PDA

View Full Version : Mastering Buoyancy skills



3rdEye
08-06-2007, 20:36
ok, so there's been several threads on buoyancy, and we all know it's one of the most important skills for being a good diver. And most of the responses to these threads have suggested practice practice pratice. I mean we all know how the power inflator works, and the general purpose of our BC, but I didn't learn much technique in my OW class concerning that, maybe more is covered in peak performance, but who knows when I'll be taking that. I can do a fin pivot and a hover, but I'm more concerned about adjusting to different depths quickly and gracefully.

What I would like to hear and what I think could help some others is specific technique for mastering that type of control. Those of you who are really good at this, what specific cues do you react to, or what specific methods do you use to control buoyancy?

For example, when you are descending say to 60 feet, are you continuously adding air to your BC? how often? how much? Or do you just plummet down and get neutral when you're at depth? How do get neutral without sitting there for 2 minutes making adjustments?

I'm convinced that there's art and technique involved here....and I'd like to learn some of that.

medic001918
08-06-2007, 20:47
The amount of air that everyone adds depends greatly on the rig they're using and how they're weighted. As far as practicing, just pick different depths and try to descend to it and stop within a certain amount of that depth (example: 60ft +/- 1ft). Work on platforms if you have a dive site with them installed. Try to hover 2 ft above, and work closer and closer. Controlling your bouyancy with the amount you inhale and exhale will go a long way as well. When you're neutral, you should be able to ascend or descend with your lungs. Try performing different tasks while holding a depth. Tasks can be air share, lift bag deployment, light deployment, etc. The more you dive, the better your bouyancy will get. Try to adjust your weighting, and not just the amount of weight but the placement as well. You'll find it will help your trim. Practice with different amounts of air in your tank as well, as that will have an effect on your bouyancy.

Shane

Dive-aholic
08-06-2007, 23:57
You just need to practice, practice, practice! :D

Actually, like Shane said, it depends on your rig. If I'm in a single tank rig with an AL80, the it's more of a gradual descent because I'm better weighted. If I'm in my doubles, the descent is faster because I'm a little heavy at the beginning of the dive.

The key to good buoyancy is perfect weighting. Make sure you are neutral for a safety stop at the end of your dive. That means you'll be about 3lbs heavy at the beginning. So the whole surface at eye level means surface above eye level at the beginning of the dive.

I typically go as fast as my ears allow and blast some air in the last 10'. This keeps me from plummetting into the bottom. The thing to remember is that buoyancy correction doesn't happen immediately. There is a lag time between action and response. If you're perfectly weighted, you shouldn't have to touch that inflator more than 3-4 times during the dive at the same depth. It's all in breath control.

namabiru
08-07-2007, 17:07
One thing that throws that off, though, is what kind of exposure protection you're wearing. I improved buoyancy through diving (as well as PPB training), but last weekend I was in two full wetsuits, and found myself bouncing off the bottom like a basketball. I was mentioning this to my fellow divers, and they suggested it was because I was in two wetsuits.

If you're shorter, like me, you may also find that your tank is causing you grief. I used to wear mine in standard position, valves just around the BCD collar, but then it was actually Dive-aholic who suggested I move my tank up so my weight was better-distributed. Now I dive so the valves are at the back of my head, and I noticed a world of difference.

So maybe play with where your tank sits.

Although I did go to Cozumel and had to keep the boat crew away from my rig, as twice I caught someone covertly trying to move my BCD back up. So know that if you go diving in a "touristy" place you may have to contend with explaining your tank placement choice.

Dive-aholic
08-07-2007, 23:36
One thing that throws that off, though, is what kind of exposure protection you're wearing. I improved buoyancy through diving (as well as PPB training), but last weekend I was in two full wetsuits, and found myself bouncing off the bottom like a basketball. I was mentioning this to my fellow divers, and they suggested it was because I was in two wetsuits.

That could be the case. It would depend on the depth. You're going to have great buoyancy changes at shallow depths. If you were anywhere deeper than 30', I'd say you were just being bouncy. :D If you were shallower than 30', it could be the wetsuits. It shouldn't even matter that it's 2 wetsuits, it's probably not being used to that combo.

cummings66
08-08-2007, 18:10
If you want a good tip, dive shallow. If you can perfect your buoyancy in 5 feet of water you'll do fine deeper. Then work on the ascents and descents, nail them so you can start and stop where you want. Use your lungs for small changes, or momentary changes in depth.

