donacheson
Contributor
Yazrick:I have read a few posts that mention buoyancy tests, and to be honnest - this is the first I hear of it.
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Is there any advice on how to get my bouyancy right ?
Some of the advice you've gotten is sound; some could be improved.
Your objective while diving should be to be able to maintain neutral buoyancy throughout a dive. The minimum amount of lead weight you need to do that is that amount required to keep you neutral just below the surface with an empty BC and near-empty tank while breathing normally. This ensures that you can always do a comfortable safety stop and ascend to the surface under control at the end of a dive.
Overweighting means you always have air in your BC and this air expands with decreasing depth, causing you to accelerate toward the surface, and compresses with increasing depth, causing you to accelerate even deeper. While being a pound or two overweight isn't difficult to handle, being 10 pounds overweight can make it difficult to maintain a desired depth or rate of ascent or descent, especially during the ascent. For a diver neutral at 15 feet with 10 pounds of lead in excess of the minimum amount, descending 10 feet means the diver is at least 1.7 pounds heavy while ascending 10 feet means the diver is at least 2.6 pounds light. These amounts mean adding at least 1.7 or dumping at least 2.6 pints of air, respectively, in order to remain neutral. By way of contrast, a minimally weighted diver in tropical gear (no neoprene) neutral at 15 feet with an empty BC and near-empty tank doesn't need to add nor remove air to/from his BC under the same circumstances.
Once a minimal weight for you and your gear is established, then you can experiment with trim (moving weights about) so you can easily swim, and even drift for a short period of time without moving hands or feet, in a horizontal position. As others have pointed out, swimming horizontally is the most efficient way.