Feature: 3 Clever Dive Watches

The International Organisation for Standards, under ISO 6425, states that a recognised dive watch should meet the following requirements: a unidirectional bezel with five minute markers; clearly distinguished minute markings on the dial; readability at 25cm in total darkness; shock, chemical and magnetic resistance; an operational indicator; oh—and of course, a 100-metre depth rating. This covers the bare minimum to qualify—but what if watchmakers went above and beyond?

Jaeger-LeCoultre Master Compressor Diving GMT 187T170

The watchmaker’s watchmaker was late to the dive watch game, its first arriving some six years after the Rolex Submariner. But true to the Jaeger-LeCoultre way of doing things, a watch that could be adequately used underwater simply wasn’t enough, and so the 1959 Deep Sea Alarm came equipped with a dive alarm—a first in watchmaking.

Fast forward to 2007, and Jaeger-LeCoultre continued its bid to reinvent the diving watch with the Master Compressor Diving GMT. Determined to prove its hard-earned reputation for over-engineering, the Diving GMT has a mammoth 1,000 metres of water resistance and a tough, lightweight grade 5 titanium case. Grade 5 indicates that the titanium has been alloyed with vanadium and aluminium for increased strength and corrosion resistance. It’s a marine and aviation favourite.

But that’s child’s play. The real engineering kicks in with the crown, which sits snug between its crown guards. But those aren’t just crown guards, because as the arrow indicators suggest, this whole collar can be turned. The thinking is this: setting a dive watch with gloves on—or even without—is a pain; the screw-down crown can be fiddly, requiring a lot of turns to seal it from water ingress.

Well then, how about this: just a half-turn of what Jaeger-LeCoultre calls the ‘Compressor’ and the crown is unlocked, ready for the time to be adjusted. Brightly coloured arrows remind the user to twist the compressor—once the time has been set—back to its dive-ready position.

And there’s a little engineering bonus, too, because those of you who’ve been paying attention will be wondering where the operational indicator—typically a second hand—is on this watch. The GMT display—useful for travelling divers—takes up the bulk of the dial space, and a second hand would add unnecessary clutter, so Jaeger-LeCoultre has a letterbox-shaped window cut into the dial which reveals a slowly turning bar—which, of course glows in the dark.

Oris Aquis Depth Gauge 733 7675 41 54 MB

There are several manufacturers—Jaeger-LeCoultre included—that have developed incredibly complex mechanical systems for measuring depth below the water’s surface, with some manufacturers like Panerai resorting to a battery powered solution instead. A quick glance at this Oris Aquis doesn’t reveal anything nearly quite so complex, its design virtually identical to the cheaper and smaller entry-level Aquis.

The reason why this Aquis doesn’t look mechanically complex is because—it isn’t. The movement provides hours, minutes and seconds, plus a date, the bezel goes around in one direction as it should—and that’s it. Why then, is this watch called the Oris Aquis Depth Gauge?

Peer a little closer and you’ll spy a small hole above the twelve o’clock marker. This isn’t the handiwork of some mutant radioactive maggot, rather a channel intentionally bored around the outer edge of the crystal to form a neat, incomplete ring. Now, pay attention, because it’s time for a physics lesson.

Boyle’s law states that the pressure of a gas is inversely proportional to its volume—that is to say that the harder a gas is squashed, the smaller it gets. Makes sense when you think about it on a molecular level, gas particles zipping about freely, enough energy to break their bonds and spread apart—until they’re squashed back together again.

That’s the principle the Aquis Depth Gauge uses to tell you how deep you are, because as the watch is submerged, water tries to fill the channel. Only it can’t, because there’s air in the way. But as the watch goes deeper and the water pressure increases, thanks to the sheer volume of the stuff piling up above, it squashes the gas into the channel further, the divide between liquid and gas readable against the yellow depth scale around the dial.

You’ll notice that the calibration of the channel and the way pressure works means that as the depth increases, the units are stacked more closely together, and by the time 30 metres is reached, the gauge becomes fairly useless. Beyond that are the realms of the professionals, however, so probably best to use the watch in conjunction with a digital diver computer anyway.

IWC Aquatimer Split Minute Chronograph IW3723-04

So, you’re on the boat, getting ready for your dive, you zero the bezel on your dive watch to the minute hand, and off you go. You’re swimming around, admiring the marine life, when you spot a cave. Interesting, you think, I’ll have a look inside. You work out that you ideally need to be back out of the cave in 10 minutes to give yourself enough time to get back to the boat, and in you go.

You’ve been inside for a while, spotted a funny looking fish with bulging eyes, and you check your watch to see how much time you have left. Only you can’t remember what the time was when you entered the cave. The bezel lets you see how much time has elapsed since you first submerged—but that’s it. Turns out you’ve spent too long in that cave and don’t have enough time to get back to the surface, and now you’re dead.

What you needed, really, was a split minute complication. You’ve heard of split seconds, a feature used in conjunction with chronographs to take a snapshot of the recorded time without having to stop the device completely—useful for timing continuous laps—and it’s exactly like that, but for the running minutes instead.

Rewind, back to the boat. Zero the bezel, dive to the sea floor. You admire the marine life, spot the cave. This time, however, you flick the split minute switch on the side of your IWC Aquatimer Split Minute, and in you go. The minute hand continues to run as normal against the bezel, but a stationary hand emerges from beneath it, marking the moment you entered the cave.

Once five minutes have passed—the difference between the split minute hand and the running minute hand—you turn around, head back out of the cave, reset the split minute with a flip of the switch so it disappears once again, surface back at the boat, and get back to the shore for margaritas and tall tales about the bug-eyed fish—this time completely not dead.

These three brands have all taken interesting and unique approaches to making their dive watches stand out from the crowd. Whether you’re looking for better engineering solutions from your diver, or a hydraulic depth gauge, or you simply want to end your underwater sojourn alive and well, between Jaeger-LeCoultre, Oris and IWC, you’re covered.

Looking for a Jaeger-LeCoultre watch? Click here to shop now

Looking for a Oris watch? Click here to shop now

Looking for a IWC watch? Click here to shop now