3rdEye
08-08-2007, 20:12
all good suggestions so far,

one question, why use the lungs for small changes, when you can swim up or down easily, and quickly? or are we talking about when hovering here? I guess it seems like to me, that would require some concentration on breathing, which I tend to not think about....but maybe i need to think about it until it becomes second nature?

creggur
08-08-2007, 20:36
If you want a good tip, dive shallow. If you can perfect your buoyancy in 5 feet of water you'll do fine deeper. Then work on the ascents and descents, nail them so you can start and stop where you want. Use your lungs for small changes, or momentary changes in depth.

I practice this in my pool 5-6' of depth.. I start at one end of the pool and swim to the light in the wall of the other end, the point is to be dead on the spot I'm aiming for on the other wall when I get there only using my breath..

I also lie flat on the bottom, keep my body rigid, keep the tip of my fins on the bottom and do "push ups" with my breath. The trick is to never break the surface and get my regulator as close to the bottom without touching... It's tricky to do, but you really get a good idea how much difference a deeper or shallower breath will make. As well as controlling when and how deep to inhale/exhale to arrive where you want..

cummings66
08-08-2007, 22:36
Because constant finning will use more air than will a simple change of breath. Look at it this way, your leg muscles use a lot of O2 and if you push them all the time you're going to use more air to support the movement.

When you get to dive with a great diver like I've been privileged to, you'll notice two things. First they don't fiddle with their inflator(s) and second they seem to do things without apparent effort. That lack of effort comes from good buoyancy control which your lungs help control. Keep in mind this is for short excursions, not a 10 minute trip down 50 feet.

The other key IMO to good air consumption is to stay horizontal, by using your lungs to help buoyancy and not finning you maintain that horizontal orientation. If you're finning down you head is low causing more drag, if you're finning up the same thing occurs. The faster the motion the worse the drag, and the worse the drag the more energy you put into maintaining it and to output that energy level you need to burn O2 and that means you're going to breathe more air. It's a cycle.

BSea
08-08-2007, 22:56
all good suggestions so far,

one question, why use the lungs for small changes, when you can swim up or down easily, and quickly? or are we talking about when hovering here? I guess it seems like to me, that would require some concentration on breathing, which I tend to not think about....but maybe i need to think about it until it becomes second nature?
if/when you go on a drift dive, all you need to do is get neutral, use your fins to steer, and use your lungs to go up or down. It's like flying. Breath in to go up over objects, then exhale to cruize back to the bottom.

Before BC's divers would use their lungs for BC's. They would have to be optimally weighted so they didn't sink or float. Those guys in the late 50's & early 60's knew what buoyancy was all about.

3rdEye
08-08-2007, 23:36
Because constant finning will use more air than will a simple change of breath. Look at it this way, your leg muscles use a lot of O2 and if you push them all the time you're going to use more air to support the movement.

When you get to dive with a great diver like I've been privileged to, you'll notice two things. First they don't fiddle with their inflator(s) and second they seem to do things without apparent effort. That lack of effort comes from good buoyancy control which your lungs help control. Keep in mind this is for short excursions, not a 10 minute trip down 50 feet.

The other key IMO to good air consumption is to stay horizontal, by using your lungs to help buoyancy and not finning you maintain that horizontal orientation. If you're finning down you head is low causing more drag, if you're finning up the same thing occurs. The faster the motion the worse the drag, and the worse the drag the more energy you put into maintaining it and to output that energy level you need to burn O2 and that means you're going to breathe more air. It's a cycle.

when I dove in Coz, my DM was a 67 yr old guy who's been diving there probably every day for the past 35 yrs, dove with Jaques Cousteau back in the day.

needless to say, his control was effortless, and you're right, he rarely fiddled with his inflator...in fact, he inflated his BC orally!

anyway, good points, I am quite an airsucker....need to work on that, it's horrible.

3rdEye
08-08-2007, 23:42
all good suggestions so far,

one question, why use the lungs for small changes, when you can swim up or down easily, and quickly? or are we talking about when hovering here? I guess it seems like to me, that would require some concentration on breathing, which I tend to not think about....but maybe i need to think about it until it becomes second nature?
if/when you go on a drift dive, all you need to do is get neutral, use your fins to steer, and use your lungs to go up or down. It's like flying. Breath in to go up over objects, then exhale to cruize back to the bottom.

Before BC's divers would use their lungs for BC's. They would have to be optimally weighted so they didn't sink or float. Those guys in the late 50's & early 60's knew what buoyancy was all about.

my first dives after certification were drift dives in Coz (as i mentioned above)...i was pretty much finning around like a doofus the whole time, first dive in the ocean, etc etc....just trying to get my bearings, and of course in awe of everything around me. anyway, a lot of the dives there was a lot of stopping and swimming to see cool things, a few of the dives were just relaxing drifts like you said....of course i was still finning too much.

Dive-aholic
08-09-2007, 11:30
Don't forget how fish do it. They don't fin up or down. They use buoyancy bladders to control their depth. Our buoyancy bladders are our lungs.

skdvr
08-09-2007, 16:05
I am by no means buoyancy control expert but this is how I feel it out on the descent. When I am diving a AL 80 I just let all the air out of my BC and let my breath out to start the descent. I recently started diving a HP 130 and I no longer let all the air out of my BC because the 130 is so heavy when it is full and then if I am descending in a deep spot I will hit the inflator on the way down as I start picking up speed. I do not want to end up planted in the lake bottom... I really do everything that I can to keep myself from having to touch anything while I am down there, and I give my wife some dirty looks when I see her reach her hand out to stop her self from hitting the bottom. She is getting better now because she is tired of hearing it from me.

Like I said I am no master but I just go by feel. You just have to remember that the changes are not sudden but you will begin to notice when they are happening as you are coming up or going down and can add air or release air accordingly...

Phil

namabiru
08-10-2007, 16:55
That could be the case. It would depend on the depth. You're going to have great buoyancy changes at shallow depths. If you were anywhere deeper than 30', I'd say you were just being bouncy. :D If you were shallower than 30', it could be the wetsuits. It shouldn't even matter that it's 2 wetsuits, it's probably not being used to that combo.

Yeah, but I dove two wetsuits at Lake Pleasant and I wasn't bouncing off the bottom like that. I honestly have no clue what was going on. It was bad, though. Usually I can rely on lungs, but I was having to inflate and such. Perhaps it was a new dive environment too. But I kinda looked like a horse's patoot, I'm sure. I used the same weight I used at Lake Pleasant too.

Would altitude ever affect buoyancy, by chance? The water was also a bit warmer, although only by 10 degrees at the most.

mwhities
08-10-2007, 17:05
I just read all the posts and by NO means am I an expert but, I didn't see one thing mentioned anytime. (Unless I read to fast and over looked it. ;p).

When you work on your buoyancy, you are in a horizontal position. At least you should be for diving. :) I'm not sure if your lungs will work for you in a vertical position. I know I constantly finned when I dove like that. (That's why an al80 only lasted 20+- minutes per dive. Now it's up to 35 or 40. :))

When you are horizontal, you are using much less O2 than you would vertically and constantly finning. So, with all of this advice that's been giving, they should be referring to your buoyancy in a horizontal position.

Michael

cummings66
08-10-2007, 23:17
Good point, always strive for a normal dive position being horizontal, but that's not always a suitable orientation. Take a wall dive where you're taking photo's, a vertical orientation could be more comfortable then.

Yes, the lungs work in that position. You don't move horizontally when you're vertical, you move up and down and the lungs work for that. It's just when you're horizontal you can move in any direction easily.

namabiru
08-11-2007, 11:53
When you work on your buoyancy, you are in a horizontal position. At least you should be for diving. :) I'm not sure if your lungs will work for you in a vertical position. I know I constantly finned when I dove like that. (That's why an al80 only lasted 20+- minutes per dive. Now it's up to 35 or 40. :))

Michael

There you go. And getting horizontal comes back to adjusting trim, distributing weight as need be, moving tank location--whatever you need to do to get yourself horizontal-able.

Before I moved my tank, my legs drug like crazy. I was hitting my tank with my butt, and disliked it very much. Now the tank bottom sits at the small of my back or just below, and I love it!

I think my next task is to work with the integrated weight places on my BC. Who knows--I may go back to a weight belt with minimal weight in the back trim pockets. It seems I'm getting drug down there too, as most the weight almost hangs down. :smiley11:

3rdEye
08-11-2007, 12:12
Now that I have my own back inflate BC, achieving a horizontal position is fairly easy, I had a lot of problems with that in a jacket style.

