DIR, RDP & computer.. ???'s from a newbie

[voop]

I apologize in advance. I am not trying to stir up a flamefeast or something similar. I am just trying to express something which concirns me a bit.

One thing that strikes me a lot -- in general and in this thread -- is that the question from the original poster to me seemed quite clear, and could be phrased simply as "what's the DIR way of computing dive / deco profiles?"

Unfortunately, the answers provided are not phrased as clearly, but amount to "You're going to enjoy this journey, my friend. Keep asking 'why' and 'how.' Keep searching" and "Buhlman is wrong and computers use an outdated algorithm" (paraphrased from a post above).

I do not know the answer myself either, not having had any GUE training. I know how Buhlman, VPM and (to some extend) RGBM works (I'm currently studying the litterature on RGBM) -- that's well doccumented in scientific litterature (and elsewhere), well tested and described in an "open" and scientific way, as well as in more popular and easilly applicable terms. That said, where the models fail are also well doccumented. All that makes me relatively comfortable calculating my profiles and add conservativism as well as what I have found to "work for me". It may not yield "optimal" (shortest possible) deco schedules, but it keeps me out of the chamber.

What I do find disturbing is, that "the DIR deco and dive profile calculation method" is elusive -- seemingly not really doccumented outside GUE circles. And any questions or probes for information are met with "it's a holistic approach, you need to take the class and convert to DIR" (again paraphrased).

As a diver and a scientist, I am reluctant to accept "new" procedures (as in "procedures which invalidate best current pratice") without the procedure(s) being openly doccumented, independantly tested and preferably peer reviewed by the broader diving medical and scientific community.

On the topic on the GUE/DIR procedures for calculating dive/deco profiles, I have found little public info besides very "broad terms", usually qualified by "take the class, it's a holistic thing". Personally, that does indicate to me that the system isn't tested following the criteria which I hold in high regard (clinical testing, peer reviewed by the diving medical and scientific community). I do believe that to be a shame, especially since the proponents of GUE/DIR seem to maintain that their procedures not only work, but that they work very very well, even.

I'd be happy to be proven wrong, if what I am looking for really exists "out there". In that case pointers to relevant material would be much appreciated.

A couple of disclaimers.

Every decompression model is exactly that: a MODEL. Hence, there are conditions under which it applies and conditions under which it doesn't apply. Publishing a model, as well as the conditions under which it is found to apply would, imho, accomodate the whole "holistic" requirements (which I assume is something about physical condition and exercise regimen, health, diet etc.)

Also, I do not believe in "Internet divers" or "textbook divers". Diving, including decompression procedures cannot be learned solely from reading and studying models. Anyone who goes diving without training takes a risk -- so one should always "take the class". However publicly available information might be what would pursuade someone like me that I should "take the class".

 

[MHK]

I apologize in advance. I am not trying to stir up a flamefeast or something similar. I am just trying to express something which concirns me a bit.

One thing that strikes me a lot -- in general and in this thread -- is that the question from the original poster to me seemed quite clear, and could be phrased simply as "what's the DIR way of computing dive / deco profiles?"

Unfortunately, the answers provided are not phrased as clearly, but amount to "You're going to enjoy this journey, my friend. Keep asking 'why' and 'how.' Keep searching" and "Buhlman is wrong and computers use an outdated algorithm" (paraphrased from a post above).

A couple of disclaimers.

Every decompression model is exactly that: a MODEL. Hence, there are conditions under which it applies and conditions under which it doesn't apply. Publishing a model, as well as the conditions under which it is found to apply would, imho, accomodate the whole "holistic" requirements (which I assume is something about physical condition and exercise regimen, health, diet etc.)

Also, I do not believe in "Internet divers" or "textbook divers". Diving, including decompression procedures cannot be learned solely from reading and studying models. Anyone who goes diving without training takes a risk -- so one should always "take the class". However publicly available information might be what would pursuade someone like me that I should "take the class".

