As you know by now, watches can do a heck of a lot more than just tell the time. Thanks to massive leaps in technology during the 20th century, watches became indispensable tools for some of the most daring and dangerous adventures on earth.
Despite some efforts dating as far back as the 17th century, a truly water resistant dive watch would not make it to market until the debut of the Rolex Oyster in 1926.
It’s pretty amazing how technical innovations can make the once impossible possible.
Let’s do a quick recap of how dive watches work and what you need to know to get the most out of them:
Without water resistance, a dive watch is like any regular timepiece. When looking at the specifications of a watch, you can tell just how water resistant it is based on its ATM number.
Rather than something you punch in to conveniently withdraw cash, an ATM number references the number of ‘atmospheres’ a watch can withstand while submerged. While it’s a fancy sounding measure of water pressure and resistance, it’s actually pretty easy to understand.
1 ATM is the normal pressure at sea level, which means the watch can withstand up to 10x the sea level pressure without any water getting in. In other words, 1 ATM is roughly equal to 10 meters of water resistance. 10 ATM would mean a cap of 100 meters, and so on.
Some brands will eschew the ATM rating and simply display the meterage of water resistance.
One thing to keep in mind is that movement in water exerts much more pressure than staying still, so something as basic as goofing around in the shallow end of the pool might give the strain of being at 2 or 3 ATM despite not diving meters below.
This is important to remember when planning ahead and calculating just how much water activity your dive watch can withstand.
Spin the Bezel
The rotating bezel is a huge benefit for deep sea divers in particular, as it allows you to track how much time you’ve been underwater and know when it’s time to head back up.
All it takes is setting the bezel to the minute hand. Once you’ve done that, you have a point of reference for how much time has passed, and you can act accordingly. Most bezels have indices in increments of 15 minutes, but it’s always good to double check before setting it and taking the plunge.
A dive watch’s helium release valve sounds intense, but serves a very basic purpose. Because pressure changes so much as you dive deeper below the surface, you want to make sure your watch is prepared to acclimate to the changing surroundings.
By injecting helium into the dive watch, you can swim with assurance that it will continue to perform at your deepest point. Once you’re ready to ascend, you can then unscrew the one-way valve as you go back to the surface. What this does is release that injected helium as pressure changes so as to avoid and leaks or damage.
The Screw Down Crown
Last but not least, the screw down crown is an excellent and common dive watch feature that ensures an extra level of protective water resistance. This type of crown creates an airtight atmosphere within the watch, preventing leaks with great success.
If there’s one catch, it’s the need to remember to screw the crown back in tightly after you unscrew it for any reason.