Because I love gin, I want to give it a perfect score...but!! A thorough discussion of "613 St"!

The 613 St, released by Sinn in April 2025, is a full-scale diver's watch with 500m water resistance, following in the footsteps of the EZM, but with a design that's more user-friendly for everyone. The editorial team at Chronos Japan, a watch magazine, wore this model for several days and thoroughly discussed its feel and performance. The team consisted of Editor-in-Chief Masamasa Hirota, Deputy Editor-in-Chief Yukiya Suzuki, editorial staff members Taketo Hosoda and Yosuke Ohashi, and transcriptionist Chieko Tsuruoka.

A new Sinn watch that follows the "EZM" trend but is more appealing to everyone

Hosoda"The watch he wore for the debate was the Sinn 613 St. In April of this year, Chronos Japan covered Watches & Wonders Geneva 2025, where Sinn exhibited at TIME TO WATCHES, which was being held at the same time at Villa Sarasin, next to the Palexpo. This model was on display at the venue. Yukiya and I spotted it and thought, 'This is great!' so we borrowed it for the debate. As you can see, it looks just like the EZM."

Hirota"The 613 St is a diver's chronograph in the Sinn EZM series (note: Sinn's flagship series, named after the German phrase Einsatzzeitmesser, which means a measuring instrument for missions). If I may say so, it is a model in which the crown of the Mission Timer EZM13.1 has been swapped to the right. Although it is water resistant to 500m, the case is relatively small, with a diameter of 41mm and a thickness of 15mm."

Hosoda"It's not EZM, but as Hirota said, it's following the trend and incorporating 'gin technology'."

(I.e."When you say it contains basic GINN technology, do you mean dry technology? It has the Ar mark on it. Is that argon?"

Hosoda"That's right, the 'Ar' mark at the 4 o'clock position on the dial, in other words, 'Ar Dry Technology'. By the way, it seems that the gas currently used is not argon gas. It is simply said to be a type of rare gas."

(I.e."Dry technology is the blue capsule that absorbs the water vapor inside the case, right? And is there a noble gas filled in addition to that?"

Hosoda"The combination of a dry capsule and rare gases creates Ar dry technology. The case is filled with rare gas, which prevents changes to the metal and also absorbs any moisture that gets in. Incidentally, the gasket used is an EDR gasket, which is moisture-resistant. Furthermore, the bezel is a special bonded type."

(I.e."It's the one with a removable bezel. If you look at the side of the case, you'll see that it's screwed in."

Hirota"In addition, this model, like the EZM13.1, uses the D3 system, a waterproofing system developed by SUG, around the crown."

big bridge"Oh, the double-packed one."

Tsuruoka"What is SUG?"

Hirota"SUG is a case manufacturer based in Glashütte, Germany. They are called Sachsen Uhrentechnik GmbH Glashütte and were acquired by Sinn in 1999. Since SUG began manufacturing Sinn cases, the quality of Sinn's cases has improved significantly. The D3 system reduces the number of parts by making the crown and pushers tubeless, and then attaches double gaskets to improve airtightness. Going tubeless is a bold design, but it certainly works to improve water resistance. This design theoretically makes it possible to use a chronograph underwater. This is a major advantage for Sinn, alongside Damascus, and is what makes the 613 St a "usable diver's chronograph."

Hosoda"As Hirota explained earlier, it's a 500m water resistant diver's watch, just like the EZM3 I own, and the design is similar. I forgot to bring it with me today, though."

(I.e."What's the difference between the EZM3 that Hosoyan has and the model in this debate?"

Hosoda"The difference is whether it has a chronograph or not. To go into more detail, the EZM3 has a 40mm case diameter, while this one is a size larger at 41mm. Oh, and there's also the difference in the calendar display. The calendar display on the EZM3 is red. Red is the first color to disappear in wavelengths underwater. This is because the aim is to minimize information as much as possible while diving. In contrast, the 613 St is white."

Tsuruoka"Huh? Well, then why did they make this model white? It's waterproof to 500m..."

Hosoda"I guess it's not that much of a tool watch. For everyday use, the white version is clearly easier to read. At first glance it looks the same as the EZM, but it's in these small details that the watch has a different character."

(I.e."The tips of the chronograph second hand and 60-minute counter hand on the 613 St are red. If you were to dive as a diver, these would disappear, so I guess that means you wouldn't use the chronograph."

Tsuruoka"But the fact that you can use the chronograph underwater is also a selling point, right?"

Hosoda"Not just this watch, but any D3 system chronograph can be used underwater."

(I.e."Well, even if you could use a chronograph, it would only have a 60-minute counter, so the bezel would be enough."

Hosoda"That's true, and I don't think a totalizer this big would be useful for actual diving."

(I.e."It may be a selling point, but honestly, I don't want to touch the pusher in the water. I'm sure the gasket is solid though."

