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Buoyancy Basics Part 3: How do I correct my buoyancy when scuba diving?

2016-11-25 12:27:29

Buoyancy Basics Part 3: How do I correct my buoyancy when scuba diving?
Perfect your buoyancy

By now you have probably read our first two articles of the Buoyancy Basics series.
Part 1: Why is buoyancy important to scuba divers?
Part 2: Buoyancy defined - positive or negative?

So, you know why neutral buoyancy is so important, and how to quickly determine your buoyancy during a dive. Let's imagine you have discovered that you do not have neutral buoyancy. Let's say you have a slightly negative buoyancy. You need to correct it, right? Right!

But how, exactly?

"That's easy", you might be thinking. "Just put more in air in your BCD!" And you would be right. But that's not the only thing you have to do.
Here's what happens quite frequently: you stop moving, check your buoyancy, and realize you're slightly negative. You add air to your BCD, and re-check your buoyancy. You feel that now you're neutral, so you start kicking again to continue your dive. And immediately you feel that you suddenly have too much positive buoyancy, because you start floating upwards! So you quickly grab the BCD's hose, and dump some air to avoid an uncontrolled ascent. You sink back down, and stop kicking to re-check your buoyancy. You will likely realize that you're too negative, again, and re-add some air to your BCD. You make 100% sure that you're neutrally buoyant, and then happily start kicking again. But you start floating upwards again!! Sound familiar?

What's happening? How come you're neutral when you're not moving, but seem to become positively buoyant as soon as you start moving?

The answer has to do, most of the the time, with body position. When you add air to the BCD, you have to make sure that before you start moving again, you get in a more horizontal position. In other words, lift your legs!

Here is why you need to do that:

What happens when you dive with a slightly negative buoyancy?
You end up in a diagonal position, with your legs lower than your torso. This way, when you kick, you propel yourself upwards with every kick, and compensate for negative buoyancy. But what is happening when you add air to your BCD? You no longer have the negative buoyancy dragging you down, so if you stay in that same diagonal position, and kick, your own fins will propel you upwards.
What you thought was a sudden positive buoyancy, is simply that your body position means your kicks are pushing you upwards.

So, let's solve this:

Add air to your BCD, and at the same time, get more horizontal. This way, when you start kicking again after your buoyancy check, you will move only forward, and not up. And you will avoid the annoying "add air - float up - dump air - sink down - start again" cycle.

Of course, it is not always easy to know if you are horizontal or not. That's where your buddy can help. Ask your buddy to let you know if you have a diagonal body position, and to help you correct it. Or, if you are diving with a SUB AQUA DiveCenter instructor or dive guide, ask for help. We will always be happy to help you improve your buoyancy, by assisting you underwater and giving you feedback if you ask.

Getting someone to actually film you with a video camera and reviewing the footage is also a wonderful way of becoming more self-aware of your diving style and body position.

Most of the time, correcting your body position while establishing neutral buoyancy will be enough to solve any issues. But once in a while you might find that even with a nice horizontal position, you still keep floating up when you try to get neutrally buoyant.

If that happens, check your breathing. Your breathing can and will affect your buoyancy. It happens, sometimes, that while we are stationary we breathe normally; but the moment we start moving we inhale a huge lungful of air and start breathing more deeply. If you do that, you will make yourself more positively buoyant, and no matter how horizontal you get, you will not be able to stop yourself from floating upwards.

Avoid this with these 5 steps:

1. Stop kicking, breathe normally, check your buoyancy.
2. If needed, add a bit of air into your BCD, until you become neutrally buoyant. Don't kick.
3. Exhale completely, and simultaneously get in a completely horizontal position (in other words lift your legs).
4. Only now start kicking to move forward, and start breathing normally.
5. Pat yourself on the back for your new-found, happy, neutral buoyancy diving style. You've cracked it!

SUB AQUA DiveCenters strive to offer the best possible service to our divers, and that includes helping them to improve their buoyancy, if they wish. Come diving with us, and don't be afraid to ask questions or ask for help/advice.

Or sign up for a PADI Peak Performance Buoyancy specialty course, if you really want some practice time with an instructor to help perfect your scuba diving style.

Continue... Part 4: Correct weighting for scuba diving