Donald signals to the divemaster that he’s reached 700 psi (50 bar). The divemaster replies with the safety-stop signal, and three minutes later, Donald is on the surface with the boat heading his way. Poor air consumption when scuba diving is the bane of not only Donald, but many divers’ existence.
Twenty minutes later, with a cup of tea in his hand, Donald is getting anxious about the rest of the group. They’re approaching 60 minutes underwater. He knows he’s not great on air, but surely nobody can continue for an hour? Ten minutes later the group hits the surface and joins him on the boat. The divemaster logs their details in his roster: 870 psi (60 bar); 1,015 psi (70 bar); and one woman has a staggering 1,740 psi (120 bar) — less than half a tank for a one-hour dive that reached depths of 82 feet (25 m).
Just how do they do it?
Using a bigger tank to compensate for poor air consumption is akin to a bad driver relying on an airbag. Somewhere along the line you’ve missed some training or not developed the skills and techniques that will allow you to log longer bottom times. I hear many vacation divers complaining about their predicament as if they were born with it, and remedying the situation is beyond their control. Common phrases include: “It’s just one of those things;” “I’m terrible on air,” “I’ll just stay shallow,” and “Give me a 15-liter tank or I’ll never keep up.”
The problem here is that big tanks create more weight, drag and discomfort, and their extra capacity is often useful only in accommodating the increased workload. In some instances, their bulkiness can cause a greater net loss of energy than a smaller tank.
But you’re a trained diver and have the certification card to prove it, so where did it all go wrong? The answer is…it didn’t. For something to go wrong it first had to be right, and it never was — you can’t undo good technique any more than you can unlearn how to ride a bicycle.
What’s the answer?
An open-water course has over 30 hours of training, but that includes fewer than two minutes of mandatory buoyancy practice in the shape of mid-water hovering, but good buoyancy is the key to lowering your air consumption. On a list of over 25 skills, it’s hoped that your buoyancy will somehow become perfect, and perhaps over several dive vacations and further practice, it may eventually improve.
In my world, it is your unequivocal birthright to learn good buoyancy control in an Open Water course. Two minutes of hovering is luck — 20 minutes is competency. Devoting valuable time to a specialist sport and coming away lacking the most important skill represents failure on a massive scale, and it adds credence to the belief that only the chosen few can succeed.
It takes less time to teach good buoyancy control than it does to deal with the negative consequences of its absence. Segregating good and bad divers, allocating private guides, de-briefing errors and lecturing about safety issues are time-consuming solutions, and help perpetuate the normalization of poor air consumption.
The main ingredients of good buoyancy control are correct weighting, mastery of your BCD, and good trim in the water; each deserves a separate mention. We’ll address all three in turn in the following three articles.
By guest author John Kean
John Kean is the author of four books and holds the PADI Master Instructor rating along with TDI’s Advanced Trimix Instructor qualification. Since 1997 he has amassed over 7,000 dives, trained over 2,000 students and project-managed several world record deep dive events. His books are available here.