Buoyancy

[Mr. Green]

Hello All, I completed class #2 of my PADI OWD course and have a question about my Buoyancy. I am a big framed guy that is 6 foot 5 inches 260lbs. We are currently pool diving with shorty wet suits and I am using 8 lbs of weight. Now, if I take a full deep breath and fill up my lungs, up to the top I go or I am not able to sink to the bottom without making sure my lungs are just about empty. In your opinion, do you think I need more weight or as I have read do I just need to learn to control my breathing a bit more? I was able to keep to the bottom of the pool by breathing correctly with no issues so it would seem that I am properly weighed. Just seeing if anyone had any additional thoughts.

Thanks a bunch and this is a really cool thing to be diving so far, Love It!!!

 

[kierentec]

you are correct that you are properly weighted. the issue is since you are a large person, you also have very large lungs; so when you take a big huge breath, you are making yourself more positively buoyant than someone with smaller lungs. this is one reason why it's typically more difficult for a large person to hover. you'll find the timing of your breaths will become very important when fine tuning your buoyancy. your instructor will be able to work you through much of this in the next pool session.
enjoy!


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[g1138]

Welcome to scubaboard.

Generally buoyancy control is the hardest the shallower you are. It becomes very tricky above 15ft because that is where the largest change in air expansion/compression occurs.

In the pool, if you're able to stay down at 8-12ft w/o having to struggle because of your breathing then I would say you're properly weighted. You'll just have to calm your breathing or do a surface dive down to descend. Sometimes though, as new divers it may be wise to overweight yourself by 2-4lbs to compensate for your lack of breath control.

 

[razorbackdiver]

I have been certified less than a year and am a good size guy myself. I had the same problem. I added 2 lbs and it helped some but mostly it's just more about learning to relax and breathe normal. In short practice, practice, practice and it will bouyany control will come.

 

[Tigerman]

Welcome overboard and yes, you sound like you are properly weighted.
You should be a bit bouyant when breathing in and a bit negative when breathing out. With your lungs "half full" you should be neutral.
If you are weighted this way and breather normally you should be able to stay neutral, in other words hover in the water.

Also keep in mind that the first few feet of water is where your breathing has the largest impact on your bouyancy, so the pool is actually harder to dive than 30 feet below the surface.
Practice makes perfect

Just as an aside; when people talk about "neutral bouyancy" that is actually somewhat of a simplification as what is actually going on is that you swing between slightly positive and slightly negative. The delay between sinking and rising in the water is what we percive as being neutrally bouyant

 

[TSandM]

6'5"? You have a big native buoyancy compensator there! You're lucky, because you'll eventually be able to do a whole lot of buoyancy control with your breathing -- but unlucky, because until you learn to control that breathing, it's going to give you fits.

I agree with everyone else that, if you can go to the bottom and remain there while breathing comfortably, you are correctly weighted.

What happens when you are distracted by swimming, or performing skills, or adjusting your buoyancy, is that your breathing changes. We all tend to breathe with our lungs full, or even hold our breath when we are concentrating, and in diving, that results in motion in the water column. New divers are often so focused on whatever they are doing that they don't even notice they are changing depth, until they're at the surface!

In addition, people read about taking long, deep breaths, and think that means huge volumes -- it doesn't. It means taking a slightly deeper breath than normal, and doing it in and out SLOWLY. You will learn to cycle your breathing around a certain point, so that you inhale, and just as you begin to move up, you begin to exhale; just as you begin to move down, you begin to inhale again. When you master this pattern, you can remain very stable in the water column.

 

[Doomnova]

I can relate as this while I'm not 6 5 I have a large lung capacity for a 5 10/5 11 person were if I take a full breath of air I'm headed on a one way trip up. Also in the shallows of a pool your also in the region where even the slightest bit of buoyancy change and you will see an effect especially positive buoyancy. If you can get your fine control down in those areas ie the shallows you'll have really good contorl down the road. Which is what I worked on after my OW the most. To the point where not with just my breathing alone I can skim along the bottom a finger or two above it and then come to a rock take a bit bigger breath and go over it and back down to where I was. Breath control though comes with time and the proper technique is as TSandM described above.

 

[spectrum]

It sounds like you had things in the sweet spot for this exercise. How do you know you have enough to stray down comfortably when your cylinder is approaching empty? That is the defining moment for establishing how much weight is enough. You can stretch things a bit by breathing shallow but if you have along shallow end to the dive or are stressed that may not work so well.

Pete

 

[TartanFrog]

I agree the weight seems right for the pool exercise but would be concerned with a safety stop with a near empty tank. It might be incredibly difficult to hold the stop without a bit more weight.

 

[DivemasterDennis]

I suggest you add pound for now. I see many new students experience what you are experiencing- it almost a hyperventilation- you get excited about an exercise and you maintain more lung volume on average than when you are calm. You will get this more under control in time, but for now the extra pound is a good idea. (TSandM's comments not withstanding) There are tie I go a pound heavy, including when teaching, when taking photos, and when I know I'll be in current and kicking more than normal. But that's just me.
DivemasterDennis