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200m deep down
- Thread startertodeep
- Start date
Thread Status: Hello
, There was no answer in this thread for more than 60 days.
It can take a long time to get an up-to-date response or contact with relevant users.
It can take a long time to get an up-to-date response or contact with relevant users.
you're right, after closer inspection of his 150m profile my revised estimate is about 3'20". 1.6-1.7m/s down. an amazingly short 5 secs or so at the bottom it would seem, and then 2.5-2.7m/s back up. still a very fast time. i'd love to see photos of his sled.
I wish there was more information about the Doppler bubble detector and the results and the rationalization for why he has decided not to breathe oxygen after each dive. There are reasons not breathe O2 while freediving. I'd like to hear their reasoning, though.
It would seem that Patrick is confident that his rapid dive speed will keep him out of harms way for DCS. And it looks like he is respecting the possibility of mirco bubbles by taking two days off after the 150m dive. Hopefully, that is enough, who knows for sure?
If his 200m dive would be completed in around 3'30" then we can make an interesting comparison with a 100m constant weight dive.
In constant weight, the dive time is around or over 3'30", exertion is high on the ascent, the descent is quite slow (sinking velocity at around 1.0m/s), the diver may or may not be cold, and may or may not have made any warm up dives.
In a no-limits dive, the dive time is around 3'30", extertion is minimal on the ascent and descent, the descent is fast, and the ascent very fast, and I would image that in Egypt, Patrick would be warm, since he doesn't need to limit the thickness of his neoprene as he would in constant weight. From the profile, it doesn't look like he slows down at all in the last 20m.
What's interesting is that in both dives, the diver spends an equal amount of time below 20m, beyond which microbubbles would be accumulated. The difference is that in the 200m case, the pressure is doubled vs. 100m, but the diver does not exert himself. I guess the question that needs to be answered is: which factors are most important in contributing to DCS? Pressure, dive time, exertion, physiological state, temperature, etc... ?
For example:
100m constant weight diver = 3'00" below 20m to 10 atm with exertion + 30 seconds above 20m.
200m no limits diver = 3'00" below 20m to 20 atm without exertion + 30 seconds above 20m
Also, I don't know how to express this in numbers, but it seems to me that proportionally, the constant weight diver spends more time in the danger zone for DCS relative to the depth. If the constant weight diver did a 200m constant weight dive, this would become immediately apparent, with a dive time of almost seven minutes!
If a constant weight diver at 100m is likely on the edge of DCS, I would assume that a no limits diver who can do 100m in 1'45" would have a much lower risk of DCS.
Anybody else have ideas on how to break this down to explain what Patrick is doing?
I still wonder how his chest will handle 20 atm of pressure....
It does sound like Patrick has worked out an interesting plan to make the depth.
It would seem that Patrick is confident that his rapid dive speed will keep him out of harms way for DCS. And it looks like he is respecting the possibility of mirco bubbles by taking two days off after the 150m dive. Hopefully, that is enough, who knows for sure?
If his 200m dive would be completed in around 3'30" then we can make an interesting comparison with a 100m constant weight dive.
In constant weight, the dive time is around or over 3'30", exertion is high on the ascent, the descent is quite slow (sinking velocity at around 1.0m/s), the diver may or may not be cold, and may or may not have made any warm up dives.
In a no-limits dive, the dive time is around 3'30", extertion is minimal on the ascent and descent, the descent is fast, and the ascent very fast, and I would image that in Egypt, Patrick would be warm, since he doesn't need to limit the thickness of his neoprene as he would in constant weight. From the profile, it doesn't look like he slows down at all in the last 20m.
What's interesting is that in both dives, the diver spends an equal amount of time below 20m, beyond which microbubbles would be accumulated. The difference is that in the 200m case, the pressure is doubled vs. 100m, but the diver does not exert himself. I guess the question that needs to be answered is: which factors are most important in contributing to DCS? Pressure, dive time, exertion, physiological state, temperature, etc... ?
