Obtaining Neutral Buoancy?

[easyrider003]

I was wondering if anyone could help me out. I got certified about six years ago and rarely go for the simple fact of I have no one to go with. Well I found a group of guys who go every month and I got back in the water today, after about two years. The weather started out at around 35 degrees in the a.m. The water was clear and about 60 degrees. I have always had trouble getting neutrally buoaynt. I was wondering if anyone could give me some tips on how to achieve this? The best I can remember is that in freshwater you are supposed to add ten percent of your body weight to your weight belt. Is that true or am I thinking of something else? Any help you could give me would be greatly appreciated. If there is anyone in the east central alabama area that would like to go diving sometime, hit me up. You can email me at easyrider003@gmail.com .

Thanks,
Michael

 

[The Kraken]

Easyrider,

Get in touch with Rick Murchison, a member and moderator here on the board. He lives in the Montgomery area.

For many, neutral buoyancy is the Holy Grail of diving. It can be found, generally speaking, after about 30 to 40 dives, DEPENDING UPON THE DIVER.

One thing that can help tremendously is to establish your weight requirements for a given dive/rig scenario. To do this, you determine your required weighting AT THE END OF YOUR DIVE with about 500 psi remaining in your tank.

This requires a little effort, but it is extremely worthwile and productive.

I know some will flame me for this, but so be it.

Start your dive knowingly a bit over weighted. If possible, use as many small weights as possible, 1 and 2 pounders if you're using soft weights. If nothing else, rent one of the mesh weight belts that utilize soft weights and rent as much soft weight (shot pouches) as you will need. As you descend, hang a bag at the 15' safety stop depth.

Dive your dive and return to the safety stop, 15', with about 500psi in your tank.

Completely deflate your BC.

Take a normal breath and (I know, never hold your breath) hold it for a couple of seconds and see what happens to your body.

If you start ascending, you need more weight. If you start descending, you need less weight.

If you started your dive knowing that you were overweighted, the second scenario will manifest itself.

Take the minimum weigh off each side of your rig until such time that you are just ever so slightly negative when holding a normal breath for a few seconds.

Exhaling will allow you descend and inhaling will allow you to ascend and keep your ascent under control.

The whole thing is about being able to hold your safety stop without buoyancy issues.

the K

 

[LIVES4SHARKS]

It is also understanding how your body should be in position before you get in the water. I was trained on a coffee table with my fins on. Holding my hands together with my knees bent and arching the back. It feels funny, and is uncomfortable, but I use this still to keep my muscle memory going on how the correct position should feel. I will have to take a pic tomorrow on a picnic table and post it here to help explain. It also helps to get a good budy in the water who will help tweak you and work to correct you till your golden. One thing to remember, if you feel crooked in the water...you are neutral..your mind plays tricks with you underwater.
GOOD LUCK!!

Happy Diving Somewhere!
Carolyn:sharks:

 

[bane51031]

I took my gear to a pool, I knew about how much weight I needed, then took a tank with approx. 550 psi in it and fine tuned the weight till I could float at eye level with a full breath and then upon exhaling would sink. Takes alittl etime to get relaxed and was able to shave off a few more pounds. Take the time to get weighted properly you will Thank yourself in the longrun....

 

[Pearldiver07]

Here's a trick I learned from an old salty diver, and have passed it on as a tip to my instructors. They have reported good results with helping divers who have been "dry" for a while...

First, you have to find water about 6'-8' feet deep (a pool is best), and have a buddy with you to assist (you'll understand in a minute). Go in with all of you normal equipment, but use a tank that has less than 1000 psi left in it.

Take an overlength weight belt with you. Put on about 80% of the "Calculated" weight you'll think you'll need up by the buckle. Now place 2 lb weights about 6" apart along the belt.

Now, holding the belt, descend to the bottom (backing in walking is easier here, but we can't always choose the environment). With an empty BCD you start doing fin pivots, holding the 80% portion of the weights to your chest. You'll notice that while you're in this position any weight that is suspended is needed to help hold you down. Weight sitting on the bottom is not necessary. I usually recommend starting with the amount of weight suspended, plus the FIRST weight that is on the bottom, just to account for breathing patterns.

Now you should be VERY close to your actual weight requirement. Get out and reposition the weights to work best for you. You should be ready for a dive. And this whole thing takes about 15 minutes.

Plus, on your normal dive you'll start with a full tank, you'll start about 5 lbs heavier, which will help you with that all-too-fun first descent. Since most people inhale deeply on that first descent in a while, you should still be able to get negative.

You'll still have to trim out and "burp" your BCD during the dive, but you should find that in shallow water at the end of the dive you should be just about perfectly trimmed out where you can control your buoyancy with breath control alone.

A side note: remember to stop finning as you start your descent. I've seen many returning divers do this without even noticing. That will prevent your descending by mistake.

Have fun diving, and I hope that this helped.

 

[Charlie99]

Getting weighted correctly and maintaining neutral buoyancy aren't really the same thing.

Being correctly weighted makes it easier to adjust the BCD for neutral buoyancy, but you will still have to adjust for the weight of air that you have consumed and for the change in buoyancy of your wetsuit as you descend and ascend. Just like having the right weight makes life easier, so does having a thin wetsuit, but obviously if you are diving in cold water, then you are stuck with a thick wetsuit and the large change in buoyancy with depth changes.

Your buoyancy will also change around 5 pounds as you breathe in and out, so what you really need to find is the right amount of air in the BCD such that you are neutral, on average, over each breathing cycle.

Most new divers spend most of their dive significantly negatively buoyant. They fin upwards at an angle to maintain depth and will sink if they stop finning. At the beginning, the most essential skill you need to learn is how to stop finning for a moment. If you sink rapidly, then you are very negatively buoyant. Start finning again and add some more air. Eventually you will get to the point where you will rise when you breathe in heavily, and descend if you exhale fully.

The effect of breathing has kind of a delayed reaction on your depth, and it takes a while to get used to how inhaling a lot will add a bit of buoyancy and stop any downward motion, and then begin to send you upward. In the same way, if you wait until you are moving upward and exhale, it will take a few moments before you start to descend.

The safety stop at the end of the dive is a good place to practice maintaining depth with no finning or arm waving. If you are horizontal, you will have more resistance to up and down movements and staying at a near constant depth will be easier.

Using a frogkick rather than a flutter kick is a tremendous aid to staying neutral. A continuous flutter kick can hide changes in buoyancy. The long glide phase of a frogkick highlights any buoyancy change.

You can make relatively large changes in buoyancy simply by spending more time with your lungs near full vs spending more time with your lungs near empty. I find that my primary, short term, buoyancy control is by my breathing pattern/fullness of lungs. That keeps me neutral, and then I adjust the BCD so that my breathing pattern is more or less centered.

Again, the key is to simply stop all movement and adjust the BCD so you average out to the same depth over each breathing cycle.

Charlie Allen

 

[rawls]

What The Kraken said....Determine neutral buoyancy at the surface. This also gives you proper weighting
What Charlie said...Your level of neutral buoyancy changes with depth.

If you are properly weighted and maintain neutral buoyancy at the surface then you won't have to make substantial changes to maintain buoyancy at depth. This saves air and energy...If you are overweighted it will take more air in your BCD to adjust your buoyancy. If you are underweighted then you will have to exert alot of energy to stay at certain depths.

All of this takes practice and since you are just getting back into diving after a 2 year hiatus then you will have to practice.

Another little trick that works pretty well is to estimate your weight and put it on. Have some extra weights at the side of the pool. With a full wetsuit...or whatever you will be wearing when you dive...and your mask and fins...try to sit comfortably on the bottom holding a normal breath. If your butt floats off of the bottom add weight 1 lb at a time until your butt is staying comfortably on the bottom....holding a normal breath. If you sink like a stone then take off weight...1 pb at a time. This works pretty well to get you properly weighted...

