Dive Watches Explained

Background

Are you a keen scuba diver or prefer to go without the tank and free dive? Either way, you should have a reliable dive watch. Being able to monitor how long you’ve been holding your breath for, or knowing how long you’ve been on the surface for is really key to your entire experience and safety. You need to know these things to an exact degree because there are limits to what the body can handle. Also, being able to monitor your time at depth means you can work out when you must start your slow ascent back to the top. Consequently, you’ll reduce the chance of getting the bends.

When you’re scuba diving, you’re diving deeper, for longer, compared to free diving or snorkelling. Your air supply is limited and time is a critical factor. Dive watches, therefore, have been designed to withstand an exceptional level of water pressure. But also to provide life-saving information that takes an element of diving away from potential human error and makes the experience all the easier.

These two major considerations went into the first dive watch, the Omega Marine, produced in the 30s. In order to keep it safe underwater, it was encased in a stainless steel case, designed to ensure durability. They put it under more pressure than a diver was ever likely to face, even, like intense heat, cold and depths for a long period of time.

How are dive watches tested?

If you’re going to wear a dive watch for diving, rather than fashion, it’s best to get an ISO rated watch. This is an internationally-recognised certificate that confirms the watch can resist moisture, pressure and will work underwater for sustained periods of time (50 hours, in testing).

During testing, the watch will also be subjected to 45 degrees Celsius for 20 mins. Testers also drip water onto the watch face during this time to test for condensation inside. The watch will be tested for the amount of pressure it can withstand, which is applied and monitored for 2 hours.

What to look for in a good dive watch

Budget depending, there are other features to look out for in a dive watch. Some come with more than one gauge that measures the time elapsed that will alert you, either by flashing or vibrating (because being underwater will muffle any noise). 

Other watches are made from an advanced ceramic composite, which is the very latest material in pressure resistance, more so than titanium or steel. 

Some come with crystals in the display that reduce glare. 

Hands should be luminous and easily seen in dark water up to 25cm away.

Your dive watch should have a screw-in crown with an O-ring to ensure water resistance. 

For ISO certification, the watch must have an indicator, that is easily seen, to suggest that the watch is working (usually, the second hand is OK).

Look for an extendable strap which can go over a wet suit.

A depth gauge isn’t necessary, in fact, they can only be found on a few watches. It depends on your needs.

Design

Dive watches tend to have a rotating bezel, too, and there’s a lot to know as to why. The function is basic. Before descending, the 12 o’clock bezel marker is lined up with the minute hand, allowing 60 minutes to pass and be read on the bezel (you should notice that dive watches tend to have a noticeable minute hand). It’s positioned in such a way that if there’s any accidental movement of the bezel, it can only move forward, which suggests more time has been spent underwater, rather than giving an illusion that there is more time to be spent. A clever safety mechanism. 

A typical scuba dive lasts 30 minutes to an hour. It depends on the depths and the fitness of the diver. The first 15 minutes on a bezel inlay are therefore usually highlighted as the end of this time period indicates one should think about their ascent. Dive watches known for being exceptionally good for this are the Aquastar Benthos and IWC Aquatimer Chronograph. 

How waterproof should a dive watch be?

Some brands will sell their dive watches with a rating of 300m or more and this is perfect for scuba diving. Some say 200m would suffice. ISO dictates that for a dive watch to be classified as such, it needs to be 100m.

All of these depths are, realistically, deeper than a non-professional diver can or will go. Recreational divers will go to a max of about 40m. Anything after this point becomes much more complex and technical to manage. 

There’s a lot of discrepancies when it comes to testing, which is done in an artificial situation, far different from what the watch would face in reality. The watch is tested in a lab, in stationary water. The watch itself is brand new. What isn’t replicated, is the sudden change in water pressure when the diver enters or emerges from the water. It also doesn’t consider the change in temperature or general knocks to the case. Ageing affects the gaskets and generally, the components aren’t as tight as they were after a few years of use.

Do we actually need dive watches?

In this day and age, with dive computers, the short answer is, no, we don’t need dive watches. Divers might wear one as a plan B for their dive computer, should it run out of battery. Dive computers are now worn around the wrist and are on the market for reasonable prices. So with this in mind, it’s not uncommon to see divers wearing two computers, rather than a computer and a dive watch. There are things a watch can’t do, like offer a gauge for depth (as noted, only a few makes do this) and pressure, as well as dive tables, so it’s questionable why one might take more equipment than is needed.

Should I bother buying a dive watch?

If you want one, yes! Lots of divers like the waterproof promise of a dive watch. If it’s guaranteed to a certain depth for diving then it’ll definitely be good for snorkeling or general swimming activities. Some people like the features such as the easily spotted hands and the rotating bezel. Perhaps you’re not even into scuba diving and you simply like the technical and sporty look. There are still reasons why you might treat yourself!

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Last Updated on April 13, 2022