Diving Watches
Anyone who enjoys scuba diving will soon enough want to look into getting a diving watch.
Though offerings are really along more of a continuum, there are two basic types to investigate.
Any watch labeled ‘diving watch’ will have to satisfy one obvious basic criteria above all. It will have to be able to withstand the pressure from diving without leakage.
Watches are commonly rated 30M or 50M, indicating they should be able to stand up to water pressure at a depth of 30m or 50m (about 100ft or 150ft).
But those measurements are made under very carefully controlled laboratory conditions of static pressure. Movement substantially increases the pressure on the watch.
So, any diving watch will need to be rated 200M at minimum in order to stand up to even a casual dive without the case getting infiltrated with water.
When even a small amount of water gets inside a watch parts can rust, electronic systems short circuit or moving parts gum up and fail.
One of the reasons a true diving watch needs to be extremely well sealed, though, is not just to keep out water. Deep dives can result in the need to spend time in a decompression chamber.
Those chambers use helium under pressure as part of ‘the cure’ and it’s much harder to keep helium out of a watch than water. Though it’s an inert (and therefore, non-reactive) gas, it can still interfere with the watch’s functions, so infiltration needs to be avoided.
Beyond the basic of having to stand up to deep water (or gas) pressure, the case and crystal need to be strong enough to not crack or gap if you tap it against something.
It can be hard to see at even just 3 fathoms (18ft, 5.5m), and there are lots of rough, hard things under the surface to brush or bang against. A casual tap shouldn’t cause your watch to leak.
The second category of diving watches goes well beyond this simple physical requirement. They provide functions that are amusing on the surface, but essential during a dive. More advanced diving watches are as much dive computer as they are a timekeeping piece.
Any diver needs to know how long he can stay under, both because of air limitations and because of the possibility of decompression sickness (‘the bends’) or nitrogen narcosis and other effects. That can be measured by an ordinary clock, but it’s important to have more than that.
One simple mechanism that you should look for is the use of a rotating bezel. That’s a small dial that you can set at the beginning of the dive. As the minute hand sweeps, it essentially acts as a visual timer. When the hand meets the pre-set number, you’re out of time.
How long you can stay under depends not only on the elapsed time, though, but also on what you’ve done during the dive. It depends on how long you swim at a given level, whether you dive straight down and move horizontally or make angles and lots of ascents and descents.
That’s pretty typical dive behavior and a good diving watch/computer will take account of it dynamically.
It’s possible to calculate that approximately before you go down, and every diver should. But there’s nothing better than real-time measurements under actual conditions.
A good diving watch will have functions that perform accurate measurements and automatic calculations. It should also be able to display that information clearly under poor visibility conditions.
Fortunately, thanks to excellent technology, there are dozens of brands, models and styles in a range of prices that provide those benefits.
Anyone who spends even a modest amount of time looking will find one that fits them like a great wetsuit.