3 ms·

The work of submerging air at atmospheric pressure vastly exceeds the potential energy value extractable from the oxygen in terms of ATP. He's using it to float

The work of submerging air at atmospheric pressure vastly exceeds the potential energy value extractable from the oxygen in terms of ATP. He's using it to float.

seiferteric 5y ago
That's what diving weights are for.
caymanjim 5y ago
I was thinking that as well; it's not going to get you more than a few breaths of air, and it's not going to be easy to submerge with one. Even bogged down with weapons and armor, I suspect it would be impossible to submerge while holding something that large filled with air.
- mod 5y ago
  Even if you could submerge it, it would require ridiculous effort to hold it submerged. I doubt one could swim across a body of water with weapons, armor, and a submerged goatskin bag and expect to make it very often.
trhway 5y ago
>The work of submerging air at atmospheric pressure vastly exceeds the potential energy value extractable from the oxygen in terms of ATP. He's using it to float. he is wearing some armor, definitely head helmet - that allows to balance the floatation, and would be beyond most human capabilities without the goatskin. So he achieves 2 goals simultaneously - extra air for prolonged diving as well as diving while donning some armor. That goatskin is like 20-30 liters - good for several minutes of breathing and those 20-30kg of extra floatation allow for the typical armor/chainmail and weapons. There is no issues with holding it submerged like other commenters suggest as he keeps it under the body, so the main force of those 20-30kg pushes onto his body up, and if anything it is very easy to belt it to the body so it wouldn't need any hands involvement to be maintained under the body. There is also no issues with drawing breath as suggested by others as the goatskin is under the same water pressure as his lungs.
- nradov 5y ago
  If you think there are no issues then try it yourself with an inflatable beach ball and some weights in the shallow end of your local swimming pool. Be sure to record a video: it's going to be hilarious watching you flail around underwater while making no forward progress.
pbhjpbhj 5y ago
What convinces you it's a working system? Making your enemies, and even your own people, think that you 'can even reach those in fortresses beyond a moat, and even archers on watch won't see you coming' surely has a lot of value. If you used it as a re-breather then surely the work needed is no greater than the work needed to submerge a lungful of air? I expect you're right that it's a float (appropriate username is appropriate!) - but the balance point seems likely to me to be a small additional volume of air as well as the lungs full capacity. Otherwise maximum horizontal distance would be attained by exhaling early when swimming underwater - that's contrary to my experience - and large lung capacity would be detrimental to swimming underwater.

The work of submerging air at atmospheric pressure vastly exceeds the potential energy value extractable from the oxygen in terms of ATP. He's using it to float.

seiferteric 5y ago

That's what diving weights are for.

caymanjim 5y ago

I was thinking that as well; it's not going to get you more than a few breaths of air, and it's not going to be easy to submerge with one. Even bogged down with weapons and armor, I suspect it would be impossible to submerge while holding something that large filled with air.

mod 5y ago
Even if you could submerge it, it would require ridiculous effort to hold it submerged. I doubt one could swim across a body of water with weapons, armor, and a submerged goatskin bag and expect to make it very often.

trhway 5y ago

>The work of submerging air at atmospheric pressure vastly exceeds the potential energy value extractable from the oxygen in terms of ATP. He's using it to float. he is wearing some armor, definitely head helmet - that allows to balance the floatation, and would be beyond most human capabilities without the goatskin. So he achieves 2 goals simultaneously - extra air for prolonged diving as well as diving while donning some armor. That goatskin is like 20-30 liters - good for several minutes of breathing and those 20-30kg of extra floatation allow for the typical armor/chainmail and weapons. There is no issues with holding it submerged like other commenters suggest as he keeps it under the body, so the main force of those 20-30kg pushes onto his body up, and if anything it is very easy to belt it to the body so it wouldn't need any hands involvement to be maintained under the body. There is also no issues with drawing breath as suggested by others as the goatskin is under the same water pressure as his lungs.

nradov 5y ago
If you think there are no issues then try it yourself with an inflatable beach ball and some weights in the shallow end of your local swimming pool. Be sure to record a video: it's going to be hilarious watching you flail around underwater while making no forward progress.

pbhjpbhj 5y ago

What convinces you it's a working system? Making your enemies, and even your own people, think that you 'can even reach those in fortresses beyond a moat, and even archers on watch won't see you coming' surely has a lot of value. If you used it as a re-breather then surely the work needed is no greater than the work needed to submerge a lungful of air? I expect you're right that it's a float (appropriate username is appropriate!) - but the balance point seems likely to me to be a small additional volume of air as well as the lungs full capacity. Otherwise maximum horizontal distance would be attained by exhaling early when swimming underwater - that's contrary to my experience - and large lung capacity would be detrimental to swimming underwater.