Air Sharing Pointers for Divers

by B. N. Sullivan

Basic diver certification courses all include instruction on air sharing. (For our non-diving readers, 'air-sharing' refers to more than one diver using the same air source.) This is a very basic and essential skill, and these days it is also quite easy, in principle.

Back in the day when I first learned to dive, SCUBA regulators only had one second stage, i.e., the part of the regulator that includes the mouthpiece. In order to share air, one diver had to take the regulator out of his/her mouth and hand it to the other diver. The second diver would take a breath or two, and then pass the regulator mouthpiece back to the first diver. This alternating pattern would continue until the divers could surface. The procedure worked, of course, but it could be quite awkward. Also, since neither diver could breathe continuously, both divers could end up experiencing considerable anxiety.

These days, most divers use regulators that have two second stages, each attached to its own low-pressure port on the regulator's first stage, i.e., the part that connects to the valve of the air cylinder. Look at the photo of our friend Dan on this page. You can see that his regulator has two second stages. The hose of the primary one passes over his right shoulder, and he is breathing through the mouthpiece. The hose of the secondary one passes under his arm, with the mouthpiece attached to his vest with a quick-release clip. This is a standard sport diving configuration.

In a popular alternative configuration, the inflator hose for the diver's buoyancy compensator has a mouthpiece on it so that it can double as a breathing device.

The advantage of using regulators with two second stages should be obvious: two divers can share the same air source simultaneously and continuously, without the need to pass the mouthpiece back and forth between them. This makes air sharing much easier, and is less anxiety-producing.

Divers are taught how to signal to each other that they need to share air, and the procedure of handing off the secondary regulator to the diver in need of air is practiced during training. They are taught that as soon as air sharing begins, the divers should begin their ascent together.

I take issue with this aspect of diver training. It seems to assume that the divers are right underneath their boat, or near to their exit point if they are shore diving. In real life, things are not often so tidy.

What happens if the divers are a good ten minute (or longer) swim away from their boat or exit point? What if they are near the deepest point of a deep dive? What if it is not prudent to surface immediately because of some other hazard -- e.g., boat traffic, or a strong surface current.

Over the years we have been in a few situations when we had to share air, and we have witnessed many other divers in such situations. Rarely, if ever, have these events happened right under a boat or very near to our exit point. Divers need to understand this and prepare for it, or they may find themselves in deep trouble (pun pointedly intended).

If the diver always stays very near to the boat or exit point, and doesn't go very deep, air sharing using the procedure taught in initial training, which I described above, probably will be sufficient. Otherwise, divers need to plan for -- and practice -- sharing air during a long swim, and during an ascent that may have to include a five minute 'safety stop' at 5 meters.

In order to facilitate swimming a longer distance while sharing air, one of the regulator's second stages should have a long hose. When divers are sharing air via a regulator with a 'standard' hose length of, say, 27 inches, they necessarily have to be very close to each other. It's difficult to swim while physically close to another diver, but that is what's required when both are sharing air and both are attached to the same air cylinder by relatively short hoses. It is much better to have a much longer hose on one of the second stages -- say 40 inches or even longer.

Won't a longer hose be a nuisance when not sharing air? Not really. You can do what cave divers do: bundle it and secure the bundle with a bungee cord. Alternatively, you can feed the longer hose under your right arm and across your front, securing the mouthpiece somewhere on the left side of your gear, instead of the right side where most divers stow their secondary reg mouthpiece. (Just be sure you show your buddy where it is before you begin the dive!)

By the way, if you do need to share air from a regulator using two shorter hoses, and you have to swim any distance, we figured out that it is easier to swim with one diver positioned above and a little behind the diver with the air supply. Imagine that the diver with the air source is going to give the air-sharing diver a piggy-back ride -- except the two divers swim, one a bit above the other. The 'top' diver can hold on lightly to the other diver's shoulder to maintain position and stay in place.

Now, a final note, but a very important one: practice. Practice air sharing while swimming longer distances. Practice air sharing while hovering at a depth of five meters as you would for a safety stop. (This is much easier to do if you have a regular dive partner, but even if you don't, get someone to practice with you from time to time.)

