed a cause, so for now, those explanations remain speculation.

What isn’t speculation is the effect on watches like this. Microbrands have already started looking elsewhere, and movement makers including Peacock, Seagull, Hong Kong Precision Technology and Hangzhou are filling the gap. We’ve seen this sort of shift before. When Swatch Group restricted the supply of ETA movements to watchmakers outside the group, competing suppliers had room to grow. The market didn’t stand still then, and it certainly isn’t standing still now.

In this particular case, San Martin has fitted the Hangzhou 6460. And this is far from a brand-new, unproven calibre. San Martin was using it in GMT watches before Seiko introduced the NH34. It’s a caller GMT too, so you can adjust the GMT hand independently, just as you can with the Seiko movement.

On paper, though, the Hangzhou gives us stronger performance figures: 28,800 vibrations per hour against the NH34’s 21,600, 25 jewels, a similar power reserve, and a claimed accuracy of plus or minus 15 seconds a day. The NH34’s published tolerance is minus 20 to plus 40. That’s quite a compelling set of numbers for a watch that hasn’t become more expensive with the movement change.

For the movement nerds among us, the 6460 uses architecture related to the ETA 2836 family, with a GMT function that, as I understand it, Hangzhou developed for this calibre. That architecture also makes for a slimmer movement, giving San Martin room to reduce the height of the watch.

And in use? The hand-winding on this example is smooth. That’s something I notice, because some movements built around this style of architecture can feel rather heavy at the crown.

I do hope NH34 availability settles down. It’s a dependable movement. But if it doesn’t, brands clearly aren’t sitting around waiting for it. They’re already finding alternatives—and some of those alternatives, including this one, make a very strong case for themselves.San Martin lists the 6460’s 28,800 beat rate and its earlier use of the calibre; TMI lists the NH34 at 21,600 with a −20/+40-second static accuracy tolerance. Swatch Group documents the staged reduction in ETA deliveries to third parties.

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