Sinn 103 St Acrylic

I finally got a Sinn.

I've been yearning for one of these ever since I attended a WatchBuys Road Show. WatchBuys.com specializes in German watches, and every year, they cart a roomful of watches from city to city, enticing watch nerds with their wares. I was smitten by Sinn, and while there are plenty of crave-worthy watches in their collection, the 103 St Acrylic was my favorite. Its $1740 price tag put it beyond my usual impulse-buy territory, so I dithered about it for a year or so, but ultimately, I could not resist the allure of this 1960's style, poor man's Breguet XX. So, now that it has joined the collection and has seen some healthy wrist time, I can tell you if it lived up to my expectations.
Sinn 103 St acrylic

Sinn calls its 103 series "the traditional pilot's chronograph" and offers several variants and limited editions. Mine might be considered the value leader of the group: polished case, acrylic crystal, and leather strap. Unlike many aviation-inspired watches, it takes this function seriously, meeting or exceeding DIN standards for anti-magnetic shielding (4,800 A/m), water resistance (rated for 200m), and shock resistance (essentially, the equivalent of a drop to the floor). Far less common is its low-pressure resistant design that ensures the crystal won't pop out at high altitude.

Sinn 103 St acrylic wrist shot

The case is just 40mm wide and 47mm long, which is a huge advantage for a slightly-built fellow like me. It has small The lugs are broad and angular, dropping sharply away from the barrel to create a more natural fit over the wrist than its otherwise flat profile might suggest. It is 15.5mm thick from case back to the top of the dome, although it appears to be slimmer. About 3mm of that figure is just the crystal. Viewed in profile, a matte black coating masks the bezel, so your eye first registers the narrow, polished case sides that bridge the lugs. Below that is a shallow brushed concave lip. Finally, the case back falls away at a shallow angle so that the flat area is only about the size of a penny. With slab sides and a flat back, the 103 would look like stout, but the 103's sculpted case and varying finishes are trim and tailored. There is much an aspiring watch designer could learn from this case.

Sinn 103 St acrylic side view

Inside, is a Valjoux 7750, a venerable Swiss cam-and-lever movement. I previously sampled this 25 jewel, automatic chronograph in the Huguenin Observer, and here I noticed the same smooth 28.8k bph sweep, firm engagement of its buttons, and crisp snap-back on reset. The 7750 features day and date wheels, and small seconds, 30 minute, and 12 hour registers. The large signed crown has an uncommonly extension and snaps into its positions with a firm pull so there is no hunting for the first or second position. Like the other functions, the date wheels set with a decidedly mechanical click.

Sinn 103 St acrylic

I love the tall acrylic dome. Some would ask why. After all, people gladly pay a premium for sapphire Sinn makes a 103 St Sapphire, and it is not as if there is any shortage of sapphire crystal watches at or even well below the 103's price point. If given the option, why choose plastic? Well, for starters, it looks cool. I dig the warm, heavy look and crazy edge distortion. Nostalgia plays a role too. Plastic domes were the norm 50 years ago so they look right at home on a mid-century design. Also, while sapphire is impossible to beat for scratch resistance, and acrylic is soft enough to scratch just by looking at it funny, it wins on impact resistance, taking hits that would shatter sapphire. Finally, acrylic is cheaper, never a bad thing in the Time Bum's eyes.

Sinn 103 St acrylic scratched crystal

I put my convictions to the test by damaging my watch in the first three days. For the life of me, I have no idea how or where I did it, but I looked down and saw a row of ugly scratches down the right side. When I had a moment, I pulled out some plastic restorer and a soft cotton cloth. I know most folks swear by Polywatch, but I have been using a 3-part system by Novus. First, I rubbed out the deep stuff with Heavy Scratch Remover, then applied Light Scratch Remover to polish, and finished it off with their Plastic Cleaner to remove any residue. Was it good as new? No. If you look very closely or employ a loupe you can see the deepest of the lot is still lurking just above the date window. Acrylic will inevitably pick up nicks and scratches over the years. You polish out most of them, minimize the worst, and chalk up the rest to character. I'm good with that.

Sinn 103 St acrylic

As mentioned above, the bezel is flat black all around. Shallow grooves above the markers provide adequate grip. The markers are printed except for a lumed triangle. A close look reveals a half-height index and fine-lined numbers that alternate size (larger tens, smaller fives). The bezel is bi-directional and has no detents. This is standard for pilot's watches but I was surprised at how little resistance there was. That said, not once has the bezel slipped out of position, so I'd chalk this up as more of a feature than a flaw.

Sinn 103 St acrylic

The dial is packed with information but still clearly legible. Due to its modest size, the sub dials occupy a good deal of real estate, reaching nearly to the center. Along with the day/date windows, they displace the numerals in their quadrants but don't truncate any. Dial text is limited to the Sinn name at 3 o'clock and "Autotmatik" in stylized script, wrapped over the hour register. No space is wasted; everything fits. A spear-tipped sweep hand and syringe hands finish the face with the proper vintage military flourish. Lume glow is excellent. The hands, markers, bezel triangle, and second hand tip all go green in the dark, offering easy readability even with just a modest charge from indoor lighting.

Sinn 103 St acrylic lume

Sinn bracelets are top quality, but for a classic pilot, I wanted black leather and contrasting white stitching. I got exactly that on the 103, but the stock strap was just a tad long for me. Most standard straps are 70/115mm or something close to it. This one is 90/115mm. Folks with bigger wrists will appreciate it; however, I ended up with an awkwardly long tail, so I swapped it out for Hirsch buffalo leather that fits the same 20mm lugs and accepts the same signed, 18mm pin buckle.

Sinn 103 St acrylic

The 103 is more expensive than most of the watches I typically review, but at $1740, it is still attainable and represents good value for the money. I've worn the Sinn 103 quite often over these past few months. I have not tested its undersea or high altitude capabilities, and although it is highly unlikely that I ever will, it is good to know that it can hack more than I will ever throw at it. On a more practical, day-to-day basis, I find that its modest size, sober presentation, and the touch of flash from its polished surfaces make it an easy choice for the office or nights out, while its general tool watch toughness and military bearing are perfectly appropriate for the weekends as well. Better still, being the Bum that I am, I still found a way to snag a bargain. Every year, WatchBuys sells its display pieces and other open-box watches at a handsome discount, so I was able to get this one for $1400. All this and a discount too? That makes The Bum a very happy man.

For more information, see WatchBuys.com. ⬩

Sinn 103 St acrylic

Sinn 103 St acrylic caseback

Sinn 103 St acrylic crown extended

Sinn 103 St acrylic strap buckle


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