Movement and its usability

(I.e."The movement is Sellita Cal. SW515, right?"

Hosoda"That's right. Some Sinn brands use the concept, but this model is exclusive to Serita."

(I.e."In essence, it's a replacement for the ETA7750. If it were, it would have a layout with a small seconds at 9 o'clock, a 30-minute counter at 12 o'clock, and a 12-hour counter at 6 o'clock, but they've deliberately changed it to just have a single 60-minute counter at 6 o'clock."

Hirota"That's what impressed me about this watch. They've probably added an intermediate car to the Cal. SW515 counter to divide it into 60 segments, but I've rarely seen similar improvements from other companies. I wonder how they managed to modify the 7750 series, which has no space around the counter? Also, the counter hand movement, which was jumping in the EZM13.1, has been changed to a constant movement that changes gradually in this model. I wonder if they decided that precise measurement isn't necessary as in the EZM. On the other hand, the addition of a day-date function solidifies its practicality. However, it's not specifically designed for daily use, and the small seconds display has been made gray to improve visibility, which is a distinctive Sinn touch."

(I.e."I didn't use the chronograph much this time, but even though it's not a 7750, there's a certain amount of weight when you press the pusher."

Hosoda"That's right. Because it has double packing, it's probably inevitable that the push-button feel will be a bit stiff. It seemed like the other members weren't using chronographs much either, and I should have brought it with me on the dive, but since it was a borrowed one, I refrained."

(I.e."Well, since it's a diver's watch, I guess it's assumed that the chronograph won't be used. There's something else that bothers me more than the feel of the buttons... but maybe everyone else is thinking the same thing."

Is it something that needs improvement, or is it the character of a modern diver?

Hosoda"What kind of place is that?"

(I.e."The design of this model is really cool, and I particularly like the 60-minute counter at 6 o'clock, but when the hour or minute hand overlaps the inset dial, it becomes difficult to tell the time. The white overlaps the white, making it hard to see. The 60-minute counter is big, isn't it? So the hand just disappears. It was extremely stressful. That's all I want to say (laughs)."

Hosoda"It's surprising how many times we've made a design that has high contrast and looks like it would be highly visible, but it turns out that this is a fatal flaw."

(I.e."They went a little overboard with the design. It doesn't feel like gin."

Hosoda"It seems that the EZM is similar but not the same. The EZM is designed to be used by special forces, and is designed to eliminate human error as much as possible. If it had been an EZM, this would not have happened."

big bridge"In the Watch Time article in issue 122 of the Japanese edition of Chronos, we featured 613 St UTC, which adds a second time zone to 613 St, and Rüdiger Bucher said exactly the same thing."

Hosoda"It's the first thing that comes to mind when someone actually wears it."

(I.e."I understand that design is a priority, and the contrast between black and white and the use of white are well done, but it's a shame that you can't read the time."

Hirota"That's certainly unfortunate. I think they wanted to clearly differentiate it from the EZM. I've gotten used to it over time, but I think the visibility would have been improved if the color of the meter had been cream or gray, for example."

Hosoda"On the EZM13.1, the 60-minute counter is black, right?"

(I.e."I think the white of the 60-minute counter on the 613 St is the key to the design. The addition of red accents makes it a good design, but as Hirota said, I feel like there could have been some ingenuity, like changing the tone."

big bridge"It might be a good idea to add a black border around the hands that have luminous paint on them."

Hirota"I love Sinn, so I would unconditionally give this model a perfect score. However, it's a shame that the register at 6 o'clock means the hands are buried in the water. You'll get used to it with use, but because Sinn has always placed a high priority on visibility, I hope they will modify the register in the future."

Watch enthusiasts are sure to find Sinn's presence a delight.

Hosoda"What do you think when you actually wear it?"

big bridge"It was a heavy watch that had a strong presence. But it felt comfortable on the wrist. It's a watch that I want to wear regularly."

Hosoda"The bracelets for this type of model aren't particularly well made. However, Sinn's bracelets have recently been gradually changing from pin-type to hexagonal joints, which means the links are thicker than with pin-type bracelets. This results in a better balance with the headstock, making them more comfortable to wear."

Tsuruoka"Even for me as a woman, it was certainly heavy when I adjusted it to fit my wrist perfectly, but it wasn't uncomfortable to wear."

Hosoda"Another improvement from the EZM3 I use is that the buckle has changed from a double-folding type to a push-button type, making it easier to put on and take off. Although the risk of it coming off has increased."

Tsuruoka"The buckle also has a function to fine-tune the size."

Hosoda"It's only a little bit. I said earlier that I didn't take it diving because it was borrowed, but that's actually one of the reasons. Previously, it had an extension type that could be worn over a diving suit, but in terms of the rate of extension, it was only enough to accommodate swelling in the arms, and it wasn't long enough to accommodate wearing a dry suit."