For example:
100m constant weight diver = 3'00" below 20m to 10 atm with exertion + 30 seconds above 20m.
200m no limits diver = 3'00" below 20m to 20 atm without exertion + 30 seconds above 20m
Also, I don't know how to express this in numbers, but it seems to me that proportionally, the constant weight diver spends more time in the danger zone for DCS relative to the depth. If the constant weight diver did a 200m constant weight dive, this would become immediately apparent, with a dive time of almost seven minutes!
If a constant weight diver at 100m is likely on the edge of DCS, I would assume that a no limits diver who can do 100m in 1'45" would have a much lower risk of DCS.
Anybody else have ideas on how to break this down to explain what Patrick is doing?
I still wonder how his chest will handle 20 atm of pressure....
It does sound like Patrick has worked out an interesting plan to make the depth.
we've all the done the maths before... a compressible volume at the surface is reduced to 6.25% of its original volume at 150m. at 200m, it's compressed to 4.76%. yes, the absolute pressure may be a third greater, but the change in volume is very small... only 1.5%.
Alun,
You're the physicist! C'mon!
If Patrick's lungs have shrank to 6.25% of their volume at 150m, and then 4.76% at 200m, that's a huge fractional change.
For example, for simplicity let's use a 10L starting volume (probably it is more than that):
10L at surface TLC
625ml @ 150m
476ml @ 200m
Fractional change in volume from 150m to 200m:
476 / 625 = .76
So there's a 25% decrease in lung volume from 150m to 200m....
You're the physicist! C'mon!
If Patrick's lungs have shrank to 6.25% of their volume at 150m, and then 4.76% at 200m, that's a huge fractional change.
For example, for simplicity let's use a 10L starting volume (probably it is more than that):
10L at surface TLC
625ml @ 150m
476ml @ 200m
Fractional change in volume from 150m to 200m:
476 / 625 = .76
So there's a 25% decrease in lung volume from 150m to 200m....
However, despite the 25% change in volume from 150m to 200m, the pressure in the lungs may change exponentially.
At 150m, the pressure in the lungs is already less than ambient pressure, i.e. a negative 'gauge' pressure relative to the water around Patrick. Suppose the negative pressure at 150m in Patrick's lungs were -0.5atm.
At 200m, the 'negative' pressure could be as high as -1.5atm, 300% of the value at 150m.
To visualize this effect, imagine a hollow metal sphere (ball), with a surface that has microscopic holes in it (hundreds of holes). This sphere is inside a big balloon.
There is a pressure sensor inside the metal sphere.
As this contraption is lowered underwater, the pressure sensor inside the sphere reads the same as the surrounding water, and the balloon gradually collapses. In my model, at 150m the balloon would be totally touching & shrouding the metal ball. From 150m to 200m, the balloon cannot collapse anymore, the only way for the balloon to collapse is for balloon material to 'seep' through the micro holes in the metal sphere. This happens a little, but not much. The pressure inside the metal sphere now becomes negative or less than the surrounding water.
Eventually, at a sufficient depth, the balloon skin breaks as the balloon material is sucked through the micro holes in the metal sphere.
So, in this model, you would understand that even between two depths that seem relatively close, there is a critical depth at which the contraption (balloon+sphere, or lungs) simply won't compress, and the negative pressure increases dramatically.
At 150m, the pressure in the lungs is already less than ambient pressure, i.e. a negative 'gauge' pressure relative to the water around Patrick. Suppose the negative pressure at 150m in Patrick's lungs were -0.5atm.
At 200m, the 'negative' pressure could be as high as -1.5atm, 300% of the value at 150m.
To visualize this effect, imagine a hollow metal sphere (ball), with a surface that has microscopic holes in it (hundreds of holes). This sphere is inside a big balloon.
There is a pressure sensor inside the metal sphere.
