How to perfect buoyancy and trim

[Lobzilla]

As already pointed out, buoyancy control is much easier when your spine is horizontal in the water, like a fish, instead of horizontal, like a drowning pedestrian. Forward/backwards movements cause then less drag whereas ascending/descending is subject to more drag. That's what you want, not the opposite. A correctly setup backplate with wing is helpful but the same can be done with most BC vest.

In my avatar picture you see me hovering with the white tanks in the (mostly) correct trim while the diver under my fins just came crashing down to the platform in an uncontrolled descent. Physics made my job simpler and the other diver's harder.

Holding the correct horizontal trim position when task loaded is easier if you tilt your head back as far as it goes and move your workspace in front of you. In the avatar photo I am fiddling with an SMB slightly below me, which I should have done right in front of me in the space between me and my buddy to the right.

Good posture makes good trim easier and good trim makes buoyancy control much easier.

You can practice the correct posture while laying sideways on a bed or an Ottoman. Keep your thighs horizontal, calves near vertical, your head up and your arms forward while reading your email or sending a few texts.

Then go into the pool and assume the correct position while laying on the bottom. Add just enough air to your BC or wing to barely get off the floor and swim around with frog kicks or modified flutter (thighs motionless) while only scraping the floor occasionally with the belt buckle. Thighs, knees, and arms are slightly higher to clear the floor. This is initially a very tiring exercise but it programs your muscle memory for the correct posture.

The other advantage of the pool practice is that if you can control buoyancy in a few feet of water you can easily control it at any greater depth, since the largest relative pressure change occurs close to the surface.

First and foremost, don't get discouraged. Every novice SCUBA diver struggles with this and sooner or later some of the same people manage to float decently even with a rebreather where your actual lung volume has no leverage on buoyancy.

 

[tbone1004]

get a mirror of some variety in a pool. Hover in the shallow end of the pool. Don't touch the surface or the floor. If you can hover in the shallow section of a pool, your trim is damn near spot on because if you go head up or head down you'll touch the surface or the bottom, and if you don't have your buoyancy spot on you'll hit the top or the bottom.

 

[MARK1992]

Can a true motionless horizontal hover be achieved? I seem to be feet heavy and struggle to maintain horizontal trim without gentle finning. I'm thinking of adjusting tank position on my BP/W and also BP/W position on my back. I dive with AL 80 cylinders, and I gathered they gain buoyancy as the dive progresses. Does this mean I should have the tank as far down as possible?

EDIT: I should add I currently dive with a 1kg weight near the upper tank band, but I suspect I don't require it. I'm afraid removing that weight would exacerbate my feet heavy tendencies.

 

[tbone1004]

@MARK1992 it can be achieved, but diving is dynamic. Your centers of buoyancy and gravity both change as a function of tank pressure, they can also change as a function of depth due to wetsuit compression or where the specific bubble migrates in a drysuit, and of course due to your breathing. Now you can stop moving, but your hands and legs may not be in the same position as they were at a different tank pressure or depth. The goal doesn't have to be a truly motionless hover, but to keep as little motion as possible.
Your al80 needs to be in a position where you can reach the valve. No lower. Most people are feet heavy typically due to overweighting with a weight belt and poor body position.

This is @Trace Malinowski and while it's not him just hovering, you can see how little motion that he has. This comes with proper gear positioning, proper weighting, and a LOT of practice to get your body to adjust itself automatically. Watch his feet sculling in the back, I suspect a lot of that motion is just because humans don't ever like to sit still, but if you can hover like that, you're pretty good. Made even more impressive by being done in mid-water. He was a training director for a technical agency for a reason....

 

[Lobzilla]

I can tell you from personal experience that diving with Trace is both inspirational and humbling. If you live near PA have him check and optimize your rig so you are not fighting unnecessarily against your gear.
The other instructors who I know to be great resources in that neck of the woods are Bob Sherwood (NY and travelling) and Jason/Wayne from Diveseekers (NJ). Pretty much every GUE and any other cave instructor will certainly get you on the right track. Many open water and Tec instructors know the "secrets" and are able to help you while others will unfortunately send you down the rabbit hole of overweighing, ankle weights, unsafe tank position, etc. The advantage of being certain your gear is squared away is knowing who needs to improve, which will take much effort and time.
But few things are as blissful as floating motionless in a crystal clear spring basin on final deco, the current slowly moving you through the sun rays, and watching the minnows checking out that strange object floating in their backyard. That's when I truly feel "one" with the water, requiring no conscious effort to be there.

 

[kensuf]

One thing that (surprisingly!!) no one has mentioned - if you’re not already diving a backplate & wing, switch to one. A steel backplate will distribute 6# fairly evenly across your back right behind your lungs. It also reduces how much lead you need to carry on a weight belt (or pockets, whatever).

Oh...and practice practice practice!!! Remember to practice your basic skills while horizontal (mask removal, reg recovery, SMB deployment).

I love single tank BPW setups. While they make it easier to get "trimmed out", you don't need one to have good trim in the water. It's about proper weighting and appropriate weight distribution, not the gear you're diving.

 

[Lobzilla]

Watching the video you will see that Trace assume a stable "skydiver" posture between tasks. As tbone1004 pointed out, the details of that position depend on many, changing factors. But having found that stable position even for a few seconds goes a long way towards making diving much more effortless and enjoyable. Like riding a unicycle or balancing on a tight rope you need to first find balance and then extend the time of staying in that "zone".
Since it happened a long time ago, we all forgot that we progressed the same way while learning to walk upright.
To second kensufs point, once you know how to walk, even clunky, partially unbuckled ski boots will get you to the food court.

 

[Lobzilla]

I love single tank BPW setups. While they make it easier to get "trimmed out", you don't need one to have good trim in the water. It's about proper weighting and appropriate weight distribution, not the gear you're diving.

+1
Unfortunately, some of the recreational BCs are so screwed up that it takes some knowledge and ingenuity to make them work.

If anyone suspects a gear problem, try this before shelling out more cash:
Put a cylinder with regulators on the bottom of a pool and try to hover next to it in "hooka" mode. No wetsuit, no BC. Find out whether and where your body needs some weight to stay neutrally buoyant and level. Repeat with wetsuit and drysuit if applicable. This may sound silly but you will build the basics and being properly weighted by yourself may come in handy if you ever need to dismount your tanks.
Then, throw an AL80 tank on your back, resting between your shoulder blades and the small of your back. Still no BC. Use an oversized belt to keep the tank in place if necessary or find a vintage harness without BC. Depending on your BMI and lung volume you may need a little weight or a thin wetsuit.
If that is much easier to dive than your BC, spend some money on more suitable gear.
If you cannot balance yourself perfectly in the water with no or minimal gear and weight, it is you who needs work, not your gear.

SCUBA stands for Self Contained Underwater BREATHING Apparatus and not for "overpriced, overstuffed buoyancy and trim convolution".

 

[DriverDiver]

I am certain it is not a gear problem but a skills problem. As I said, I am improving slowly with each dive, I guess practice and growing confidence. I'm just not anywhere near where I want to be at. I see guys in the water like in the video posted and want to be like that in the water. I am going diving tomorrow morning to try some of the things suggested in this thread.

 

[DogDiver]

Best suggestion. Come down to north Florida and take a cavern and intro course over 3-4 days. I learned more in 3 days then I did as an open water instructor with 36 years of Great Lake Wreck diving.