(I.e."For a land diver, it's more than enough. 500m water resistance gives you peace of mind not only when diving, but also when exposed to water under dynamic pressure."

big bridge"For actual diving, a silicone strap would be better."

Hosoda"By the way, Sinn's watches don't comply with ISO 6425, but they are certified by the German standards DIN and DNV, so they are definitely divers' watches. If that's the case, there may be room for improvement in the bracelet specifications. However, according to the ISO standard, there must be luminous paint for each hour, and this has been properly addressed."

(I.e."The luminous paint is quite bright, and if it's that bright, it's easy to see in the dark, no matter where you are. It's really practical in that regard."

Hirota"To add a bit about the comfort, the balance between the head and tail is good. Despite the large, heavy movement, the raised case back, and the soft-iron anti-magnetic case, it fits comfortably on the wrist, probably because the thick bracelet distributes the weight. It's not 'superb,' but it's comfortable enough."

(I.e."It's certainly stainless steel, and you can feel the weight, but it's not uncomfortable to wear. I personally think this weight is a comfortable sensation. The first mechanical watch I bought was the Sinn 203, equipped with the ETA7750. It was stainless steel, and when I put it on my wrist it really felt present. It was heavy, but that's what gave me the joy and sense of ownership of my first mechanical watch. Once you get used to a watch, it feels lonelier when you take it off. Sinn has always had a stable center of gravity, so I think its weight is a good thing. I felt that this is the kind of goodness that hasn't changed since the old days."

big bridge"By the way, what did you all think of the shape of the lugs? They're quite small, but the sharp facets give the whole piece a luxurious feel, which I personally like."

Hosoda"I've gotten used to seeing it myself, but that's certainly true. Also, although it's become more fashionable, it still has that instrumental feel to it. What do you think about that as a woman?"

Tsuruoka"Stylish... I think it's full of tool-like feel. I think Hirota-san would like it (laughs)."

(I.e."It's stylish, sophisticated, and a design that gin lovers will love."

Hosoda"The bezel is still made of aluminum."

(I.e."While other companies are increasingly using ceramic outer bezels, the nostalgic feel of aluminum is nice. Like the bezel, the stainless steel exterior is very Sinn-like and I like it."

Hosoda"The good thing about this finish is that scratches don't show up."

(I.e."Polished stainless steel is cool in its own way, but scratches are always noticeable. That's where I feel they're going all out with tool watches."

Hirota"It doesn't have the obvious luxury feel of having different satin and polished finishes, but it has the high quality that is characteristic of SUG today."

Hosoda"Wearing this model for the debate this time made me realize once again how important it is for a watch to have a strong presence. I realized that being thin or light is not always the best, and that's what makes watches so interesting."

An easy-to-access geek watch

TsuruokaFinally, could you discuss which demographic this model will reach and how it will be positioned within the Sinn collection?

Hosoda"Although Sinn watches have become more expensive, this model is still in the 60 yen range, so it's a good entry point to mechanical watches. I also think it will serve as an entry-level model for watch enthusiasts."

(I.e."Rather than being a watch lover, I feel like I'm more of a 'watch geek'. The other day, there was an event at Sinn DEPOT in Shibuya, and I showed up with Hirota-san, and the faces of the customers there looked the same as they did over 20 years ago (laughs)."

Tsuruoka"That's wonderful. Your target has remained consistent for 20 years."

Hosoda"The people selling it haven't changed much either (laughs)."

(I.e."It's a brand that is supported by the same people, both from the retailer side and the consumer side, in a good way. Even though we can generally say watch lovers, many of Sinn's customers are people who value watches as a tool, rather than those who are into casual or fashionable styles. It's also good that it's a German brand."

Hosoda"Among the Sinn models, the 613 St may be a model with a lower barrier to entry than the EZM and others. Its right-hand crown and other features make it easy for the average user to get into."

(I.e."It really feels like a consumer product."

Hosoda"They were trying to make the popular otaku model a little more approachable. This is the result of that effort."

(I.e."It could be an entry-level model, both among mechanical watches and among Sinn watches. You can start from here and then delve deeper into the core of the brand. The sellers at Sinn Depot are knowledgeable, so they'll answer any questions you have. Also, in a good way, the fact that they're still using the ETA7750 and its replacements makes it the perfect entry-level model. My first Sinn model was also equipped with an ETA7750, so maybe I have a strange attachment to it (laughs). I often think I'm winding the mainspring, only to find that the rotor is just spinning (laughs). It's fun, and gives me a sense of security. I've said a lot, but in the end, it's all about loving Sinn."

Hosoda"When I joined Chronos, the watch I bought with my first bonus was a Sinn."

Tsuruoka"All watch enthusiasts start off with Sinn!"