I'm going to be going up to the lake tomorow for some diving, they have a giant helicopter suspended at 50' in 70' of water, so I figure that will be a good place to hone these skills around something interesting that I can hover all around and over, etc.

skdvr
08-11-2007, 15:41
Let us know how it goes...

Phil

cummings66
08-11-2007, 18:25
What lake are you going to? Beaver Lake has a helicopter in it as well. To be honest buoyancy control at 50' is a cake walk, try it at 10 if you want to fine tune it.

To be honest one of my best dives was done at a depth of 17 feet.

3rdEye
08-12-2007, 20:51
What lake are you going to? Beaver Lake has a helicopter in it as well. To be honest buoyancy control at 50' is a cake walk, try it at 10 if you want to fine tune it.

To be honest one of my best dives was done at a depth of 17 feet.


well, i do....on a safety stop @ 15'. And yeah, i suppose it is a bit harder for some reason. And today we dove at Dutch Springs in PA. Here's the helicopter: http://www.dutchsprings.com/ImageHelicopter.htm

so, here's some notes on my diving today.


First dive was the helicopter, which is a large helicopter @ 88' long and 22' high. The bottom of it is at about 55'. So, this gave me something interesting to play around while fine tuning my buoyancy. Now that I was much more focused on it, I found I was easily able to get neutral, and hover perfectly after a few adjustments of the inflator. I could hover still, and drop when exhaling and breathing a bit shallow and exhaling faster. And could rise by inhaling to full capacity and exhaling much slower. One thing I had picked up in my OW classes a few months ago was exhaling very little by making a T-T-T-T-T with my tongue, as to only release a few bubbles, this allows you to keep that breath for quite a while, probably up to 30 secs to a minute if you wanted to. So, I did quite well on this dive, slowly rising and falling with just my lungs, kicking very little. Tried different positions - straight up, horizontal, upside down, etc. etc., all around the craft, at different depths, sometimes making small adjustments to the inflator, but not much. Occasionaly I would sink too much or rise too much.

When it came time for the safety stop, we ascended to 15' on a line.


The second dive involved more swimming, first to a wreck of a firetruck at about 25', then to some platforms, then along a wall that went down to about 50' or so. This went ok, gave me a chance to work on control while swimming. Safety stop this time was in open water, not really near anything, and with poor visibility, so that was a challenge. By the last minute, I finally did get leveled off at 15'. I find it much harder to acomplish that without any visual focus point, because you often don't realize you are ascending or sinking.

Third dive was more swimming to a few boats and a cessna at 20', schoobus at 40' then back a platform for more practice, where I did fin pivots and hovers extremely easily, and practiced hovering horizontaly over the platform at different distances.

So, good day of diving and skills practice. I think that eventually, this will become second nature...kind of like driving stick. Right now, as long as I can concentrate on it, I can pretty easily do what I want to do. Now at least, I know what I need to work on.

More practice...

Also, being as it was out dive shop's customer appreciation day, my dive buddy won a free photo specialty class (taught in the big shark tank in the Camden Aquarium I believe).....I walked away with a neoprene cap and a mousepad....hahah...oh well.

Thank you all for your replies.

lucidblue
08-12-2007, 21:27
We definitely did much better with buoyancy today. I'm still having issues when we hit the colder water below the thermocline. It is much harder for me to control my buoyancy at that point. I'm most comfortable from 20-40 feet. Like 3rdeye said, it's much easier to control buoyancy when there is a point to focus on. I have more detail I can add later, I'm just too exhausted right now.

I was really thrilled to win the underwater photography specialty class... I never win anything worthwhile. It's nice to get a specialty class free. This is one I definitely wanted to take at some point, but wasn't sure it was worth paying for.

torrey
08-12-2007, 22:10
I tend to drop without adding any air until I'm about 10 feet from the bottom, then I'll add a good shot of air until I almost stop, then use small shots on the inflator until I'm right above the ground and neutral.

lucidblue
08-16-2007, 18:57
There's a good article in this month's Scuba Diving magazine about the 6 Tips for Perfect Buoyancy. I'll summarize a little later if I have time. Covers a lot of what was discussed here in a very clear cut way.

