Reducing your air usage.
Its is common that beginners believe that they are using too much air, and look for ways of reducing it. These are my thoughts.
Why we use air.
We need the oxygen in the air which we breathe, we need to also breathe to remove the carbon dioxide waste products. The more oxygen our metabolism needs, the more air we will breathe.
So why do beginners need more air.
Inexperienced divers have not yet mastered buoyancy control, so they use their muscles (finning and hand movements) to adjust their buoyancy, the extra use of muscles requires more O2 hence more air. Experienced divers use just their buoyancy devices (including their lungs).
If you watch inexperienced divers underwater you will see that they are not horizontal in the water column, so some of their finning effort is used to keep them from sinking.
Even when stationary inexperienced divers use more
Beginners often have poor finning technique, so that muscle use is not converted into motion efficiently.
How to use less air
If you stop moving underwater (just freeze) and start to sink you are not neutrally buoyant. This is because your buoyancy device is not adequately inflated. (Even an overweighted diver can attain neutral buoyancy, tech divers do this at the start of all their dives)
· Carry the right amount of weight (and in the right place)
An over weighted divers with a normal BC does not normally have a horizontal attitude (the weight at the waist pull down, buoyancy in the jacket pull up at the chest). To compensate for poor trim requires effort and air. The extra drag by swimming around with a partially inflated jacket, and the force needed to propel the extra weights which are being carried uses more air. Wings and integrated weights help achieve a good trim, but single cylinder recreational divers can still get the right trim and weighting with a conventional BC.
The fitter you are, the quicker your heart returns to a normal heart rate after exercise. If you have a long surface swim to a site, or carried your kit a long way you will start the dive with an elevated breathing and heart rate.
After a period of underwater exercise, a fitter person returns to a normal breathing faster than a less fit one.
Do lots of slow lengths, not a few rapid ones as this will help the right muscles develop. Try and do as many lengths underwater as you can as the underwater finning is no the same as surface finning (1 in 3 is a reasonable target to aim at).
Borrow a larger cylinder for the first 10’s of dives; you won’t need it after that.
DO NOT skip breathe.
As you become more experienced your underwater breathing pattern may change, but spending your dive thinking about breathing is not a way to enjoy a dive.
Excess carbon dioxide in the blood also causes the vasodilation of blood vessels, this may increase blood flow to the brain increasing the effects of Nitrogen Narcosis and increasing nitrogen ongassing in the brain.
Disadvantages of being ‘good on air’
If you reduce your muscular activity, you reduce the heat which is produced by your muscles. As you become more experienced you may notice that you get colder than you used to on dives.
The more subtle reason than just your buddy becoming low on air, is that if you need to air share with your buddy you must have enough air for them as well as you.
Your reserve must be enough for their needs, so a 50 bar reserve in my 10 litre tank is adequate for me but not for a gas guzzling novice, when diving with a novice: I must leave a larger reserve.