Tank pressure, hose length and the air consumption rate are some of the factors that are vital in the success of sharing air while diving. With regards to air consumption rate, divers have to know their companion’s level of air consumption since it serves as a basis whether the diver has to share air with a diving companion. With regards to hose length, sharing of air is most likely effective when air hose measures about two to three feet from the user.
Think you’re ready to share air? You may want to think again. Here are a few tips the training manuals probably didn’t teach you.
OK. You know the basics: Always carry an alternate air source – octopus, Air II, pony and reg, Spare Air – appropriate for your diving. Always review with your buddy what alternate air source you have and where it is. If a low-on-air situation occurs, pass your alternate air source or primary according to plan, establish contact and positive buoyancy, then make a controlled ascent – including a safety stop if air supply allows. That’s pretty much it, right?
You might be surprised at just how unprepared you and your buddy might be to share air.
* Are you diving with a Hoover? Your preparation to share air begins well before you enter the water. What do you know about your buddy’s air consumption? Does he suck it up faster than a vacuum cleaner? Or does she seem to sip air like a fine wine, always ending a dive with more air than you? This isn’t a competition, but knowing your buddy’s rate of air consumption can help you make better decisions under water and possibly avoid having to share in the first place.
* Does it work? One of the problems with an alternate air source is that we tend to ignore it until the next annual tune-up – or emergency. In the meantime, it may have lost performance, become full of sand, developed a loose mouthpiece or a frozen purge button, etc. A low-on-air situation is not the best time to find out your alternate air source is non-functional. A good habit is to occasionally complete your safety stop breathing from your alternate air source.
* How long is your hose? Having an alternate air source is one thing; having it or your primary on a hose long enough to reach your buddy without a struggle is another. While it doesn’t have to be as long as a caver’s or wreck diver’s hose (capable of being passed ahead or behind), it should extend approximately two to three feet in front of you and allow the second stage to fit comfortably in your buddy’s mouth.
* What’s your tank pressure? Surfacing with at least 500 to 700 psi in your tank already makes a lot of sense: You might just need that air if something unexpected happens – a reverse squeeze, rough surface conditions, heavy kelp or a rescue for instance. But here’s another reason: As tank pressure decreases, the work of breathing for many regulators increases. (Indeed, the U.S. Navy originally set the 130-foot depth limit in the 1950s because of the poor performance of that era’s regulators below five atmospheres.) If your regulator is not designed for high performance-the ability to continue delivering the air demanded of it despite increased respiration and lowered tank pressures – or if it has lost performance due to poor maintenance, the stress of a second diver on it could cause overbreathing: the inability of a reg to deliver the air demanded of it. Being prepared to share air means having a well-maintained reg as well as an adequate supply of air.
* So what is your regulator’s performance rating? You can’t find it out from the manufacturer, the internet, other divers or other dive magazines. The only independent regulator tests done in the U.S. for consumers are by ScubaLab. ScubaLab’s evaluations are based on laboratory and ocean tests. Why? You can’t determine a reg’s true performance potential by breathing on it in a dive store or on a relaxed recreational dive. You must stress-test regulators on a breathing simulator and in the ocean at depths greater than 130 feet. Only in this manner can you find those regs with the back-up performance you may need one day, whether in a low-on-air situation, sharing air or in some other unforeseen emergency.
* Are you prepared for non-textbook air sharing? During pool practice, the low-on-air buddy calmly approaches you, calmly gives the “let’s share air” signal, and calmly takes your proffered second stage. Unfortunately, that’s not always the case in a real emergency in the real ocean, where the low-on-air buddy is more likely to swim furiously to you and, without giving a polite hand signal, snatch your second stage right from your mouth. That’s why to be truly prepared to share air, you must be ready to find and use your own alternate air source and be ready to take control of a buddy who may be panicked.