Skipping surface intervals - DIR or not?

[Soggy]

I don't think you've taken a nitrox class either, because PPO2 is not affected by repetitive dives. I think what you are referring to is daily O2 % limits or OTUs, which may or may not be a problem in this case. 100ft on EAN32 is a 1.3 PO2. Even with brief surface intervals, the daily exposure limits to a 1.3 are pretty long (don't have a table handy). Pulminary O2 toxicity doesn't really come into play much in recreational diving.

Re-read the the guy's post. He's talking about doing repeditive dives to 100' using EAN32 for 30 minutes WITH little to no surface interval. Diving like that will get your PP02 to 1.6 in no time and he will be lucky if he doesn't go into convulsions. It's pretty easy to figure out, just look at your tables (which are conservative to begin with) and you will see how fast he will end up with a PP02 of 1.6. I'm not trolling, I'm just pointing out that this person has a very unsafe attitude towards diving and it's likely that he's going to seriously injure himself, others around him, and/or kill himself. I would rather dive solo than dive with him or even be in the same waters as him.

I've not taken ANY DIR classes, but I do know that the main point of DIR is diving as safely as possible in your environment and what this guy is telling us is not safe, which is not DIR.

lol about the buddah comment.

 

[MXGratefulDiver]

Re-read the guy's post. He's talking about doing repeditive dives to 100' using EAN32 for 30 minutes (and over 90 minutes for a total bottom time) WITH little to no surface interval. Diving like that will get your PP02 to 1.6 in no time and he will be lucky if he doesn't go into convulsions. It's pretty easy to figure out, just look at your nitrox tables (which are conservative to begin with) and you will see how fast he will end up with a PP02 of 1.6. I'm not trolling, I'm just pointing out that this person has a very unsafe attitude towards diving and it's likely that he's going to seriously injure himself, others around him, and/or kill himself. I would rather dive solo than dive with him or even be in the same waters as him.

You may be sincere ... but you obviously do not understand the concept of partial pressure. Please go back and review your Nitrox manual, before you misapply something you don't understand and hurt yourself. FWIW - PPO2 is not affected by repetitive diving ... it is strictly a function of depth and EAN mix.

I've not taken ANY DIR classes, but I do know that the main point of DIR is diving as safely as possible in your environment and what this guy is telling us is not safe, which is not DIR.

Perhaps ... but don't you think it's a bit presumptuous for someone who has not taken a DIR class to be telling those who have what is or isn't DIR?

... Bob (Grateful Diver)

 

[MXGratefulDiver]

I don't think you've taken a nitrox class either, because PPO2 is not affected by repetitive dives. I think what you are referring to is daily O2 % limits or OTUs, which may or may not be a problem in this case. 100ft on EAN32 is a 1.3 PO2. Even with brief surface intervals, the daily exposure limits to a 1.3 are pretty long (don't have a table handy). Pulminary O2 toxicity doesn't really come into play much in recreational diving.

According to NOAA tables, maximum daily exposure at a PPO2 of 1.3 ATA is 180 minutes.

... Bob (Grateful Diver)

 

[Jay Roy]

Somebody has been feeding you a line of bovine scatology..
PP02 is not governed by dive time, its the relation of Oxygen percentage and Depth..EAN32 will be a PP02 of 1.3 no matter how long...

Re-read the guy's post. He's talking about doing repeditive dives to 100' using EAN32 for 30 minutes (and over 90 minutes for a total bottom time) WITH little to no surface interval. Diving like that will get your PP02 to 1.6 in no time and he will be lucky if he doesn't go into convulsions. It's pretty easy to figure out, just look at your nitrox tables (which are conservative to begin with) and you will see how fast he will end up with a PP02 of 1.6.

 

[amascuba]

My mistake everybody. I went through and read in my book while on my lunch break and figured it out. Somebody ban me from posting in the morning hours before I've had a chance to feed my brain the necessary caffiene to operate will they?

 

[Jay Roy]

I've been following this thread from the start, and there is one thing that I thought of right away...My Palm version of Dplan (GUE software) will give you an error if you try to plan a 2nd dive with an SI less than 30 mins....So the only option is to call it one dive. So 2, 20 min dives to 100 feet is really 1 dive for 40 mins, with an ascent time of about 13-15 mins...

 

[Spoon]

They are not required if you did a proper DIR ascent and are in good shape, etc. At least that's what I was taught in DIR-F. The idea is to off gas underwater on ascent rather than on the surface. But you are required to do a very slow ascent with deep stops, so it's not like you are gaining something for nothing.

i dont recall martin mentioning eliminating dive stops altogether. i do remember the emphasis on slow ascents and emphasis on off gassing underwater but would assume that you would still have to perform the obligatory si's

Also i see your point in trying to squeeze in the extra dives since its all paid for but think it is quite dangerous. i have gotten bent before from taking my profiles too close to the edge. a little si wont hurt and the longer your si is the better. better safe than sorry.

 

[*Floater*]

i dont recall martin mentioning eliminating dive stops altogether. I do remember the emphasis on slow ascents and emphasis on off gassing underwater but would assume that you would still have to perform the obligatory si's

I think the idea was that you take whatever time you need or want between dives, it's certainly not a race to get back down, but you don't have to worry about it either because you are supposed to be mostly off gassed if you did everything right and are in good physical shape, and so forth. if you do this wrong then you may get bent.

Also I did email martin and he made some suggestions but basically okayed this. I know some people think this deco algorithm is a bad idea, but then don't use it, and if you have a problem with others applying things they learned in dir-f then take it up with the instructor. I actually just posted the original thread to ask whether dive ops in Egypt were cool with non-standard dive practices, and then it went on this tangent and got split here.

And while it's an interesting topic I'd first have to explain the system in its entirety for us to proceed further, yet I don't want to do that because if GUE wanted their procedures to be publicly available then they would probably have published them somewhere. In fact, I believe GUE will publish them with their OW course material, so then people can read all about it and debate it further.

For those who do want to discuss it further right now, I think the question really is how fast can a diver off gas almost completely underwater and how to do it? (I believe George Irvine claims he's clean within 30 minutes even after his harshest deco dives wihtout using longer deco than anyone else.) Or to make this more specific, is it possible for a diver using ean32 on a 100' 30 min dive to off-gas almost completely during a 10 min ascent?

 

[Sideband]

For those who do want to discuss it further right now, I think the question really is how fast can a diver off gas almost completely underwater and how to do it? (I believe George Irvine claims he's clean within 30 minutes even after his harshest deco dives wihtout using longer deco than anyone else.) Or to make this more specific, is it possible for a diver using ean32 on a 100' 30 min dive to off-gas almost completely during a 10 min ascent?

If that were even remotely close to true then a diver could do a 100' dive, make a 10 min. ascent and then jump on an airplane with no worries.

Joe

 

[Snowbear]

For those who do want to discuss it further right now, I think the question really is how fast can a diver off gas almost completely underwater and how to do it? (I believe George Irvine claims he's clean within 30 minutes even after his harshest deco dives wihtout using longer deco than anyone else.)

EAN 100 helps.

Or to make this more specific, is it possible for a diver using ean32 on a 100' 30 min dive to off-gas almost completely during a 10 min ascent?

No. And nothing I've read from Pug or Doc's threads suggests this. It was also not suggested or implied in my DIR-f or Tech1 classes.

Obviously you are free to do your dives any way you see fit, but you will be hard-pressed to find anyone with DIR training to any level endorse what you are proposing here

If you do try this, please let us know how you fared... if you are able