Buoyancy question how do you maintain a sitting hover?

[FishWatcher747]

When my kids years ago watched Sesame Street they had a segment that had a picture of 4 things. They would for example have 3 different fruits and an elephant. The jingle went 3 of these things belong together, one of them does not, can you pick out which one doesn't belong together?

Well with the 4 principles of diving which one doesn't belong together?

Answer is Trim.

So you take a new diver, run him/her through OW maybe AOW and then advise them to dive as much as they can safely to improve. In my case I am very visual. I can follow a better diver or a guide and learn a lot. I can imitate proper propulsion, breathing, and buoyancy and improve just by continuing to dive. It just happens.

But my trim didn't improve. Because it is not really an in water skill. You can't try harder to improve trim. You can't dive more to improve trim. Yeah you can put your arms out and feet up to butt if you are feet heavy but that is just a bandaid.

I suspect to truly know I have achieved proper trim I need to adjust weight so I become head heavy then back off just enough to become neutral. How many divers have ever done that experiment? Not many I suspect.

 

[MichaelMc]

I suspect to truly know I have achieved proper trim I need to adjust weight so I become head heavy then back off just enough to become neutral.

Something you can do to make the discovery process easier is to hold a small bit of weight in your hand(s) (2 to 4 pounds is good) and move it up or down your body to see what position gets you closest to balanced. Then put them back in some weight pocket and after the dive adjust based on what you learned.

Again, as you say, not a technique often mentioned in instruction manuals, as techniques for determining the amount of weight are.

(An advanced version is to have pockets with spare room and several one-pound weights total between them at the waist, hip and shoulders that you can reach, open, add or remove weight from, and close underwater and just fix things up as needed without getting out. But that is only feasible to fix modest goofs is the distribution, to make fine-tuning with legs and hands easier.)

 

[Blackcrusader]

So you take a new diver, run him/her through OW maybe AOW and then advise them to dive as much as they can safely to improve. In my case I am very visual. I can follow a better diver or a guide and learn a lot. I can imitate proper propulsion, breathing, and buoyancy and improve just by continuing to dive. It just happens. But my trim didn't improve. Because it is not really an in water skill.

It would seem your instructor did not teach you about trim properly as it really is an in water skill. I went on a dive with a woman who had only done 8 dives since her OW Certification who had excellent trim. Her instructor was BSAC and PADI but would not certify divers who did not know how to have horizontal trim and buoyancy. He spent time on the dives getting students to concentrate on those skills. I've seen some instructors on training dives do nothing more than have the diver follow them but never practice trim and buoyancy. It is easy to get trimmed horizontally and it doesn't matter what gear you use. As another member suggested, have some weights in your hands with your arms in front. You will see a big difference in how you can get into trim when weight balanced for it.

 

[The Chairman]

Because it is not really an in water skill.

Of course, it is. Your arms and legs can change your trim a good bit. One thing many 'rototillers' have in common is that they scull with their hands almost incessantly which drives the head up. Instead, fold your hands and put them out in front of you to move your CoG forward a bit. The further out, the more your head will descend. Bend your knees and you can get a good tilt forward to look at that special critter.

Time should also be spent in class teaching the student how to shift weights to get perfect trim. The last game of my OW class is underwater Jenga. It's a part of the final test that will allow them to graduate from the pool to OW. First, the student has to demonstrate that they can descend and ascend with just their breathing. After they do that three times without the use of their BC, they go to the weight line where I have set out a half dozen soft two-pound weights. Again, without touching their BC, they pick up the first weight and breathe themselves neutral. Once that looks good they pick up another weight, establish neutral buoyancy and repeat this until they can't pick up any more. The class record is 14 lbs and my personal record is 18 lbs. However, I require guys to do at least 6 pounds and women at least 4 lbs. Of course, they have to shed these weights without rocketing to the surface. Then, with the pile of weights just in front of us, we start building houses. Two sides and a roof and now let's add two more sides and a roof. It's fun and you can hear them laugh when the weights slide to one side ruining their build. Look what they're doing. They are having to hover in place, pick up two pounds and then place that weight in a specific spot. They're just inches off the bottom, doing an awesome hover, keeping their trim, and having a great time. That is control. That is what I want in a diver.

 

[FishWatcher747]

Chairman, with all due respect, and I love your Jenga game, but try that with a bunch of 45 degree divers and see how it works out for you.

You have already established their weight distribution (trim) before this exercise. I agree trim can be altered by body position. But one cannot show proficiency at trim without knowing how and doing proper weight distribution while setting up your kit before the dive. And this may include weight distribution not allowed by just using a weight belt, integrated weight belt and trim pockets.

