The Iceni
Medical Moderator
. . . and I thought I was pedantic, UP!
Nitrox END confusion
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Paul... seriously... I didn't mean to be pedantic... I was merely answering the question.
Now hows about that 30/30 gas.... do you suppose a fella could use it as air but reduce his depth calc by 15% because of the >O2?
The Iceni
Medical Moderator
Never joke.
Now you've lost me, UP! Please tell me you don't!
Dr Paul Thomas once bubbled...
Never joke.Now you've lost me, UP! Please tell me you don't!
My bet is that he does. Also, my bet is that if you run some profiles through a decompression software 30/30 works out real close to EAN30.
You're right Paul... I'm not good at math and 15% is harder for me to figger than 20%... so I figger it at 20%.Dr Paul Thomas once bubbled...
Never joke.Now you've lost me, UP! Please tell me you don't!
Anyway... experiment with some deco planning software and see what you come up with.
The Iceni
Medical Moderator
Bin there, Dun that!
Which brings us back to
Now for those who would like an explanation of . . . .
Dr Deco
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Dear Readers:
Thanks
I was away for a few days and not able to make a network connection. Many thanks for all of you who wrote in on this query.
Roundabouts
When I was in graduate school in the 60s, we had a visiting professor from England who often would use the expression, What you lose on the swings you gain on the roundabouts. We in Michigan were never quite able to understand the exact meaning of this obscure and possibly esoteric aphorism. Dr P, what does this actually mean? We knew it applied to childrens playground apparatus , but that was really the best we could do. What is a "roundabout?"
No doubt, we in the USA would say, "In the end, all things equal out."
Dr Deco :doctor:
Thanks
I was away for a few days and not able to make a network connection. Many thanks for all of you who wrote in on this query.
Roundabouts
When I was in graduate school in the 60s, we had a visiting professor from England who often would use the expression, What you lose on the swings you gain on the roundabouts. We in Michigan were never quite able to understand the exact meaning of this obscure and possibly esoteric aphorism. Dr P, what does this actually mean? We knew it applied to childrens playground apparatus , but that was really the best we could do. What is a "roundabout?"
No doubt, we in the USA would say, "In the end, all things equal out."
Dr Deco :doctor:
MonkSeal
Contributor
What you gain on bridge you lose on the river crossing.
Probably it means that sum of your efforts is always equal. I'm I right, Dr Paul ?
Probably it means that sum of your efforts is always equal. I'm I right, Dr Paul ?
I figure it is his way of saying, "Since helium comes out as fast as it goes in what you gained going down you lose coming back up."
The Iceni
Medical Moderator
Hi Dr Deco and all,
Here I am again demonstating that our two races are separated by a commom language. This expression is so commonly used in England that I took it fore granted that you would all understand its inherent meaning.
I suppose the easiest analogy is Oesop's fable of the tortoise and the hare. In this story the two had a race and as you know a hare can run much, much faster than any tortoise so this one assumed that he did not need to run very fast in order to win.
Indeed he was so confident that he stopped half way for a rest in the certain knowledge that even if the poor old tortoise caught him up he could soon overtake him again.
He fell alseep as he rested in the hot sun and the tortoise quietly chugged along past him to the winning post and won with a fine margin. They both took about the same time to complete the course but the slower tortoise won.
The interpretation is that what the hare gained in speed he lost due to overconfidence.
Now to the expression itself.
Two small children were taken by their mother to a playground where the only apparatus were swings and a roundabout (merry-go-round or carousel?). There were lots of children already there and Tom quickly gets the only remaining place on the swings much to Jane's annoyance. Her mother quietly points out to Jane that there are plenty of places on the roundabout and that it is just as much fun so why doesn't she spend her time waiting for her turn on the swings by riding on the roundabout.
To her surprise Jane really enjoyed being spun around very fast and soon forgot all about the swings. So what Jane lost on the swings she gained on the roundabout.
In common parlance this expression is inherently understood to mean what Dr Deco says
So! Helium does not behave at all in the same as nitrogen but in these particular profiles and with these mixes it is indeed swings and roundabouts!
It is a national passtime of ours to play with words and to use such figures of speech. That is partly why foreigners, even "English" speaking Americans, find spoken English, English so difficult to understand at first.
swings and roundabouts.
Here I am again demonstating that our two races are separated by a commom language. This expression is so commonly used in England that I took it fore granted that you would all understand its inherent meaning.
I suppose the easiest analogy is Oesop's fable of the tortoise and the hare. In this story the two had a race and as you know a hare can run much, much faster than any tortoise so this one assumed that he did not need to run very fast in order to win.
Indeed he was so confident that he stopped half way for a rest in the certain knowledge that even if the poor old tortoise caught him up he could soon overtake him again.
He fell alseep as he rested in the hot sun and the tortoise quietly chugged along past him to the winning post and won with a fine margin. They both took about the same time to complete the course but the slower tortoise won.
The interpretation is that what the hare gained in speed he lost due to overconfidence.
Now to the expression itself.
Two small children were taken by their mother to a playground where the only apparatus were swings and a roundabout (merry-go-round or carousel?). There were lots of children already there and Tom quickly gets the only remaining place on the swings much to Jane's annoyance. Her mother quietly points out to Jane that there are plenty of places on the roundabout and that it is just as much fun so why doesn't she spend her time waiting for her turn on the swings by riding on the roundabout.
To her surprise Jane really enjoyed being spun around very fast and soon forgot all about the swings. So what Jane lost on the swings she gained on the roundabout.
In common parlance this expression is inherently understood to mean what Dr Deco says
So getting back to UP's point. In the dives he quotes I guess when using helium the added penalties derived from using helium as far as the slower compartments are concerned are offset by the advantages gained with respect to lessened penalties with respect to the faster compartments (or visa versa), resulting in a deco profile much the same as with air.
So! Helium does not behave at all in the same as nitrogen but in these particular profiles and with these mixes it is indeed swings and roundabouts!
It is a national passtime of ours to play with words and to use such figures of speech. That is partly why foreigners, even "English" speaking Americans, find spoken English, English so difficult to understand at first.
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