Buoyancy woes. Need help.

[diverdad87]

I'm on my 12th dive. Trim is improving, air consumption is improving as well. However I am having a issue with holding a steady depth.

I attempt to get neutral. Add a puff of air to BC. Get close, add another puff and it's like I go from one extreme to another and I start heading up. I am giving the air time to start working, dropped some weight, etc. Im wasteing air on this and I feel like I'll never get this down. It's either sink or ballon up.

Anyone have suggestions on how to fix this?

 

[NJDiverMark]

Practice as redundant as it sounds

 

[CamG]

Greetings diverdad87 and it sounds like you might just need to work on tweaking your weighting till you find the perfect weighting.
It takes some time and dives to narrow it down, do not worry it will come.
The best way to find that perfect buoyancy is to stay in the water and have a positive attitude.
Having a good dive buddy and or mentor is another big help.
You might think about purchasing some smaller weights 1 or 2 lbs, I used ankle weights for about a year to get it just right.

Being over-weighted will cause the up and down symptoms you describe.
It also is very taxing diving with extra weight a tell tale sign is if you are having to carry a lot of air in your BC you probably could shed a few lbs off your belt or pocket.
Start with small increments when you are experimenting and do a proper weight check at the surface.
If you are struggling seek help from a DM or Instructor to come to your aid.
Once you have a good grasp on the skills to tune your buoyancy it is a matter of time till you narrow it down.

Good luck and always dive safe within your training limits.
CamG Keep diving....Keep training....Keep learning!

 

[Drewski]

It's most likely your breathing. Neutralize at depth as you indicated, then exhale completely. Watch what happens. Slow your breathing rate by relaxing. Stay in one spot until until you are breathing slowly and without much effort.

Now, neutralize again. Keep in your mind that you want an even and steady breathing rate, but without big gulps of air. You're probably experiencing what you are because you are progressively inhaling more and increasing total chest expansion. If you start to get positive, slow down, relax, exhale again and start over.

When you get this right, you will near the bottom at the beginning of the dive, set to neutral then use just your breathing to control buoyancy for the rest of your time underwater.

Good Luck!

 

[coldsmoke]

Yeah - most likely it's your breathing. BC adjustments are more for relatively major buoyancy adjustments while your lungs are for fine tuning. As a new diver it's difficult to realize the impact that breathing can have and the lift potential of your lungs.

Next time you're out try to use your bc very little. Experiment with just how much control you can have just by using your lungs. Remember that changes are slow so anticipate it and make the change a little before you actually want to experience it.

Good luck,

Hunter

 

[Ripple in still water]

You might find that it helps to bias your BC inflation to being a bit negative. Ultimately, as you know, you want to control your buoyancy at a given depth range with your breathing, but if you are having trouble with this, it helps to just stop fiddling with BC for a bit. I find it harder to control my buoyancy if I'm slightly positive than if I'm slightly negative. Unless you are sinking like a stone, if you are too negative to control your buoyancy easily with your breathing, you ought to be able to ascend a bit until things feel right. The idea is to get a feel for controlling your buoyancy w/o using the BCD.

 

[Charlie99]

Some numbers to put into perspective the change in buoyancy from changes in lung volume:

Tidal volume, the normal resting inhale/exhale while on land is only about 1/2 liter or 1 pound.

Vital Capacity, the amount of air from a vigorous inhale all the way down to a vigorous exhale is 3 to 5 liters, or about 6 to 10 pounds of buoyancy change.

We tend to breathe more deeply underwater, so you buoyancy at the top of a normal inhale is probably 4 or 5 pounds more positive than at the bottom of a normal exhale.

------------------------

A fellow diver asked me once how I knew when to add or release a bit of air from my BCD, and I couldn't explain how I knew. On the next dive, I figured out that I had grown accustomed to automatically adjusting my average buoyancy by changing breathing pattern. If I needed a bit more buoyancy, I would tend to inhale a bit more, and exhale a bit less. Vice versa if I needed to be a bit more negative. Once my breathing pattern automatically shifted off of center significantly, I would re-center my breathing by adjusting the BCD.