I accept that you are not looking to start a flame war, but I confess to not understanding your point in light of your disclaimers.. In other words, your disclaimers are part in parcel the reason we can't be more specific in our answers via newsgroups. In our classes we cover decompression theory in great detail, and explain in excruciating detail how and why we do what we do. But those discussions take place over a class that are 3 - 6 days long and involve much detail, to attempt to provide answers absent that detail over a scuba newsgroup is somewhat irresponsible in my view. It has been my expereince that many divers don't understand the totailty of the issue during scuba newsgroup exchanges, and quite frankly understanding a part of what we do or how we do it could lead to injury. In the final analysis, and frankly in all candor, we have numerous classes that are available to teach this stuff and we simply can't give it all away over a newsgroup..

Moreover, I'll note that very often I get private e-mails or phone calls asking for more detail which we readily provide, but I'm a firm believer that you simply can't learn everything we teach by cherry-picking the questions on a scuba forum so in many respects we have a balancing act in certain areas, decompression theory being one of our more cautious areas. Furthermore, this isn't the first time this issue has been asked so there is a wealth of information wherein I have in fact gone into greater detail.. I may not always get the balance correct, but in all fairness it's a fine line and an imperfect medium..

Hope that helps..

 

[MHK]

First off, Thanks Mo2vation and Arnaud for the words of encouragement. You guys are great and I enjoyed diving with you, checking out your gear and everything.. I'm hoping some of your skill has rubbed off.

next, MHK, Thanks for the great response, but the little square in my log book is still blank and I'm staring at it with a confused look. This might not be an easily answerable question here on the scubaboard. This was never a post about whether or not DIR philosophy allows computers. I'm all for the "brain engaged mode" underwater and safety is what draws me toward DIR. Up until this weekend (thanks to a 120cuft. tank) I always ran out of air before bottom time in the table ndl. Also boat dives, such as the Yukon, fit nicely on the table and bottom time is when you get back to the mooring line. The problem this saturday is that half of my dive time was spent on the ascent from max depth. Now, Shouldn't I be taking on nitrogen at that time??

I wish I could figure out how to post my dive profile, but I'll try to explain it. Lets take the dive on the Sue Jack, second dive of the day....

1.) for the first seven minutes we decended to a depth around 87 feet.
80 ft/7min= 11.4 ft/min.
2.) We hung out on the wreck for nine minutes (16 min total time) and
depth was between 87 and 68 foot.
3.) Then we headed back at a slow ascent which has a nice straight line
when graphed and follows a slope of about 4 foot per minute.

So my questions are....

1.) At that slow of an ascent aren't I still taking on more nitrogen on the way back? at 60 foot, 50 foot etc?

2.) Is it safe to use my bottom time as 16 minutes for this dive- SSI says
bottom time is time till you start your direct ascent at 30ft/min- not 4
foot per minute.

I want to know how to figure out nitrogen loading on the multilevel dives without just looking at the time left on my vyper. At my job I give lots of drugs that run continously based on weight and although the pumps can be programmed and make it a "brainless" operation, I still like to do the calculations myself. I want that same understanding when it comes to diving.

Thanks in advance,
Tony.

Tony,

It's very hard to get into specific profiles over a NG, call me if you wish and I'll be happy to go over it.. In short, you are comparing apples to oranges. And by that you make mention of the idea that under the SSI table you would be "on-gassing" during your deep stops.. That is precisley why we take issue with Buhlman. BTW, I'm also a SSI instructor so I take your point and in my OW classes I teach here's the SSI table and here's why we believe that divers need to understand more about decompression theory. All too often what you find is that new divers take the tables as gospel. I volunteer at the Catalina Hyperbaric Chamber and one of the funniest stories that was told to me by Mark Tulin who works there also, was a day when a diver pulled his boat into the chamber and insisted that he get treated immediatley. Mark asked a serious of questions: profiles, joint pain, hydration etc. all the questions one would assume should be asked. After the initial interview wherein the diver had no pain, no signs or symptoms of DCS Mark asked him why he was here. His response was that because according to his computer he was bent.. Mark threw the computer into the chamber and said "OK we'll treat the computer"..

