HOW TO MANAGE YOUR AIR CONSUMPTION WHILE DIVING ? 

AIR CONSUMPTION WHILE DIVING

Even beginner scuba divers know that once you’re underwater, you’re working with a limited supply of air! What’s more, the tanks of compressed air attached to our buoyancy control devices often vary in size and capacity: the bigger the tank, the longer you’ll be able to dive for. However, diving with a larger volume of air does nothing to change the rate at which this air is consumed. Controlling your air consumption during a dive is therefore essential in order to safely return to the surface or perform decompression stops, while still keeping a quantity of security air (also known as the “reserve”), generally equal to 50 bar. As such, a pressure gauge is an essential tool for every diver. Directly connected to the tank, it provides real-time information regarding the quantity of pressurized air still available in the tank. The diver then has to make an estimate on the basis of his or her ‘air autonomy’, as well as other factors, such as the depth at which they’re diving.

IS IT POSSIBLE TO IMPROVE YOUR AIR CONSUMPTION WHILE DIVING?

Several criteria have to be considered if you want to improve your technique and better manage your air consumption while diving.
Let’s go over them in detail… 

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1

GOOD HEALTH AND GOOD SHAPE FOR DIVING

It’s easy enough to understand that for optimal air consumption, it’s essential for a diver to be in good shape. You’ll also have to feel comfortable when in the water, making your gear extremely important. Make sure that your wetsuit fits you properly and is suitable for the water temperature where you’ll be diving. Your BCD shouldn’t be over-inflated, and be sure to use the right amount of lead.

2

WEIGHTING

Your buoyancy control device and weighting system go hand-in-hand. If you’re using too much lead, you’re going to need to compensate by inflating your BCD, which uses up considerable quantities of air. Also, divers can often become short of breath as a resulting of fighting against being over-weighted!

3

GOOD THERMAL INSULATION

Thermal protection also has a major role to play in air consumption. Always remember that you’ll lose body heat almost 20 times faster in the water than in the air, and that the cold definitely isn’t a diver’s friend! Few things are more unpleasant than being cold while diving. To warm up, the body will start burnings its fat and sugar stores, which also uses up oxygen. In other words, a warm, well-fitting wetsuit won’t just help you keep warm, it’ll help to avoid increasing your air consumption.

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4

STRESS MANAGEMENT

As a result of stress or nerves, beginner divers can sometimes feel a jump in their heart rate. Feelings of nervousness are common in inexperienced divers: as well as the unfamiliarity of the underwater environment, sometimes there isn’t a lot of light or even any at all, making it harder and harder to see the pressure gauge. All of this can cause the diver to start feeling stressed or overwhelmed, which leads to higher air consumption. To fight this, try focusing on the vibrant underwater flora and fauna, the shipwrecks, the fish, and the exciting characteristics of your dive site. Remember: you aren’t alone, and you can always trust your dive leader.

DEPTH

So, why do we use more air at 20 metres than on the surface? Boyle’s Law (also known as the Boyle-Mariotte law) says that at a constant temperature, the pressure of a gas is inversely proportional to the volume of the space it occupies. Consider this: during a period of moderate effort, a man breathes approximately 15 to 20 litres of air per minute. On the surface, the air that we breathe has a pressure of one bar. At a depth of 20 metres, the surrounding pressure is now at three bar, meaning that a diver at 20 metres will consume three times more air than on the surface - around 45 litres per minute.

We therefore see that air consumption increases with depth. In concrete terms, this means that a diver with enough air for about two hours on the surface will only have enough for a third of that time when diving at a depth of 20 metres.

TAKING IT EASY

When diving, it’s important to exert as little effort as possible. When moving around, remember to take advantage of the currents, keep finning to a minimum, let your weights do the work, and follow the underwater environment’s natural landforms. Reducing your level of physical exertion will help you to consume less air.

DON’T HOLD YOUR BREATH!

Despite what you might think, holding your breath (or skip-breathing) isn’t the best way to consume less air - in fact, it’s quite the opposite! Holding your breath stops your blood cells from getting a supply of fresh air, even as your body continues to produce toxic carbon dioxide. This lack of  ‘renewed’ air will gradually create an imbalance, encouraging your brain to respond to what it perceives to be a stressful environment. This in turn will lead to a feeling of being out of breath, ultimately increasing your air consumption.

A FEW FINAL TIPS

To sum up, the rate at which air is consumed when underwater is impacted by a number of different elements, depending on the diver, their diving gear, and even their environment. It’s important to remember that you mustn't push yourself too hard when diving, and that your diving equipment must always be suitable and properly maintained. Of course, the best way to reduce your air consumption is by practising! The more you dive, the more you’ll be comfortable with your equipment and the underwater world. The more relaxed you are and the less effort you exert, the better your air consumption will be!

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                ARTICLE CO-WRITTEN WITH

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                Victor, retail assistant at Decathlon in Dunkirk

                I'm a retail assistant in the diving and surf sports department at Decathlon in Dunkirk. I began diving during my internship, 4 years ago. Then I had an opportunity to start going through my levels. Today, I'm up to FFESSM (French Federation of Undersea Studies and Sports) Level 1.

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