Buoyant1
08-16-2007, 20:23
--snip--
Third dive was more swimming to a few boats and a cessna at 20', schoobus at 40' then back a platform for more practice, where I did fin pivots and hovers extremely easily, and practiced hovering horizontaly over the platform at different distances.

--snip--




Did you approach the Cessna from the bottom of the "island" that's such a cool way to see that thing!

I love Dutch, I was just there on the 9th! If things work out for this weekend I may be going there.

Did you make it out to the Trolley?

lucidblue
08-16-2007, 22:07
So the "6 Secrets of Buoyancy Control" article in this month's Scuba Diving states these factors affect your buoyancy:

Factors that don't change once you've selected them and start your dive:
Ballast Weight
Trim

Factors that constantly change during dive:
Tank Weight
Exposure Suit
Depth
Breath Control

The main point is that most divers are overweighted right from the start, because they have trouble with their descent. A few tips to help you get descend with the proper weight are:

1. Be patient it takes the wetsuit a couple minutes to get fully wet.
2. Reach up and keep the inflator hose above your head, stretching it a little.
3. Rock backward a little, helps get an air bubble air out that a lot of BCs trap behind your head.
4. Relax.Hold your right arm tight at your side and stretch your legs downward while pointing your fins. Don't move around a lot.
5. Keep exhaling until you start sinking. Then only take shallow inhales until you're below 5 ft.

There's also an option about forcing your descent by going head first.

The article goes into detail about each of the other factors listed above, but I'd be copying the article if I got too far into it. Definitely worth reading. I'm going to focus on all of the points mentioned during my next dive.

cummings66
08-16-2007, 23:00
You mean they tell you to descend head first if you can't get down? I assume they tell you to be properly weighted so you can hold a stop right?

I'll have to get the magazine and read the article I suppose.

3rdEye
08-18-2007, 10:47
Did you approach the Cessna from the bottom of the "island" that's such a cool way to see that thing!

I love Dutch, I was just there on the 9th! If things work out for this weekend I may be going there.

Did you make it out to the Trolley?

we started that dive at the Silver Comet, then to another boat on the way to the cessna, so we came up from 60'....the cessa is pretty neat because all around it drops off into deep water.

didn't make it to the trolley or the crane yet, still a lot of things I have yet to see there

torrey
08-20-2007, 09:15
You mean they tell you to descend head first if you can't get down? I assume they tell you to be properly weighted so you can hold a stop right?

I'll have to get the magazine and read the article I suppose.

I had to do a lot of this at a local scuba park over the weekend. I had forgotten my weights, but I was paired with somebody who didn't know the park, so I didn't want to have to get out and go get them. I wasn't heavy enough to descend, so I had to fin down (only about 20 ft or so max). Once down, I was relatively neutral as long as I didn't hold my breath. It became a little more of a pain as the tank started emptying, but I managed to make it work. Now I know that I may have been slightly overweighting myself to begin with when not wearing a wetsuit.

3rdEye
08-09-2008, 21:41
and many dives later, still practicing my buoyancy.....i feel like i've gotten much better. Still working on getting my trim dialed in perfect....and working on kicks as well. Here's some photos showing my trim, and a link to a video of me practicing over a platform at Dutch today.

YouTube - buoyancy control (http://www.youtube.com/watch?v=YzNEn7EP_S8)


feel free to post any criticisms or observations/suggestions :smiley20:

Jenn
08-09-2008, 22:05
I have enjoyed reading everyones advice regarding bouancy. This is something I am looking to master too. Everyone has some great advice and I can't wait to get out there and try some of the things out that I have read from you guys. Thanks for the advice.

rongoodman
08-09-2008, 23:28
and many dives later, still practicing my buoyancy.....i feel like i've gotten much better. Still working on getting my trim dialed in perfect....and working on kicks as well. Here's some photos showing my trim, and a link to a video of me practicing over a platform at Dutch today.

YouTube - buoyancy control (http://www.youtube.com/watch?v=YzNEn7EP_S8)


feel free to post any criticisms or observations/suggestions :smiley20:

The first one looks pretty good. In the second two, a slight arch in your back might keep your knees from dropping.