Anyway the point of course is that mathematical models set for the lowest common denominator shouldn't be the be end and end all of what a diver knows about decompression theory.. The shape of the ascent curve is the penultimate issue, but the only way traditional modeler's can provide divers information is in depth and time.. It's a hard issue to discuss via scuba forums but feel free to contact me and I'll go over it further.

E-mail me at mhk@gue.com or call me at 310-458-8860 if you have added questions..

Hope that helps..

 

[DepartureDiver]

I'd like to address several things. First to Tony's question … while it will take you awhile to understand the indepth details of what you are trying to ask (i.e. enjoy the journey), you have asked some basic questions on how to perform your dive and log it. As to whether you are ingassing during your ascent, this answer depends upon what model and theory you will most believe, but in short, the answer is while you may be ingassing some, the "critical compartments" will be offgassing if you are within your no-stop time limits. So as long as you leave your maximum depth (or an acceptable calculated average depth) within an acceptable the no-stop time (i.e. your dive tables) and ascend towards the surface, a multi-level depth or a safety stop, you are not penalized for being at a shallower depth. So to specifically answer your second question, it is acceptable to use your bottom time as 16 minutes for your dive. You can also "log" your dive for the full underwater time using either the maximum depth or the "average maximum depth". If your concern is how it will look in your logbook to have a long underwater time at a depth of 87 feet, just make a notation that it was a multi-level dive. Your question might be better phrased as not what your nitrogen loading is, but what time do you have left at your next depth or what is your credit. This can be learned with a basic multi-level dive calculation (which I'll let you learn at your favorite dive store). You will learn that anytime you ascend to a shallower depth, you will gain back time. GUE's 120 rule will work in general as long as the average depth calculation is done properly and this can also give you more time as you ascend to a shallower depth.

Now to some other comments, I have also found that GUE's deco procedures are elusive and my dive team and I have tried to be very specific with some GUE instructors to learn their deco procedures. I too am concerned that their procedures are not put down in writing (at least not that I can find) and that it is only taught verbally. This is not meant to be GUE bashing since I believe the GUE DIR fundamentals class is probably one of the best classes any diver can take I have only found GUE instructors to be very competent. But I have an issue when procedures cannot be readily ascertained and open to discussion and comments from the diving and scientific community. One example is that my dive group tried to ask some specific questions on a dive that a GUE rec triox class performed at our local high altitude dive site. We discovered that absolutely no altitude conversations were done. After much prodding, the answer that was finally received was that GUE did not believe that altitude conversions were necessary. While there was some logic behind the ideas (which I don not subscribe to), I have not been able to find it in writing. The bottom line is to understand what is know as well as what is not known so that you can make an informed diving/deco decision underwater.

 

[roccoh]

Or, you could read through this thread like I did the last two days, it clarified a lot.

Thank you MHK!

 

[voop]

I accept that you are not looking to start a flame war, but I confess to not understanding your point in light of your disclaimers.. In other words, your disclaimers are part in parcel the reason we can't be more specific in our answers via newsgroups. In our classes we cover decompression theory in great detail, and explain in excruciating detail how and why we do what we do. But those discussions take place over a class that are 3 - 6 days long and involve much detail, to attempt to provide answers absent that detail over a scuba newsgroup is somewhat irresponsible in my view. It has been my expereince that many divers don't understand the totailty of the issue during scuba newsgroup exchanges, and quite frankly understanding a part of what we do or how we do it could lead to injury. In the final analysis, and frankly in all candor, we have numerous classes that are available to teach this stuff and we simply can't give it all away over a newsgroup..

MHK, first of all thanks for taking this in the spirit in which I wrote it. I was thinking of you when I wrote my original posting, and I am glad that you took the time to respond. Thanks in advance, it's great to have you on the board!

I can gladly clarify what I mean by my disclaimers -- fundamentally, I believe that we agree, but just to be sure.

I would be very hessitant (to say the least) at taking advice from a scuba newsgroup or a "random website" and use in situations where my life depended on it. I.e. if someone should say "Ok, here's a step-by-step procedure...", I'd be the first to read it and the last to follow it. I simply do not just trust what I read without substantial justification or proof that it actually works. I've seen the inside of a chamber, and have no desire to need to go back.