Ever since we began diving together, we have occasionaly practiced swimming at least ten minutes while sharing air. We also have practiced sharing air while hovering in place for a safety stop. We have done this exercise three or four times a year. Then one day, while we were more than a 10 minute swim from our exit point, and at a depth of about 120 feet (37 meters), a high pressure hose on my regulator popped. Oh the bubbly froth that instantly ensued! But there was no panic. Jerry passed his secondary reg mouthpiece to me right away, and turned off the valve on my air cylinder. The two of us set off toward our exit point, swimming easily together -- side by side, but with enough space between us that it was not at all awkward or cumbersome, thanks to a longer-than-standard hose length on Jerry's secondary reg. We even did a five minute safety stop before surfacing. Our practicing had served us well.

Divers, Cover Yourselves!

by B. N. Sullivan

For the past few months, virtually all of our posts here on The Right Blue have focused on interesting species of marine life we have come to know. Feedback on those articles has been positive: our readers seem to enjoy learning about creatures that inhabit the sea. But we also have been nudged by a few readers to get back to writing about diving -- as in, "Enough with the critters, already. Get back to diving stories!"

Well, okay then. How about some tips for divers?

Over the course of a few decades of diving, we have learned a number of useful things that, for one reason or another, are not taught to divers in formal training courses. The first is a simple rule that usually does not occur to divers until after they have had a bad experience or two. Cover yourselves!

In colder water, divers must cover themselves in drysuits or heavy wetsuits in order to retain body heat. But we believe that divers should be completely covered even when diving in warm tropical locations. These days, there are plenty of lightweight dive suits designed specifically for use in warmer waters.

We see many, many divers here in Hawaii -- mostly (but not only) tourists -- who seem to think that because they are in the tropics, they should just wear a shortie suit. We see them jumping into the water with their arms and legs exposed. Worse yet, some wear no dive suit at all, donning their dive equipment right over their bikinis. Guess what happens? Sooner or later, they get wounded!

It is very easy to brush against something -- a rock, a coral head -- even when you are trying to be careful not to touch anything. Sometimes it happens because the diver is not paying attention. Other times there is a little surge, just at the wrong moment. In any case, sooner or later some part of your exposed anatomy will collide, however briefly, with something in the water, and you will get cut or scraped.

In addition to those kinds of bumps and scrapes, it happens that there are many critters in the water that can bite or sting. Some are very tiny -- stinging plankton so small that you cannot see them in the water column -- so you cannot take evasive actions. Other are big enough to spot -- jellyfish come to mind -- but even then, you run a risk of being stung. Just because you see the critters doesn't mean you can count on completely avoiding contact.

The best way to prevent many of these inadvertent stings and scrapes is to wear a full suit that covers you from your wrists to your ankles. Wear boots or neoprene booties inside your fins. And wear gloves.

Now, we know that many dive operators discourage or even prohibit divers from wearing gloves. We also know the reason for that: they don't want to encourage divers to pick things up or handle them, and they figure if the divers are not wearing gloves, they may be less inclined to touch things.

Fair enough, but short-sighted. There are just too many situations where the protection afforded the diver by gloves outweighs the momentary protection of the reef and its critters afforded by bare-handed divers.

We think of it like this: we're grown-ups. We know we shouldn't recklessly handle things that dwell underwater. We know that touching corals (and many other things) can damage them. We promise we won't do that -- not because our hands are bare, but because we know better.

At the same time, what happens if we are shore diving and need to grab onto rocks at our exit point? We can very easily get cuts and scrapes on our hands, that's what.

If we are diving from a boat, what happens when we need to hang onto a mooring line or an anchor chain in order to remain stationary for our safety stop? Lines and chains that have been in the water for awhile are certain to be covered with algae, hydroids, and even teeny-tiny crustaceans. If you don't believe me, just have a look at the second photo on this page -- a 1:1 macro shot of an actual mooring line, totally encrusted with an entire ecosystem of its own! Hanging onto such a line is going to disrupt some of those things anyway, regardless of whether your hands are bare or gloved. But hanging on with a bare hand will really hurt. Said teeny-tiny crustaceans will cut your hand like little razors, and if you happen to grab onto a hydroid, you will know it, believe me. They sting like a son-of-a-gun -- and you will never forget the experience!

So then, even if you don't want to wear gloves for the entire dive, do carry a pair in your pocket at all times, just in case you have to hold or grab onto something for your own safety.

Dive like grown-ups. Cover yourselves completely to protect yourselves from scrapes and stings; but at the same time, do keep in mind that being covered (and thus protected) does not excuse you from responsibility for avoiding physical contact with the reef and the creatures that call it home.

Diving then and now - Part 1

by B. N. Sullivan

One of the earliest posts in The Right Blue tells about our training as divers. In the post I mentioned that I first learned to dive in 1970. That's right -- 38 years ago!

Diving has changed a lot since 1970, mostly because of improvements in equipment. We decided it would be fun to review the progression of those changes for our readers. This exercise will take several posts, so bear with me.

To start things off, have a look at the picture at left. That's me, in 1970, when I was a newly minted diver. (No, I wasn't angry -- the sun was in my eyes!)

When we first unearthed this old photo, I had to laugh. That red thing I'm wearing looks like a life vest pilfered from an airliner, but it's not. Known as a 'horse-collar' vest -- for reasons I'm sure are apparent! -- it was used primarily for surface flotation.

Dive gear is very heavy, and can be cumbersome. Swimming on the surface with, among other things, a metal tank on your back, and lead weights arrayed around your waist can be incredibly daunting at times. When the flotation vest was inflated, it helped counteract that weighed down feeling, and enabled divers to keep their heads above water while waiting for a boat, or swimming to shore. Those horse-collars were not very comfortable, however.

The vests had little CO2 cartridges inside. The CO2 could be released to rapidly fill the vest in an emergency, but most of the time, we blew the things up by puffing into the little inflator hose. The CO2 cartridges were single-use only, and it was expensive to replace them all the time, so we really did restrict ourselves to using them only when we were struggling or in a jam.

Fortunately those dopey horse-collar vests with the CO2 cartridges are no longer used by sport divers. They've been replaced by buoyancy control devices (BCDs for short), in the form of vests, jackets, or pouches (called 'wings') attached to a harness. These days, BCDs are inflated at the push of a button, with air supplied from the scuba tank through a special low-pressure hose. Divers can and do still use the BCD for flotation on the surface, but they also make use of the device underwater. By adding a little puff of air to the BCD at depth, divers can adjust their buoyancy, compensating for the weight of their gear.

The next thing I spotted in the photo was the tank -- or rather the valve on the tank -- and the regulator. We were using "J-valves" on scuba tanks at that time. There was no such thing as a submersible pressure gauge, so we could not monitor how much air we had left in our tanks once we entered the water. Tanks fitted with "J-valves" had a mechanism that blocked the diver's air supply at a certain (low) pressure level. The valve had a lever on it that the diver could pull to release the remaining air, known as the 'reserve' air. Believe me, that reserve wasn't much, but it would provide a few more breaths -- usually enough to get to the surface (we hoped!).

The regulator in the photo is a single-hose demand flow regulator, which was a pretty sophisticated rig at that time -- compared to, say, a double-hose regulator. Those old double hose regs required the diver to sort of suck the air out of the tank! We still use single-hose demand flow regulators, but the ones we have now have numerous ports on the first stage -- the part that attaches to the tank valve. To those ports we attach various pieces of gear, including power inflators for our BCDs, submersible digital pressure gauges so that we can continuously monitor our air supply, and one or more extra second stages -- the part of the regulator that has the mouthpiece -- to facilitate sharing air with a dive partner if need be.

Note the clunky old analog depth gauge that I'm wearing on my wrist in that photo. Key pieces of dive management gear in those days were the depth gauge and the dive watch or timer. Those relics now have been replaced by digital electronic decompression computers which continuously sense depth, keep track of elapsed time, and recompute every few seconds how long we can safely remain at a given depth -- as well as many other bits of information that I won't go into until another time.

Even our wetsuits have changed. The one I'm wearing in the photo had no lining and was extremely difficult to get into -- just rubber against skin. Everyone carried a box of cornstarch or a can of talc in their gear bags then. We applied it liberally before donning our suits, but it made quite a sticky mess, and often didn't help the process all that much. These days our suits are lined with Polartec or other soft materials that make them as easy to slip into as a pair of jeans.

Ahh, the good old days!