Reasons to Use a Dive Computer

Dive computers are wonderful tools. But like all tools, they’re only as useful or safe as the operator. Technology should never be used as an excuse to abandon thoughtful action and common sense. Remember, turning on a computer shouldn’t mean turning off your brain. Under no circumstances should you remain at depth until your dive computer reads zero minutes. This practice, sometimes termed “riding the zero,” is ill-advised because it’s like walking to the edge of a cliff, dangling your toes over and assuming that you won’t fall. Always begin your ascent to a shallower depth with, at the very least, a few minutes of no-decompression time remaining. Now to the broader issue.

The fundamental point here is understanding what’s meant by “decompression.” Many divers falsely assume that unless one purposely halts an ascent and “hangs” for some time, then he or she has not engaged in decompression. This is a false and potentially dangerous assumption. Any ascent, whether or not you stop, is a form of decompression. This is why many decompression experts abhor the term “no decompression” diving, and prefer the label “no stop” diving. Whether it involves required stops, all diving involves decompression.

Scuba Diving Watches

As to your specific question, according to the model programmed into your computer, you need not halt your ascent as long as the display doesn’t indicate such action is necessary. Indeed, in this instance a direct ascent would not violate the mathematics programmed into your computer’s memory. But here’s where the rub begins. No matter how well-tested and used a mathematical computer model may be, none can ever truly simulate the intricacies of what is actually occurring inside a human body. And even if we get to the point where mathematics can approach this level of sophistication, no model will ever be able to take into account individual physiological differences or anomalies. There is a vast difference between theory and practice or mathematics and your tissues.

The safest way to add some form of “fudge factor” into all this uncertainty is really pretty simple. The first step is, as I advised, never remain at depth until you have zero time remaining. A second practice, which experience is showing to be even more important than once believed, is to slow your ascent. One of the best features of dive computers is their ability to monitor ascent rates. Make sure that you pay close attention to this rate, and when possible come up even more slowly than the computer allows. This appears to be especially important during the final, shallow phase of your dive.

Finally, it’s vitally important to follow a practice which has become a standard procedure in diving – the ubiquitous safety stop. At the end of every dive, halt your ascent at a depth of 15-20 feet (5-6 m), and remain there for at least three to five minutes. But remember, this does not mean that you can then hurry to the surface once the safety stop has concluded. That final ascent from 15 to 20 feet (5 to 6 m) – the region of greatest change in volume – is critical. Make sure that even these final few feet are covered in a very slow and deliberate fashion.

Cressi Sub Edy II Scuba Diving Computer Wrist Watch

The first Cressi-sub computer integrated into a wristwatch. Weight and size are very compact making the instrument suitable for everyday use, and not only specifically for diving. Despite its compact size, Edy combines complete programmes for three different dive types in a single instrument:

• scuba diving (air or nitrox)
• technical diving (bottom gauge and timer down to 200 meters)
• free diving

It is also a digital wristwatch, great looking, complete with dual time zone and alarm, and can be backlit to read data when there is poor illumination.

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