I also recognize that it is impossible, within the context of a newsgroup posting or a www-forum posting, to give any kind of complete description of the procedures. And even if it was possible, it would not suffice: part of my professional life involves teaching complex technical topics, and I know first hand that even the best written text does not replace the ability to ask questions in a class-setting. So we agree completely on those didactic issues.

Now that that's squared away....doctors Buhlman, Spencer, Wienke et. al published their findings in medical journals, scientific and technical books and more popular and directly applicable texts such as diving manuals. I am wondering if references to the procedures developed by GUE are available in the same type media? That's the kind of materials I am interrested in learning about. If you (or anyone) have such references, I would be very pleased to learn.

I'd love to follow one of those classes with a week set asside to discuss deco theory, btw., and really "pick the brain" of one of you guys -- but it hasn't worked out thus far (and I probably do not have the required credentials to attend a GUE class anyways...)

Moreover, I'll note that very often I get private e-mails or phone calls asking for more detail which we readily provide, but I'm a firm believer that you simply can't learn everything we teach by cherry-picking the questions on a scuba forum so in many respects we have a balancing act in certain areas, decompression theory being one of our more cautious areas. Furthermore, this isn't the first time this issue has been asked so there is a wealth of information wherein I have in fact gone into greater detail.. I may not always get the balance correct, but in all fairness it's a fine line and an imperfect medium..

Hope that helps..

I perfectly understand why neither GUE nor you want to go into all the nitty-gritty details on a WWW-base forum or a newsgroup. And, as I stated, I agree 100% that this media is not the right one for such topics. So if I was to rephrase my question, it would be something to the effect of "can anyone point to any suitable written references -- scientific papers, textbooks etc -- detailing the theory behind the decompression procedures, taught by GUE?"

MHK, your posts are always helpful, and I for one appreciate your being around here and participating in threads such as thisone.

 

[voop]

Tony,

It's very hard to get into specific profiles over a NG, call me if you wish and I'll be happy to go over it.. In short, you are comparing apples to oranges. And by that you make mention of the idea that under the SSI table you would be "on-gassing" during your deep stops.. That is precisley why we take issue with Buhlman. BTW, I'm also a SSI instructor so I take your point and in my OW classes I teach here's the SSI table and here's why we believe that divers need to understand more about decompression theory. All too often what you find is that new divers take the tables as gospel. I volunteer at the Catalina Hyperbaric Chamber and one of the funniest stories that was told to me by Mark Tulin who works there also, was a day when a diver pulled his boat into the chamber and insisted that he get treated immediatley. Mark asked a serious of questions: profiles, joint pain, hydration etc. all the questions one would assume should be asked. After the initial interview wherein the diver had no pain, no signs or symptoms of DCS Mark asked him why he was here. His response was that because according to his computer he was bent.. Mark threw the computer into the chamber and said "OK we'll treat the computer"..

Now THAT's a good one

Anyway the point of course is that mathematical models set for the lowest common denominator shouldn't be the be end and end all of what a diver knows about decompression theory.. The shape of the ascent curve is the penultimate issue, but the only way traditional modeler's can provide divers information is in depth and time.. It's a hard issue to discuss via scuba forums but feel free to contact me and I'll go over it further.

E-mail me at mhk@gue.com or call me at 310-458-8860 if you have added questions..

Hope that helps..

Again, I agree. I have been more than disappointed with almost all of the training (from both rec and tech) agencies that I have received over the years when it comes to "decompression theory". It's mostly amounted to "here are some very abstract terms and models -- and this is how you use this set of tables". It may suffice for introductory rec training, but for advanced and tech training I think it's disappointing.