Now when I did my pool sessions I was in a bathing suit. Likely my trim wasn't bad with just a weight belt and jacket BCD and AL80. Now most of my diiving has been in full 7mm wetsuit, hood and boots even in Key Largo in January in 71 degree water. A diver in that configuration has to learn to set up his kit in an entirely different way to have proper trim (ankle weight around neck of cylinder, 2nd tank band high up with trim pockets etc.).

I'm guessing trim is 75% setting up your kit properly and 25% altering your body position.

 

[Raphus]

I'm guessing trim is 75% setting up your kit properly and 25% altering your body position

I kinda disagree.
If the kit is set up totally unbalanced(trim), its hard to get in good trim.
I dive very different configurations.
Dry, 7mm semi dry in local quarrys.
5mm in pool
And 0.5mm in really warm water(carribean), if not too deep.

I have never used trim pockets. Only integrated weigth pouches in my bcd.
And lately i switched to bp/w, which is of course much easier to get in good trim.

I am not an experienced diver at all, but i had never any problems to get in good trim. And i stay always horizontal.
So in my opinion(could be wrong of course) its more about body position then weighting.

But we are talking about owd students.
They are heavily task overloaded by just staying alive. (joke)
If their equipment and weigth is in a good set up, its easier for them to get in a kinda horizontal position.

In my limited experience as a DM trainee, i observed student who had a very bad trim. These students very overweighted and finning so stay neutral.
So i think, a weigth check should be enough to get them in good trim on their owd.

 

[FishWatcher747]

Raphus said "I kinda disagree."

It should be said I have long legs (was a high hurdler) and probably have more of a leg heavy problem than most. So my conclusions may not apply to most people.

 

[MichaelMc]

Arms and legs can shift balance up to the limits of their wetsuit encased density difference from water and their length. After that, they have no more to give.

Unless you enter the water close enough balanced for your arms and legs to make up the difference, nothing you do with your body in the water will get you effortlessly holding any orientation like some other divers. Nothing. So learning how will be very hard. No matter how much you watch other divers and try to imitate their body positions or moves. Your balance was too far off to fix in water given your arms, legs, wetsuit and fins.

I think this is FishWatcher's point. At that stage, you have to get out of the water and do something on land before the next dive. You need to move some ballast, likely higher.

There may be something in water about other divers, like high tank or shoulder weight pockets, tank neck weights, or steel plates, that gives you clues about how to get balanced and horizontal like them. But you can't just mimic their body underwater. You have to also mimic what their gear achieved before getting in the water, a reasonably balanced weight distribution.

So being neutrally balanced is a skill you need to exercise:

• on land, through gear selection and setup to achieve close to balanced ballast distribution, and
• in water, through the use of arm and leg extension to fine-tune, rotate, and adapt to conditions.

Now, if you enter the water close to balanced and you watch the leg contractions and extensions of divers that stay balanced and effortless, likely from resting frog kick pose, then you could learn. (Or all of this could be in the dive training manual, but that is crazy talk.)

For the land setup part of balancing, watching a diver whose body allows them to be balanced with all ballast low on their hips is not helping a diver who needs ballast higher.

 

[FishWatcher747]

Thank you MichaelMC you put it better than I could.

So we have a fairly standardized weight check protocol to get properly totally weighted for a dive. If we change equipment we automatically check our total weighting and adjust accordingly.

My suggestion for education is we instruct divers to also do a trim check with each of your equipment configurations (I'm sure experienced divers already do this). To do so I think arms should be out front in a relaxed way, not straight out, not at sides. Similarly legs should not be straight back and not heels to butt, lower legs more of a 45 degree upward angle. Are you foot heavy? Are you head heavy?

Then the key for me is there should be better education about what to do with the results of your standardized trim check. Are new divers aware about options for moving weight up? Like tank neck weights, adding a higher tank band with trim pockets, shoulder weight pockets, or a steel plate and even various ways of adding weight to a backplate. I sure was not and would have liked more education about the options.

For those that have a body type that gets you close to weight balanced with a standard setup, count yourself lucky.

 

[Raphus]

One mayor factor is the heigth of the tank.
Most students wear the tank way to low.
So instead of adding (moving) trim weigth its often enough to put the tank higher.

Some tipps here and there should be included in an good owd. But the standart short cheap owd has not enough time to to this in depth.

My goal is becoming an instructor. Because i like teaching.
And i wonder, how an owd can improve without adding much time.

Of course its always best to do long pool sessions and all that stuff that some instructors in SB are doing. Which is perfect, but not doable in every dive center. And some students dont want to soend more money and time.