One of the most important skills a diver can learn is buoyancy control, and in order to master that skill every diver must understand what pieces of her or his SCUBA gear determines if buoyancy during a dive is positive, negative, or neutral.
And every diver must know how to address an out of control buoyancy situation when one piece of equipment or another doesn’t work properly. Or when an improper choice of equipment goes unnoticed until after you descend to depth.
The goal of skillful buoyancy control is to stay at a specific level in the water column. Once you reach your diving depth you should ascend, and descend, no more than a foot or two with each breathing cycle.
When your buoyancy goes too far negative you risk plunging into the bottom. That’s a threat to aquatic life because every time you contact coral you kill it. It poses a threat to your life when you dive in an overhead environment because you might get trapped under some object, and run out of air – or you might not be able to get back to the surface.
When your buoyancy goes too far positive you shoot toward the surface. That’s a threat to your life because you risk burst lungs, and/or decompression sickness.
Over the years I faced a number of different situations that sent me into both negative, and positive, conditions. And a few times only the fact that I stayed always aware of my position in the water kept me from risking personal injury.
Each piece of gear influences your buoyancy differently, but some items of your scuba equipment interacts with others. You can’t just focus on only one thing during your dive while ignoring everything else.
Four main diving tools effect your buoyancy in ways that might cause you to suffer personal injury, or do damage the our underwater environment.
The first piece of scuba gear that always comes to mind is the buoyancy control device, or BCD. By controlling the amount of air in the BCD bladder divers keep themselves at a steady depth in the water column.
I’ve had my inflator valve suddenly start leaking air into my bladder on a dive. That sent my buoyancy into a positive condition, and my BCD wanted to take me straight to the surface. The opposite situation to that is when the bladders leak air outward, and you enter a negative condition.
Your scuba weight selection sometimes throws your buoyancy out of whack. When you under weight yourself your buoyancy goes positive as you progress through your dive.
One example of how two different pieces of equipment influence each other is that as you breathe air from your tank, the scuba air tank becomes more positively buoyant. You’ll need enough weight to compensate for that.
Over weighting creates the potential hazard of overwhelming the lift capacity of your BCD, and you might not get back to the surface. That’s an extreme case of choosing too much weight. At the very least excess weight makes you fight your buoyancy to stay level by constantly adding and releasing air to, and from, your bladders.
Your wetsuit changes your buoyancy over time. When you first get that brand new dive suit the material is good and thick – and it has a positively buoyant quality. As your suit ages the material starts to compress, and the positive quality of the buoyancy decreases. That suit will always have a degree of positivity. Just be aware that it changes, and in time a wetsuit will become less buoyant.
Other items of equipment to be aware of are your diving accessories. Dive lights, and underwater cameras most often are positively buoyant. Scuba divers normally don’t think to include these accessories into their buoyancy configuration, and as a result the weight selection is made without these items as part of the setup process.
The level of positive buoyancy that most accessories have is usually low, but it adds up with each accessory that you attach to your equipment profile.
It’s your responsibility as a skilled diver to master the art of neutral buoyancy control when you dive. You must know how to deal with any problems that happen to effect your buoyancy. That includes maintaining your scuba gear in proper working order, and knowing how to handle a sudden occurrence of malfunction – or dive profile change.