Diving And Air Consumption

scuba diver against sun

Increase your Dive Time on Fiji's Stunning Reefs - A Discussion On Diving And Air Consumption by Richard Akhtar

Fiji’s reefs are known worldwide as being some of the richest in the world teeming with life and colour. For the purposes of this discussion, the key elements of this ‘life and colour’ are that they occur in tropical waters – generally warm and clear - and also at relatively shallow depths.

Yes, of course, Fiji has abyssal walls and drop offs and pelagic action to suit anyone’s taste but the fact of the matter is the most abundant life on coral reefs is at less than 20 metres. This is great news for those wishing to spend their time under water rather than sitting on the dive boat. We do not have the extreme physiological impact of cold water and rarely are dives limited by no-decompression times but rather by air consumption. Therefore there is a real opportunity to max out on your underwater time.

For many, however, short dives are the reality and there is the frustration of having to do your safety stop and end the dive whilst other divers are still enjoying being underwater with plenty of air still in the tank. Inevitably, when those other divers return to the boat they are asked ‘how do you do that – what is your secret’. This always prompts the macho ‘how much air do you have left’ discussion between everyone on the dive boat – (there obviously has to be some competitiveness to diving!) – But what are the underlying reasons for the disparities.

It is well documented that there are physiological differences between men and women! In terms of diving, women statistically fare better than men with regards to air consumption. Lung capacity is generally smaller as is muscle mass – both are air consumption relevant. It’s not a golden rule, but you can assume that someone 5 ft tall and 110 lbs will consume less air at rest than someone 6 foot 4 inches and weighing 200 lbs.

So, can we do something about our own air consumption underwater or do we have to put up with what we are given by nature? As a dive resort owner who has completed over 1500 dives in the last 5 years in Fiji (mostly as a guide or instructor) I have some personal opinions and observations on this subject. Some you may agree with – others not – let me know. Before I continue, let me state the obvious. All of us learned on our first ever dive course (whichever agency sanctioned) that it is essential we breathe continuously underwater. That is not to say that we might not pause now and again however breath holding, withholding breathing, skip breathing or whatever you want to call it can lead to serious problems. See what you think of my suggestions , try them out and then see if your breathing is even the real issue at stake.

Comfort / skills

This is a fairly obvious place to start. Unless you are comfortable in the water and confident of your diving skills can you ever be relaxed enough to achieve optimum air consumption? Being relaxed (or able to be relaxed) is the key to everything I discuss below – the more relaxed and natural you are underwater the easier diving will become - it is a self fulfilling prophesy. Do a deal with yourself – practice 1 thing you are uncomfortable with on every dive (yes, even mask clearing or removal!) until it becomes second nature. After that, don’t stop – do it because you enjoy it!

Positive buoyancy at the surface

This is a huge issue and should have been stressed time and again on your initial dive course. In my experience, over 30% of all qualified (and experienced) divers we take diving are slightly out of breath before they start their first dive, especially when they have not dived recently! Think what this will do for air consumption on the dive. Why is this the case? They are paddling, don’t have enough air in their BCD’s, are uncomfortable with the surface conditions etc. Basically, they forgot to trust and use their equipment. It’s not only air consumption at stake here. A large percentage of all diving incidents occur on the surface, mostly through over exertion.

A good way to overcome this is to hang about on the surface. Let the dive boat pick someone else up first after a dive whilst you float around. Have enough air in your BCD to lie back and stop kicking completely. If there is a short swim to the dive site, it is often easier to do this a couple of metres under the water than at the surface – especially in choppy conditions. Believe me; if you can avoid getting even slightly out of breath you will save masses of air.

Depth

As already mentioned, it is not essential to go deep or stay deep on Fiji’s reefs. You might want to go and look at something specific at depth but if you find you use more air than your fellow divers, try reducing the average depth of your dive. With clear water, you can happily be a few metres above the other divers and still stay in touch. Assuming a conservative air consumption of 20 litres per minute at the surface and also assuming you breathe a tank from 200 bar at the start to 50 bar back on the surface (total 1800 litres) – at an average depth of 15 metres you will have enough air for a 36 minute dive. At an average depth of 10 metres you will have enough air for a 45 minute dive. This is a massive 25% increase in time. Why not spend time exploring the shallows during the latter part of the dive. This is perfect in the tropics as you will see a huge amount of life in great natural bright light. It is also great for your dive profile and repetitive dive no decompression limits.