FWIW, there's been a discussion on one of the other boards about relying on lungs for buoyancy control, and several people have pointed out that if you depend on them too much, you're liable to lose it when you get task loaded and your breathing pattern changes. Their recommendation was to use the wing/BC to get neutral, and to then breath normally.

stairman
08-10-2008, 06:02
I use my lungs to keep from touching the bottom occationally.If my wing doesnt catch me in time.Its important to remember that locking the throat should never be done when ascending.We all know that but some may get caught up in buancy practice and make a mistake.I read once that a lung injury can occur with only 3 ft. of depth change while ascending if the glottis is closed.In cave diving the constant up and down profile of the columns will definetly make you proficient in buancy and trim.Touching the bottom in certain places could cause a silt storm that would decrease vis dramatically.Timing is the key to know when to inject air and how long.Lung power[to stop desending]is a last resort because a headacke can develop from increased loading of co2 from incomplete respiration.I was trained to inhale slowly,pause for 2-3 seconds and exhale slowly but more important FULLY! The pause is not done by locking the throat.If you dont exhale fully before taking in a new breath you will retain some co2.

brandon
08-10-2008, 15:01
I usually use the safety stop as a good 3 minutes to practice buoyancy control in 15-18 feet of water. Nothing extreme, I just try to hover as motionless as possible without ascending or descending more than a couple inches.

-B

sravin1
08-10-2008, 22:00
[quote=3rdEye;18488]ok, so there's been several threads on buoyancy, and we all know it's one of the most important skills for being a good diver. And most of the responses to these threads have suggested practice practice pratice. I mean we all know how the power inflator works, and the general purpose of our BC, but I didn't learn much technique in my OW class concerning that, maybe more is covered in peak performance, but who knows when I'll be taking that. I can do a fin pivot and a hover, but I'm more concerned about adjusting to different depths quickly and gracefully.

What I would like to hear and what I think could help some others is specific technique for mastering that type of control. Those of you who are really good at this, what specific cues do you react to, or what specific methods do you use to control buoyancy?


here are two drills we practised with our instructor.

1. in the quarry where we got certified, there is a platform from which you can practise giant strides and other entries. our instructor hangs a rope tied to a weight from the platform into the water. the rope has a carabiner attached to it every 5 feet (knot at every 5 feet) up to 35 feet. we would have to perform a controlled descent and remove the carabiner from every knot. after this we would have to perform a controlled ascent where we attach the carabiner back to the knot.

2. we would have bars t 15, 25 and 35 feet. we would then descend to 15 feet and remain parallel to the bar for 3 minutes. then to 25 feet and remain there for 3 minutes and then to 35. we would then do the same on the ascent. it is imperative that you do not move your feet while you are performing this skill. no propulsion. just buoyancy.

JipThePeople
08-23-2008, 00:20
I consider myself to have pretty good buoyancy skills. I must admit, I got more out of the PADI Peak Buoyancy Specialty course than I anticipated. It was only two dives, but it was a really good course. I think with any dive course, you get out of it what you put into it.

freeski4ever
08-23-2008, 00:32
LOL!!!! Why am I not surprised that PADI has a "PADI Peak Buoyancy Specialty Course"?? I wonder when they will implement their "regulator breathing course"

scubadiver888
08-23-2008, 10:52
all good suggestions so far,

one question, why use the lungs for small changes, when you can swim up or down easily, and quickly? or are we talking about when hovering here? I guess it seems like to me, that would require some concentration on breathing, which I tend to not think about....but maybe i need to think about it until it becomes second nature?

First, what everyone has been noting is that air compresses with depth. If there is air in your BCD it will compress with depth and you need to adjust by adding air to the BCD. If you have a wet suit, the thicker the suit, the more air in the neoprene. The air will compress at depth and you will have to add air to your BCD to adjust. The reverse happens as you come up.

I'm not fantastic at buoyancy... yet... but the one thing I have noticed is that for basic recreational diving, small adjusts works best. If I notice myself becoming negatively buoyant it is probably too late. I've been getting in the habit of giving a little air before I notice I need it. I just get a feel for it. As I'm going down my mind thinks, "I have been travelling down for a bit, give a little squirt." I do it more often in fresh water than salt water. I do it more often if I'm wearing 14mm of neoprene instead of 3mm.

Second, if you are swimming up and down in the water column, you are using up air. The more you swim the more air you use up. Since I've learnt to use my breath for the small adjustments I am never the first guy out of air. My 30 minute dives are now 60 minute dives. it is AMAZING how much a difference this can make. I think it might also be because you are more aware of your breathing if you use it to control your depth.

Darrell