THERE ARE DEFINITE BENEFITS, both tangible and intangible, to diving with someone else. We are human beings, after all – we like to share our experiences and we also derive a great deal of emotional security from the company of others.
There are also occasions when having a buddy around can be of enormous practical assistance.
If you become entangled in fishing-line or a net, a buddy can see the situation much more clearly than you and is better placed to extract you.
If you become confused or anxious, your buddy’s mere presence and calm disposition can be reassuring; and if you suffer a serious marine-life injury, you may need a buddy to get you safely to the surface and out of the water.
Arguably, the strongest argument for diving with someone else, however, is that you can assist your buddy in an air-supply emergency or that your buddy can help you.

A couple of years ago, the folk at Advanced Diver magazine in the USA ran a few scenarios using a standard set of equipment on a full 12-litre cylinder placed at a depth of 30m.
They found that a burst intermediate-pressure hose emptied the cylinder in less than 90 seconds. A purged (that is, freeflowing) regulator did not take much longer, causing the cylinder pressure to plummet from 200 bar to zero in just 154 seconds.
So, if you’re using a single cylinder with no back-up when you’re diving at any sort of depth and something like this happens, you’re unlikely to have enough time to make an ascent at a safe speed on your own.
You’re going to need someone to share their air with you.
There is also the possibility that you might start a dive on an almost empty cylinder without noticing, and run out of air while still at depth.
This has been the experience of a number of divers who thought they were much too careful for something like this to ever happen to them!
This is why we all learn at an early stage in our diving lives how to assist another diver with an air-supply emergency. Despite this, however, real-life situations like this often end badly, with one or both divers coming to harm.
In this article I suggest ways in which you can train and configure your equipment to give you and the people with whom you dive a better chance of survival when one of you suddenly finds yourself out of air.

In standard diver training, the drill begins with two divers kneeling facing each other. One signals calmly to the other that they have run out of air.
The donor hands over their octopus regulator, they establish a mutual grip and, after a minute or so, on a signal from the instructor, the drill is ended and the out-of-air diver returns the octopus and starts breathing from their own regulator again.
The drill is then repeated with the divers exchanging roles. A development on the theme has the two divers execute a timed swim together once they have begun air-sharing, then return to the starting point.
The benefit of these exercises is limited. First, they presuppose an unrealistic scenario where two divers are side by side and stationary when the emergency occurs.
Second, the manner in which the drills are conducted is unlikely to induce any significant degree of stress in the participants, whereas a real-world air-supply emergency is a highly stressful event. Third, the sequence fails to include an ascent.
Two divers, both breathing heavily under stress and sharing a cylinder, need to have an immediate ascent at the front of their minds, because their air supply is likely to become rapidly exhausted.
Unfortunately, the exercises they have practised are more likely to make them think that the act of air-sharing is the most important thing, and that once this has been established the emergency is over.
If anything, the situation has become even more serious. There are now two divers at risk instead of one, and any delay in ascent could be critical.
The emergency is not over until both divers are buoyant at the surface.

Of course, the air-sharing swim is supposed to simulate an ascent, and a good instructor would explain that, but it is commonly accepted that, when called to action in an emergency, you are far more likely to remember something you have done than something you have been told.
People involved in a stressful situation will act according to instinct rather than intellect, and instinct is developed by repetitive rehearsal. This is the concept behind the progressive series of drills
I describe in the text box accompanying this article, which take you through increasingly realistic scenarios, allowing you to gradually develop both your technique and your confidence.
Practise these with your buddy or dive team. I would recommend a team of three: two divers executing the drills and the third person acting as observer / safety diver and providing an objective critique of the air-sharing divers’ performance. Roles should be exchanged during each session.