Equipment

Again, as you learned in your dive course, equipment causes drag through the water, drag means extra effort which means higher air consumption. You learned therefore that the gear you carry should be streamlined. What I am about to say may not be popular as many divers are very attached to their ‘gear’. Consider streamlining your gear by not taking it in the water in the first place or better still, leaving it at home! I can virtually put money on the guy who has been diving for years and is carrying half a dive shop underwater with him will be the first up.

It’s always a matter of personal choice, but when diving in tropical waters you really can pare down to the bare essentials. Why not take off your dry suit inflator hose – you won’t need it. It feels so much better when you’re not laden down with all the latest gadgets and it does wonders for your air consumption (and excess baggage charges!). If you don’t have the ideal tropical setup, consider hiring you gear – your dive resort should have plenty of high quality equipment available for rental.

Weighting

Correct weighting is essential for efficient air consumption. Weighting is a key component in buoyancy control (discussed below) but also has a tremendous impact on your efficiency in the water. Overweighting tends to drag the lower part of the body down so even if neutrally buoyant, divers need to kick continuously to remain horizontal in the water. All that kicking requires energy which requires air. To make matters worse, if you are over weighted, you will need to add more air to your jacket to remain neutrally buoyant at depth – your jacket will therefore have more volume causing more drag through the water. A double whammy on your air consumption! Additionally, the more weight you carry, the more inertia you have (think about a truck braking as opposed to a car) meaning it takes more effort to change direction and as we know effort equals air – is there such a thing as a triple whammy? Under weighting will have similar impact on your air consumption as you struggle to kick down towards the end of a dive whilst your tank is trying to pull you up.

Remember you will breathe 1.5kg plus of air during your dive so always adjust your weight for the air you expect to have at the end. If you are correctly weighted for 1 dive are you necessarily correctly weighted for another (assuming no changes in wetsuit etc)? Not necessarily! If diving in current, which is frequently in Fiji, I find it easier to be slightly over weighted. You can use less energy if having to swim into a current by ‘falling’ into it using your extra weight. Also if there are up currents you can use the weight to your advantage without having to swim down. At any rate, think about the dive you are doing and weight accordingly.

Buoyancy

Mastering your buoyancy is a key skill relevant to all aspects of your diving. If you have complete buoyancy control you can eliminate extraneous movements underwater. As water is so dense, all movements use much more energy than the same movement on land and hence use more air. Correct buoyancy also allows you to perfect the fin kick of your choice to propel you most efficiently through the water. There are many fun exercises you can do to hone your buoyancy but something you should do all the time on every dive is use fixed visual references to give you a continual picture of where you are relative to everything else. If you catch buoyancy lapses quickly, you spend less energy correcting them thus conserving more air.

Trim

If you get yourself neutrally buoyant but find that you fall forwards, backwards or to one side or another then your trim needs adjusting (imagine everyone on a small plane suddenly standing up and all moving to one side!). You can correct yourself in the water, (using movement, energy and therefore more air) as many times as you wish however you will always fall back unless you correct the cause. The solution is normally as simple as shifting a weight slightly. It won’t fix itself - don’t put up with it!

Arm movement

If you’ve ever done an aerobics class, there’s a reason the instructor makes you do all those arm movements until you feel that they are going to drop off. It’s exactly the same reasoning that made your diving instructor want to tie you arms to your side during your first dive course. The introduction of upper body movement can increase your metabolism by up to 30%. Great if you want to burn calories in an aerobics class, disastrous for air consumption on a dive – enough said!

Pace / kick style / movement

Divers often show their personalities in the way they dive – there are those who are very busy buzzing about the reef and those who are laid back and going with the flow. Guess who normally lucks out on air consumption? During training, I often get my students to see if they can increase their dive speed by just 50%. Sounds easy however the effort required leaves them and me gasping for breath after about 30 seconds. That particular dive doesn’t tend to last very long!

