Hands-On: Luminox Scott Cassell Deep Dive Automatic 1520 Series


There are dozens of watch brands, at price points across the board, that produce timepieces inspired by or even developed in cooperation with military units, from Panerai’s divers to IWC’s pilots to Jaeger-LeCoultre’s Navy SEALs field watches. There are, on the other hand, just a small handful of brands — most of them on the affordable end of the spectrum — that military professionals and law enforcement officers actually wear on missions. One of the leaders in this category is Luminox, which collaborated with underwater explorer, filmmaker, and seasoned counter-terrorism operative Scott Cassell — you may have seen him in documentaries on the Discovery Channel, Animal Planet, and the BBC, among many others — to produce a special series of professional-grade diving watches in its Deep Dive Automatic collection. I got my hands on one of the latest models in the series and had the chance to speak with Cassell about its origins.

Luminox Scott Cassell Deep Dive Automatic - reclining
The Luminox Scott Cassell Deep Dive Automatic is now available with a blue sunray dial with matching rubber strap and aluminum bezel.
Scott Cassell wearing Luminox
Scott Cassell “fell in love with Luminox watches” on a mission to hunt drug dealers in the jungles of Colombia.

While the watch is ruggedly handsome, especially this new model with the sharp blue-on-blue color scheme, the Luminox Scott Cassell Deep Dive Automatic is not a “desk diver” by any means. It’s 316L stainless steel case, at a substantial 44 mm in diameter and 17 mm thick, is water-resistant to 500 meters, far exceeding the minimum 100 meters required for ISO 6425 certification as an internationally recognized divers’ watch. Aiding in this impressive performance beneath the depths are both a sapphire crystal and a solid caseback that are twice as thick as on standard diving watches, at 3 mm.

In addition to its ratcheting unidirectional dive-scale bezel with blue aluminum insert, which is used to set dive times, the case is equipped with a patented bezel-locking system (BLS) that serves a dual purpose: it locks the bezel safely in place to prevent a potentially life-threatening, inadvertent changing of the preset dive time, and also locks the fluted, screw-down crown into place to ensure the watch’s water resistance.

All of these details and others were developed with the input of Cassell, a longtime wearer of Luminox watches. He recalls his first meetings at the Swiss watch brand’s offices in San Rafael, CA with founder Barry Cohen: “Some guy named Barry called me up and said he was from Luminox and he wanted to build a watch around me,” Cassell relates. “At first, I thought he was a salesman so I hung up on him! But he called me back, assured me he was for real, and I agreed to meet with him. When I went to the offices, I literally brought all the different types of wetsuit gloves I wear on missions and I said that if I can’t operate the watch with these gloves on I can’t use it. Also, for the dial size, I didn’t want a really giant watch because it would compete for space with the other gauges I wear on my wrist, like a dive computer, compass, meteorological meter, whatever. We worked with my average visual acuity, I put my mask on to read the finished dial, and we had the perfect size that it needed to be.”

Luminox Scott Cassell Deep Dive- Crown
The screw-down crown has an engraved Luminox logo.
Luminox Scott Cassell Deep Dive- Dial - Date
The day and date are on display in a double window at 3 o’clock
Luminox Scott Cassell Deep Dive- Dial - logo
A double LLT tube at the 12 o’clock marker provides orientation in the dark.

Another practical feature the Deep Dive Automatic offers to professional divers is its built-in helium release valve, which can be used in pressurized environments deep underwater, such as diving bells. Divers in these environments breathe a helium-rich air mixture, with the tiny helium molecules inevitably seeping into the watch over time. If too many of these molecules build up inside, i.e., if decompression stops while ascending after a long immersion are too short, the pressure could damage the watch, potentially shattering its crystal. The valve on the Luminox (labeled with the chemical label for helium gas, “He”) is designed to automatically release these built-up molecules.

Luminox Scott Cassell Deep Dive- helium release valve
The built-in automatic helium release valve is useful in saturation diving.
Luminox Scott Cassell Deep Dive- Crown Lock
A patented locking mechanism secures the screw-down crown as well as the unidirectional rotating bezel.

The Luminox brand, of course, derives its name from its watches’ most noteworthy feature, their dials’ constant visibility under any and all lighting conditions owing to the use of Luminox Light Technology (LLT), which uses tiny tubes filled with tritium gas that glow brightly for up to 25 years. The advantage here is that unlike Super-LumiNova — the luminous paint used on most other watches, which requires an external light source to activate its glow — tritium itself is radioluminescent, meaning when the lights go out, the luminous parts of the dial will glow brightly even if the dial has not soaked up ambient light beforehand. On the Scott Cassell Deep Dive Automatic, the LLT tubes that appear on the prominent minute hand (the most important hand one uses during diving) and the 12 o’clock index glow a bright orange in the dark, while those used on indexes emit a shimmering ice blue — the last color, according to Luminox, that a person’s eyes register as he or she descends into the darkening underwater depths. The color contrast between the minute hand and the hour markers, of course, aids in legibility.

