RULE #4: Use Your BC Less

It sounds counterintuitive to say that you can control your buoyancy better by using your buoyancy control device less often, but that's how it works. For example, suppose you're a bit negative and slowly drifting deeper, so you squirt a little air into your BC. Suppose further that, by chance, that one squirt was exactly the right amount of air to make you neutral. But you don't stop descending immediately because you've got downward momentum. Your body and dive gear, though nearly weightless, have a lot of mass and take time to slow and stop, just as an ocean liner coasts forward long after its engines stop.

Your descent is gradually slowing, but you don't realize it so you assume you're still negative and squirt a little more air into your BC. Now you're actually a little positive, but that's not obvious either, because after you come to a stop you will seem to pause there for a moment or two. "Ah, I'm neutral," you think, but in fact the small amount of lift in the second squirt of air is gathering its strength, so to speak, and gradually beginning your ascent.

When you notice you're now moving upward, you dump a little air, making you neutral. But nothing happens immediately so you dump more air, and now you're negative again. And so on. This is why many divers seem to be constantly fiddling with their BC controls and bobbing up and down in the water column. What's needed is the patience to wait three or four seconds to see what happens after that first squirt of air before you hit the button again.

Naturally, you need to use some judgment. If you're dropping like a rock, you need to be more aggressive with your BC controls. Overweighting and a thick wetsuit or a dry suit complicate the situation too, because they expand or contract with depth changes and exaggerate your buoyancy changes. But, as you zero in on neutral buoyancy, you want to wait longer and longer before pushing those buttons.

Once you've found neutral buoyancy, you don't want to mess it up by touching the buttons again. You can make small buoyancy changes, to hop over a barrel sponge, for instance, by inhaling and holding it (with your chest, not by closing your throat). Likewise, you can get temporarily negative by exhaling as much as you can and holding that for a few seconds. You can make depth changes of four or five feet by using your lungs alone, without messing with your BC and losing that hard-to-find neutral buoyancy.
 

RULE #5: Drop Two Pounds

Don't worry too much whether the water comes to your chin or your eyes when you float on the surface. The weight calculation methods involving your height, weight, shoe size, whatever, just get you into a very big ballpark--within, say, four to six pounds of the right amount of weight.

In-water buoyancy checks can be inaccurate too, especially when done off the dive resort dock at the beginning of your vacation. During your first hours in the water, you're still keyed up and moving your arms and legs a little, which creates lift. The result is almost always too much weight, because when you can't get under the surface, it seems obvious you're too light, so you add lead. The real problem is getting rid of lead until you're within a pound or two of the minimum. And the only sensible, realistic way to do that is to experiment where it matters, at the end-of-dive safety stop with a nearly empty, buoyant tank. Here's the drill:

Step One: After finding that ballpark weight and checking it off the dock, take two pounds off your belt and put it in your BC pocket where you can get at it under water. So far, you're still carrying the same amount of weight. Now go diving.

Step Two: At the safety stop near the end of your dive, when you're down to 500 psi or so, hand the loose weights to your buddy. That's not too much extra weight for him to manage, or too much for you to lose--especially if you can grab an ascent line.

Step Three: Work on getting air out of your BC until you are neutral again. Roll on your back, for example, to move any air bubbles inside to your exhaust valve so they can be expelled. You should be relaxed now and not generating lift by finning unconsciously, but to be sure, grab your fin tips in the "Buddha" position. Can you hang neutral? Then you didn't need those two pounds and can leave them behind on the next dive.

Step Four: Before your next dive, return to step one and try to get rid of another two pounds. Keep it up until you can stay perfectly neutral at the safety stop with about 500 psi