Bouyancy and Holding Breath...

Im a newbie (8 dives). My first 5 bouyancy sucked...bad. I was wearing 26lbs with a 3MM farmer john. Read on here about not finning when trying to go down, not letting breath out, etc, etc. Dives 6,7,8 were in very tropical area, I was determined to NOT use that much weight so I could take advantage of my air and have over a 25 minute dive.

So dive 6 I used 16, YEAH MAN! Bouyancy isnt so hard anymore! No longer did I sink like a rock only to rise like a baloon, SWEET! Dive 7 I used 14, Dive 8 I used 12. Each dive was my longest dive ever... YES!

So anyway, now I understand the ability to control bouyancy with breath which I can now do very nicely. Here is my problem/lack of understanding.

When I exhale I start to sink, when I inhale I start to rise... so how do I hover without holding my breath? I watched a DM hover 3 inches off the bottom starring at a lobster for a minute and she never went up or down, cant remember if she was making bubbles (should have paid attention to that).

So how do ya do that without holding your breath?

Bascially with my new found breath controlled bouyancy my swimming in a straight line horizontally probably looks like a nice even set of long peaks and troughs. When swimming over the flat bottom I breath in, go up a foot or two, breath out and go back down a foot or two. If Im not paying attention I have to take a quick, deep breath to not get too close to no touchy stuff...

Am I still overweighted? I can do the 15ft, half tank half breath hover with no air in the BC, what gives?

The deeper you are the less impact your breathing will have on control. If you are half tank no air in the BC at 15 feet you might want to add a pound or two. As for holding your breath, you know that can't be the answer, try not breathing so deeply to start with, novice divers tend to nearly fill their lungs with each breath, but that isn't how you breathe up here. On the surface you use maybe 1/4 to 1/2 your lung capacity and you neither empty them on exhalation or fill them on inhalation. Relax and practice, sounds to me like you're most of the way there.

Theres a slight delay in action between adjusting buoyancy and anything happening - the same goes for breathing cycle. Take a full lung of air underwater and you'll have 2 seconds or so before you start to rise, breathing out is the same.
To keep a constant depth you (i) dont take full in/out lung breaths - just breathe normally and (ii) you can get an in/out rate that means its happening too quickly for large changes in buoyancy to take effect.

Diversauras:

The deeper you are the less impact your breathing will have on control.
..snip..

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Just to throw in my 0.02c.
If I expand my lungs by 2 litres, I displace 2kg of water and generate 2 kg of buoyancy at any depth.
The lower apparent sensitivity at depth then comes from the fact that the pressure change resulting from any resulting vertical movement is a lower percentage of the absolute ambient pressure so there is less positive feedback from the BC expansion which would amplify the initial movement.

What mike just said was....the deeper you are the greater the pressure so any minor buoyancy changes aren't as apparent as when your are shallower..ie: less pressure.

String mentioned that there is a delay to the reaction to the breathing cycle, so part of boyancy is also timing the breathing pattern. At the time you start to float, try to be exhaling, so that when the sinking starts, your breathing cycle is beginning to inhale. You learn to use the delay to your boyancy advantage
Takes lots of practice though...

What Tom said.

jepuskar:

What mike just said was....the deeper you are the greater the pressure so any minor buoyancy changes aren't as apparent as when your are shallower..ie: less pressure.

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Nice translation. :frlol:

--tom--:

String mentioned that there is a delay to the reaction to the breathing cycle, so part of boyancy is also timing the breathing pattern. At the time you start to float, try to be exhaling, so that when the sinking starts, your breathing cycle is beginning to inhale. You learn to use the delay to your boyancy advantage
Takes lots of practice though...

Click to expand...

I see what youre saying. I think I could manage this, Ill have to try that. I think Im more reactive as in opps, Im getting closer to that coral...BIG BREATH IN...up and over...now Im too far up...breath out to go closer, little breaths in to stabalize my decent.

I figured the answer would just be practice but wanted to see if there was a trick I was missing.

Thanks for the advice ya'll

String:

(i) dont take full in/out lung breaths - just breathe normally and (ii) you can get an in/out rate that means its happening too quickly for large changes in buoyancy to take effect.

Click to expand...

These negatively impact SAC rate though, IME anyway. Try to maintain a slow steady pace of near full breaths for the best exchange of O2 and Co2 and you get better consumption. IMHO the "rythym method" like Tom describes is the most desireable balance. Using the shallow breath or speeding up respiration should be for quick periods of absolute still like taking pictures. If you find yourself crashing into the bottom on the down cycle you might be too low in the water column to begin with as well, especially during point-to-point travel. One mistake I see often in newer divers is wanting to be so close to the bottom they are nearly dragging the mask. YMMV