Obviously all movement cannot be cut out on a dive else you would never go anywhere. It is very important therefore that movements should be as energy efficient as possible. Because of the density of water, slow steady movements are most efficient – there is no use fighting water, it will win every time and rob you of your air to boot. Pace your dive and try to develop an efficient fin kick which allows you to kick and glide, kick and gliiide, kick and gliiiiiiiide – you get the idea.

Photography

‘Well what about it?’ I hear you ask. And my answer may be unpopular with a lot of people. In my opinion most divers take cameras into the water before they have sufficiently honed their diving skills. Destruction of the reefs aside (as out of control diver/photographers crash into it) this is a discussion on air consumption. A camera is another piece of gear to cope with. It causes drag, is a distraction and can task load someone who still has skills such as buoyancy to master. All of these factors will cause an increase in air consumption. With the revolution in digital cameras and housings, underwater photography is within reach of many divers and of course it is great fun. If you are concerned about your air consumption and dive with a camera, do an experiment. Leave the camera on the boat for 1 dive and see if it makes a significant difference. If so (and I believe even the most experienced photographers use more air when taking photos than diving without a camera) you have a simple decision to make – enjoy the fun of photography or enjoy extra dive time. In time you will be able to do both but maybe leave the camera behind sometimes so you can hone your diving skills. Of course that’s going to be the dive when you bump into a school of hammerheads, 20 mantas………..

Physical Fitness

It would seem to make intuitive sense that good cardiovascular fitness would lead to better air consumption. It is however a difficult one to prove as there are so many variables at play. I can’t find any strong studies on this subject and think that it would be fascinating to conduct one. On one hand you have fitter people being able to make better use of air relating to exercise but on another you have increased muscle ratio and higher metabolism burning more calories at rest. Yoga has certainly shown many benefits in diving; it helps stress management, improves mental alertness, teaches you how to relax, improved use of senses, increases flexibility and concentration on breathing techniques. Overall it would seem to make sense that as in any sport, a diver should maintain some degree of physical fitness.

Breathing techniques

Note how far down the list I have put breathing techniques and this is the one people feel holds the magic answer. I firmly believe that if you address all the previously discussed headings, relax and get the basics right, you will see an improvement in your air consumption. Again, yoga teaches breathing techniques as part of relaxation and there are some things you can try underwater. It is widely accepted that in diving, breathing should be slow and deliberate (as in yoga) using the full normal range of the lungs. I and others have found that reversing your normal pattern of breathing can really help you use air more efficiently hence conserving it. At rest, your normal breathing pattern will be; breathe in, breath straight out, pause with empty lungs for second or 2 and then repeat. Try reversing this by breathing in slowly, pausing at the top of the breath, breathing out slowly then immediately in slowly again with no pause at the bottom of the breath. I find I adopt this pattern automatically when diving – try it and see if it works for you.

Final Thoughts

I have discussed 12 aspects of our sport where I believe you can make a difference in your air consumption. Some may only yield tiny results, some larger or none at all. I am convinced however that if you are concerned about high air usage and address all of these areas you will see a continued and significant improvement. I hope that divers reading this will have their own views and other suggestions that I have missed – it would be great to hear your comments. This is where we come full circle in the discussion on improving your air consumption underwater. Diving is like many sports, the more you do, the better you get at it and the easier it all becomes. As things become second nature you can relax your body and mind allowing you to take full advantage of the air that you take underwater with you in your tank.

Copyright Richard Akhtar. Richard was born in England & gravitated to water based activities from an early age starting with fishing & adding windsurfing, sailing & rowing before eventually ‘discovering’ diving in 1996. Becoming an immediate dive addict, he has been lucky enough to dive many hotspots around the world & spent considerable time & energy planning how to leave his previous career for a new one where he could combine his diving passion & working life. Richard fulfilled this in May 2002 by buying Matava Resort next to the Great Astrolabe Reef on the island of Kadavu in the Fiji Islands. He particularly enjoys the remoteness of this unspoilt location as much of the diving is exploratory. He has also thoroughly enjoyed working with experts attracted to the diversity of the fish & coral life & has recently started collecting ID data on the many Mantas in the area. Richard is a PADI Instructor & through active environmental programmes has achieved the Project AWARE Go Eco status for Matava. http://www.matava.com; http://divingfiji.blogspot.com; Article Source


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