Yo-Yo - Too deep of a breath?

[Likes2Cruise]

I'm a newly OW certified diver and I'm experiencing an issue with my bouyancy at depth (well, around 20').

I take the described slow deep (not so deep as to fully expand the lungs) breaths with long full exhales - the result is a lift of about 3-4'. When I am done exhaling, I'm heading quickly toward the bottom.

As a result, I end up shortening my breath and either not exhaling fully or not inhaling fully and getting my breathing all messed up. Often, the result is a yo-yo effect that keeps me feeling off balance and a bit out of control.

Even more dangerous is the ocassional issue of continuing to go up if I don't fully exhale, causing me to have to vent the BCD and exhale fully to reverse the ascent.

Am I doing something wrong? Is there something I should be doing different (not breathe so deep)?

Thanks for any advice.

 

[Dark Wolf]

Being a new diver myself, I can relate to your problem! But the more that you dive, the better it will get. You will get more comfortable in the water, and with your gear in particular. Just give it time and keep diving, and you will be amazed. Being from the MidWest, diving in low vis really helped me. It makes every inch seem like a yard!
Don't give up, it gets much better. Then you will find new skills to work on!!

 

[1_T_Submariner]

Are you sure it is just your breath that is changing. Do you stop kicking? or moving in some other way?

Did you do a bouancy check with an near empty tank?
With a near empty tank you should be weighted so you float with your ears about level with the water (no air in your BC) and your lungs full (it will be hard not to kick if you are over weighted) then exhale you should descend slowly. I suspect you are over weighted and have a lot of air in your bc to compensate.

 

[munkispank]

Also- these problems seem to be amplified in semi-shallow water (15-20 ft range) my buddy and partner always has more trouble in the shallows in terms of this almost yo-yo feeling. In reality when I watch him he is just sinking and rising slightly as you would with a regular fin-pivot, but for some reason it feels to him like he is more out of control. If you have checked you weight and BC inflation as mentioned above, then perhaps you are over-breathing? (too deeply I mean) Relaxation will help to 'naturally' develop the slow rhythmic deep breathing which you are aiming for.

 

[Twiddles]

For me yo-yo was directly related to, too much weight. If your overweight and you have alot of air in your BC (Frankly at 20' you shouldn't have much) you will have large swings up and down while breathing. Try dumping some weight. Remember that in order to descend at the surface you may need to exhale and cross your legs for the first 10 feet in order to descend.

 

[spectrum]

Twiddles is on the right track!

Some amount of porpoising is normal with a deep slow breathing cycle. Knowing your dive physics tells you it has to happen. Normally its about half of what the OP described on the order of 1-2 feet. If you have too much weight then you have way too much air in your BC and that will amplify the porpoise effect. So step 1 is a good weight check:

Remember to set your weight so that you bob vertically at eye level at the end of your dive with an empty BC, an average breath, your feet still (crossed) and about 500 PSI in your cylinder. A deep breath should get your mask out of the water and a deep exhale should sink your mask. Do all of this while breathing from your regulator. The end of the dive is the defining moment for your weight requirement and you want just enough to let you stay down in the shallows with a light cylinder.

The rest of it you can manage with technique. Remember that buoyancy changes have a time delay before you really move vertically. If you pay attention you can learn to start your inhale just before you sink and begin your exhale just before you rise. There will still be some depth fluctuation but a tiny change in your kick or body posture can further smooth your path. It takes a little practice before it's automatic but being conscious of it all is the first step.

When you are trying to be very still in close quarters you will probably need to confine your breathing to a narrower and perhaps somewhat shorter cycle. There are some parts of many dives where it seems like I am breathing more for buoyancy management than for respiration, especially in surge. In the end lower the volume breaths trade off for higher frequency and it's all good for intermittent periods.

Pete

 

[DA Aquamaster]

As indicated above, when you inhale and exhale you are changing voulume and bouyancy so some rise and fall will occur. And as indicated above there is some lag due to inertia involved.

Also as indicated above, any extra gas in the BC needed to compensate for being overweighted will increase the volume of air that is expanding and contracting as you rise or fall - further aggravating the bouyancy change. This will be much more pronounced at shallow depths (30 ft or less) where the change in volume per foot is proportionately greater. Wet suit compression and expansion is also a factor, but a very,very small one.

It will also be more of an issue early in the dive with a full tank as the gas in the full tank weighs about 5 lbs and that extra weight needs to be compensated for with more gas in the BC.

At the end of the dive with about 500 psi in the tank you should be neutral at 15 feet with absolutely no gas in the BC (some BC's have a bad habit of trapping air so you need to be sure it is all vented). In most cases this will leave you floating at about eyeball level at the surface with full lungs an sinking slowly when you exhale. If this is not the case add or subtract weight as needed to acheive this condition.

When you get your weighting right you can work on your bouyancy by holding your fin tips in a "budda" position and float in mid water. This will prevent you from using hands or feet unintentionally and will give you a good feel for the rise and fall that occurs as well as for the lag that occurs due to inertia. If you rise or sink unequally, dump or add a very small amount of gas until the ups and downs even out.

Control in this position may take a bit of practice to acheive, but once you have it you will be able to apply it to your normal diving.

The important thing to remember is to NEVER close your airway as doing so can cause an air expansion injury in just 2 or 3 feet of depth change. You can "hold" your beath or pause at the top of an inhalation by keeping your diaphragm expanded as long as you do not close your airway -expanding air needs to be free to vent through your throat ad mouth.

 

[Likes2Cruise]

Thanks for all the input.

As far as weight, before the last dive I did another weight check, with full tank, then added 4 lbs - total of 18lbs. This seems to be consistent, and at times seems too little when I get to 800psi as I begin to have trouble staying down.

I have some suspicion that I may not be getting good venting from my BCD, but have not been able to confirm that. On my next dive I plan to make my buddy aware of the issue and have her check visually to see if she can see any air trapped in some odd spot. I wear a back inflate BCD, so would think this should not be an issue, as there are no side bladders.

 

[munkispank]

good idea to check for the trapped air pockets in your BC- this can make a big difference as you ascend and the air added at depth to compensate bouyancy expands. My original BC form many years ago had awful problems with small pockets of trapped - my new BC allows me to easily vent from back rear and top of BC and this really helps.

good luck and keep us all updated of what you experience on your next dive.
(ps - Tampa is my old home - I miss it !)

 

[Ber Rabbit]

Make sure when you dump your bc you roll so the dump valve is the highest point. I have a ScubaPro Ladyhawk and have to slightly exaggerate my body position to make sure my left shoulder (the dump I normally use) is higher than both my right shoulder and my butt. If you are in a "butt up" orientation (I see this sometimes with new divers when they are concentrating on dumping their BC) the air pocket will be at your hip and you need to use the hip dump or get your butt down/shoulders up.
Ber :lilbunny: