A question about buoyancy control at shallow depth

[grf88]

I still don't believe that changing your CG or the movement of any air spaces will have any effect your bouyancy.

Your ballast and the water volume displaced by air remains the same, no matter what position the air pocket(s) is in. It will effect your trim around but not change any bouyancy values.

Raising the flexible air spaces to a higher location will cause the air in them to expand and displace more water thus creating buoyancy. If you are rotating about your centre of gravity these air spaces will be at a shallower depth than they were previously when you were horizontal. This is further exaggerated by the fact that any air in your BC will also rise within the BC to a higher location both relative to the BC and the diver.

 

[Teamcasa]

Raising the flexible air spaces to a higher location will cause the air in them to expand and displace more water thus creating buoyancy. If you are rotating about your centre of gravity these air spaces will be at a shallower depth than they were previously when you were horizontal. This is further exaggerated by the fact that any air in your BC will also rise within the BC to a higher location both relative to the BC and the diver.

By higher location, do you mean relative to the surface? If so, I'd agree. If you mean, a diver at say 40' goes from horizontal to verticle but reamains in the same place/depth in the water column and the air pocket moves to the top of his BC and or drysuit makes him more bouyant, then no, I don't think so.

The water pressure surrounding the air keeps the air volume the same, regardless of the flexibility of the material holding the air in one spot.

 

[grf88]

By rotating about your centre of gravity the air spaces move to a shallower depth as you become more vertical. If you have almost no air in your BC you can actually descend by rotating your body the other way but the effect is not as pronounced. I practice my buoyancy regularly in the pool and this is when I discovered it.

 

[TMHeimer]

I had a lot of buoyancy problems at first (like everyone). Particularly on my OW check out dives, where we were given a weight belt without doing a buoyancy check (no time to do that for everyone when we're in wetsuits in Nova Scotia in Nov.). Being overweight was the culprit. After buying my own gear and doing the buoyancy check pretty much all my problams disappeared. Taking the Peak Perf. Buoyancy course helped some. Weight distribution was covered. There are several fine tuning techniques, but by far I found just being properly weighted the answer.