The U-Boat Capsoil series was officially released in November 2018. They just released the second iteration of the concept, called Darkmoon. This new line takes a more minimalist approach with a lower entry price, but looking at it, we can’t help but think of other oily timepieces—because in the watch industry, there’s nothing new under the sun or under the moon. (Watch brands love the moon, especially the dark side for some reason).
“CAPSOIL goes beyond the boundaries of traditional design, combining innovative features with vintage-inspired lines. The oily liquid flows into the dial, rendering it an absolute deep black, amazingly magnifying the view of the hands, as if without glass Seems to flow freely.” -U-boat
While both are futuristic and cool oil-filled watches, they cannot be compared from an engineering and design standpoint. The biggest difference between the Capsoil and the Type 3 (and Type 5) is that the Ressence is a mechanical watch, while the Darkmoon is powered by a $16.95 Swiss quartz movement.
Visible through the exhibition-style caseback. Although, the U-Boat seems to have listened to criticism that it’s a quartz cheap watch, and the newer models have a solid caseback that doesn’t have a running seconds hand (making it less obvious that it’s a quartz watch).
The movement is a 2-hand Ronda 712 movement with a battery life of about 60 months. Capsoil/Darkmoon models have red text on the dial that reads: WORKS BETWEEN 0/+60 C. Interestingly, the Ronda tech sheet lists the 712 as operating at 0-50 C.
A quartz movement makes sense because a mechanical watch won’t work when fully submerged in oil. Ressence overcomes this obstacle by inventing the dual-chamber case, injecting oil into the upper half and air at the bottom.
Innovation doesn’t stop there. When it launched, the Ressence Type 3’s claim to fame was that it was a crownless watch that was wound and set by rotating half of the case’s bottom (inflated) half. The U-Boat Capsoil isn’t crownless, but they did make it a destructive piece by moving the slender crown to the left side of the case.
Another difference is that the fake U-Boat has a bubble.
We know by performing a DIY oil filled model that results can be achieved without air bubbles, but this requires extra time and precision. U-Boat said they deliberately left a bubble under the crystal so the oil could be seen floating around. Maybe production scalability was part of their decision to get out of the bubble, or maybe it was because the bubble proved that there was indeed oil in it.
The bubbles work well with the borderless curved crystal (another element that feels similar to Ressence), but it’s a bit like Panerai’s upside-down Cyclops floating beneath the crystal. Some people will absolutely love it, while others will be annoyed by having a spirit level strapped to their wrist.
The original Capsoil piece has a door at 3:00 that says Unscrew to Fill Up. It remains to be seen whether the foam will get bigger or smaller over time, and how “fill” will affect it. What we do know is that your local watchmaker most likely won’t want to touch it when you send it in for a new battery, so be prepared to hear it has to be returned to the U-Boat for service.
Either way, we love how U-Boat has incorporated foam into the marketing identity for its Capsoil and Darkmoon product lines.
The oil-filled collection is available as a 44mm 2-hand model or a 45mm chronograph. None of the models have dates. They ship on a 22mm lug width vulcanized rubber strap with U-BOAT CAPSOIL text. The hands and markers of the black dial feature the “Old Radium” Super-LumiNova lume.
The case can be steel or black DLC. But this is for the steel DARKMOON model (ref: 8463) with mineral crystals and 50m water resistance.
Overall, the Darkmoon looks like an interesting watch.