On the two occasions that people ran out of air on a dive and came to me for assistance, they both arrived unnoticed from above and behind, and grabbed the regulator out of my mouth. Both also dragged my mask off in the process!
This is what typically happens when you run out of air. At the moment you suddenly realise that you have no air to breathe, you stop swimming and instinctively hold your breath. This causes you to float upwards.
Assuming that you have enough self-control and awareness to resist making a panicked runaway ascent, the next thing you do is look around desperately for someone nearby who has air and swim as fast as you can to reach your prospective saviour, who is now usually below you.
As you swim, the anxiety you originally felt on finding yourself airless increases with the effort you are expending, and the gradual build-up of carbon dioxide in your body.
By now, you have only one thought in your head: “I need air!”
The concept of politely requesting assistance with a series of calm gestures could not be further from your mind.
The equipment set-up that most divers use is a regulator on a short hose in their mouth and an octopus regulator on a slightly longer hose, secured to the right side of the BC.
From above, the octopus is invisible, so you just grab the most obvious source of life-saving air you can see, which is the regulator in the diver’s mouth.
Having taken it, you quickly find that the hose is so short that, to breathe from it properly, you need to turn it around.
This presses you up against the diver’s right-hand side, making it hard for them to reach their octopus without pushing you away. A confused, chaotic struggle takes place and sometimes, as the history of diving tells us, disaster ensues.

As well as improving your technique by practising real-life drills, you can anticipate, prepare for and reduce the risk of air-supply emergencies by adopting a regulator set-up similar to those that technical divers use. The following is an example.
Your primary regulator should be attached to a brightly coloured hose. The second stage should ideally be brightly coloured too, and a number of manufacturers offer options.
The hose should be at least 1.5m-long and, depending on your size and shape, the extra length can be wrapped over your chest, tucked into loops of tubing along the side of your harness or BC or tucked into your waistband.
The important thing is that it all comes free easily when it is deployed.
Your back-up second-stage regulator should be black and attached to a black hose to make it less obvious than the primary. This hose should be as short as possible, while still allowing you to move your head freely when you’re breathing from it. You keep it on your upper chest, under your chin, held in place by a length of cord or surgical tubing looped around your neck.
When an out-of-air diver approaches you to share air, the colour coding will attract their attention and direct them to the regulator you want them to take.
The length of the hose will then allow them to remove themselves to a reasonable distance from you once they have taken it.
When the regulator leaves your mouth, all you need do is dip your chin and pop your back-up into your mouth with one hand. You will then both be breathing comfortably and ready to begin a controlled ascent together.
The combination of real-life drills and a well-thought-out regulator set-up can turn an air-supply emergency from a potential disaster into a minor inconvenience.
Practise the techniques often so that they become completely instinctive.

To be practised in a swimming pool or calm, shallow, protected body of water.

1. You and your buddy position yourselves 10m apart. Your buddy “runs out of air” and swims towards you without breathing.
2. When you see your buddy signal that they need air, prepare whichever of your second stage regulators is on the longer hose and give this to them when they arrive.
3. Begin air-sharing, then ascend slowly together.
On arrival at the surface you auto-inflate your BC while supporting your buddy as they orally inflate their BC.
4. Repeat the drill, alternating roles and increasing the distance between you until the person who is out of air starts experiencing significant stress towards the end of the non-breathing swim.
5. Then add a new level of difficulty. Turn your back so that you cannot see your buddy coming, and do not prepare a response until they arrive and spin you around.
6. Finally, practise the drill while you are both swimming, one following the other, so that your buddy is in the realistic position of having to catch up with a moving target to share air.

Do not end any of the drills until both divers are at the surface and positively buoyant.

To be practised during ocean dives.

1. Begin phase 2 only when you are both comfortable with the phase 1 drills.
2. Once in a while, particularly at the beginning of a dive season, agree that one or other of you will initiate the drill at some point during a normal dive in open water. Advise anyone else diving with you that this is what you intend to do, so that they don’t mistake it for a real emergency and try to intervene.
3. Then practise the drill as you did in the pool, first when you are swimming close together in the shallows, then extending the distance and depth as you become more accomplished.
4. Always follow an out-of-air swim with an ascent and establishment of surface buoyancy so that the sequence is burned into your minds and becomes automatic.
5. Finally, to test yourselves in a realistic scenario, involve a third person to act as the trigger for the drill. Ask them to watch for a moment in the dive when it looks as if you or your buddy has become distracted, or when you have drifted a little further apart from each other than usual. Then, the third person should signal to one of you that you’re out of air. This initiates the drill.

Read more from Simon Pridmore in Scuba Confidential – An Insider’s Guide to Becoming a Better Diver and Scuba Professional – Insights into Sport Diver Training & Operations, both available on Amazon in a variety of formats