Like Charlie also said...for you to be neutrally buoyant you need to be able to be "quiet"...basically hold your position without finning...Keep practicing and keep diving frequently and you will get there. Neutaral buoyancy simply isn't one of those get it overnight skills...

 

[RoyN]

It comes right after when all the planet lines up in the center and then a beam from the Heavens Shine on you and then you become completely neutral like a fish.

For me after completing my 50th or 60th dive, I can float easy, but you must be properly weighted too. Other then, just go and have fun!

 

[String]

There is no magic formula for guessing your weight - you need to use one of the techniques to actually work it out.

As for neutral buoyancy, as well as getting weight correct the answer is to dive. The more you dive the easier it gets.

 

[jbd]

The aforementioned Rick Murchison posted a thread titled something like, Perfect Buoyancy--why it isn't. It might have been Neutral Buoyancy--why it isn't. That thread would be good for you to read as he clearly describes how bouyancy is a dynamic state for us as divers. As such we must be constantly controlling what state of buoyancy we are in as we progress through a dive.

As the Kraken noted, one get the weighting correct for the rig and the envirionment(salt or fresh water). Then as Charlie99 notes, the diver must take into consideration the consumption of the breathing gas as well as any level of compression of ones exposure proection.

For an object to be neutrally buoyant in a liquid, it must weigh the same as the liquid that it displaces. If the object weighs more than the liquid displaced it will sink i.e negatively buoyant. If the object weighs less than the liquid displaced it will float i.e. positively buoyant. These are the three states of buoyancy positive, neutral and negative. As properly weighted divers, at a given depth, we move through these three states with each respiratory cycle. As we inhale we move towards a more positve state of buoyancy. As we exhale we at first become less positive, then briefly become neutral, and then as the exhalation continues we move towards an increasingly negative state. Then, because we need to breathe, the process starts all over again.

At the same time, there are some other places where changes are taking place that have an effect on our state of buoyancy. The BC. The suit whether dry or wet. Also the abdomen. These are all pressure or depth related. The cylinder(consumption of the breathing gas) is getting lighter but maintaining the same diplacement.


Being in control of all of this makes diving a relaxing and enjoyable experience. Or it can be (see Charlie99's post) a constant struggle of finning upward to keep from sinking. Very tiring and not at all enjoyable.

Getting to this nirvana of neutral buoyancy need not take as long as 50 to 60 dives as it did for our friend RoyN. Nor does it take awaiting the alignment of the heavens. There are no formulas to use. Its a simple matter of the laws of physics. You will need some shallow, calm water and a buddy with you. Here is the method I use with my students starting with weighting for skindiving and then for scuba diving.
First I set up a weight belt with close to 30 lbs of weight on it. I either start with a couple of 5 lb'ers or 4 lb'ers. Then some 3's then some 2's. All spaced a few inches apart. This gets laid on the bottom
in about 5 feet of water. Here is the process

1.) Don all your gear except weights, with BC completely empty and drysuit completely burped, and wade into the water and stand over the belt.

2.) If the tank is full, as at the beginning of a class, take a nice big breath(not from the regulator), hold it and drop down to the weight belt and grab ahold of the belt near an end weight and hold it close to your body just below your navel. Still holding the weightbelt just go completely limp and relaxed. while still holding your breath. As the seconds tick away, you will float upwards until you have raised enough weight at which point you will stop ascending. If the tank is at 500 psi take a much smaller, more normal breath.

3.) You handydandy buddy will now count up what weight was lifted off the bottom.

4.) You will stand up and can commence breathing once your mouth is clear of the water.

This is the amount of weight it takes for you to be neutrally buoyant in that gear in that water environment. Please note, you can not be making any physical movements once you have taken ahold of the belt and placed it close to your body just below you navel. You must be very still, but very relaxed.

Please do this kind of thing before making your big boat trip. It will make things so much more enjoyable for you during that trip.

Also make sure you read the aforementioned Rick Murchison thread.