(side-node: for the even just slightly mathematical minded, deco models and theory are, IMHO, quite an interresting topic)

 

[MHK]

I'd like to address several things. First to Tony's question … while it will take you awhile to understand the indepth details of what you are trying to ask (i.e. enjoy the journey), you have asked some basic questions on how to perform your dive and log it

Now to some other comments, I have also found that GUE's deco procedures are elusive and my dive team and I have tried to be very specific with some GUE instructors to learn their deco procedures. I too am concerned that their procedures are not put down in writing (at least not that I can find) and that it is only taught verbally. This is not meant to be GUE bashing since I believe the GUE DIR fundamentals class is probably one of the best classes any diver can take I have only found GUE instructors to be very competent. But I have an issue when procedures cannot be readily ascertained and open to discussion and comments from the diving and scientific community. One example is that my dive group tried to ask some specific questions on a dive that a GUE rec triox class performed at our local high altitude dive site. We discovered that absolutely no altitude conversations were done. After much prodding, the answer that was finally received was that GUE did not believe that altitude conversions were necessary. While there was some logic behind the ideas (which I don not subscribe to), I have not been able to find it in writing. The bottom line is to understand what is know as well as what is not known so that you can make an informed diving/deco decision underwater.

Brian,

If I recall correctly you were part of the team that came to our class in Sacramento. If I am correct I thought Andrew and I spent atleast 3 hours of our time explaining our procedure to you, granted the bulk of the discussion was respecting rebreathers, but I guess my point is that we aren't elusive. In all fairness to some of my colleagues, teaching scuba is the sole source of income for the bulk of GUE instructors in our database, is it fair to them to give away everything that is offered in our classes over the internet?? But more to the point, more often then not it is much too difficult to make a point about a "theoretical" models via some of the scuba forums. Many on some of the lists only real desire isn't to engage in fruitful discussion, but to start a flame war and then blame GUE for all of the nastiness.. I've unsubscribed to several lists in the last few months simply because I was sick of the nonsense that goes on on various lists. That isn't to say that I think you fall into that catagory, it's just to note that there are a lot of people that don't share a desire to learn and/or discuss, but the hold a desire to start flame wars.. Discussing theoretical decompression models in mediums such as that becomes particularly difficult. The fact is that we subscribe more along the lines of the VPM or RGBM models. In fact Weinke specifically notes the contribution of the WKPP in his studies.. The point I'm trying to make is that in our classes we spend a great deal of time discussing ascent rate strategies.

Also, I think you inadvertantly mis-quoted our position on altitude as well. This all stemmed from a trip report written by one of our students after the Tahoe class, it has been distorted and taken out of context and no matter how many times I address the issue some continue with the misinformation. In the instant case, Kevin wrote a trip report and spoke glowingly about a 3 day class, one dive of which took place in Lake Tahoe at approx. 6,000'. The dive was a recreational dive using a 30/30 for 20 minutes and a max depth of ~100' [ these numbers are off the top of my head since I'm speaking from memory] but the point was that this one dive did not require any altitude adjustment, but those that want to criticize GUE have ignored anything else we say about the issue and cling to a misguided belief that we said "ignore altitude in every case"..If we don't believe in altitude adjustments why did JJ include altitude in DecoPlan?? There are times when altitude adjustments are required and other times when they are not. In this one day of diving, doing a recreational dive on a 30/30 mix there was no adjustment required. It's specifically cases like this one which makes many hesitant to participate because once a rumor gets started in cyber-world some will never let it go..

Anyway, our intent isn't to be elusive, but there are also time and places for discussions and part of what we sell is dive classes. I'd offer that no other agency in the world comes close to giving away as much information for free as do the instructors at GUE, at some point we just can't give away all of our class information for free over the internet to some that have little clue what we are talking about, but just want to argue with us anyway. Again, not saying that was your intent, but there are many out there that fall into that catagory.

I hope that more fully explains our position but I remain available for follow-up's..

Regards

 

[MHK]

MHK, first of all thanks for taking this in the spirit in which I wrote it. I was thinking of you when I wrote my original posting, and I am glad that you took the time to respond. Thanks in advance, it's great to have you on the board!

I can gladly clarify what I mean by my disclaimers -- fundamentally, I believe that we agree, but just to be sure.

.

I think part of the frustration that some of us at GUE share is as follows: [And I'm speaking on behalf of myself, but some of my co-instructors have expressed similar views.]

