Buoyancy trick?

[mickd]

I have read somewhere about a technique to achieve perfect neutral buoyancy that has something to do with holding your deflator hose horizontally. Is there any credence to this? I haven't yet had a chance to try it in the water, but physics of it kind of make sense in that holding it horizontal while you're in a horizontal trim (and the deflator button pressed) should allow any excess air to escape, but not all of it. Can anyone out there elaborate on this or debunk it?

 

[AfterDark]

I have read somewhere about a technique to achieve perfect neutral buoyancy that has something to do with holding your deflator hose horizontally. Is there any credence to this? I haven't yet had a chance to try it in the water, but physics of it kind of make sense in that holding it horizontal while you're in a horizontal trim (and the deflator button pressed) should allow any excess air to escape, but not all of it. Can anyone out there elaborate on this or debunk it?

Never heard of it sounds like BS. I stay neutral the whole dive never hold my inflator hose except to inflate. If there is any "trick" it's in breathing and weight distrbution. Truth of the matter is you need to be aware of what's happening around you. After awhile you'll "feel" when your neutral and when your not.

 

[divebunnie]

I am with AfterDark on that one... how can holding your hose horizontally create neutral buoyancy? If you are ascending, you are likely to find that you are then unable to deflate enough in that position to remain neutral, and if you are descending and not adding small spurts of air to your jacket along the way, you will guaranteed find yourself negatively buoyant very quickly.

Practice makes perfect, just remember as you go down you will need to add little bits of air, and likewise as you go up you will need to dump little bits of air... as you swim along, you can use your lungs to fine tune any temporary changes in depth. Hope that helps

 

[ScubaWulf]

It may have to do with the technique of holding it basically parallel with the bubble in your BC while you are ascending. As the air in your BC expands while you rise any excess will come out basically keeping you balanced for buoyancy while you are coming up. If you have really good buoyancy there won't be very much air if any to come out while you come up though. I'm still a very new diver myself but I've worked hard on buoyancy. I may add a shot or two of air once I descend but it will be minimal. Even with minimal air in there I have tried this and it seems to work. I'm sure more experienced can comment on this technique.

 

[kathydee]

Proper weighting is also important. If you're overweight or underweight holding buoyancy is quite a bit more difficult.

 

[mickd]

Let me clarify. I'm not really concerned with my buoyancy. I'm well weighted (I actually don't use any weight with my bp/w) and don't have any problems with it. I just read about this odd technique and wondered if anyone knew anything about it. It seemed kind of strange to me, and I haven't been able to locate the source again.

 

[Kilili]

'Tis nonsense.

 

[captain]

It may have to do with the technique of holding it basically parallel with the bubble in your BC while you are ascending. As the air in your BC expands while you rise any excess will come out basically keeping you balanced for buoyancy while you are coming up. If you have really good buoyancy there won't be very much air if any to come out while you come up though. I'm still a very new diver myself but I've worked hard on buoyancy. I may add a shot or two of air once I descend but it will be minimal. Even with minimal air in there I have tried this and it seems to work. I'm sure more experienced can comment on this technique.

Correct, it is a technique to use to maintain a stable buoyancy condition when assenting not to maintain neutral buoyancy at all times.

 

[Soggy_Diver]

I have heard of this idea of holding the hose horizontal before, and played around with it once.

Theoretically, if your only source of buoyancy were your BC, then if you are neutral, and you open the valve, and hold the hose roughly horizontal, then as the air in the BC expands, the excess will trickle out. This would keep the volume of air in the BC constant, and your buoyancy neutral. This does not depend on keeping the hose exactly horizontal, but tipped a bit downward, to the point where the bubbles are just on the verge of trickling out.

But here is what really happened: I tried it wearing a 7 mm wetsuit. So as I ascended the air slowly trickled out of the BC, as expected. BUT, the wetsuit was also expanding, increasing my buoyancy. So in fact, I had to vent additional air to stay neutral through the ascent. I could do this by tipping the hose up a bit more vertically.

So it is more like a throttle: you tip the hose down to get a bit more buoyant as you ascend, and tip the hose up to get less buoyant as you ascend. But really, this is a pain; it is easier to just vent little puffs of air as you ascend to stay neutral.

 

[g1138]

The way I heard it was when ascending vertical you hold the hose up but with the inflator nozzle pointed down. It prevents you from venting all your air too quickly, and helps with controlling your ascent so you don't vent all your air and start to sink.

I do this just to keep water out of my bladder. I've never actually tried to continue holding the button down after I felt neutral. I just cut off my purge whenever it felt right.
The trick does not work with horizontal positions though, since the air may be trapped away from your purge.