But let’s let Scott Cassell tell you in his own words: “The first time I wore a Luminox watch,” he said, “I was working in Colombia with an intelligence operation against the drug cartels with the military. We were issued all of our equipment and part of our issue would always be a watch that we would use for the mission and then give back. We’re talking rations, survivor equipment, your weapons, your rounds — everything is all issued to you and then you give it back for maintenance in between missions. When I saw the Luminox, I thought, well, that looks nice, but I was focused on a very serious mission and didn’t need to be enamored with a watch. At 2 o’clock in the morning that night, I was laying in the forest, dressed up like a bush with my sniper rifle, watching my targets crossing a bridge, I remember looking down thinking that my watch was so bright that they might be able to see it. So I rolled the watch to the soft part of my wrist, inverted it, and as I was looking down at the forest floor I could see leeches crawling around, illuminated by the light from the watch because it was so bright. I thought that was amazing. When you’re on a mission like that, after a certain time most watches will no longer glow and the only way you can read the time is by watching the stars or by illuminating that watch with a flashlight, and when you’re a sniper that will get you killed; you can’t do anything that draws attention to yourself. The Luminox fascinated me because it stayed perfectly visible all night, it never faded out. So I fell in love with Luminox watches and later learned that one of the first things that brand ever did was to make its watches available for special operations groups including the Navy SEALs. Everybody I know in that world who’s used them has loved them.”

Luminox Scott Cassell Deep Dive- Dial - Hand
Two tritium-filled micro gas tubes help the tip of the minute hand to stand out.
Luminox Scott Cassell Deep Dive- Dial - Lume
Contrasting luminous colors on the hands and indices make for an easy read of the time in the dark.

“Automatic” in the model’s name does not refer to the helium-release valve but to the watch’s movement. While many of Luminox’s watch models are outfitted with quartz movements, this one is powered by a Swiss-made, self-winding mechanical movement. (Luminox doesn’t disclose the movement’s origin, but does tout that the watch itself meets the criteria — much stricter since a 2017 revision of the law — of “Swiss Made.” The movement, which drives the central hours and minutes display, along with a central seconds hand and a day-date function in a double window at 3 o’clock, is covered by a solid steel caseback engraved with Scott Cassell’s “Great White” submarine and the names of the two non-profits that he supports. The day-date display, incidentally, can be set via the crown’s second position in either English or German, the latter being the mother tongue of the Swiss city of Pfäffikon, where Luminox is headquartered.

So why did Cassell, who worked with Luminox to create a timepiece perfectly suitable for mission usage, opt for a mechanical automatic movement in the Deep Dive rather than a quartz movement, which is more precise and regarded as more of a workhorse? “Automatic perpetual watches are so much smarter than battery-powered watches,” he explains. “Like every piece of equipment, before you go on a mission you need to double check everything on a watch. How old is that battery? Is it going to absolutely be working when I’m done with my mission?  Is it going to endure the whole time or is it going to die halfway through? You can verify the age of the battery through the quartermaster who issued you the watch, and if it’s a week old or more, I’m not going to take it into the field. With automatic watches, you don’t have to worry about that, and that’s incredibly important. Some of my expeditions are a month long or longer; I don’t need a watch to die halfway through a mission and that has happened to me. Bringing an extra watch battery, bringing the device so that you can remove the caseback to change it — that’s just more tools and more stuff you’ve got to carry with you. I’ve had two watches with batteries die on me at the most inopportune times, and when that happens, what can I do? I can’t go buy one at Target; I’m in freakin’ Africa!”

Luminox Scott Cassell Deep Dive- Bezel Lock
Luminox has received a patent for its BLS Bezel Lock System.
Luminox Scott Cassell Deep Dive- Back
The caseback features a relief engraving of Cassell’s submarine and the names of his charities.

The Luminox Scott Cassell Deep Dive Automatic Ref. 1523 that I review here (there is also a new version in black-PVD-treated stainless steel, Ref. 1521) is offered with a removable blue rubber strap with a special sweat-resistant backing and a brushed stainless steel buckle and comes in a specially designed water-resistant gift box in which owners who use this watch to dive can also stash their mobile phones, cameras, and other personal gear. And at $1,900, for a Swiss-made automatic timepiece with a professional-grade depth resistance and proprietary technology, most would find it fairly priced indeed. The good news for those, like Cassell, who care about the environmental health of our world’s oceans, is that a portion of the proceeds from sales of the Scott Cassell Deep Dive go to support two of its namesake’s non-profit organizations: Sea Wolves Unlimited, an organization dedicated to protecting endangered undersea species, and Undersea Voyagers project (UVP), dedicated to the overall health of the ocean. “I really appreciate this partnership,” says Cassell of his collaboration with Luminox. “This watch has funded exploration and conservation of the ocean more than any watch I’m aware of, and I think it’s the most ocean-friendly watch in the world, and I’m absolutely proud to be a part of that.”

2 Responses to “Hands-On: Luminox Scott Cassell Deep Dive Automatic 1520 Series”

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  1. Randy Rogers

    Very nice mention by Cassell of Barry Cohen, without he and his creativity there would be no Luminox Brand.

    Reply
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