Buoyancy question

[kafkaland]

There seem to be two effects at play here on the physical side: first, you are trapping some bubbles under you, moving you up because of the increased buoyancy. Second, the water below you has a lower density because of the air bubbles, which means you move down. I'm not sure what the net effect is, but it definitely results in instability.
Then, there is your reaction to it. Instability means your breathing pattern changes, most likely you inhale more to cope with the situation, almost like getting ready for some physical challenge. That means you're going up. But it's something you have control over. Just focus on breathing normally, and don't let the bubbles throw you off balance.

 

[joe10540]

Sounds to me like a fun experiment is in order. On your next dive after you've gotten yourself neutral swim overtop of all the other divers and see if the bubbles get trapped in your gear and make you ride up or if the density change makes you settle lower. Maybe you were holding your breath focusing on the bubbles instead of your bouyancy and that caused you to rise up a little. Either way just enjoy the experience and stay mindful of your surroundings. Your depth could also have an impact on the amount of disturbance another divers exhaust can cause. Stay safe and remember if it's not fun (or making you money) it's not worth doing.

 

[maulotaur]

Thanks for all the advice! I am certain I was messing things up in some way-lost focus, bigger inhale, or multiple things. Good part was, I was not too deep and caught it before going all the way up. Other than this, I kept things controlled.

 

[boat sju]

Ever heard the theory that methane bubbles are to blame for disappearances in the Bermuda Triangle? I think the physics supports The Chairman.

 

[blac86]

I always exhale if I'm in another divers exhaust to avoid being pushed up.

 

[Jim Lapenta]

It's kinda fun to pass over a group of divers and feel this.

 

[maulotaur]

I am going to the quarry this coming weekend. Hopefully, I can recreate the situation and make sure everything goes smoothly this time.

 

[txgoose]

The exception is when I have students and sit above and slightly behind them so they forget about my presence and I have better control if needed

During my cert dives, I needed to repeat the nav portion. I distinctly remember the instructor's hand coming down from above and giving me the "I don't think you are where you think you are" signals. (This really just involved him redirecting me back to the platform, and the redirection not being the direction I thought it should be.) Anyway, felt like the hand of the scuab-god coming from above. It was memorable in the sense that I realized how quickly the instructor disappeared from my brain, but was able to quickly re-enter it when I was task loaded.

Not to digress OP's post. Just an affirmation of your positioning if a new instructor is reading along.

 

[txgoose]

I am going to the quarry this coming weekend. Hopefully, I can recreate the situation and make sure everything goes smoothly this time.

Provided your awareness of the "rude diver" thread, this actually sounds like it could be a god bit of fun. Learning a bit about how the bubbles affect your body and buoyancy. Have fun with it.

 

[Bob DBF]

Ever heard the theory that methane bubbles are to blame for disappearances in the Bermuda Triangle? I think the physics supports The Chairman.

Yes, the problem is that the ship has a hull that does not trap bubbles underneath, a diver will collect some of the air and become more buoyant. Also, if you watched the documentary, the amount of bubbles needed to destroy the buoyancy of water is massive compared to divers exhaust.


Bob