I helps to use a frog kick, because it has a glide cycle where you aren't kicking. If you are flutter kicking, periodically pause to check your buoyancy.

--------------------------

The 15' safety stop is a great place to practice buoyancy control. Staying horizontal adds a bit more resistance to vertical motion and makes it easier. Try to learn how to stay at more or less constant 15' without kicking. Once you have mastered that skill, using your lungs to fine tune your ascent/descent will be easy.

If you find 15' safety stop without kicking impossible, try doing a non-kicking hover at 30 or 40', where your wetsuit compression/buoyancy doesn't change much with depth.

 

[DevonDiver]

Get your weighting perfected and you'll be able to fine-tune your buoyancy by using your breathing. The will eliminate the need for that extra 'puff' of air...and consequently eliminate the 'up & down' over-correction symptoms you describe.

You will be surprised by the difference between the amount of weight you actually need, compared to the amount of weight you think you need. Guaranteed.

 

[Charlie99]

Greetings diverdad87 and it sounds like you might just need to work on tweaking your weighting till you find the perfect weighting.........You might think about purchasing some smaller weights 1 or 2 lbs, I used ankle weights for about a year to get it just right.

Being over-weighted will cause the up and down symptoms you describe.

Get your weighting perfected and you'll be able to fine-tune your buoyancy by using your breathing. The will eliminate the need for that extra 'puff' of air...and consequently eliminate the 'up & down' over-correction symptoms you describe.

You will be surprised by the difference between the amount of weight you actually need, compared to the amount of weight you think you need. Guaranteed.

There is a significant different between being overweighted and being negatively buoyant.

Being perfectly weighted reduces the buoyancy problem a bit, but if you have a thick wetsuit, even with "perfect" weighting you will be significantly negatively buoyant at depth, and will have to add air to the BCD.

There is not much difference between being 4 pounds overweighted and adding another couple of millimeters of wetsuit thickness.

Perfect weighting helps, but it is not a silver bullet.

Not having a wetsuit is even more helpful.

 

[dpaustex]

Congrats on your 12th dive!!!

On the buoyancy, you are to be commended for working on it. As an instructor, I think it is one of the things that takes the most practice, and people find a bit frustrating.

First, make sure your weighting is correct. As you may recall, you should weight such that you float eye-level with weights and no air in your BC, and not holding a deep breath, but just a normal inhalation breath.

If you have access to a pool, I suggest doing this in your LDS pool. Take your fins off, so you won't feel the urge to kick (messes up most students, as they won't stay still in the water). Next, exhale and do a very slow descent. Give physics a chance to work....that is, as you empty the air from your BC and start to slowly descend, quit letting the air out.

You will notice that as you descend (while diving), that as you start to descend, you go down faster and faster. This is because your wetsuit and gear is compressing at depth. However, if you're doing this in the pool, you'll mainly use your lungs.

In the pool, I have student descend to the bottom. Then, add a SINGLE short (and I mean as quick as you can get air in, then let off the inflator button) burst of air into your BC. Relax, and go through a breathing cycle of a couple of breaths. It is very important while working on buoyancy not to hold your breath.

NEXT, if that single short burst doesn't work. Add one more. Repeat the whole process, until you almost feel yourself about to lift off the bottom of the pool. Next, inhale a BIGGER breath, and you should feel yourself start to rise. This "bigger" breath is called a "top breath", wherein you are inhaling a little more than normal. As you rise, exhale slightly, then go to a normal breathing pattern. You should be able to rise and fall a foot or two, just by using your breathing, once you've got the right air in your BC.

Don't get frustrated!!! Keep practicing, and if you're having issues, talk to your instructor, or ask the shop. Everyone will be happy to help you out.

Once again, you are to be commended for realizing you have an issue, and that it needs work. Once you nail your buoyancy, you'll find that once you're at depth, you'll almost never use your inflator/deflator. The only time you'll use it is to let air out on your ascent to your safety stop, and then to inflate when you're back on the surface.

Stick with it, and you'll be amazed at how much enjoyable diving is with good buoyancy!!!