Sinn U50 Hydro

For over 60 years, German watchmaker Sinn has been making watches renowned for their durability, functionality, and technical innovation. Their watches have been used by explorers, pilots, and even astronauts, and they have a reputation for being able to withstand the most demanding conditions. The new Sinn U50 Hydro is no exception.

The U50 Hydro is a professional diving watch that is water-resistant to an incredible 5,000 meters (500 bar). It is made from high-strength, seawater-resistant German submarine steel, and its case is TEGIMENT-hardened, making it exceptionally scratch-resistant. The watch also features HYDRO technology, which fills the case with oil to improve readability underwater and prevent fogging.



The U50 Hydro is available in three variants: Tegiment, non-Tegiment, and SDR (black hard coating). It also comes with a choice of three strap options: bracelet, fabric strap, or rubber strap. So, whether you're a professional diver or just looking for a tough and stylish watch for everyday wear, the U50 Hydro has you covered.

Sinn was founded in 1961 by Lothar Witzig, and the company has been committed to making high-quality, functional watches ever since. In the 1980s, Sinn developed the TESTAF pressure test, which is still used today to test the water resistance of their watches. In the 1990s, they introduced the Ar-Dehumidifying Technology, which prevents watches from fogging up. And in the 2000s, they developed the TEGIMENT Technology, which hardens the surface of their watches to make them more scratch-resistant.

Sinn's commitment to quality and innovation has made them a favorite among watch enthusiasts around the world. Their watches are not only stylish and functional, but they are also built to last.

The U50 Hydro is part of Sinn's U50 collection, which is a series of professional diving watches. The U50 watches are all water-resistant to 500 meters (50 bar) and are made from high-strength, seawater-resistant German submarine steel. They also feature TEGIMENT Technology and are equipped with sapphire crystal glass that is anti-reflective on both sides.



The U50 collection includes a variety of models, including the U50, U50 SDR, and U50 T GSG. The U50 is the basic model, while the U50 SDR has a black hard coating and the U50 T GSG is coated with Tegiment and features a special GSG-9 bezel.

The U50 Hydro is a mid-size diving watch with a 41mm case diameter. It is available in three variants: Tegiment, non-Tegiment, and SDR (black hard coating). The Tegiment and SDR variants have a matte black dial, while the non-Tegiment variant has a white dial. All three variants have indices and hands that are coated with luminescent color for better visibility in low-light conditions.

The U50 Hydro is powered by a Swiss-made Ronda 715 Li quartz movement. The movement is anti-magnetic as per DIN 8309 and is functionally reliable from -20°C to +60°C. The battery has an extremely long service life and the movement has an end-of-life function that prevents the watch from stopping suddenly.

The U50 Hydro is a versatile watch that can be worn for both diving and everyday use. It is tough, stylish, and packed with features that make it a great choice for anyone who needs a reliable and functional timepiece.



One of the most unusual and distinctive features of the U50 Hydro is its HYDRO Technology. Instead of air, the watch is filled with a specialized, transparent oil. This may seem counterintuitive, but it results in a remarkable set of benefits. Primarily, the refractive index of the oil almost perfectly matches that of the sapphire crystal, drastically reducing reflections and creating a sense that there's almost no crystal at all. This translates into superb legibility underwater, regardless of the angle from which you view the watch.

Moreover, HYDRO Technology eliminates the potential for condensation to form inside the watch. Even under extreme and sudden temperature changes, your U50 Hydro remains unfazed. A diver needn't worry about moisture compromising the delicate movement inside – or obscuring a critical reading underwater.

As mentioned in Part One, the use of oil and its density does necessitate the use of a quartz movement for the U50 Hydro. However, this is not a sacrifice; Sinn ensures accuracy with its choice of the Swiss-made Ronda 715 Li quartz movement. It offers long-lasting performance, an integrated temperature sensor for reliable operation within a wide range, and even an end-of-life indicator, warning you well in advance if your battery needs replacement.

If robust materials and engineering are crucial prerequisites for a serious dive watch, the U50 Hydro certainly delivers. The case and crown are crafted from high-strength German Submarine Steel. This isn't just a flashy name – this specialized steel, used in actual submarine construction, offers exceptional resistance to seawater corrosion and extreme pressures. Additionally, it possesses fantastic non-magnetic properties – further ensuring that the watch's timing will remain uninfluenced by its environment.



As we've touched on before, Sinn is a master of materials development, and with the U50 Hydro, you have the option of an even more resilient casing thanks to TEGIMENT Technology. This surface-hardening process results in extraordinary scratch resistance. Whether navigating rugged underwater terrain or bumping into hard-earned dive trophies on your shelf, the U50 Hydro in this configuration can take the hits with little or no visible surface damage.

Let's talk about functionality as you prepare for a descent. The U50 Hydro, like classic dive watches, features a unidirectional rotating bezel. Its ratcheting action lets you mark critical times with accuracy and confidence. Additionally, Sinn takes safety a step further, making the bezel captive. This means the bezel must be actively moved into a position before allowing rotation, minimizing any chance of it turning accidentally – and causing you to miscalculate your available dive time.

In a clever bit of ergonomics, the U50 Hydro's crown sits at the 4 o'clock position. This unconventional placement helps prevent the crown from digging into the back of your hand while diving or engaging in vigorous physical activity. Sinn puts functionality at the forefront with this deliberate design choice.

Finally, you have the decision of a bracelet, fabric, or rubber strap for your U50 Hydro. The bracelet option brings a classic appeal and can also benefit from TEGIMENT hardening if you opt for that variation. Fabric offers lightweight comfort for active use, and rubber remains an enduring favorite for water activities. All straps attach to robust 20mm lugs, making the swapping of styles swift and convenient, should you feel a change is in order.



Regardless of which style suits you, be confident that Sinn has considered how every detail interacts for a smooth and enjoyable overall experience.

The Sinn U50 Hydro, even through an in-depth examination, reveals far more than its spec sheet indicates. It's a culmination of Sinn's years of dedication, its obsession with practical innovation, and an unwavering focus on making watches that will accompany their owners into extraordinary circumstances.