Some of the Joys of Scuba Diving. What about yours?

[lowwall]

You forgot you were in a drysuit, didn't you? I hate when you rip a big fart and it f's up your buoyancy

It does make you wonder how many bar that fart was at before the expansion.

 

[tursiops]

It does make you wonder how many bar that fart was at before the expansion.

Yeah, I was wondering about that. I suppose the maximum pressure wou.d be ambient plus whatever strength your sphincter is...and when it comes out it is still at ambient. So it is all about your sphincter....so of course i asked Google AI.

"A healthy person can generally hold a pressure between 120 and 180 mmHg during a voluntary squeeze, which involves the external anal sphincter. The internal anal sphincter, which provides resting tone, generates pressures around 60 to 80 mmHg. These are measurements taken during a manometry test, where a catheter measures the pressures generated by the anal sphincter muscles, and they are important indicators of anal sphincter function and continence."​

So, 180mm Hg is about 0.24bar
We need to know how much gas we are talking about. Again, Google AI:

"Fart volume varies significantly, with individual farts ranging from about 33 to 125 ml, and the total daily gas expelled can be between 476 to 1491 ml (nearly two 16-ounce soda cans) for normal individuals. This volume depends on factors like diet (especially fiber content), swallowed air, and the composition of gut bacteria, with gas production often increasing after meals."​

So, 125ml might produce additional buoyancy of 125g (0.28lb) at most.

At 66 ft (20m) the ambient pressure is 3 atm, call it 3 bar, so the expansion factor is just 8%, so you might get 0.26 lbs ((0.12kg) lighter.

I don't think you'd notice even a hefty fart.

​

 

[lowwall]

It does make you wonder how many bar that fart was at before the expansion.

I checked the literature. Looks like it's normally quite low, but can reach as high as .3 bar (if I've read this correctly). I'm not sure that's enough to make a noticeable difference, at least from a single event.

Intraluminal pressure patterns in the human colon assessed by high-resolution manometry - PMC

Assessment of colonic motor dysfunction is rarely done because of inadequate methodology and lack of knowledge about normal motor patterns. Here we report on elucidation of intraluminal pressure patterns using High Resolution Colonic Manometry ...

pmc.ncbi.nlm.nih.gov

"Simultaneous pressure waves (SPWs) were the most prominent propulsive motor pattern, associated with gas expulsion and anal sphincter relaxation, inferred to be associated with fast propagating contractions. Isolated pressure transients occurred in most sensors, ranging in amplitude from 5–230 mmHg."

 

[tursiops]

Yeah, I was wondering about that. I suppose the maximum pressure wou.d be ambient plus whatever strength your sphincter is...and when it comes out it is still at ambient. So it is all about your sphincter....so of course i asked Google AI.

"A healthy person can generally hold a pressure between 120 and 180 mmHg during a voluntary squeeze, which involves the external anal sphincter. The internal anal sphincter, which provides resting tone, generates pressures around 60 to 80 mmHg. These are measurements taken during a manometry test, where a catheter measures the pressures generated by the anal sphincter muscles, and they are important indicators of anal sphincter function and continence."​

So, 180mm Hg is about 0.24bar
We need to know how much gas we are talking about. Again, Google AI:

"Fart volume varies significantly, with individual farts ranging from about 33 to 125 ml, and the total daily gas expelled can be between 476 to 1491 ml (nearly two 16-ounce soda cans) for normal individuals. This volume depends on factors like diet (especially fiber content), swallowed air, and the composition of gut bacteria, with gas production often increasing after meals."​

So, 125ml might produce additional buoyancy of 125g (0.28lb) at most.

At 66 ft (20m) the ambient pressure is 3 atm, call it 3 bar, so the expansion factor is just 8%, so you might get 0.26 lbs ((0.12kg) lighter.

I don't think you'd notice even a hefty fart.

​

There is also a discussion on Reddit:

 

[VsubT]

Skydivers experience the opposite gastro-barometric phenomenon in reduced ambient pressure as the plane ascends. I’ve seen people ejected from aircraft for heinous emissions, commonly known as “the smell of fear”.

Brings new meaning to gas management.

Lance

 

[MB NZ]

You forgot you were in a drysuit, didn't you?

1) Lost at sea incident. Let it go after about 3 hours which was good in its own way.

2) Diving with seals which were incredibly interactive, much more than normal. Shallow, so a very long dive. I wasn't going to end the dive for a bathroom break.

 

[NothingClever]

One of the more rewarding joys for me are the single women who are 20 years my junior, have reliable income of their own, want to adopt kids from poor nations, speak several languages, are conversant in Baroque composers and delight in engaging in a relatable manner with people from all walks of life. It's fun how these sophisticated dive bunnies just throw themselves at me wanting to be my dive buddy so they can learn about buoyancy control, canister lights and the finer points of DPV battery management. I've had to bring on board a paper number dispenser, like the kind at a delicatessen, to handle the throngs.

I'd tell you guys more but my wife just yelled at me to get off ScubaBoard, go pick up my daughter from practice and to change the cat litter when I get back home.

 

[OTF]

SCUBA drysuits are typically not worn for extended periods, and they get some filling and venting with buoyancy changes. But surface drysuits are another story - they're a bit more comfortable for extended wear and also have no fill or vent ports. So you can spend an entire day farting one up and not realize until doffing it. A full day's bagged gassious emissions hit you all at once, on top of some seriously musty garments. Truly a scent to behold.

 

[BoundForElsewhere]

You forgot you were in a drysuit, didn't you? I hate when you rip a big fart and it f's up your buoyancy

Does it really, though? The gas was already in you so it's just displacing outside of you and instead, inside the drysuit.

Or is it a factor of compressed vs. less compressed gas? SubaBoard propeller-heads ENGAGE!

 

[Jcp2]

Does it really, though? The gas was already in you so it's just displacing outside of you and instead, inside the drysuit.

Or is it a factor of compressed vs. less compressed gas? SubaBoard propeller-heads ENGAGE!

Well, if it came out, then clearly there was a pressure differential, and there would be increased displaced volume, so increased buoyancy for drysuit, decreased for wetsuit.