Step by Step Bouyancy Technique

[gnulab]

Hi Divers,

I would to ask for some clarification and specific, step-by-step guidance what's the correct way to achieve motionless hovering while underwater.

I am still a newbie, logged only 19 dives and I have only been with 2 different DM all these while.

I know that the 1st step in achieving good bouyancy is to find the correct amount of weight we need, followed by the correct trim. Also, even those who could remain motionless, strictly speaking they are bobbing up & down, except the distance travelled is only within 10cm range (my guess), is that right?

This is the 1st DM explanation:
1. Exhale completely & empty the air in BCD at the surface in order to descent.
2. Then, at the bottom, inhale completely (BCD is completely empty of air at this point).
3. Depend entirely on our lung to control our bouyancy.
However, I think there is a flaw. When say you're at 18m, inhale 6 liters of air, exhale 6 liters of air. When I want to ascend to & maintain at 12m, I have to inhale 6 liters, and exhale 3 liters. Since my lung is acting as a bouyancy "device", it must maintain 3 liters of air in order to maintain my dept at 12m. But then again, our body requires 6 liters of air to function properly, so how is that method possible? (figures are arbitrary)

Another DM told me I should repeat the fin pivot.
1. Exhale completely & empty the air in BCD at the surface in order to descent.
2. Then, at the bottom, inhale completely (BCD is completely empty of air at this point).
3. If I don't rise, exhale completely and introduce a short burst of air into the BCD.
4. If I rise, then rely on my lung to fine tune my bouyancy. If I still haven't risen, then repeat step 3 till I can manage to rise from the bottom, then move to step 4.

Both DM did mentioned that it comes with practice. Is there a correct way or everybody is just different? A member (nitroxnut) seems to be leaning the school of thought that there is a correct way to achieve it, while some members advised to dive more and try what works for oneself.

If both advice are wrong, I'll highly appreciate if some guru could provide step by step instruction.

Thanks!
Henry

 

[oly5050user]

I would suggest to go back to your instructor and ask why this was not covered in your ow course and training dives..if it was then sign up for a peak performance buoyancy class..if it was not covered in ow class ask for money back.

 

[Dash]

Im no expert but I dont believe you should think of, or use your lungs as a buoyancy device. It may lead you into holding you breath, which may result in a lung injury.

This does not mean you cant time your breaths to make a big inhale and rise just as you approach something underwater that you want swim over, or exhale to lower yourself, but you dont change your breathing or hold back breathing to maintain a certain depth. Your BC controls that function.

 

[ScubaSteve]

Im no expert but I dont believe you should think of, or use your lungs as a buoyancy device.......

Once you achieve neutral buoyancy, you should use nothing other than your lungs to control your position in the water column.

As has already been stated, this should have been covered in your OW classes. If it was not, get your money back and report the instructor to the appropriate agency. If it was, as for another pool session as a refresher with the same instructor.

1. Figure out your weighting
2. Exhale and let out (from your BC) enough air to allow you to break the surface and start descending.
3. Start adding small "tufts" of air into your BC while breathing normal and equalizing often on descent. You add the small amounts of air so you do not start a runaway descent due to lack of buoyancy. WATCH your depth always.
4. Ensure you stop above your desired depth and STOP. Watch your guages while you breathe and see if you are neutral.....add or remove air from your BC in small amounts as required to get you neutral.

This is the very basic idea for a true beginner. I do recommend that you go back to your instructor though.

 

[Dash]

Im not sure why you quoted me but in case I didnt explain myself clearly let me say that we are in agreement. Set nuetral with your BC, and your lungs can be used to move you up and down, provided you do not use your lungs to "hold" a depth and you never stop breathing.

 

[don Francisco]

Think of your lungs as the secondary bouyancy management tool. Establish your breathing pattern and adjust inflate/deflate your BC so as to be neutral at the average of your lungfull. You'll be slightly bouyant on the inhale and slightly negative on the exhale, but the plus/minus 3#s is only .02gs and so won't make much immediate impact on your position, with inertia and the water resistance keeping you fairly stable at your desired depth.