Take for example the "peer-review" mantra that we hear very often. Some of the dives that are done at Wakulla simply have no peers. I don't mean that to come off arrogantly, but I mean that to say there isn't a book that is written or a study that has been peer-reviewed to validate the ground-breaking stuff that is being done there. So on the one hand, many scream for peer-revie then the WKPP invites Dr. Morgan Wells, Bruce Weinke, Erik Baker, et. al to study what is being done at Wakulla and then all of a sudden people accept the dives that they are doing because someone else studied their dives and, in essence, validated what they do every week.. I like to cite for example the NOAA recommendation(s) about 02 exposure. Most know only what the tables are published and assume that if you extend the 1.6 for greater then 45 minutes you'll suffer an oxygen toxicity hit. Whereas week in and week out the exploration divers at Wakulla spend upwards of 6 hours at 1.6.. Accordingly, they have figured out ways to do it, they've identified the weakness in the earlier studies, but unless someone else "validates" what they do every week they are questioned.. Not that I'm making light of the work that guys like Wells, Weinke, Baker et. al are doing because I hold them in high regard, I'm just juxtaposing the issue.

Now that being said, I have no problems at all with divers that want to ask questions and understand, but where I get frustrated sometimes is with people who have absolutely no desire to understand the issue, and can't accept that explorer's that are doing ground-breaking and world record type dives aren't following a peer-reviewed study they are blazing new trails.. That disconnect is often times difficult to square with " My PADI tables says that I can do 90' for 21 minutes" and if you are doing something different then that you need to give it away for free on the scuba forums and provide a peer-review study..

FTR, I'm not suggesting that you are doing this, nor am I suggesting that the majority do this, but many in our little cyber-community want to know what we do but don't want to admit that they like GUE so they take the tactic of starting fights, asking us to prove our point and then they steal our information without having to admit to their dive buddies that they are closet DIR diver ;-) Anyway I thought I'd throw in a little conspiracy theory for levity ;-)

I think we agree for the most part, and in all candor I often struggle with the right balance of how much to put on the NG's and how much to hold. For example, the example I used above about exceeding the 1.6 of 45 minutes, taken out of context or used with about the benefit of training a diver could get hurt..

Hope that helps.

 

[DepartureDiver]

Hi Mike ... yes, good memory … and I think your memory of the altitude depth, etc. is correct. No, not my intention to make inflammatory remarks and none were meant that way. I too have taken myself off some lists for that reason. So that it is not misunderstood, I never meant to state that GUE did not have altitude procedures, but that we were told that by one individual, and that it could not be confirmed one way or the other since it was not in writing (one way or the other) ... at least that's my understanding ... and perhaps I too have fallen prey to a rumor that altitude is ignored by GUE. But this rumor mill is part of my point. Your point is well taken that instructors must make a living, but this is where the uncertainty of what GUE is advocating comes from ... it is hard to get concrete information if it is only disseminated to those that take a class. I must admit I do not understand GUE's altitude procedures and when they are and are not necessary simply because I have not been pointed to them. We have also tried to get some more info on GUE's deco philosophies and were told in essence by an instructor that a class must be taken. Again, quality instructors must be able to make a living to continue their work and education, but at times it does make it difficult to understand or analyze a procedure if it is hard to obtain. As I stated, what was told to me regarding altitude had some logic to it even though I personally disagreed with it. I just personally would like to be able to reference material. Also, I am assuming that your statement that no altitude corrections for the referenced dive were needed is because is was within no-stop limits. I can agree that based upon the manner in which the dive was performed including GUE’s slow ascent and stops, it was a nicely performed dive. But in conclusion, I consider myself fairly well informed and educated, but I don’t have the information needed to analyze, critique or perform procedures when they are hard to find, including whether a 20/30 mix at 6200’ elevation to 100’ (for 20 minutes if my memory is correct) falls within a no-stop dive or needs no conversions. I may well become an advocate of these procedures when I am introduced to them, just as I am an advocate of the GUE-F class. I was simply agreeing with some other postings that I wish GUE’s procedures were a little more readily obtainable. I hope this is taken in the spirit it was intended.