Fortis Marinemaster M-44 DLC: A Darker, Tougher Evolution of the Dive Watch

By Brent Robillard

From sky to sea

Fortis has never been shy about building watches meant to take a beating.

For decades the Grenchen-based brand has leaned into a tool watch identity—first with aviation pieces that found their way into space programs and later with dive watches designed for serious underwater use. The Marinemaster M-44 sits firmly in that latter category: a large, purpose-built dive watch designed for professionals.

Now Fortis has taken that concept one step further with the Marinemaster M-44 DLC, arriving in two new versions—Gravity Black and Black Resin—both finished in a dark, stealthy coating that pushes the ruggedness of the platform even further.

Fortis Marinemaster M-44 DLC in Black Resin

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Key Features of the Fortis Marinemaster M-44 DLCA Marinemaster in Black

The headline change here is the case treatment. For the first time, Fortis has applied its Dianoir® DLC coating to the Marinemaster line.

DLC, or diamond-like carbon, is not exactly new territory in watchmaking. But Fortis is making a point of how hard this particular treatment is. According to the brand, the coating achieves around 4,500 Vickers hardness, which is dramatically harder than untreated stainless steel and designed to resist scratches, corrosion, and general wear.

Fortis Marinemaster M-44 DLC on wrist in Gravity Black — Fortis Marinemaster M-44 DLC in Gravity Black

In practical terms, that means the watch should shrug off the kind of daily abuse that tends to mark up conventional steel cases—door frames, desk edges, and the occasional dive ladder. The dark coating also gives the watch a very different visual character. Where earlier Marinemasters had the bold, instrument-like presence typical of modern dive watches, the DLC models look visually more restrained. The overall vibe is deliberately monochromatic: anthracite-black surfaces, minimal visual noise.

It’s a look that suits the Marinemaster well, I think.

Dial closeup of the Fortis Marinemaster M-44 DLC in Black Resin

Dial close up of the Fortis Marinemaster M-44 DLC in Gravity Black

Built Around the M-44 Platform

Underneath the new coating, the watch remains built on the familiar M-44 architecture. Water resistance sits at 500 metres and Fortis’ Lock System helps ensure that the crown and case remain secure under pressure.

As with most modern Fortis tool watches, legibility is a clear priority. The dial layout is straightforward and uncluttered, allowing the oversized hands and indices to do the heavy lifting. It is the sort of design that makes sense underwater.

Fortis Marinemaster M-44 DLC on a rubber strap — DLC bumps the hardness to 4500 vickers

Kenissi Power Inside

Inside the new Marinemaster beats Fortis Werk 11, a manufacture calibre developed in collaboration with Kenissi, the movement specialist known for supplying robust automatic calibres to a number of respected Swiss brands.

The movement is COSC-certified, features a 70-hour power reserve, and uses a variable-inertia balance for regulating timekeeping. Rather than adjusting the hairspring to regulate the rate, tiny screws on the balance wheel itself are used to fine-tune the oscillation. It is a system that tends to hold its adjustment more consistently over time and is widely used in higher-end mechanical movements.

Fortis has also emphasized structural stability within the movement. An oversized bridge with double fixation helps improve resistance to shocks and vibration.

Case back of the Fortis Marinemaster M-44 DLC denoting 500m of water resistance and the Werk 11 calibre inside — Powered by the Werk 11 and water resistant to 500m

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A Tool Watch That Knows What It Is

There is something refreshing about the Marinemaster line.

Many dive watches today lean heavily on nostalgia or vintage aesthetics. Fortis, by contrast, seems more interested in building watches that feel contemporary, technical, and unapologetically functional.

The new Marinemaster M-44 DLC lives up to that ethos. The darkened case, durable coating, and robust Kenissi-based movement all point in the same direction: a watch designed to perform, but equally reliable as an everyday companion.

The Fortis Marinemaster M-44 DLC Gravity Black and Black Resin models officially launch today and are available from the brand website.

Fortis Marinemaster M-44 DLC on wrist in Black Resin — Fortis Marinemaster M-44 DLC

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About the Author

Brent Robillard is a writer, educator, craftsman, and watch enthusiast. He is the author of four novels. You can follow him on Instagram.

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