You also have to be aware of any unconscious finning since that can propel you up or down according to your trim, upsetting your efforts to hover.

As you master hovering, manage trim by adjusting the position of your weights as and by body control. As it all comes together, you'll probably find you can shed a few pounds as you get more comfortable in the water. Ideally you'll want enough weighting to comfortably hover at 15' with little or no air in your BC.

As someone mentioned, your instructor should have covered this and started you out properly. If you do AOW before mastering bouyancy, definitely tell the instructor that bouyancy and trim are high on you list of reasons for the course.

 

[Diver0001]

Henry,

I guess you're asking this because you're having trouble with it. Assuming you have the right amount of weight and your kit is more or less normal then I would say stop trying to "think" it and just try to "feel" it.

The feeling you're looking for is like being "carried" or "held" by the water. Breathing in and out will cause you to go up and down with a short delay of a couple of seconds. Once you have this delay figured out and you "feel" the water carrying your body then you're nearly there. After that the rest is just a matter of refinement.

R..

 

[psychocabbage]

what worked for me... because everyones idea was way off for me.. at least they way they described it.

I get in the same body of water wearing what I am going to be diving in. My wife comes with me holding weights. I have no air in my BC and I breath normally (remember the key to diving is to breathe...) She hands me weights until I can start to sink.. Not plummet.. sink..

Being new, you think to submerge you need to go down fast..but in reality there is a fine line between bouyant and not... that line is where you want to be.. so lets say you have all your gear and can now go down with 8lbs of lead. 10 lbs would of got you down faster but 8 does the job. If I want to decend faster, I swim down as fast as my ears can clear.. This helps me because when my dive is over, I dont so much add air to the bc as I slowly swim up watching my ascent rate. Once I get to the surface or near it (5ft) I inflate my bc and let it keep me up..

If I fine tune any, its going to be very tiny bursts and usually when going to a valley or peak and then after the obstacle or area is traversed, I let the air back out so the change in depth/pressure doesnt become an issue..

 

[TSandM]

Think about it. You get in the water carrying 80 cubic feet of gas, of which you are willing to use about 65, maintaining that 500 psi reserve. 65 cubic feet of gas weights about five pounds, so you are starting out carrying five pounds that you are going to "throw away" into the water. Therefore, at the beginning of the dive, you need to be five pounds more negative than you will be at the end of the dive, where you want to be neutral in very shallow water.

If you let ALL the air out of your BC, and never put any in (and we assume that you are not wearing any exposure protection that can compress), then at the beginning of the dive, you are five pounds negative, and you'd have to keep enough air in your lungs to counter that. It might be possible, but it would be uncomfortable and probably lead to not breathing very well. What you need is something to COMPENSATE for those five pounds . . . And that's a buoyancy compensator, which is why you wear one. (If you ARE wearing neoprene exposure protection, it will compress as you go down, and you have to compensate for that, too.)

So, at the beginning of the dive, you let enough air out of your BC to begin to descend (often, that may not be all of the air that's in it). As you descend, you will need to puff a little gas into the BC at intervals (I do it when I equalize my ears, and that works pretty well for me) so that you don't get too far off neutral as your suit compresses. When you reach the bottom, a sharp inhale or another puff of gas into the BC should be enough to get you neutral. When you are "neutral", you will rise and fall gently with your breathing, just a little bit. You can always test to see if you ARE neutral by exhaling and seeing if you drop a bit, or inhaling to see if you rise (do this while you aren't finning, though; finning can confuse the picture).

Of the two approaches you outlined, the second one is better, at least to me.

 

[rollerboi]

In my OW class, the instructor had us do a body weight check without our BC/tank on to determine the base amount of weight needed.

I found that I actually don't need any weight to get down. I've been throwing on a 2-pound belt just to trim me out a bit. I get nice and horizontal with the weight centered in front like a belt buckle. At depth, I only need a few tiny puffs of air when diving without a suit.

And lately, I've just been going down and hitting a few puffs when I'm at my desired level, very much like Lynn (TSandM) describes. I'm at the point where it's been pretty much a 'by feel' thing. I think if you focus too much on technique you overthink your way through it.