Seven Dive Watch Myths Debunked
Originally published by Jason Heaton on Hodinkee.
There may be no more misunderstood type of timepiece than the dive watch, which is strange because it is arguably also the most popular kind. Dive watches are loved for their ruggedness, their sporty good looks, and their perceived ability to make almost anyone wearing one a little more like Dirk Pitt or James Bond. Much of this perception comes from the images and hyperbolic copy we see in watch company marketing, that depicts a stubbled, black-clad diver emerging from the sea wearing his 2,000-meter oversized watch. But the realities of dive watches are often much different from those many of us have come to believe. And the less dives watches are used for their original purpose, the more pervasive the myths become. Here are some of the most common dive watch misperceptions and the reality hiding behind them.
MYTH: The rotating bezel helps you keep track of how much oxygen you have left.
There are a few things wrong with this statement, which I’ve taken verbatim from a recent dive watch press release, and you don’t have to be a diver to know that. First of all, the timing bezel, while versatile, is fairly dumb. It does one simple thing—track the passage of time, up to an hour. You could stare at your bezel for an entire dive and still accidentally suck your tank dry if you don’t also check your submersible pressure gauge regularly. Now, you could approximate how much air you’ve got left if you know your air consumption rate; i.e., how much you breathe in a given amount of time, but that’s more useful for creating a dive plan than it is reason to ignore your pressure gauge.
The other thing wrong in this statement is the use of the word, “oxygen” which I see misused far too often with reference to diving in general. Most recreational divers breathe compressed air—21% oxygen, 79% nitrogen and trace amounts of other gases—but to breathe pure oxygen below 20 feet of water depth is toxic and can cause convulsions, and usually an unpleasant death by drowning.
A dive bezel can be used for a lot of things—timing total dive time, decompression stops, swim distances and surface intervals. But until watchmakers figure out how to sandwich a pressure gauge inside a watch case, your dive watch is never going to tell you how much oxygen—or air—you have left.
MYTH: An orange (or bright) dial enhances underwater visibility.
Bright dial colors have become a bit of a calling card for dive watches and we can trace that lasting trend back to 1967 and one brand—Doxa. As legend has it, Urs Eschle, the designer of the now-famous Doxa SUB 300, decided to test a variety of dial colors in murky Lake Neuchâtel and found that orange was best for underwater visibility. But while orange made the Doxa an icon and found its way onto countless other watch dials from Breitling to Seiko, it isn’t the best.
Water absorbs the colors of the light spectrum one at a time as a diver descends. Reds tend to disappear first at a mere 15 feet, followed by orange, and so on.These colors simply turn to a dull grey, unless they are fluorescent, in which case they all glow to great depths. It turns out that the colors that stay visible the longest underwater are yellow and blue, but this is all a moot point because the legibility of a dive watch really has nothing to do with the dial color, but rather the amount of contrast between hands and the dial. And for that, nothing really is better than a black dial with big fat white hands, specifically the minute hand.
MYTH: A vented strap helps your wrist breathe.
This isn’t so much a myth as it is a specific design feature whose use is unappreciated (or misunderstood) by those who don’t experience it firsthand. That rippled rubber strap found on Citizens, Seikos, Panerais and IWCs is one of the most ingenious innovations in dive watch history and it doesn’t even have to do with the watch itself.
Water pressure exerts a force equivalent to the entire weight of the atmosphere above us for every 10 meters a diver descends. This has the effect of squeezing anything compressible in its way, from eardrums to soda cans. Thus, a neoprene wetsuit sleeve slowly gets compressed against a diver’s arm as he goes deeper. A conventional watch strap, such as a NATO or flat rubber, will simply then get looser and looser, causing the watch head to flop on the wrist. In 1975, Seiko was the first to introduce the accordion “vented” rubber strap on its groundbreaking 600-meter Professional dive watch, which introduced a slew of other innovations like L-shaped shaped gaskets and a protective bezel shroud.
To counteract the effects of water pressure, a diver needs to “over-tighten” the vented strap, essentially pulling the ripples out flat, before entering the water. As the wetsuit compresses and the wrist circumference shrinks, those ripples slowly take up the slack and the watch stays tight. It’s a delightfully simple solution and a design feature of a dive watch as recognizable as a rotating bezel. But it is essentially useless on dry land and if you want your wrist to breathe, it’s better to just get a strap that has holes in it.
MYTH: A helium release valve will let you dive deeper.
I’ve made my feelings clear before about helium release valves, but I’m setting personal opinion aside here to address the oft-cited, and erroneous notion that these valves somehow allows a watch, and its owner, to venture deeper into the sea. While it may be true that the tiny percentage of commercial or military divers who do make use of a watch’s “burp valve” often go deeper than the rest of us, that’s more a function of their work environment than it is their watch’s prowess.
Helium release valves merely relieve an overpressure of helium inside a watch case that is most often experienced while working out of a pressurized habitat. You can read Jack’s excellent synopsis of saturation diving for more detail. The reality is, many commercial saturation divers leave their watches behind inside the habitat when they exit to work, since it is of little use on a long shift and potentially a liability. So while the watch is exposed to high pressure, it often isn’t even water pressure, so the meters of water resistance don’t matter a whole lot. And the helium that gets into the watch doesn’t come from the water, but from the gas inside the habitat. Regardless, most commercial divers don’t work at depths much deeper than 200 meters and often much less.
Dive watch fans tend to appreciate over-engineering, and while the backstory of the helium release valve and its early development is fascinating, it won’t help you dive any deeper.
MYTH: 100 meters of water resistance is not enough for diving.
Overkill is a good thing when it comes to gear that gets used in harsh environments, but let’s consider the numbers. PADI, the largest professional dive instructor organization, states that 60 feet, or about 20 meters, is the depth to which basic Open Water certification cardholders should dive. Get your Advanced Open Water certification and PADI divemasters will take you to 130 feet, or 40 meters. A 100-meter watch is more than double that depth, and so will be just fine. It also will likely be slimmer, lighter, and less expensive than one rated to the absurd depths we see nowadays on many divers. In fact, I’ve seen more than a few divers wearing plastic 50-meter water resistant Timex Ironman watches as a backup timer.
The earliest dive watches had relatively modest depth ratings, and that was in the 1950s—an era when watches were worn regularly as necessary underwater instruments. The first Rolex Submariner was rated to 100 meters and the Blancpain Fifty Fathoms was so named because it was thought that the maximum depth to which a diver could safely descend was 50 fathoms, or 300 feet (a little less than 100 meters). In actuality, deeper than 187 feet, the partial pressure of the oxygen in compressed air becomes dangerously high and can become toxic.
But don’t take my word for it. ISO 6425—the international standard that lays down specifications for what can be called a “dive watch”—states that the minimum water resistance should be no less than 100 meters. So while we all appreciate a 1,220-meter dive watch for its impressive engineering, let’s not pretend that an Oris Diver 65 or Rado Captain Cook won’t time a dive as well as a Sea-Dweller. Even if you flail your arms underwater (read on).
MYTH: Flailing your arms underwater adds to the water pressure on the watch.
Ah, this old chestnut: the notion that swimming or swinging your arms underwater adds an additional measure of extreme water pressure acting on a wristwatch. So those who want to wear their watches for water aerobics or re-enacting Thunderball fight scenes should think twice about their choice of dive watch. But it’s simply not true.
The fact is, there is no discernible increase in water pressure on a watch’s gaskets no matter how hard you swing your arms. I’m no physicist, but according to someone who’s done a lot more research than me, you’d have to be moving your arm 32 miles per hour in order to raise the pressure by one atmosphere (the equivalent of an additional 33 feet or 10 meters of depth) and that’s only if the pressure hits the gasket at a right angle, which it doesn’t. You see where I’m going with this—swimming with a watch that has almost any measure of water resistance is a non-issue. Anyway, you’ll notice that seasoned divers don’t use their arms much, since swinging them around decreases hydrodynamics and increases effort, which in turn depletes a tank’s air supply more quickly.
MYTH: Divers wear dive watches.
If you only looked at press releases, watch brand websites and promotional photos, you might assume that a dive watch is an essential piece of gear for a scuba diver. But step foot on a dive boat anywhere in the world, and you’re not apt to find a single watch on a wrist that’s not a digital dive computer. The truth is, in the evolution of the dive watch, by the early 1990s, dive computers became state of the art, due to their ability to dynamically track depth and calculate nitrogen tissue loading, no-decompression limits, and decompression stops. No longer did a diver need to carry a laminated set of tables with them, or do math in their head underwater.
That said, there are still plenty of good reasons to dive with a watch, and I never backroll into the blue without one opposite my dive computer. First off, short of carrying a second dive computer, it’s a handy backup bottom timer that, in tandem with a mechanical depth gauge, can be used “old school” to time a safe dive in case your computer goes on the fritz. Secondly, there are other things that can be timed underwater for which a digital dive computer isn’t as well suited, such as swim distances for navigation, turnaround and rendezvous times, or safety stops. Topside, it’s also easy to spin the bezel to track surface intervals, boat ride times, and the all important post-dive happy hour.
All these purposes aside, to wear a dive watch diving is to celebrate the heritage of this most purpose-built timepiece ever devised. Wearing a dive watch ties you to the lineage of great watches in history and the explorers and adventurers who’ve worn them before. It also is a nice keeper of memories to which you can refer when you’re back at your desk. That scratch on the clasp? From a penetration dive on the Thistlegorm wreck. The scuff on the crystal? A brush on some coral while lionfish hunting in Curaçao. A dive watch is a tangible celebration of our adventurous spirit and an encouragement to go out and do cool stuff. And that may be the best reason of all.
Photos: Gishani Ratnayake
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