As this contraption is lowered underwater, the pressure sensor inside the sphere reads the same as the surrounding water, and the balloon gradually collapses. In my model, at 150m the balloon would be totally touching & shrouding the metal ball. From 150m to 200m, the balloon cannot collapse anymore, the only way for the balloon to collapse is for balloon material to 'seep' through the micro holes in the metal sphere. This happens a little, but not much. The pressure inside the metal sphere now becomes negative or less than the surrounding water.
Eventually, at a sufficient depth, the balloon skin breaks as the balloon material is sucked through the micro holes in the metal sphere.
So, in this model, you would understand that even between two depths that seem relatively close, there is a critical depth at which the contraption (balloon+sphere, or lungs) simply won't compress, and the negative pressure increases dramatically.
Attachments
Eric, 10 years ago perhaps, not any more though. physics is a mug's game! 
yes, there is a large difference when comparing the final compressed volumes. but when you consider how much the lungs have to compress in total there isn't much difference. but i guess it's those last few ml that really make the difference...
how can you be sure that the pressure is less than ambient at 150m. i don't think anyone knows this for sure yet. perhaps the pressure is equalised.
yes, there is a large difference when comparing the final compressed volumes. but when you consider how much the lungs have to compress in total there isn't much difference. but i guess it's those last few ml that really make the difference...
how can you be sure that the pressure is less than ambient at 150m. i don't think anyone knows this for sure yet. perhaps the pressure is equalised.
It seems that until now there is no squeeze problems, but I`m still concerned about DCS. The Doppler echocardiography has a high Negative Predicted Value so it will be useful that they continue looking for Bubbles in the next dives. But still you can get bent without finding any cardiac bubbles (this is due to microbubbles ). It`s at your own risk
I`m worried with the high speed ascents because this increase risk of DCS, and also will be good to know how is the warm up (if he do any), because deep warm up, can build up N2 tissue stores. And at 200 meters exposure the nitrogen tension in 5-min tissues will increase.
He is not a novice freediver and have a good physiologic knowledge, so I think he has figured out this before.
It will be nice to know if he`s using some kind of computer model to calculate PN2 in different kind of tissues to have safe surface intervals, in fact surface interval is the best way to avoid DCS in breath-hold diving (with the literature available at this moment) along with reducing bottom time and number of dives per day.
I`m worried with the high speed ascents because this increase risk of DCS, and also will be good to know how is the warm up (if he do any), because deep warm up, can build up N2 tissue stores. And at 200 meters exposure the nitrogen tension in 5-min tissues will increase.
He is not a novice freediver and have a good physiologic knowledge, so I think he has figured out this before.
It will be nice to know if he`s using some kind of computer model to calculate PN2 in different kind of tissues to have safe surface intervals, in fact surface interval is the best way to avoid DCS in breath-hold diving (with the literature available at this moment) along with reducing bottom time and number of dives per day.
I bet I'm not the only one thinking, "what the hell IS this mysterious training method". No inwater training at all?
Pretty cool, I guess atleast a world record is in the cards even if he doesn't make 200...Which by the looks of it is not out of reach. Exciting times, I wish there were other ways to keep updated than one web page (which in itself is cool and more than sometimes is available in these things). You know...Video and stuff.
Pretty cool, I guess atleast a world record is in the cards even if he doesn't make 200...Which by the looks of it is not out of reach. Exciting times, I wish there were other ways to keep updated than one web page (which in itself is cool and more than sometimes is available in these things). You know...Video and stuff.
He's explained the judge situation pretty thorougly on the web page, in the Q&A section...http://www.patrickmusimu.com/QA.html
I for one think he makes some pretty good arguments, besides, no-limits has always been kind of it's own game all together. It's all about who's been the deepest, I don't think people put much weight on who ratified it. It's a bit different for those diciplines where there are actual competitions.
I for one think he makes some pretty good arguments, besides, no-limits has always been kind of it's own game all together. It's all about who's been the deepest, I don't think people put much weight on who ratified it. It's a bit different for those diciplines where there are actual competitions.
Check it out... He is getting very close to his mark now. 170 meters already !!!
http://www.patrickmusimu.com/TUD.html
http://www.patrickmusimu.com/TUD.html